Centrifugal Compressor Optimization Final Report

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EML 4905 Senior Design Project

A B.S. THESIS

PREPARED IN PARTIAL FULFILLMENT OF THE

REQUIREMENT FOR THE DEGREE OF

BACHELOR OF SCIENCE

IN

MECHANICAL ENGINEERING

Centrifugal Compressor Optimization

Final Report

Xavier Medina

Gianfranco Pisani

Fernando Lopez

Advisor: Professor George Dulikravich

November 17, 2014

This B.S. thesis is written in partial fulfillment of the requirements in EML

4905. The contents represent the opinion of the authors and not the

Department of Mechanical and Materials Engineering.

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Ethics Statement and Signatures

The work submitted in this B.S thesis is solely prepared by a team consisting of Xavier

Medina, Fernando Lopez, and Gianfranco Pisani, and it is original. Excerpts from others’

work have been clearly identified, their work acknowledged within the text and listed in

the list of references. All of the engineering drawings, computer programs, formulations,

design work, prototype development and testing reported in this document are also original

and prepared by the same team of students.

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Table of Contents Ethics Statement and Signatures ..................................................................................................... ii

List of Figures ................................................................................................................................ vi

List of Tables ............................................................................................................................... viii

Abstract ........................................................................................................................................... 2

1. Introduction ............................................................................................................................. 3

1.1 Problem Statement ........................................................................................................... 3

1.2 Motivation ........................................................................................................................ 3

1.3 Literature Survey .............................................................................................................. 4

1.4 Survey of Related Standards ............................................................................................ 4

1.5 Discussion ........................................................................................................................ 5

2. Project Formulation ................................................................................................................. 6

Overview .......................................................................................................................... 6

Project Objectives ............................................................................................................ 6

Design Specifications ....................................................................................................... 7

Addressing Global Design ............................................................................................... 8

Constraints and Other Considerations .............................................................................. 9

Discussion ...................................................................................................................... 10

3. Design Alternatives ............................................................................................................... 11

3.1 Overview of Conceptual Designs Developed ................................................................ 11

3.2 Optimized Design Alternatives ...................................................................................... 11

3.2.1 ModeFRONTIER® Algorithms ............................................................................. 13

3.2.2 Graphs and data validation...................................................................................... 15

3.3 Design Alternative.......................................................................................................... 20

3.4 Integration of Global Design Elements .......................................................................... 20

3.5 Feasibility Assessment ................................................................................................... 21

3.6 Proposed Design ............................................................................................................. 21

3.7 Discussion ...................................................................................................................... 22

4. Project Management .............................................................................................................. 23

4.1 Overview ........................................................................................................................ 23

4.2 Breakdown of Work into Specific Tasks ....................................................................... 23

4.3 Gantt Chart for the Organization of Work and Timeline ............................................... 24

4.4 Breakdown of Responsibilities Among Team Members ............................................... 24

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4.5 Commercialization of the Final Product ........................................................................ 25

4.6 Discussion ...................................................................................................................... 25

5. Engineering Design and Analysis .......................................................................................... 26

5.1 Overview ........................................................................................................................ 26

5.2 Kinematic Analysis and Animation ............................................................................... 26

5.3 Dynamic/Vibration Analysis of the System ................................................................... 27

5.4 Structural Design ............................................................................................................ 28

5.5 Force Analysis ................................................................................................................ 30

5.6 Stress Analysis ............................................................................................................... 31

5.7 Material Selection .......................................................................................................... 32

5.8 Design Based on Static and Fatigue Failure Design Theories ....................................... 33

5.9 Deflection Analysis ........................................................................................................ 34

5.10 Component Design/Selection ......................................................................................... 35

5.11 Component Design Simulation ...................................................................................... 36

5.12 Finite Element Analysis ................................................................................................. 37

5.13 Design Overview ............................................................................................................ 38

5.14 Cost Analysis.................................................................................................................. 38

5.15 Discussion ...................................................................................................................... 39

6. Prototype Construction .......................................................................................................... 40

6.1 Overview ........................................................................................................................ 40

6.2 Description of Prototype ................................................................................................ 40

6.3 Prototype Design ............................................................................................................ 41

6.4 Parts List ......................................................................................................................... 42

6.5 Construction ................................................................................................................... 42

6.6 Prototype Cost Analysis ................................................................................................. 44

6.7 Discussion ...................................................................................................................... 44

7. Testing and Evaluation .......................................................................................................... 46

7.1 Overview ........................................................................................................................ 46

7.2 Design of Experiments - Description of Experiments ................................................... 47

7.2.1 Experiment 1 – Average Miles per gallon .............................................................. 47

7.2.2 Experiment 2 – Dynamometer Testing ................................................................... 48

7.2.3 Experiment 3 – Compressor Test Bench ................................................................ 49

7.3 Test Results and Data ..................................................................................................... 50

7.4 Evaluation of Experimental Results ............................................................................... 51

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7.5 Improvement of the Design ............................................................................................ 51

7.6 Discussion ...................................................................................................................... 52

8. Design Considerations ........................................................................................................... 53

8.1 Assembly and Disassembly ............................................................................................ 53

8.2 Maintenance of the System ............................................................................................ 53

8.2.1 Regular Maintenance .................................................................................................. 53

8.3 Environmental Impact .................................................................................................... 54

8.4 Risk Assessment ............................................................................................................. 54

9. Design Experience ................................................................................................................. 56

9.1 Overview ........................................................................................................................ 56

9.2 Standards Used in the Project......................................................................................... 56

9.3 Contemporary Issues ...................................................................................................... 56

9.4 Impact of Design in a Global and Societal Context ....................................................... 57

9.5 Professional and Ethical Responsibility ......................................................................... 57

9.6 Life-Long Learning Experience ..................................................................................... 57

9.7 Discussion ...................................................................................................................... 58

10. Conclusion ......................................................................................................................... 59

10.1 Conclusion and Discussion ............................................................................................ 59

10.2 Evaluation of Integrated Global Design Aspects ........................................................... 59

10.3 Evaluation of Intangible Experiences ............................................................................ 59

10.4 Commercialization Prospects of the Product ................................................................. 60

10.5 Future Work ................................................................................................................... 60

References ..................................................................................................................................... 62

Appendices .................................................................................................................................... 64

A. Detailed Engineering Drawings of All Parts, Subsystems and Assemblies ................... 64

B. Copies of Used Commercial Machine Element Catalogs .............................................. 65

C. Detailed Raw Design Calculations and Analysis ........................................................... 66

D. Project Photo Album ...................................................................................................... 69

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List of Figures

Figure 1. Breakaway commencing at the aft edge of the shock wave [1] ___________________________________ 5

Figure 2. Shrouded Impeller. ____________________________________________________________________ 1

Figure 3. Unshrouded impeller. These impellers also tend to have complex 3-D shaped blades. ________________ 1

Figure 4. Two-dimensional impeller blades. ________________________________________________________ 1

Figure 5. Zones on compressor map of turbocharger that are most important from design/research and

development standpoints [4]. ____________________________________________________________________ 2

Figure 6. Illustration of the inducer and exducer of compressor wheel [9]. ________________________________ 3

Figure 7. Impeller removed from a Mitsubishi TD04 turbocharger. ______________________________________ 7

Figure 8. TD04-13T compressor housing. __________________________________________________________ 7

Figure 9. 3D sketch guideline for impeller blade. To the right are the eight parameters which will be altered. ____ 12

Figure 10. Explanation of how evolutionary algorithms work just as selective breeding. _____________________ 14

Figure 11. Above shows eight parameters and desired goal objectives. __________________________________ 15

Figure 12. 3D Graph of angle and initial angle with respect to the average velocity. _______________________ 16

Figure 13. Plot of Average Velocity vs Initial Angle _________________________________________________ 17

Figure 14. Plot of Avergae Velocity and Angle _____________________________________________________ 17

Figure 15. Design Generation of Angle ___________________________________________________________ 18

Figure 16. Design Population of Initial Angle ______________________________________________________ 19

Figure 17. Final Solidworks CFD Study __________________________________________________________ 19

Figure 18. Gantt chart. _______________________________________________________________________ 24

Figure 19. Frequency simulation performed to assess vibration. _______________________________________ 28

Figure 20. Where the rounded edges needed to be made. _____________________________________________ 29

Figure 21. Life of the blade after going through 𝟏𝟎𝟕cycles. ___________________________________________ 29

Figure 22. Damage that is present after 𝟏𝟎𝟕cycles. _________________________________________________ 30

Figure 23. Direction of rotation and the forces that are felt. ___________________________________________ 31

Figure 24. Image showing areas where stress is experienced. __________________________________________ 32

Figure 25. Where failure would occur by dropping below a certain Factor Of Safety. _______________________ 34

Figure 26. Deflection could occur in the red areas. __________________________________________________ 35

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Figure 27. 3D printed prototype done by Ryan Lucia. ________________________________________________ 41

Figure 28. Polyjet 3D printed acrylic of final design from WB Engineering. ______________________________ 43

Figure 29. Visual example of a turbocharger system undergoing fatigue and performance tests. ______________ 46

Figure 30. Air compressor that will blow air through turbine side of turbocharger. _________________________ 50

Figure 31. Computer that is directly connected with air compressor to get all readings. _____________________ 50

Figure 32. Optimized wheel avg velovity vs. Stock wheel avg velocity. ___________________________________ 51

Figure 33. Wastegate Actuator. _________________________________________________________________ 54

Figure 34. Turbocharger clamp holding the turbine housing with the cartridge. ___________________________ 54

Figure 35. Coolant lines with 17mm banjo bolts and 4 copper washers. __________________________________ 55

Figure 36. Oil return line connected to the CHRA. __________________________________________________ 55

Figure 37. Destroyed turbine blade from Subaru turbo. [15] __________________________________________ 54

Figure 38. Technical drawing for concept design. ___________________________________________________ 64

Figure 39. Mitsubishi TD04-13T Turbo Rebuild. ____________________________________________________ 65

Figure 40. Adaptation of Bernoulli’s Equation. _____________________________________________________ 66

Figure 41. Compressor wheel from used turbo. _____________________________________________________ 69

Figure 42. Top view of 3D printed acrylic. ________________________________________________________ 70

Figure 43. Stock compressor wheel alongside 3D printed ABS plastic final design. _________________________ 70

Figure 44. Rendering of final design. _____________________________________________________________ 71

Figure 45. Used compressor wheel, 3D printed ABS plastic, 3D printed polyjet acrylic. _____________________ 71

Figure 46. Clearance between final design and housing.______________________________________________ 72

Figure 47. Measurement with L ruler. ____________________________________________________________ 72

Figure 48. Isometric view of final design in 3D printed acrylic. ________________________________________ 73

Figure 49. First clearance test with rough 3D printed ABS plastic. _____________________________________ 73

Figure 50. First clearance test. _________________________________________________________________ 74

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List of Tables

Table 1. Average required fuel economy (mpg) under final CAFÉ standards. ............................................................. 8

Table 2. Table of responsibilities. ................................................................................................................................ 23

Table 3. Tabulated Cost Analysis ................................................................................................................................ 39

Table 4. Southern Gear final estimated quote price. ................................................................................................... 44

Table 5. Incodema3D final estimated quote price. ...................................................................................................... 44

Table 6. 1click3Dprint final estimate quote price. ...................................................................................................... 44

Table 7. Full tabulated data with simulation results of 90 random generated designs. .............................................. 66

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Abstract

In an effort to reduce fuel consumption and remain competitive in an automotive industry that

continues to increase regulations for environmental protection there has been an increase the use

of turbochargers. Due to this increase in demand, there is now a greater need for a centrifugal

compressor that provides a wide and stable operating range that delivers a high-pressure output at

a competitive price. The analysis of the phenomena that occurs within a centrifugal compressor is

extremely challenging and presents three-dimensional unsteady flow analysis with the addition of

thermal flow and expansion. Based on experimental and numerical simulation analysis, this team

will develop a blade design for a centrifugal compressor using computational optimization

methods. The ultimate goal of this project is to create a blade design that results in a wider optimum

operating range whilst increasing the pressure ratio without decreasing the mass flow rate that the

engine requires for stable combustion.

