Optimization of Cooling Water Pump By Changing Impeller ... · PDF fileOptimization of Cooling...

IJSRD - International Journal for Scientific Research & Development| Vol. 2, Issue 03, 2014 | ISSN (online): 2321-0613

All rights reserved by www.ijsrd.com 1001

Optimization of Cooling Water Pump By Changing Impeller Blade Angle

Using CFD Analysis Maulik B. Patel

1 Professor. K.P. Khamar

2

1PG Student (I.C. Atomobile)

2Assistant Professor M.Tech. (Design Engineering)

1Laljibhai Chaturbhai Institute of Technology, Bhandu, Mehsana, Gujarat, India

Abstract--- To study about the behaviour of flow inside the

cooling water pump, we done extensive search and gone

through number of research papers and blogs. Many

researchers carried out their analysis on cooling system

components like radiator, coolant, water jackets, fin

materials etc. but it is very difficult to find the researcher

that works on cooling water pump. Cooling system consist

centrifugal pump which is widely used in other industries.

After reviewing some research papers on centrifugal pumps

we found that most of the problems are related to cavitation

and efficiency. Computational Fluid Dynamics (CFD)

analysis is one of the advance tool used to understand the

behaviour of fluid. A detailed CFD analysis is done to carry

out the flow pattern inside the impeller which is an active

component of pump. After analyzing some old water pumps

of various vehicles we found that major problem that pump

is facing is due to cavitation effect on blades at High RPM.

This research is aimed to analyze the flow behaviour by

modifying the impeller design by choosing blade angle.CFD

analysis is done using ANSYS CFX software.

Keywords:- Impeller, Blade Angle, Automotive Pump,

CFX, Flow Rate, Cavitation, Efficiency

I. INTRODUCTION

A centrifugal pump is the key part of the automotive cooling

system that keep circulates the coolant through the system

and takes away the excess heat generated by combustion of

fuel inside the engine cylinder. In the centrifugal pump

impeller is the key part which circulate the coolant through

thorough the pump. However, design and performance

prediction process of impeller is still a difficult task. The

significant cost and time of the trial-and-error process by

constructing and testing physical prototypes reduces the

profit margins of the pump manufacturers. Due to this

reason CFD analysis is used as advanced tool to design and

analyze the flow inside the impeller. Moreover, design

modification can be done easily and thus CFD analysis

reduces the product development time and cost. This

research is carried out the analysis of existing cooling pump

of car (Maruti SUZUKI Alto), to improve the efficiency of

pump and reduce the cavitation effect inside the pump by

changing impeller blade angle.

Fig. 1: Construction of Centrifugal Pump

II. LITERATURE REVIEW

A. M.H. Shojaee Fard And F.A. Boyaghchi: 2007 [1]

in this

study the centrifugal pump is used to obtain the experiment.

Here, three different viscous fluids are used for study and

impellers with different outlet angles are used.

Centrifugal pump is single axis suction and vane

less volute casing and impeller of 208mm outside diameter

and with 6 backward curved blades. It is driven by three

phase AC electric motor, whose rated power is 5.5 Kw and

speed is 1450 RPM.

For investigating the influence of blade outlet

angles, three impellers with blade outlet angles of 22.5°,

27.5° and 32.5° are manufactured and simulated.

Working fluids are special transparent viscous oil

refined from crude oils and trap water. They are Newtonian

fluids verified by using rotary viscosity meter. The density

and kinematic viscosity of the oils are 875 kg/m³ and

43×10^-6 m²/s and 878 kg/m³ and 62×10^-6 m²/s,

respectively. The density and kinematic viscosity of the tap

water are 1000kg/m³ and 1×10^-6 m²/s, at 20°c,

respectively.

The pump suction and discharge pressure are

measured by pressure gauges and the torque meter is used to

measure the shaft torque and speed of the pump.

The pump design is shown in below figures

Fig. 2: Impeller configurations with blade outlet angle of

27.5°

Fig. 3: Impeller configurations with blade outlet angle of

22.5°

Optimization of Cooling Water Pump By Changing Impeller Blade Angle Using CFD Analysis

(IJSRD/Vol. 2/Issue 03/2014/260)


Comparisons of numerical and experimental results

for various blade outlet angles are shown in below figure.

Fig. 4: Influence of different blade outlet angles on

performance of centrifugal pump when handling the viscous

oil (υ=43×10^-6 m²/s)

Fig. 5: Influence of different blade outlet angles on

performance of centrifugal pump when handling the viscous

oil (υ=62×10^-6 m²/s)

III. CONCLUSION

When the blade outlet angle increases, the width of wake at

the outlet of impeller decreases, this phenomenon causes the

improvement of centrifugal pump performance when

handling viscous fluids.

Centrifugal pump performance goes down when

the pump handles high viscosity working fluids because of

high viscosity results in a rapid increase in the disc friction

losses over outsides of the impeller shroud and hub as well

as in hydraulic losses in flow channels of pump.

A. ZHU Bing, CHEN Hong-Xun: 2012 [2]

in this study low

specific speed centrifugal pump was designed with pump

head and flow rate are 20meter and 14m³/hr respectively.

There are four cylindrical 2-D blades in the impeller with a

blade inlet diameter ( D1 ) of 0.0534 m, an outlet diameter (

D2 ) of 0.255 m and a rotating speed of 1 450 RPM.

Here all the main parameters were in same

conditions, and a new structure of impeller with small vise

blade was designed and put aside of the suction surface of

the main blade at the leading edge. Thus a gap is formed

between the overlap area of the main and vice blades. This

type of design is shown in below figure.

Fig. 6: Scheme of Conventional impeller

Fig. (7): Scheme of Gap impeller

Result

Fig. 8: Cavitation performance comparisons between

conventional impeller and gap impeller

The experimental cavitation performances of the

conventional and gap impeller centrifugal pump were

displayed at two flow rates (one is at best efficiency point

(BEP), and another is at 1.35Q/QBEP) as shown in fig. 2.7

It is shown that the gap impeller can greatly suppress the

generating of cavitation, which is more obvious at a larger

flow rate.

Fig. 9: Iso surface of water vapor volume fraction (σ

=0.178) for conventional and gap impeller respectively




It is shown that cavitation is fully developed and

there is some blocking in the region close to the inlet and

shroud of conventional impeller, while there is only a

primary cavitation on the main blade lading suction surface

located in the controlled gap tunnel for the gap impeller.

IV. CONCLUSION

The structure of gap impeller can effectively inhibit

cavitation generating, which is more apparent in large

flow area.

The numerical prediction of cavitation performances

agree well with experimental results qualitatively.

A. B.Jafarzadeh, A.Hajari, M.M.Alishahi, M.H.Akbari:

2011[3]

in this study the simulated pump includes a two way

inducer and a 6-blade impeller with Dimpeller / Dinlet of

1.53 and Doutlet / Dinlet of 0.56. The rotational speed of the

pump is over 13000 RPM

Here various turbulence models like standard K-Ɛ

model, RNG K- Ɛ model and RSM model are utilized at a

constant blade number of 6 for the pump and these three

turbulence models were compared with the available

experimental data.

Then after the effect of number of blades on the

pump efficiency will be analyzed through three blade

number of 5, 6 and 7.

Result

Fig. 10: Head coefficient v/s Flow coefficient with three

different turbulence models and one available experimental

data

The curves show that with increasing the flow

coefficient, the head coefficient is decreased. Comparing

various turbulence models data with experimental data, it

has been concluded that each of these turbulence models

provide acceptable results, but two models RNG K– Ɛ and

RSM show better agreement than the standard K– Ɛ model.

Fig. 11: Head coefficient v/s Flow coefficient with different

numbers of blades

In low flow rates, head coefficient for 6 and 7-

blade pumps are very close and higher than 5-blade pump.

With increasing the flow rate, the head coefficient for the 5-

blade pump does not change but this characteristic for 6 and

7-blade pumps decreases. The 6- blade, however, has a

steeper slope than the 7-blade pumps and shows a strong

decrease of head coefficient at higher flow rates. Generally,

it is clear that the impeller with 7 blades has the highest

head coefficient when compared with 5 and 6- blade pumps

at all ranges.

V. CONCLUSION

In the present investigation numerical simulation of a high

speed centrifugal pump was performed, the best result

appears to be obtained by RNG K-Ɛ model.

Investigation on the effect of numbers of blades on

the efficiency head co efficient shows that the impeller with

7 blades has the highest head co efficient when compared

with 5 and 6-blade pumps at all ranges

VI. . PROBLEM IDENTIFICATION

From the literature review, we come to know that, the

design parameters of SI engine pump are calculated by

computers with more accuracy and convenience when it

needs to change any parameter of pump. However, the

actual tests are still required to compare the results carried

out from computers.

After reviewing all research papers on centrifugal

pumps we found that most of the problems are related to

cavitations and low efficiency. After analyzing some water

pumps of vehicles we found that major problem that pump

is facing is due to cavitation effects on blades and also

cooling efficiency is not good for high speed of engine.

This research aimed to study the cavitation

phenomenon on existing water pump and reduce the

cavitation phenomenon by changing the impeller blade

angles but without affecting the performance of cooling

system. The improvement in the performance of the pump is

predicted up to 5-10 % which directly results in to improved

engine power output.

VII. RESEARCH METHODOLOGY

Measuring the water pump (SI) dimensions and features

using reverse engineering tool system.

By using CAD software pump’s solid model is

developed.

Practical data of pumps is taken from research carried

out on it.

Meshing of solid model is done using FEA tool at

different operating conditions on the model.

Evaluation of pump’s performance with different

configurations.

Modify the pump’s blade angle and evaluated its

performance using finite element model

Recommendation and suggestion is welcome at the end

of the project.