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1. Introduction

1.1 Problem Statement

Due to the constant increase in fuel cost and increased regulations seen in the automotive

industry, a trend has been noted in the downsizing of engines, resulting in a increase in the demand

of turbochargers. Turbochargers create the benefit of equally powerful engines with a reduction in

fuel consumption.

The purpose of this project is to create a blade design that results in a wider optimum

operating range by optimizing the compressor wheel’s blade shapes. The specific compressor that

will be optimized will be a Mitsubishi TD04-13L. The design constraints will include the housing

of the compressor in order to focus solely on the optimization of the blade design. The goal of this

project is to increase the maximum efficiency of the system by at least 7% while also improving

the efficiency in the important regions of the compressor’s operating range, such as the areas near

the surge region and the choke region.

1.2 Motivation

The motivation for studying a centrifugal compressor is mainly due to the increased in

price in fossil fuels and a growth of interest in the area of efficiency in the car industry. The uses

of centrifugal compressors are currently downplayed heavily in the car industry due to the lack of

power that they produce in the racing industry. Approaching the optimization of the centrifugal

compressor through this senior design project will show that there is an interest and that there are

practical applications for this type of technology. The team has selected this project for the

opportunity to apply advanced concepts and techniques that have been presented during the pursuit

of a Bachelor’s degree such as thermal and fluid mechanics.

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1.3 Literature Survey

Centrifugal compressors are a result of complex phenomena at play that manages to

achieve a pressure rise while adding kinetic energy to a continuous flow of fluid through either a

rotor or an impeller. This kinetic energy is then converted to an increase in potential energy by

means of a diffuser that slows down the flow of fluid creating static pressure at the outlet.

The inlet to a centrifugal compressor is typically a cylindrical pipe that may have features

such as vanes in order to help rotate the flow, as well as pressure and temperature measuring

devices. These vanes add what is known as, prewhirl, to the fluid making it possible to reduce the

Mach number at the inlet. The relative Mach number at the inlet will be given by equation 1 below:

𝑀1 =

𝑉1

√𝛾𝑅𝑇1

(Eq. 1)

where,

𝑇1 is the static temperature at the inlet.

𝑉1 is the Velocity at inlet

𝛾 is the specific weight of the fluid

𝑅 is the gas constant (R=8.314 J/mol x K)

The Mach number is important at the inlet because shockwaves can occur on the curved

part of the impeller from the air that is breaking away as shown below in Figure 1.

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Figure 1. Breakaway commencing at the aft edge of the shock wave [1]

As the relative velocity reaches the speed of sound, this separation causes huge pressure

losses and drastically affects the efficiency of the compressor. A disadvantage that arises when

using prewhirl is that the work capacity is reduced since a whirl component has already been added

to the fluid before entering the impeller.

Once the fluid has entered the impeller, it enters the only rotating aerodynamic part in a

centrifugal compressor. It is the most critical component, and provides all of the kinetic energy

that will be added to the gas as well as being responsible for up to 70% of the static pressure rise

in the system. A well-designed impeller will result in a well-designed compressor because they

have been calculated to achieve efficiencies in excess of 96%. There are two categories for

impellers: shrouded (Figure 2) or unshrouded (Figure 3), and their blades can be either two-

dimensional (Figure 4) or three-dimensional (Figure 3).

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Figure 2. Shrouded Impeller.

Figure 3. Unshrouded impeller. These impellers also

tend to have complex 3-D shaped blades.

Figure 4. Two-dimensional impeller blades.

Each different design has its own advantages and disadvantages. Unshrouded (open)

impellers can operate at much higher rotational speeds, equating to higher pressure ratios.

Shrouded (closed) impellers deliver pressure ratios of 3:1 or less, while open impellers can reach

pressure ratios upwards of 10:1 [3]. While that may be an advantage, open impellers also tend to

be less efficient due to losses associated with tip leakage flow, which does not occur in closed

impellers. Tip leakage flow is the flow of fluid the leaks over the rotating blades and flows in-

between the blades and the housing causing losses in pressure. Different factors are taken into

consideration when selecting the type of impeller to be used in a compressor, one of them being

the impeller flow coefficient, 𝜑 [1].

𝜑 =

𝑄

𝑁 × 𝐷23

(Eq. 2)

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Where:

Q is the impeller flow capacity

N is the operating speed

𝐷2 is the exit diameter

The impeller flow coefficient relies on the flow range that the compressor will be subjected

to. Impellers that have low flow coefficients are described by long, narrow passages, while

impellers with high flow coefficients have wider passages in order to adjust for the higher flow

rates [2]. For this study, the mass flow rate of a typical engine for a typical American driver will

be used as the base line for the compressor’s size. The composition of gas to be compressed as

well as the ranges of pressures and temperatures of the gas as it enters the compressor must also

be specified for a certain application.

Figure 5. Zones on compressor map of turbocharger that are most important from design/research and development

standpoints [4].

From a design point, there are certain zones within the operating range of the compressor

that are more important than others shown below in Figure 5. A turbocharger operates within the

green zone when a vehicle is in idle and while accelerating from a standing start, making this

Pre

ssure

Ratio

Eff

icie

ncy

Volume Flow (m3/s)

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region very important during city driving. This region is also critical in terms of eliminating turbo

lag, which dictates the peak torque point of the engine and the amount of emissions produced. The

red zone in Figure 5 has to do with supplying the engine with high volumes of air that is needed

in driving at higher speeds. In this region, the stress subjected to the impeller is at its highest. The

deciding factor related to the performance in the red zone is the compressor’s ability to meet the

additional demands of high-altitude driving since it is this variable that causes the impeller to reach

its highest speed [5].

Figure 6. Illustration of the inducer and exducer of compressor wheel [9].

The configuration of these blades play a major role in the efficiency and the pressure rise

that is seen when the fluid is exiting the impeller. Once the fluid (air in this case) has passed the

inducer, it goes through the exducer, which converts all of the kinetic energy of the fluid into

pressure by slowing down its velocity as shown in Figure 6. At the very tip of the exducer the

velocity of the fluid is at its fastest which leads to the Mach number to be in excess of unity. These

high Mach numbers can cause shockwaves, which propagate downstream causing cyclic loading

of the impeller [2]. This loading can lead to early fatigue failure if the frequency is of the same

order as one of the natural frequencies of the impeller vanes. Once the fluid has passed the diffuser

it is received by a collector, which also can take several forms. If it is a large chamber, it is called

a Plenum, but when it is collected into an object that looks similar to a snail shell it is termed as a

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volute or scroll. The collector’s purpose is to gather the flow that has been discharged from the

diffuser and deliver it towards a downstream pipe that could also contain valves and

instrumentation that gauge the performance of the compressor [4].

1.4 Survey of Related Standards

Standards are created with regulation and requirements whether it be for safety, feasibility,

machinability, or fitting. These regulations are put in place to keep everything organized and make

designing follow a certain rubric. Here are a few of the standards that standard turbocharger

systems have to follow:

1. American National Standards Association (ANSI)

The American National Standards Institute is a private non-profit organization that

oversees the development of voluntary consensus standards for products, services,

processes, systems, and personnel in the United States. The standards used for the

manufacturing of this prototype follow the guidelines from this association.

2. American Society for Testing and Materials (ASTM)

ASTM International, known until 2001 as the American Society for Testing and

Materials, is an international standards organization that develops and publishes voluntary

consensus technical standards

3. Society for Automotive Engineer (SAE)

SAE International, initially established as the Society of Automotive Engineers, is

a U.S.-based, globally active professional association and standards

organization for engineering professionals in various industries. Principal emphasis is

placed on transport industries such as automotive, aerospace, and commercial vehicles.

4. American Bearing Manufacturing Association (ABMA)

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It’s an industry trade group that deals with all aspects of bearing technology. This

project does not directly relate to this association, but the surrounding components, mainly

the center housing and rotating assembly of a turbocharger make use of their standards.

5. Unified Thread Standards (UTS)

Defines a standard thread form and series—along with allowances, tolerances,

and designations—for screw threads commonly used in the United States and Canada. It

is the main standard for bolts, nuts, and a wide variety of other threaded fasteners used in

these countries.

1.5 Discussion

The purpose of this project is to bridge the divide between the better performing high quality

compressors, and the more economically viable compressors. Using the same high quality

manufacturing processes while maintaining performance and durability will be the top priorities

for this project. In the process of creating this centrifugal compressor, the cost of manufacturing

will become the main challenge in creating this product in order to make it appealing for

commercial use. Another priority for this project is an effective design that improves the

performance and efficiency of the compressor over a larger range. Achieving these goals will result

in more fuel-efficient cars producing the same power with less fuel.

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2. Project Formulation

Overview

Current turbocharger and supercharger companies use designs that tend to be simple and

cheap to produce. The performance of their product is largely overlooked when it comes to

commercial vehicles due to the greater importance of decreasing cost. These lower price options

use simply designed wheels, poor quality manufacturing processes and low cost materials. The

designs that are used in modern day compressors in automotive turbochargers have a range of

seven to five impeller blades depending on the make and model. The combination of material and

manufacturing processes as well as outdated designs reduce the overall performance of

commercial turbochargers. On the other hand, high performance companies use high quality

materials, with high tolerances in the manufacturing processes, with improved wheel designs and

strength.

Project Objectives

The purpose of this study is to bridge the divide between the better performing high quality

compressors, and the more economically viable compressors created by cast molding. Using the

same high quality manufacturing processes while maintaining performance and durability is vital

to the success of this study. In the process of creating this centrifugal compressor, the cost of

manufacturing will become the main challenge in creating this product in order to make it

appealing for commercial use.

For the impeller design in this study, a desirable outcome would be a high efficiency value

throughout the operational speed range that would not abruptly become inefficient along the upper

limits of the operational speeds. With this in mind, the specific goal for this project becomes

creating an impeller blade that will increase the pressure difference at a set operational speed. This

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goal can be achieved by the process of multi-objective optimization, which will use CFD data from

90 randomly generated designs and the genetic algorithms used in modeFRONTIER® in order to

maximize the pressure ratio and efficiency, while reducing the moment of inertia. If this goal can

be achieved, then the increase in fuel efficiency in a vehicle with the same parameters could be

improved with just the modification of the compressor in the turbocharger system.

Design Specifications

In order to create an effective centrifugal compressor, certain physical considerations must

be made such as manufacturing material and processes, tolerances, and overall blade design. But

before any of these considerations can be taken, the type of system that will be supported by this

compressor must be determined. It became apparent that a turbocharger that was already available

to test would become the logical choice for a case study in the optimization of a centrifugal

compressor. This led to the selection of a Mitsubishi TD04 turbocharger, which was currently

installed inside a team member’s Subaru Impreza WRX. The dimensions for this impeller are

detailed further along this report in the design prototype section.

Figure 7. Impeller removed from a Mitsubishi TD04

turbocharger.

Figure 8. TD04-13T compressor housing.

Figures 7 and 8 above is the compressor housing and impeller that were removed from a

Subaru Impreza WRX. This particular impeller had already experienced 170,000 miles of driving

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before being removed from the engine, showcasing the excellent quality of construction that

Mitsubishi is known for and what this case study strives to accomplish in the prototype design.

This turbocharger system is an ideal candidate for optimization due to its small size, and

its capability of being tested in real-life working conditions alongside an exhaust turbine. Its small

size also means that this particular compressor could be used with many other downsized

turbocharged engines that are becoming more popular in the automotive market [10] in order to

increase fuel efficiency.

Addressing Global Design

Many countries around the world are implementing higher fuel efficiency standards for all

automotive companies within the next 10 to 20 years. In the US, the Corporate Average Fuel

Economy (CAFE) created in 1970, to increase the average fuel efficiency of all automotive

companies to 34.1 mpg for combined cars and trucks by the year 2016 described by Table 1 below

[11].

Table 1. Average required fuel economy (mpg) under final CAFÉ standards.

In the future it seems that the electric car alongside hydrogen fuel cell technology will

become the most prominent power source for the general consumer’s vehicle, but the dependency

in fossil fuels will remain. The addition of turbochargers to downsized engines can increase the

vehicles fuel efficiency without any compromises in performance while the electric car matures

into an economically feasible alternative.

“During the past decade, turbochargers have moved from a niche technology in the high-

performance market segment to an integral part of manufacturers’ mainstream emission control

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and fuel economy strategies,” Gott said. “Because they are compatible with virtually all engine

technologies, they represent a global growth opportunity, making substantial gains even in the

limited-growth markets of the U.S., Japan and Europe [14].” With that stated, the design created

for this study will address the global market by means of Multilanguage technical drawings and

service manuals (i.e., English, Spanish, German, French, and Portuguese) if one desired to install

this impeller in their turbocharger system.

Constraints and Other Considerations

The process of producing a turbocharger takes into account of many different aspects of

the engine in order to create an efficient system that could perform effectively for the lifetime of

the vehicle. In this case study, only the aspect of the compressor was taken into account, which is

an integral part of a turbocharged engine system. It affects the amount of spool time, pressure ratio,

inlet air temperature, efficiency, and capacity of the engine, which affects many parts of the system

such as the intercooler, the turbine, and the piston seals among other things within the engine. Any

changes that will be done to a turbocharging system affect other aspects of a vehicle and should

be taken into consideration. With an increase pressure ratio as this prototype aims to achieve, a

more effective intercooler is necessary to cool the air in order to not increase the temperature

experienced within the combustion chamber [12].

Cost is another consideration that needs to be taken into account for the scope of this study.

The process of developing a blade design for an impeller could perhaps be the largest expenditure

due to computing time, man-hours, and a verification of simulations. The method of manufacture

also affects the cost of the product and depends on the intricacies of the design, manufacturing

process, and tolerances. Several considerations were taken for this study, but all of the processes

called for a prototype production cost in excess of $1000 dollars. For an initial sizing in order to

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test for clearances, rapid prototype methods such as plastic ABS plastic 3-D printing will be used.

It is paramount that for the final prototype a material that is suitable for the amount of stresses that

will be applied when revolving at extremely high speeds won’t deform and cause a failure to the

system.

Discussion

A turbocharger is a rather simple device that recycles energy from the engine and produces

more power with the same engine displacement. In order to improve an existing system, there are

several components within the system that could be enhanced such as the compressor wheel. The

preparation for this project was created based on many books and journal articles of companies

that continuously improve the many components that are present in a turbocharged engine system.

The difference in this case study versus the others seen in many journal articles is the

implementation of a random-geometry generator paired with powerful multi-objective optimizing

algorithms in order to create an efficient impeller at a certain rpm. This method of design

formulation allows for the creation of one prototype that could be bench tested in the real world in

order to verify the FEA and CFD analysis that were performed indeed increased the performance

of the impeller without the need of a trial-and-error process.

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3. Design Alternatives

3.1 Overview of Conceptual Designs Developed

The conceptual designs developed for this study are based on the current geometry of a

TD04-13T compressor housing. In order to use a multi-objective optimization algorithms, it is

necessary to produce a large amount of data that reflect the fluid dynamics of the system. In order

to produce this data many alternate designs are required to be simulated. Using a random-geometry

generator code gracefully provided by Sohail Reddy of the MAIDROC laboratory, 90 alternate

designs were created and altered with eight parameters.

3.2 Optimized Design Alternatives

The optimization of any component is based on controlling and altering particular

parameters that are characteristic of a given design. These specific parameter that have been chosen

as vital design points, done either at random or at a specific trend, produce a design component

that will outperform the original component. These parameters are related to mathematical

phenomena, which make this process more intricate. However, this process also produces the best

possible design in the shortest amount of time, which equates to an overall lower cost. A trial and

error process can be used in order to achieve the same outcome, but that process may take a longer

time and will not guarantee a desired result. As mentioned before, it requires a complex analysis

and development of the data, a process that will be explained shortly.

The geometry of the blades on the compressor wheel determines the air velocity that exits

from the compressor housing. This geometry has different parameters and points; all of these

parameters are linked between them. For the optimization process, parameters are modified in a

certain ways in order to achieve the desired result. The idea of doing this is to obtain different

results from different geometries.

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Figure 9. 3D sketch guideline for impeller blade. To the right are the eight parameters which will be altered.

The ultimate goal for changing these parameters is to achieve the highest average velocity from

the compressor, which will result in the highest efficiency and performance. Each parameter

changed produces a different geometry that will allow for the study of computational fluid

dynamics (CFD) results. The average velocity will be used instead of the maximum because it will

indicate roughly how much pressure can be created from the compressor. In order to optimize the

results each parameter must be modified at least 10 times, subsequent of 90 designs.

These modifications are at a random, following no particular pattern, just within a specific

range that was determined by the geometry of the blade. Once these random numbers are generated

and the parameters are modified on the CAD model a CFD simulation is performed in order to

calculate the average velocity and the maximum velocity. The full tabulated data of all simulation

results of the randomly generated designs can be found in Appendix C.

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Once the studies for each design have been performed, the data is put into the optimization

software, modeFRONTIER®, a program that performs multi-objective and multi-disciplinary

optimization. The software modeFRONTIER® was provided by the FIU MAIDROC laboratory

and the resident graduate research assistant Rajesh Jha. This program streamlines the

multidisciplinary approach in the design process by simultaneously considering multiple

parameters to determine the optimum solution. The main advantage to using this optimization

process is the ability to choose the optimization strategy, depending on the design space boundaries

along with the accuracy of a reliable, improved design. Another advantage to this process is being

able to create a design from the ground up on the computer, with improved performance without

ever needing to perform real world tests until the fabrication of the prototype. This cuts cost on the

design process as well as time, depending on the computing processing power that is available.

Once modeFRONTIER® has generated a batch of geometries, they will then be verified through

more CFD and FEM analysis. The geometry that produces the most appealing results, in this case

the highest average velocity, is selected for prototyping and testing.

3.2.1 ModeFRONTIER® Algorithms

In order to obtain the design population, evolutionary algorithms were used together with

a response surface, both of which were needed for the design generation. An evolutionary

algorithm (EA) basically uses mechanisms inspired by biological evolution, such as reproduction,

mutation, recombination, and selection. Similar to selective breeding in plants and animals, the

solution to these optimization problems, play the role of individuals in a population, and the fitness

function determines the quality (performance) of the solution. The advantage to using this

algorithm is that it does not make any assumptions with regards to how close or far the different

individuals and their properties affect the performance.

14

ModeFRONTIER® has a number of evolutionary algorithms to choose from. The

algorithm that was chosen for the project’s objective was NSGA-II, which creates optimal

designs by grabbing multiple objectives and optimizing the goal desired. It optimizes designs by

using mathematical algorithms to solve multi-objective problems. The centrifugal compressor

required the use of multi-objective optimization due to all the different parameters that were

being considered.

The figure below shows how the evolutionary algorithm works with the analogy of the

breeding in horses. In the first generation we have 4 different horses, or parameters, these 4

parameters will be altered to generate new values, but each horse will be combined with another

one to generate a child, or design. This new design will use both parents information, and it can

also mutate to generate random creations.

Figure 10. Explanation of how evolutionary algorithms work just as selective breeding.

Response surface algorithms define how the different dependent and independent variables

affect each other in terms of optimizing the final goal. The two main RSA that were used were

the Gaussian Processes and the Radial Basic Functions. The main reason for the use of two

15

different algorithm was to compare the result, making sure that the output was within a 1% or less

difference. The method used for the final design was radial basic function.

After all the variables were used on the optimization, the final output generated over 8,000

designs, which show increased average velocity. After filtering the plethora of designs, the

maximum desired values were found and stood out with these 3 designs shown below.

Figure 11. Above shows eight parameters and desired goal objectives.

3.2.2 Graphs and data validation

The first graphs shown below (Figure 12) is an illustration of a 3D graph of how two of the

most influencing parameters, the twist angle of the blades and initial (lower) angle of the loft, are

improving and maximixing the air velocity. One can notice that the maximun value of the graph

for average velocity is 124 m/s, which doesn’t match the final output of 134 m/s, this is because

the 2 parameters named before alone improved the design in the most radical ways while the other

6 remaining paramenters were resposable for the extra 10 m/s.

16

Figure 12. 3D Graph of angle and initial angle with respect to the average velocity.

The graph below (Figure 13) shows how the initial angle of the loft as it varies, changes

the average output velocity. As the angle between the horizontal plane and the initial loft increase,

there is a section where it exhibits a trigonometric function, but the further the angle is increased,

the more linear the relationship becomes. The spot indicated on the graph is the angle that was

nominated for the prototype, resulting in an initial angle of 67.22 degrees.

17

Figure 13. Plot of Average Velocity vs Initial Angle

The graph below shows how as the angle between blades varies, changes the average output

velocity.

Figure 14. Plot of Avergae Velocity and Angle

18

This graph shows the design generation as the angle between the blades varies, at the

bottom of it can be seen that the design generation, creates many design on this region since the

maximized value was between 75 and 74 degrees

Figure 15. Design Generation of Angle

A similar situation happens with the initial angle of the loft.

19

Figure 16. Design Population of Initial Angle

Part of the validation process was to verify that the output from the optimization will match

the output from the CFD study on Solidworks, lastly the output design parameters were modified

on the compressor wheel to allow for the simulation to be ran. The optimization average air

velocity was 134 m/s and the output from the CFD study was 130.28 m/s, which meant that the

results were within the limits of tolerance, which was a 2.85% error, between the optimization and

CFD study.

Figure 17. Final Solidworks CFD Study

20

When optimizing there is a process that needs to be followed on how many different

designs need to be created. A set number of parameters are chosen and then according to the

number of parameters that are going to be modified a number of minimum designs can be made.

ModeFRONTIER® created over 8,000 designs that could be chosen by using mathematical

algorithms. A data table, which can be found in Appendix C, has to be provided and then using

the inputs and outputs, certain output goals can be chosen and those goals will be optimized.

3.3 Design Alternative

One of the design alternates is choosing one family of blades. When choosing only one

family of blades more blades will need to be added to get similar results to the chosen design.

Most high-performance turbochargers are benefitting from using two families of blades. The GTX

series turbochargers from Garrett are one of the industry professionals that currently have one

family of blades and 11 blades in total to produce high boost pressure. The problem with creating

a one family, many blade configuration is that machining becomes complicated with the really

small tight tolerances that are needed. CNC machining of this type of configuration is very

expensive because custom sized tool-bits are needed to make the small gap between blades.

3.4 Integration of Global Design Elements

The method of optimization that was used to create the proposed design, could also be

used for many other fields as diverse as art, biology, marketing, genetics, operations research,

social sciences, physics, politics and chemistry. This is mainly due to the unique property

evolutionary algorithms possess in not making any assumptions of the capabilities certain

21

parameters can produce in the right combination. The production of more efficient and better

performing products would benefit from using the algorithms ModeFRONIER® provides the

users with, and could possibly change the manner in which many designers create their product

prototypes. The only downside to using this method is the amount of data needed for accurate

results, which would depend on the number of parameters that could need to be altered.

3.5 Feasibility Assessment

Turbochargers have a big global market that is always increasing in demand and thus

supply must increase as well. Many automotive manufacturers around the world are being pushed

to increase fuel economy in all cars. Most car manufacturers are using turbocharger technology

to provide this increase in fuel economy. This technology is in high demand and keeps increasing,

therefore the value to be attained outweighs the cost of research and development. Following the

supply and demand curve of this technology can dictate maximum feasibility of this project.

3.6 Proposed Design

The centrifugal compressor that will be created for this project will compose of two major

components: the impeller and the housing. The CAD design of the compressor blade impeller was

created by using the modeling software, SolidWorks and is one complete solid piece. This design

was finalized once the process of blade optimization was completed. The physical design consists

of an aluminum wheel with seven main blades and a set of smaller vanes in-between these blades.

In order to create an impeller with the highest coefficient of efficiency, the spacing between the

impeller and the housing must be minimized, requiring extremely high tolerances in the

manufacturing process in order to reduce the tip leakage flow. Which leads to the other major

component of this centrifugal compressor system, the housing.

22

The effect that the housing has on the performance of a centrifugal compressor is

not as apparent as the impeller that is found inside. Noting the difficulty of creating

compressor housing out of a mold it was decided to use a housing component that was

already fabricated. A Mitsubishi TD04 housing component was chosen for this product due

to its small size relative to the majority of high performance turbochargers in the market

with the idea that a small turbocharger will be used in downsized engines with the intention

of improving fuel efficiency. Figure 7 shows the compressor housing that will be used in

conjunction with the compressor wheel. Another reason why this specific housing was

selected is for the opportunity to test the compressor with the current turbocharger installed

on a 2004 Subaru Impreza WRX. This vehicle is an example of engine downsizing in the

market, which has already been noted as a trend in the automotive industry. The process of

testing the compressor will be elaborated in the Prototype Analysis section of this report.

3.7 Discussion

Optimization needs to be elaborate and detailed and requires a lot of understanding of the

mathematical algorithms that are used in the modeFRONTIER® software. It requires previous

knowledge of how the program works and how it generate the designs. The feasibility of the

project scope is very important because it deals directly with if the project can and will be done or

not.

23

4. Project Management

4.1 Overview

The timeline depicted below is a projected overview of how the project is going to be

managed. Tasks will be split accordingly to each strength of each team member. Being able to

work with the strengths of each team member maximizes the efficiency of the team collaboration.

The estimated completion date for this project is November 20, 2014. This date is ideal for all of

the team members in that it does not overlap onto other responsibilities or holidays.

4.2 Breakdown of Work into Specific Tasks

As shown below in Table 2, the responsibilities for this project were shared amongst the

team members evenly. All of the team members were actively involved in conducting research,

CAD modeling, performing CFD analysis, testing, and writing. The colored boxes represent the

responsibility that a team member was associated with throughout the duration of the project. The

blank boxes show where the team member had no involvement during the project.

Table 2. Table of responsibilities.

Responsibilities Xavier Medina

Fernando Lopez

Gianfranco Pisani

Research

CAD Modeling

CFD Analysis

Optimization

Manufacturing

Testing

Writing

24

4.3 Gantt Chart for the Organization of Work and Timeline

Figure 18. Gantt chart.

4.4 Breakdown of Responsibilities Among Team Members

As team leader, Xavier Medina was involved in all of the processes of this project, but it

does not mean that his workload was greater than that of the other team members. He had a major

role in the CFD analysis due to circumstances such as processing power and flexibility. He also

had a role in the manufacturing process of the prototype along with the testing. Gianfranco had a

major role in the CAD modeling aspect of this project and created the base computer model needed

in order to create the random designs and run the software simulations. In addition to creating the

CAD modeling, Gianfranco along with Xavier handled the optimization process of the project

using modeFRONTIER®. Fernando’s major role in this project was the editing of the report along

with the testing and manufacturing of the prototype. His involvement in the testing and

manufacturing is because he is the owner of the vehicle that is being used in this project and he

will be around the prototype the most.

1/11 3/2 4/21 6/10 7/30 9/18 11/7

Identify Team & Project

Develop Detailed Plan

Conduct Research

CAD Modeling

Software Simulation (FEM Analysis)

Software Simulation (CFD Analysis)

ModeFRONTIER Optimization

Initial Test

Preliminary Manufacturing

CNC Machining

Final Testing

25

4.5 Commercialization of the Final Product

Marketing campaign for this product could be geared toward a number of companies.

Design could be shown to Mitsubishi, since stock turbocharger that was used for constraints on

project is from the Mitsubishi line. Another alternative would be DieselSite Wicked Wheels

Company, which specialize in turbo-diesel engine technology. They deal with creating custom

blade configurations that outperform the blade profile set in standard diesel-turbochargers. All

custom designs are made and manufactured to specifically follow all dimensions of stock housings,

so modifications can be done by only changing the compressor wheel.

4.6 Discussion

Tasks were divided up according to the strength of each team member to maximize the

efficiency and flow of the team’s efforts. In the end everyone had a role in every single aspect of

the project. Proper team chemistry allowed for the best configuration in doing certain tasks

simultaneously alongside each other. Dividing this big project into manageable chunks makes

the task of managing the sub-phases of this study easier to handle.

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5. Engineering Design and Analysis

5.1 Overview

This section of the study involves the actual design and analysis of the prototype that will

be manufactured. Some of these analyses include structural, kinematics/computational fluid

dynamics (CFD), vibrational dynamics, stress, and deflection. Using these analysis, a final

prototype can be created in order to validate the claims produced by the simulations. All of these

simulations were created by using Dassault Systemes’ SolidWorks.

5.2 Kinematic Analysis and Animation

The primary analysis that are performed for this project is kinematic in nature.

Computational fluid dynamics (CFD) were used to simulate the flow of air through all of the

designs that were created. An important aspect of this computation are the boundary conditions

that dictate the environment surrounding the compressor wheel. The boundary conditions

consisted of atmospheric conditions for both the inlet and the outlet, and an environmental

temperature of 27 degrees Celsius (298 K). The surface was assumed to be perfectly smooth and

adiabatic. These conditions were used in order to simplify the simulations and shorten the

computational time that will require the majority of time.

The rotational speed of the impeller dictates the performance of the compressor, therefore

the optimization parameter that needs to be isolated is the angular velocity. Since the objective of

this project is to increase the efficiency throughout the operational speed of the compressor a range

needed to be established. It was estimated that the maximum velocity of smaller turbochargers to

be roughly 150,000 rpm, therefore the design speed of the prototype to be optimized was selected

to be 140,000 rpm. This would ensure that the maximum compressor efficiency would not be

27

reached towards the higher end of the engine speed, and result in a higher efficiency throughout

the different volumetric flows of the engine.

5.3 Dynamic/Vibration Analysis of the System

The dynamic analysis consists of a centrifugal test set to rotate the compressor wheel to

the limit of its rpm, which is roughly 150,000 rpm or 15,700 rad/s. It must also be noted that this

limit could be reached by the compressor, but only be reached at the very limits of the entire engine

system.

The compressor wheel when spun at its limit could experience vibration from the point of

contact of the shaft, and propagate through the blades causing minor deflections (fluttering). This

vibration analysis could be done by performing a frequency simulation on the compressor wheel

component. The frequency achieved is 8311.1 Hertz, and at this frequency is when the deflection

can be seen on the second family of blades as shown below.

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Figure 19. Frequency simulation performed to assess vibration.

5.4 Structural Design

The compressor wheel blades are the biggest point of concern when it comes to structural

design. Since the compressor wheel is being spun in excess of 100,000 rpms the edge of where

the blades meet the body need to have rounded fillets and edges. These rounded edges allow for

dissipation of the centrifugal force that is generated by the high velocity rotations.

The following picture will show where these modifications were made. The stress analysis

will go in more depth on the reasons for why these rounded edges are needed.

29

Figure 20. Where the rounded edges needed to be made.

The life cycle of the compressor wheel has to be very high since it is operating under

extreme conditions. A fatigue life test simulation was created to analyze how long it would take

under operating conditions for the compressor wheel to finally fail. The results are illustrated in

the figure below.

Figure 21. Life of the blade after going through 𝟏𝟎𝟕cycles.

Fillet

Fillet

30

Figure 22. Damage that is present after 𝟏𝟎𝟕cycles.

5.5 Force Analysis

The main force acting on the compressor wheel is centrifugal force, which is generated by

the high speed of rotation. This force is created because of its moment of inertia being in the center

of where the bore is for the shaft. When rotating, the blades are being subjected to a reaction force

from the air molecules when increasing the velocity of the air. This reaction force turns into

centrifugal force as shown below.

31

Figure 23. Direction of rotation and the forces that are felt.

5.6 Stress Analysis

Stress analysis needs to be done to assess the compactibility of the design and how it deals

with the forces that it is subjected to. It would indicate as to where certain stresses are being seen

and the areas that they affect. The main problem that was found was that at the point where the

blades and the main core meet, the curve had a lot of stress due to the area that was involded. This

area needed to be changed and 5 mm fillets were done at the points in order to increase the surface

area and decrease the stress. This allowed for a more sustainable stress dissipation. Finally, the

highest stress was 92 MPa which is less than the yield strength.

was considered to determine the different points on which modifications were needed as

stated before. On this section the reason and sizing of the fillets will be covered.

Centrifugal

Force

32

Figure 24. Image showing areas where stress is experienced.

5.7 Material Selection

When making material selection several possibilities were contemplated. Since the

material that had to be used didn’t only have to be strong enough to withstand the continuous

punishment of operating conditions, but also had to be light to decrease the inertia and allow for

an easier spool. The material had to be machinable and rust resistant in order to be able to be

manufactured.

Initially the best material would be magnesium WE43, which has the lowest density and

very high strength, followed by aluminum and finally titanium in respect to density. With respect

to strength, titanium takes the top position, followed by aluminum and magnesium, respectively.

33

For pricing purposes the cheapest option was aluminum, since magnesium and titanium alloys are

particularly expensive.

The decision was to use aluminum 7075, which offered the best properties out of the three

proposed series. A wide variety of materials could be used for the project, but from all of them

the most suitable was the ASTM 7075 (aluminum alloy). Aluminum offered properties that are

similar to all the previous materials, but aluminum could make the design cheaper and easily

machined. Titanium is a lighter choice and has more strength, along with magnesium, but the

price is not suitable for the project’s purpose. Aluminum offered economic cost efficiency without

sacrificing quality which is an important part of the design.

5.8 Design Based on Static and Fatigue Failure Design Theories

For the project’s application, static analysis was not taken into account because of its nature

of being a purely dynamic component. The fatigue failure design theory specifies on the cyclic

loading of the component under operating conditions. The load in question in this project would

be centrifugal forces acting on the compressor’s blades. One of the biggest problems would be

having sharp edges on the inside of the blades. Fillets are needed to make machinability easier

and also to address the fatigue failure that could happen. With fillets the blades have less of a

chance of experiencing critical stresses at the base of the blade and thus decreasing the chance of

fatigue failure.

Fatigue failure could be seen on the following figure. The compressor wheel has no

specific point as to where it would fail first. The figure shows where the component would fail

which is the whole component would fail, if failure were to occur. The lowest factor of safety

obtained was 1.3 at the limit of the rpm. This further shows that as the rpms drops the factor of

safety increases.

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Figure 25. Where failure would occur by dropping below a certain Factor Of Safety.

5.9 Deflection Analysis

The displacement or deflection provides a disadvantage. The rpms of the design show how

centrifugal force could predominantly demand careful considerations. Deflection can be seen on

the design at the red points. As was explained previously the vibration that occurs from the point

of contact where the shaft and compressor wheel touches and propagates through to the blades of

the wheel. This propagation of vibration produces a small fluttering effect on the small blades that

can be seen as the point of deflection. Although there are deflections they are within the

performance limits and do not affect the performance of the compressor wheel. Even at the highest

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rpm setting, the deflection is very minimal showing a deflection of 0.003187 mm to almost no

deflection.

Figure 26. Deflection could occur in the red areas.

5.10 Component Design/Selection

The basic shape of the compressor wheel was based on standard designs that were

commercially available. The procedure of the used shape of blades came from trying to first

resemble existing design, and then, improve the existing ones by using every tool that was

available and could develop the final design, meaning, flow simulation and optimization. Also

considerations on 2 or 1 family of blades were taken.

36

5.11 Component Design Simulation

In order to determine the performance of the design, a flow simulation was created in

SolidWorks with a rotating region. This rotating region was the blade design, but in order to able

to test the wheel a compressor housing was needed as well. The compressor housing used for the

simulation was modeled using similar techniques that were used for the wheel. These two parts

had to work together in order to generate velocity values that would then be used to calculate the

pressure difference created by the system. After weeks of design considerations and modeling

changes, an assembly with proper flow conditions was achieved. After the complete assembly of

the 3D model, including wheel and housing, the project was ready for the next step, simulation

testing and initial conditions.

For the initial conditions it was important to have the correct ones, since the compressor

system works in a particular way, and these conditions were needed to generate accurate results.

Initially there are three main conditions or parameters, inlet, outlet and rpm. These three

components will determine the performance. To be able to understand the reason of these three

conditions, a review of how the compressor wheel generates the difference in pressure is needed.

Compressor wheels are inside compressor housings and these two parts work together to

create pressure difference. This is achieved by a divergent circular cross section that gradually

increases its diameter as its turns around the compressor wheel. The compressor wheel accelerates

the incoming air by drastically increasing its velocity, therefore, increasing its kinetic energy.

Following Bernoulli equations:

𝑔ℎ1 +

𝑝1

𝜌+

𝑣12

2= 𝑔ℎ1 +

𝑝2

𝜌+

𝑣22

2

(Eq. 3)

Where:

g is gravity

37

h is height of fluid

p is pressure

𝜌 is density of the fluid

v is velocity of the fluid

In the compressor side system some assumptions can be made:

ℎ1 = ℎ2 (Eq. 4)

𝜌 = 1𝑘𝑔

𝑚3⁄ (Eq. 5)

𝑝1 = 101 𝐾𝑃𝑎 (Eq. 6)

Following these assumptions a simplified version of Bernoulli’s equation can be used:

𝑝1 − 𝑝2 = (

𝑣22 − 𝑣1

2

2)𝜌

(Eq. 7)

It is possible to determine the pressure difference by utilizing Eq. 7 above. As the circular

cross section of the housing increases its diameter, the velocity of the flow decreases, increasing

the pressure. So the objective was to generate the highest pressure difference at the limit of the

compressor wheel which was 12500 rad/s, or 140000 rpm, which is a common limit used in today’s

turbocharger due to lubrication and bearing technology. So far one of the conditions was defined,

now the inlet and outlet conditions will be defined as well. The conditions for the inlet and outlet

are atmospheric pressure the reason behind this is because the pressure difference is being tested

by determining how high the air velocity is in the housing. Since a higher velocity difference will

automatically generate a higher pressure difference, it results in a better design.

5.12 Finite Element Analysis

SolidWorks is a program that doubles up as a Finite Element Analysis solver. When

designating mesh sizes in all simulations, they were generally set to be coarse. Mesh sizes required

38

to be coarse because of limited processing power on the computers that ran the simulations.

Attempting to run a finer mesh size resulted in a catastrophic error in SolidWorks and would shut

down the program. The mesh that also needed to be created due to the complex geometry of the

blade is a 3D dynamic mesh that is very difficult to simulate in SolidWorks. ANSYS is another

software simulation program that could be used to create and run Computational Fluid Dynamics,

but due to limited processing power and time, this simulation could not be generated.

5.13 Design Overview

The design objectives were always kept in mind across all the design aspect. Simulations

could have been performed better by using more advanced simulation programs. Boundary

conditions could have been researched to create a better, ideal testing simulation of CFD.

5.14 Cost Analysis

In the cost analysis, every expense will be reported and added to a final amount, three

categories which would best sum up and take into account the amount of work and cost necessary

are as follows: materials, design, manufacturing, and testing. The following sections go in-depth

for each category but the following table sums up the total cost associated with this project

involving everything from man-hours to materials.

39

Table 3. Tabulated Cost Analysis

ID Name Res Duration Cost

ID (hours)

1.1 Conduct Research EIC Computer Lab 85 $21.25

1.2 CAD Modeling

1.2.1 SolidWorks Modeling EIC Computer Lab 140 $35.00

1.2.2 Visual Basic Coding Random Geometry (Sohail) 1 $-

1.2.3 Measuring Physical Model Impeller and Housing 2 $120.00

1.3 Software Simulation

1.3.1 FEM Analysis Analysis 90 $22.50

1.3.2 CFD Analysis Analysis 90 $22.50

1.4 Optimization

1.4.1 ModeFrontier Optimization Personal Computer 1 $0.25

1.5 Manufacturing

1.5.1 Raw Materials ASTM 7075 (Aluminum alloy) 0 $60.00

1.5.2 Plastic 3-D Printing Concept Manufacturing 4 $30.00

1.5.3 CNC Machining 5-axis CNC Machining 12 $280.00

1.6 Testing

1.6.1 Initial Testing Dyno runs/MPG testing 8 $320.00

1.6.2 Test of Prototype Dyno runs/MPG testing 8 $120.00

Total Hours Total Cost

441 $1,031.50

5.15 Discussion

Certain issues came up when designing the component, which was expected. The issues had

to be resolved to be able to make a viable component. Being able to identify these problems and

resolving them confirms the understanding of the analysis and simulations. Also understanding

the limitation of processing power better helps understand the problems that arose when generating

the CFD analyses.

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6. Prototype Construction

6.1 Overview

Manufacturing a prototype is a very important aspect of every design project. Making sure

that the correct type of manufacturing process is chosen is fundamental in producing a prototype.

With turbochargers every process is expensive because it is such an intensive and intricate piece

of machinery that needs to be manufactured.

6.2 Description of Prototype

The compressor wheel was initially manufactured through the process of 3-D printing in

ABS plastic. Ryan Lucia, a current undergraduate student at FIU, and his MakerBot® 3-D printer

created the plastic model at a cost of $20 per model which included the material that was used to

create it. This first prototype was used to be able to check if the design is close to the physical

housing of the Mitsubishi TD04-13T turbocharger.

41

Figure 27. 3D printed prototype done by Ryan Lucia.

The final design prototype that would be ideal is to be made of aluminum 7075 through the

process of CNC machining using a 5-axis machine. This type of detail that is needed is crucial

when dealing with an object such as a turbocharger compressor wheel. The piece not only needs

to be machined with a lot of detail, but the tolerances are extremely tight. Rotating components

also have an extra thing that needs to be worried about which is correct rotational balancing. Any

slight imbalance in the compressor wheel when rotating in excess of 100,000 rpms could result in

catastrophic failure.

6.3 Prototype Design

A random design is chosen from the thousands of designs that were tabulated by the

modeFRONTIER program. From this random design it is simulated one more time to make sure

42

that the goals that were supposed to be achieved through the optimizing algorithm are achieved.

The prototype that was chosen is one with curves that make machining easier and would not be as

steep to make sure manufacturing is easier.

6.4 Parts List

Rolled barstock of aluminum 7075 was needed to be provided to the machining company

Southern Gear. The material would be used to create the small compressor wheel geometry. A

small piece would be mounted on the CNC 5-axis machine and then machined out of the billet of

aluminum. The CNC 5-axis machine also would need two specific modules from GibbsCam to

be able to program the pathway for the tools to create the turbo machinery geometries.

6.5 Construction

The construction was going to be done with current IAB board member, Mr. Allan Arch,

CEO of Southern Gear. Southern Gear had an onsite 5-axis CNC machine that could perform the

machining of our prototype design. Problems arose in this area, with Southern Gear not having

the specific module that is needed to program the CNC machine.

They do not create compressor wheels, so naturally the two modules that would be needed

to program the machine to create the pathway would be missing. Without two modules that are

needed to program the CNC machine so that it can make a pathway for the tool, the machining in

aluminum could not be done. The level one 5-axis Multiblade module comes out to about

$3,375.00 with a yearly maintenance of $375.00. In addition to the level one module, the level

two module also needed to be added one to create the more complex geometry that was needed for

the prototype design. The level two 5-axis Multiblade module is priced at approximately

$13,275.00 with a yearly maintenance of $1,475.00. A rough estimate quote was still drafted by

Southern Gear’s manufacturing engineers to be able to reflect as much as possible on the actual

43

cost of this project. The quote for machining the prototype out of aluminum was about $1,800.00.

It was assessed that for the project objective of only creating one compressor wheel, the price was

out of reach.

Other options were explored such as aluminum 3D printing done by Incodema3D. The

quote for the prototype came out to about $1,337.65, which was also too much for a self-sustained

project. After exploring further options with manufacturing professor, Richard Zicarelli, it was

decided to pursue a high resolution 3D printing option. WB Engineering is a company located in-

state that utilizes a polyjet process of 3D printing the compressor wheel in acrylic. A quote was

drafted up by WB Engineering to be priced at $149.04.

Figure 28. Polyjet 3D printed acrylic of final design from WB Engineering.

44

6.6 Prototype Cost Analysis

Tables 4, 5, and 6 below show the estimated quote prices that were provided by trhe

separate companies that were researched as alternative options for manufacturing. As seen

Southern Gear would’ve been the optimal choice since it would actually have been manufactured

and machined. The budget being a self-funded project meant that it was not a viable option.

Table 4. Southern Gear final estimated quote price.

Company Description Cost

Southern

Gear

GibbsCam 5-Axis MultiBlade Level 1 Module $3,375.00

GibbsCam 5-Axis MultiBlade Level 2 Module $13,275.00

Machining Cost $1,800.00

Total $18,450.00

Table 5. Incodema3D final estimated quote price.


Incodema3D Additive Manufactured Part (DMLS) Aluminum AlSi10Mg $1,337.65

Total $1,337.65

Table 6. 1click3Dprint final estimate quote price.


1click3Dprint Multi-Jet-Printing Acrylic-Like $149.04

Total $149.04

6.7 Discussion

The manufacturing process of this project was unfortunately not able to be done to the most

desirable outcomes. Due to budget constraints, the aluminum compressor wheel could not be

manufactured for proper real-world testing.

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7. Testing and Evaluation

7.1 Overview

Testing on turbocharger compressor wheels are very intensive. Turbochargers have to be

able to function continuously at the limits of its operating conditions for many cycles. The figure

below shows a test bench of a turbocharger system, where the extreme temperatures and rotational

forces at work cause the turbine housing to glow red after a certain amount of time and exhaust

pressure loading.

Figure 29. Visual example of a turbocharger system undergoing fatigue and performance tests.

Only during extreme conditions and for short periods of time will the turbocharger system

experience this amount of heat generation. Turbo manufactures must test these systems in this

manner in order to verify that there won’t be any failure, typically running these test continuously

for upwards of 16 hours. For the scope of this project and with the resources available, these types

of tests are economically feasible but there are alternatives to this extreme testing. The following

section will go into depth of the possible experiments that could verify the design of the prototype

compressor created through multi-objective optimization.

47

7.2 Design of Experiments - Description of Experiments

Performance data will be collected from the stock turbo within Fernando Lopez’s 2004

Subaru WRX. There are two different ways of getting performance data out of the stock turbo that

is currently in the car, by calculating miles per gallon (mpg) and by performing dynamometer

testing. A third way in which a comparison test could be created is in creation of a test bench for

the compressor that would create a controlled environment for the system. This third method does

not take into account several parameters such as a variation in temperature, environmental

pressure, vibrations, and losses due to turbine inefficiency.

7.2.1 Experiment 1 – Average Miles per gallon

The first experiment will be approximating the gas mileage of the car before and after the

modification of the compressor wheel. A path of approximately 100 miles will be mapped out

using Florida’s highway system where the car will be ran under constant conditions as shown

below in Figure . Weather data will need to be collected on the days that gas mileage runs will be

done in an attempt to recreate every gas mileage run, such as humidity, temperature, time of day,

and barometric pressure. The car will be taken to the same gas station and to the same gas pump

in order to minimize the number of variables in these approximations of mpg. After machining the

final prototype and installing it into the car, the gas mileage tests will be done again under the same

conditions. This type of experimentation will directly relate the effect of a compressor impeller to

the mpg or the fuel efficiency of a car. It has been hypothesized that a compressor wheel that has

been optimized to perform more efficiently within a certain rotational velocity could increase the

overall fuel efficiency of a vehicle by 5%. The results from this experiment validate the prototype’s

performance from a practical approach that is simple for the masses to understand.

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7.2.2 Experiment 2 – Dynamometer Testing

The second experiment that will be performed will involve placing the car on a chassis

dynamometer. Certain mechanic shops have these performance-reading machines that collect real-

time instantaneous data from the car such as horsepower, power generated, air-to-fuel ratio ratings,

carbon emission output, torque curve readings, boost generated, etc. A dynamometer in a machine

shops performs all of these readings within a controlled environment. The car is situated on drive

rollers with sensors which measure the torque being delivered, which could be used along other

sensors for a summary of the vehicle's performance. The dynamometer system being used should

have emissions sampling, measurements of engine speed and load control, data acquisition, and

safety monitoring enveloped in a complete test cell system.

There are three types of tests that can performed using a chassis dynamometer:

1. The engine is held at a steady state, meaning that the engine is held at a specific rpm, or at

several different rpms for a given time.

2. The engine is tested under a load and allowed to rev up in rpm, between a certain ranges.

This is commonly known as a sweep test.

3. This final test type involves changing the engine power and speed throughout the test

cycle. This type of test could follow standards used by the EPA in order to determine the

different dynamics of a car or engine.

These preliminary tests will be done to collect as much performance data from the stock

turbo as well as the entire vehicle. Once the prototype has been created and properly installed, the

same bench tests will be performed using the same equipment and parameters. The tests that will

be specified in the performance mechanic shop will have to do with the boost pressure buildup

(spool time), power and torque increase (or decrease), and fuel efficiency. These dyno pulls will

also be used to test and affirm that the final desired product can withstand the revolutions that a

49

turbo is subject to experience. The dynamometer tests will push the turbo to produce a full range

of performance data alongside the performance of the engine.

New and old data will be charted and plotted side-by-side to show comparisons between

stock turbo and final product turbo data. This data will be used as a validation for the SolidWorks

simulation results that have been charted. The results from this experiment are more reliable than

the other forms of experimentation due to the nature of dynamometer tests and demonstrate a real-

world performance validation of the compressor in relation to the entire system.

7.2.3 Experiment 3 – Compressor Test Bench

This experiment being performed will validate the performance of the compressor to the

simulations performed within SolidWorks. Turbochargers rely on a source that provides high

temperature and high pressure gases. Normally these gases will come from the exhaust stroke of

an internal combustion engine. Since an internal combustion engine is a complex system that

emits harmful carbon monoxide gases testing the turbocharger outside of the car becomes

expensive and difficult to do even without including an engine as the source of exhaust gas.

Since the scope of this project was only the optimization of the compressor wheel, a

feasible test bench could be created that did not involve the hazardous conditions turbochargers

were designed to endure. This also led to the certain conditions that were used in SolidWorks.

Two parameters will need to be measured: the rotational speed and the output air velocity. The

boundary conditions used in the SolidWorks simulation need to be recreated within this test

bench include environmental pressure (101 kPa) and temperature (25 C).

50

Figure 30. Air compressor that will blow air through

turbine side of turbocharger.

Figure 31. Computer that is directly connected with air

compressor to get all readings.

7.3 Test Results and Data

As mentioned in the section above, a test bench would need to be created that can rotate

the turbine wheel in excess of 100,000 rpms by pushing pure compressed air through the turbine

exhaust gas pipe. This compressed air will spin the turbine which is directly connected to the

compressor wheel blade and thus the compressor wheel will rotate in unison with the turbine

wheel. As mentioned above in the prototype section, the optimal material could not be used to

manufacture the prototype, thus debilitating the testing process.

It was stated that the prototype that was created is a polyjet 3D printed acrylic prototype.

Although this material is stronger than the conventional ABS and PLA plastic 3D printed pieces,

it still cannot withstand operational conditions for testing. Rotating this piece in excess of 100,000

rpms can potentially force the component to explode from the centrifugal force that it is being

exerted to.

51

7.4 Evaluation of Experimental Results

Since no testing can be done there are no real-world physical experiment results to evaluate.

All processes of designing the experiments are detailed so that for future work testing can be done

when funding is available for further research and development.

7.5 Improvement of the Design

After getting test results from running the designed experiments, discrepancies can be

noted in the simulations and changes can be made in the development process.

From a simulation standpoint, it can be seen by the figure below, that the optimized wheel

does produce better overall average velocity across the spectrum of operating conditions.

Following from the bottom spectrum of the rpms, to the top, the optimized concept design can

produce a higher overall average velocity. With a higher average velocity it produces a more

stable increased pressure ratio.

Figure 32. Optimized wheel avg velovity vs. Stock wheel avg velocity.

0

20

40

60

80

100

120

140

0 2000 4000 6000 8000 10000 12000 14000

Ave

rage

Air

Vel

oci

ty

RPM in Rad/s

Wheel Comparison

Optimized Wheel Stock Wheel

52

7.6 Discussion

The testing of the compressor wheel component tends to be very arduous and demanding. The

compressor wheel has to be able to meet the cyclic loading of the operating conditions throughout

cycles. As stated in the structural design section, the compressor wheel could be put under

operating conditions and pushed to the limits for many cycles and almost no damage would be

noticed. Unfortunately, due to the extreme cost in manufacturing an impeller blade that could

withstand the immense rotational forces a functioning prototype could not be created. A bench test

was formulated that could theoretically test the compressor, by means of rotating the turbine blades

with the help of compressed air. The fuel efficiency test was also not able to be performed, but it

is hypothesized that there would be an increase of roughly 3-5%. Over the lifetime of the

compressor, there are major savings to this minor increase, aiding in reducing CO2 emissions.

53

8. Design Considerations

8.1 Assembly and Disassembly

The disassembly and assembly of a turbocharger unit is specified within this report only refers to

the Mitsubishi TD04-13T installed on a 2004 Subaru Impreza WRX. If this modification is to be

made for another unit, then there is a different set of instructions tailored specifically for said unit.

It has been assumed that the turbocharger has already been removed from the vehicle. Everything

shown in this section has been adapted from ©Stage Infinity, under the Mitsubishi TD04-13T

Turbo Rebuild section of their website. It must be noted that not balancing the shaft with the new

compressor could be extremely dangerous to the condition of the turbocharger and is not

recommended. Below is a list of tools that will be needed in order to disassemble the turbocharger

unit:

10,12 mm wrench

8mm socket

hammer

flathead screwdriver

large-bore snap-ring pliers (3” bore minimum, a high quality one is recommended such as

a McMaster-Carr PN# 5415A64)

Penetrating lubricant like WD40, Liquid Wrench, etc.

Touch-up paint, White Out, or similar painting tool with small brush (substitutions possible

– read full page to understand what it is needed for)

A reasonably sized area should be used for this project, with some rags and paper towels handy as

well as a small container to store the parts that will be removed. The most delicate part in this

54

turbocharger is the compressor wheel and the turbine wheel. And the most troublesome part of the

disassembly and assembly of this unit is the snap ring for the compressor. This is where safety is

important: always wear safety goggles when working with snap rings. Under high compression if

they slip uncontrollably, snap rings could be shot across the room at a very high speed.

Disassembly:

1. Remove all hose clamps and hoses. There should be hoses going to the wastegate actuator

and compressor housing. Set these parts in a container, as they will be reused.

2. Remove the wastegate actuator (2 12mm bolts and 1 retaining “E” clip) as shown in Figure

15.

Figure 33. Wastegate Actuator.

Figure 34. Turbocharger clamp holding the turbine

housing with the cartridge.

3. Remove the clamp around the center housing and rotating assembly (CHRA - 1 10mm bolt)

shown in Figure 16. Remove the bolt and nut completely from the clamp and put these in

your parts container, as they will be reused.

4. Remove the 17mm banjo bolts and coolant line from the CHRA as shown in Figure 17. Some

penetrating fluids may be needed in order to remove these bolts. With the lines removed,

thread the bolts back in to keep debris out or plug the holes with something else and put the

55

bolts and line in the parts container. Make sure to keep the 4 copper washers, unless they are

being replaced.

Figure 35. Coolant lines with 17mm banjo bolts and 4

copper washers.

Figure 36. Oil return line connected to the CHRA.

5. Remove the 2 10mm bolts holding the oil return line to the CHRA as shown in figure 18. The

flange may have trouble coming off, but once it does take note on the condition of the gasket

material that will be stuck to the surfaces. A new gasket might be needed upon assembly. Set

the oil return line in the parts container, and thread the bolts back into the CHRA, and plug

the oil hole in order to not dirty the inside.

6. Use the large bore snap pliers to remove the snap ring holding the compressor from the

CHRA.

7. Before removing the compressor wheel, the nut must be marked with paint in relation the

CHRA. When being assembled the markings must be lined up.

8. Using an 8mm socket for the compressor wheel nut and a 12mm socket that fit well enough

to hold the turbine nut, remove the compressor wheel nut and put it in your parts

container. NOTE: the TD04L-13G’s compressor wheel nut is reverse threaded, so go

clockwise.

9. It is recommended that the new compressor wheel be rebalanced alongside the shaft and the

turbine in order to ensure that there will not be any unwanted vibrations. This can be done at

53

a local shop for a service fee. The nut should be tightened to the torque specs supplied in the

service manual, roughly 6-8 ft-lbs and lined up with the paint along the CHRA

For reassembly, the following steps may be used.

1. Slide the new compressor wheel back onto the shaft and line up the marks that were marked

on the nut and the CHRA.

1. Clean the oil return line’s gasket surface well and remove all old gasket material. Clean the

gasket surface on the CHRA in the same manner.

2. Reassemble the oil return line with the new gasket. Torque the bolts to 3-4 ft-lbs.

3. Reassemble the coolant line with the copper washers (one between the pipe and the CHRA,

another between the bolt head and the pipe). Torque the bolts to 22 ft-lbs.

4. Reattach the wastegate actuator/controller and vacuum hoses. Give the bolts a “good snug”

but don’t overtighten them, as they are threaded into the semi-soft aluminum compressor

housing.

8.2 Maintenance of the System

8.2.1 Regular Maintenance

In general, a turbocharger needs little maintenance for the entirety of its lifetime. The

typical lifespan for a turbocharger depends on many factors, such as time spent creating boost,

and any modifications to the engine system that do not favor the loading conditions the turbo was

designed for. In the case of the TD04, the lime time could be rather long, in some cases lasting

more than 180,000+ miles without much maintenance. Since this particular study is only focused

on the compressor, there isn’t any maintenance that could be directly related to this component.

Typically, the maintenance of a turbocharger would result in a complete overhaul of the bearings

and seals, as well as the cleaning of both the turbine and compressor blades.

54

Figure 37. Destroyed turbine blade from Subaru turbo. [15]

The image above depicts the damage that could be cause from the failure of the bearings

in a turbocharger due to the lack of maintenance. In the specific case, a banjo bolt which filters

the oil before reaching the bearings was clogged, starving the bearings of oil. This simple

replacement could have prevented this sort of catastrophic damaged that would render a

turbocharger useless.

8.3 Environmental Impact

The impact that is caused by the creation of this prototype is an overall neutral impact.

The amount of fuel that could be saved in the lifetime of the compressor could be equated to the

similar environmental cost of creating this prototype out of a billet of aluminum. If this

compressor were to be created out of 3D printed methods, then the impact could be positive due

to the reduced amount of metal that is used to create each part, as well as a reduced energy cost.

8.4 Risk Assessment

The risk associated with this part is rather large due to the extreme conditions that will be

experienced during the lifetime of the component. The worst case loading is used in order to

evaluate the risk associated during extreme loading of the blades. A harmonic response analysis is

vital in order to evaluate the stresses associated during resonance values. Using all of the CFD

55

results and using the Von Mises criteria it was calculated that the resulting impeller had a factor

of safety of 1.68. The harmonic response analysis resulted in a deflection of 0.003187 mm. Which

is less than the deflection experienced from the load the blades bear from the fluid.

56

9. Design Experience

9.1 Overview

Designing this compressor wheel is a complex job that required a lot of SolidWorks

experience to be able to make the concept and have it automated so that changing parameters were

easy enough. Creating the housing with ideal dimensions to properly make the simulations that

were needed.

9.2 Standards Used in the Project

There is no association that provide set standards for turbochargers, but there are certain

testing standards that are regulated by the Society of Automotive Engineers (SAE). There is a

manuscript that is available for the price of $70.00 to have a detailed description of all the testing

standards and regulations that need to be followed.

ASTM standards were also used when deciding on the type of material that could be

machined for the concept design. The proper regulations need to be followed when testing the

safety of this material.

9.3 Contemporary Issues

The contemporary issues that are being addressed in the scope of this project deal with

fossil fuel dependency and improvement of fuel economy in cars. The downsizing of engines

require turbochargers to allow for more power buildup, while still providing great fuel economy.

The dependency of fossil fuels is something that needs to be addressed and be helped along

the way. Many car manufacturers are going through research stages of electric and hydrogen fuel

alternatives for cars. Until that research can be validated and developed fossil fuels are still being

used, thus creating the demand for better fuel economic cars. Car manufacturers decide to go with

57

turbocharged engine systems to be able to have smaller engines in cars. They want to provide

maximum power without sacrificing fuel economy as much.

9.4 Impact of Design in a Global and Societal Context

The demand for turbocharger technology is increasing globally and in conjunction with the

demand for increased fuel economy. Since this demand is growing globally, the impact that the

project has is relevant in today’s global market. The impact that this project has on everyday

society is that people normally don’t want to sacrifice performance for fuel efficiency. Car

manufacturers are attempting to bridge that gap to provide drivability enjoyment and still be

environmentally-conscious.

9.5 Professional and Ethical Responsibility

As an engineer there are many responsibilities that have to be upheld. It is understood that

as a group of people who design things that are being utilized by people every day, worldwide, all

things have to be safe for consumer use. With this project it affects how society commutes and

thus needs to be impeccable when it comes to performance. The project objective would be to

make sure that the design and use of this product will be safe for people’s cars and perform as

advertised.

9.6 Life-Long Learning Experience

The full research and development of this project has shown that theories and information

is always changing. Existing theories can always be applied in new and different ways and

information is always being adapted into new technologies. Life-long learning is paramount to

being a well-rounded individual with understanding of all modern-day engineering phenomena.

58

9.7 Discussion

This project is suitable even for professional engineers, since as stated, optimization is a

very complex and arduous process. It is challenging for undergraduate and post-graduate

engineers that are looking to further their understanding of a common mechanical component that

is being used more and more in today’s market. It delves deeply into advanced fluid dynamics

phenomena that remains a mystery even amongst today’s engineers. It allows an engineer to

challenge the understanding of fluid dynamics, manufacturing abilities, and manufacturability

assessment.

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10. Conclusion

10.1 Conclusion and Discussion

The motivation is the biggest driving force for the passion of optimizing the compressor.

Being able to optimize this technology to make it optimal for everyday use is something that can

produce a big demand. Fuel economy is a rising problem that more and more people are becoming

aware of. Society is becoming more aware of being environmentally friendly and this technology

could provide a different option that allows expanding into a field to create more efficient engines.

Improving compressors is a big step on the fuel consumption field, since it will make an already

efficient system even more efficient, this technology will for sure impact today’s markets, and

making a change is a big possibility and with the proper study and development.

10.2 Evaluation of Integrated Global Design Aspects

As been noted in all global design aspects, turbocharger technology is a huge increasing

global market. There will be an increasing demand for it in many years to come. This demand

creates a supply for engineers that understand the concepts behind how turbochargers work.

Turbocharger technology will always be around as long as there is a dependency for fossil fuels.

10.3 Evaluation of Intangible Experiences

When taking on a new project there is always an uneasy feeling of where to start or how.

In engineering there is an abundance of information about physical phenomena, and yet among all

that information there is still a vast expanse of things yet to be discovered. In the midst of this

whole project, the team has been subjected to tremendous pressure, obstacles, and satisfaction.

Being that the team consists of a group of engineers that live, eat, and breathe automotive sports

performance, this project exudes feelings of familiarity. Turbocharger technology is used a lot in

the racing performance world, and being able to research ways to provide the excitement that

60

comes with modifying a car and enhancing its performance, while still achieving a clean conscious

among environmental standards is extremely gratifying. There is a deep sense of pride and joy

when recognizing that a lot of what has been learned in the length of the team’s collegiate career,

can be used to fuel a passion that burns from within. When something that is enjoyed as a hobby

can actually be crafted into a career, it is in most times, unheard of. There is a quote that resonates

all these feelings in one simple sentence, “If you do what you love, you’ll never work a day in

your life”.

10.4 Commercialization Prospects of the Product

The feasibility assessment of the project explains how there is a huge demand from this

market and many chances to grow. Following the feasibility assessment and pursuing turbocharger

companies, the commercialization future of this project is very bright. DieselSite Wicked Wheels

is a company that would be the first of many that is looked at for commercializing this project’s

idea and design. There are many turbocharger companies that this idea can be pitched to such as

Garrett, Honeywell, Cummins, Caterpillar, Mitsubishi, Borg Warner, Bosch, Turbonetics, and

many more.

10.5 Future Work

In retrospect, there are a lot of areas where things can definitely be done more intensively,

such as the simulations. It is common knowledge that when dealing with Computational Fluid

Dynamics (CFD) there are better simulation software programs than SolidWorks. ANSYS is a

software that can run intensive CFD analysis and was not used in this project’s scope. There are

also many companies that can evaluate the overall design of the compressor wheel design, such as

CFturbo Software and Engineering. When looking for machining possibilities, DieselSite Wicked

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Wheels could be a possibility that can deliver a quality product. More importantly, the biggest

obstacle that was faced was funding and it is something that could be improved.

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References

1. Whitfield, A. & Baines, N. C. (1990). “Design of Radial Turbomachinery.”, Longman

Scientific and Technical.

2. Aungier, Ronald H., (2000). “Centrifugal Compressors: Strategy for Aerodynamic Design

and Analysis.”, American Society of Mechanical Engineers.

3. Goria, Rama S.R (2003). “Turbomachinery: Design and Theory.”, Decker Mechanical

Engineering

4. Robinson, Chris & Hutchinson, Brad. (2013). “Turbo compressor optimization.”, ANSYS

Inc.

5. Zangeneh, M., Nikpor, B., Watanabe, H. (2010). “Development of a high performance

centrifugal compressor using a 3D inverse design technique.”, Cummin Turbo

Technologies Ltd.

6. Ibaraki, S.,Tomita, I., Ebisu, M., Shiraishi, T. (2012). “Development of a Wide-range

Centrifugal Compressor for Automotive Turbochargers.”, Mitsubishi Heavy Industries

Technical Review Vol.49 No.1.

7. Zhou, Yayun. (2010). “Optimization with Ruled Surface.”, Logos Verlag.

8. Wilcox, Ed. (2000). “Practical Methods For Field Performance Testing Centrifugal

Compressors.”, Conoco, Inc.

9. Garret by Honeywell. (2012). "Wheel Trim." Retrieved September 20, 2014, from:

http://www.turbobygarrett.com/turbobygarrett/wheel_trim

10. U.S. Department of Energy. "Energy Efficiency & Renewable Energy." 2012 Annual

Merit Review, Vehicle Technologies Program. (2012).

63

11. National Highway Traffic Safety Administration (NHTSA). "CAFE-Fuel Economy."

Retrieved November 20, 2014 from: http://www.nhtsa.gov/fuel-economy

12. Bell, Corky (1997). "Maximum Boost: Designing, Testing, and Installing Turbocharger

Systems", Bentley Publishers.

13. ©Stage Infinity. "Mitsubishi TD04-13T Turbo Rebuild." Retrieved November 23, 2014

from: http://www.stage-infinity.com/2007/09/28/mitsubishi-td04-13t-turbo-rebuild/

14. Honeywell Turbo Technologies (2014). "2014 Global Turbo Forecast." Retrieved

November 20, 2014 from: http://turbo.honeywell.com/whats-new-in-turbo/2014-turbo-

forecast/

15. 1A Blog (2012). "Is your turbo Subaru on borrowed time?." Retrieved November 25,

2014 from: http://blog.1aauto.com/2012/05/30/got-subaru-turbo-read/

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Appendices

A. Detailed Engineering Drawings of All Parts, Subsystems and Assemblies

Figure 38. Technical drawing for concept design.

65

B. Copies of Used Commercial Machine Element Catalogs

Figure 39. Mitsubishi TD04-13T Turbo Rebuild.

66

C. Detailed Raw Design Calculations and Analysis

Figure 40. Adaptation of Bernoulli’s Equation.

Table 7. Full tabulated data with simulation results of 90 random generated designs.

BSR TSR Angle BSPy BSPz TSPy TSPz InitialAngle Average V Max V

1 1.3 3.1 88 10.875 -13.1 16.48 -18.4 56 116.111 701.408

2 1.3 2.2 94 10.625 -13.3 16.09 -17.7 26 105.905 442.422

3 2.8 3.7 79 10 -14.3 16.74 -19.45 56

67

4 3.4 1.3 73 11 -13.7 15.83 -20.15 44 122.956 761.344

5 1.9 2.8 88 10.375 -12.7 16.48 -18.4 74 111.054 458.486

6 2.2 1.9 85 10.5 -13.5 16.61 -17.35 62 117.615 556.984

7 3.7 3.4 100 9.875 -12.5 15.96 -19.1 32 103.272 456.158

8 3.1 2.5 91 10.875 -13.1 16.87 -19.8 80 117.91 455.994

9 1.6 4 76 10.25 -14.1 16.22 -18.05 50 120.802 411.994

10 1.6 1.3 88 9.875 -14.3 16.35 -17.35 80 118.522 457.038

11 3.1 2.8 73 10.5 -13.3 17 -19.1 50 120.079 608.834

12 4 1.9 82 10.125 -12.9 15.96 -20.15 68

13 2.5 3.4 97 10.75 -13.9 16.61 -18.4 38 101.283 735.641

14 2.2 2.2 79 10 -12.7 16.48 -17 44

15 3.7 3.7 94 10.625 -13.7 15.83 -18.75 74 97.965 628.581

16 2.8 1.6 100 10.25 -14.1 16.87 -19.8 32 108.284 525.369

17 1.3 3.1 85 10.875 -13.1 16.22 -18.05 62 119.712 441.177

18 1.3 1.6 73 10.875 -12.7 15.83 -19.45 74 128.399 452.815

19 2.8 3.1 88 10.25 -13.7 16.48 -17.7 44 109.733 720.78

20 3.7 2.5 97 10.5 -14.3 16.22 -18.4 56 110.661 487.945

21 2.2 4 82 9.875 -13.3 16.87 -20.15 26 110.657 463.037

22 2.5 2.2 91 11 -13.9 17 -18.75 50 111.101 492.726

23 4 3.7 76 10.375 -12.9 16.35 -17 80 119.812 413.706

24 3.4 1.3 85 10.75 -12.5 16.74 -18.05 38 120.122 833.287

25 1.9 2.8 100 10.125 -13.5 16.09 -19.8 68 105.807 459.986

26 1.6 2.5 79 10.375 -13.9 15.96 -19.1 32

27 3.1 4 94 11 -12.9 16.61 -17.35 62 105.841 521.627

28 4 1.9 88 10 -13.3 16.35 -18.4 44 105.841 521.627

29 2.5 3.4 73 10.625 -14.3 17 -20.15 74 118.834 500.628

30 1.9 1.6 97 10.125 -13.1 16.74 -18.75 56 109.64 520.03

31 3.4 3.1 82 10.75 -14.1 16.09 -17 26 114.942 432.097

32 2.8 2.2 76 9.875 -13.5 16.48 -17.7 68

33 1.3 3.7 91 10.5 -12.5 15.83 -19.45 38 114.295 475.831

34 1.3 1.3 82 10 -14.1 16.87 -18.4 62 121.638 511.517

35 2.8 2.8 97 10.625 -13.1 16.22 -20.15 32 108.102 508.753

36 3.4 2.2 88 10.25 -12.7 16.61 -19.45 74 121.634 668.243

37 1.9 3.7 73 10.875 -13.7 15.96 -17.7 44 121.043 689.082

38 2.5 2.5 100 9.875 -12.9 15.83 -18.05 26 99.603 454.196

39 4 4 85 10.5 -13.9 16.48 -19.8 56 116.071 590.602

40 3.1 1.6 79 10.125 -14.3 16.09 -19.1 38 120.805 778.342

41 1.6 3.1 94 10.75 -13.3 16.74 -17.35 68 107.114 459.192

42 1.9 1.9 73 10.5 -12.9 16.87 -18.4 44 123.855 792.368

43 3.4 3.4 88 9.875 -13.9 16.22 -20.15 74 117.226 673.151

44 4 1.3 94 10.875 -13.5 16.48 -19.1 26 117.717 449.969

68

45 2.5 2.8 79 10.25 -12.5 15.83 -17.35 56 116.63 463.709

46 2.2 1.6 91 10.75 -13.7 16.09 -17.7 80 119.856 586.095

47 3.7 3.1 76 10.125 -12.7 16.74 -19.45 50 119.006 632.36

48 3.1 2.2 82 11 -13.3 16.35 -18.75 62 118.388 459.318

49 1.6 3.7 97 10.375 -14.3 17 -17 32 96.856 520.948

50 1.3 2.5 88 10.125 -13.5 16.74 -20.15 50 119.094 433.789

51 2.8 4 73 10.75 -12.5 16.09 -18.4 80 120.295 454.629

52 3.7 1.6 82 9.875 -13.1 17 -17.35 38 120.052 807.531

53 2.2 3.1 97 10.5 -14.1 16.35 -19.1 68 106.4 479.721

54 2.5 1.3 76 10.375 -13.3 16.22 -19.8 74 125.066 503.446

55 4 2.8 91 11 -14.3 16.87 -18.05 44 114.898 514.692

56 3.4 1.9 100 10 -13.9 15.96 -17 62 109.791 528.285

57 1.9 3.4 85 10.625 -12.9 16.61 -18.75 32 120.986 488.721

58 1.6 1.9 97 11 -12.5 16.48 -19.8 56 123.958 481.339

59 3.1 3.4 82 10.375 -13.5 15.83 -18.05 26 124.317 504.685

60 3.7 2.5 76 10.75 -13.9 16.74 -17.35 68 129.993 496.261

61 2.2 4 91 10.125 -12.9 16.09 -19.1 38 121.09 510.223

62 1.9 2.2 85 10.875 -14.1 16.35 -19.45 32 107.536 431.058

63 3.4 3.7 100 10.25 -13.1 17 -17.7 62 98.43 493.191

64 2.8 1.3 94 10.625 -12.7 15.96 -17 50 119.38 476.699

65 1.3 2.8 79 10 -13.7 16.61 -18.75 80 126.109 479.253

66 1.3 1.9 94 10.375 -13.1 16.61 -18.05 68 105.54 429.295

67 2.8 3.4 79 11 -14.1 15.96 -19.8 38 122.135 440.775

68 3.4 2.5 85 10.125 -13.7 16.87 -18.75 80 119.732 471.428

69 1.9 4 100 10.75 -12.7 16.22 -17 50 105.888 530.54

70 2.2 2.2 76 10.25 -13.9 16.35 -18.4 32 124.881 475.854

71 3.7 3.7 91 10.875 -12.9 17 -20.15 62 111.132 446.68

72 3.1 1.3 97 10 -13.3 16.09 -19.45 44 117.43 516.313

73 1.6 2.8 82 10.625 -14.3 16.74 -17.7 74 128.095 470.584

74 1.9 2.2 100 10.875 -13.9 16.61 -17.7 44 107.772 460.685

75 3.4 3.7 85 10.25 -12.9 15.96 -19.45 74 119.21 677.719

76 4 1.6 76 10.5 -12.5 17 -18.75 26 122.234 452.31

77 2.5 3.1 91 9.875 -13.5 16.35 -17 56 107.992 451.221

78 2.2 1.3 79 11 -12.7 16.22 -18.4 80 127.881 484.661

79 3.7 2.8 94 10.375 -13.7 16.87 -20.15 50 109.894 662.817

80 2.8 1.9 88 10.625 -14.3 15.83 -19.1 62 117.992 446.076

81 1.3 3.4 73 10 -13.3 16.48 -17.35 32 126.001 453.217

82 1.6 1.9 82 9.875 -12.5 16.74 -19.8 50 120.193 826.157

83 3.1 3.4 97 10.5 -13.5 16.09 -18.05 80 108.432 621.51

84 3.7 1.3 91 10.25 -14.1 16.48 -17 32 109.192 509.27

85 2.2 2.8 76 10.875 -13.1 15.83 -18.75 62 114.489 462.523

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86 2.5 1.6 94 10.125 -14.3 15.96 -20.15 68 111.776 497.388

87 4 3.1 79 10.75 -13.3 16.61 -18.4 38 117.588 444.523

88 3.4 2.5 73 10.375 -12.7 16.22 -17.35 56 118.789 459.106

89 1.9 4 88 11 -13.7 16.87 -19.1 26 109.487 462.956

90 1.6 1.6 76 10.625 -13.5 17 -19.45 56

D. Project Photo Album

Figure 41. Compressor wheel from used turbo.

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Figure 42. Top view of 3D printed acrylic.

Figure 43. Stock compressor wheel alongside 3D printed ABS plastic final design.

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Figure 44. Rendering of final design.

Figure 45. Used compressor wheel, 3D printed ABS plastic, 3D printed polyjet acrylic.

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Figure 46. Clearance between final design and housing.

Figure 47. Measurement with L ruler.

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Figure 48. Isometric view of final design in 3D printed acrylic.

Figure 49. First clearance test with rough 3D printed ABS plastic.

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Figure 50. First clearance test.

Centrifugal Compressor Optimization Final Report

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Transcript of Centrifugal Compressor Optimization Final Report