VIII. CFD ANALYSIS OF PUMP USING DIFFERENT BLADE

OUTLET ANGLES

A. Modeling Of Cooling Pump: As computer-aided design

(CAD) has become more popular, reverse engineering has




become a viable method to create a 3D virtual model of an

existing physical part. The reverse-engineering process

involves measuring an object and then reconstructing it as a

3D model. The pump model geometry is complex and

asymmetric due to the blade and volute shape. The 3D CAD

software was used to make 3D model of Engine water

pump.

Fig. 12: CAD Model of Cooling Pump

B. Model Of Impeller:

Fig. 13: Model of Impeller In Bladegen

BladeGen is a component of ANSYS

BladeModeler. The BladeModeler software is a specialized,

easy-to-use tool for the rapid 3-D design of rotating

machinery components. Incorporating ANSYS, Inc’s

extensive turbomachinery expertise into a user-friendly

graphical environment, the software can be used to design

axial, mixed-flow and radial blade components in

applications such as pumps, compressors, fans, blowers,

turbines, expanders, turbochargers, inducers and others.

C. Mesh Generation: In computational fluid dynamics,

meshing is a discrete representation of the geometry that is

involved in the problem. Essentially, it assigns cells or

smaller regions over which the flow is solved. Several parts

of the mesh are grouped into regions where boundary

conditions may be applied to solve the problem.

Fig. 14: Meshing in Rotating Fluid Domain

Table 3.1 Details of Mesh Generation

Blade Total No. of Elements Total No of Nodes

Angle (°) (Element type is

Tetrahedra)

20° 650540 136587

30° 648529 136182

38.3° 633923 132272

40° 631968 131798

50° 621366 129537

D. Input Data: In this research first of all we analyze the

behaviour of flow on impeller by considering the Speed

=3000 RPM and Flow Rate=0.8 kg/s remain constant for all

case and then best efficient angle will be selected.

Table. 3.2:

Impeller Specification

Impeller Outside Diameter 61 mm

Inlet Diameter of Impeller 38 mm

Flow Type Radial Flow

Blade Type Circular 2D

No of Blade 7 (CCW)

Head(measured from bottom of radiator

to the inlet to water jackets) 0.5 m

Fig. 15: Total Boundary Details

Theoretical Calculation Of Efficiency At Different Outlet

Blade Angle:

E. Input Data

Inlet diameter of impeller D1= 38 mm = 0.038 m

Outlet diameter of impeller D2 = 61 mm = 0.061 m

Speed N = 3000 rpm

Vane angle at inlet Ө = 22°

u2

V

w2 ß Ø

V

2

Vf

2

V1

=Vf

1

Vr1

u1

Ө




Vane angle at outlet ɸ = 38.3°

Water enters radially means α = 90° and Vw1 = 0

Velocity of flow Vf1 = Vf2

Input power = 34 kW (engine bhp at maximum rpm)

1) Tangential Velocity Of Impeller At Inlet And Outlet Are:

u1 = ΠD1N / 60 = 3.14*0.038*3000 / 60 = 5.5690 m/s

u2 = ΠD2N / 60 = 3.14*0.061*3000 / 60 = 9.5818 m/s

2) From Inlet Velocity Triangle:

tanӨ = Vf1 / u1 = Vf1 / 5.5690

tan 22 = Vf1 / 5.5690

Therefore, Vf1 = Vf2 = 2.2500 m/s

3) From Outlet Velocity Triangle:

tan ɸ = Vf2 / (u2-Vw2) = Vf2 / (9.5818-Vw2)

tan 38.3 = Vf2 / (9.5818-Vw2)

Vw2 = 6.7328 m/s

4) The Work Done By Impeller Per Kg Of Water Per

Second:

(Vw2 * u2) / g = 6.5761 m

5) Weight Of The Water Lifted = Ρ*G*Q = 1000 * 9.81 *

0.0007 = 6.867 Kg:

6) Efficiency Of Pump:

ɳ = (ρ*Q* Vw2* u2) *required head/ input power =

66.40 %

Table. 2: Output Data

Blade

Angle (°)

Calculated Efficiency

(%) Head Achieved (m)

20° 34 % 3.3209 m

30° 56 % 5.5524 m

38.3° 66.40 % 6.5761 m

40° 68 % 6.7395 m

50° 76 % 7.5149 m

Blade Angle (°)

15 20 25 30 35 40 45 50 55

Effic

iency

(%)

30

40

50

60

70

80

Blade Angle (°) vs Efficiency (%)

Blade Angle (°)

15 20 25 30 35 40 45 50 55

Hea

d (m

)

3

4

5

6

7

8

Blade Angle (°) vs Head (m)

IX. RESULT AND DISCUSSION

For the CFD analysis of cooling pump, results are obtained

at different outlet angles of impeller. The values of mass

flow rate, speed and inlet pressure are also given as

boundary conditions values to the CFD solver equation.

Pressure contours will provide pressure values at all

locations of fluid profile and streamlines will give visualized

flow pattern and velocity of fluid at different locations too.

Fig. 16: Static Pressure Contour at 20° Outlet Angle


Fig. 18: Static Pressure Contour at 38.3° Outlet Angle






Fig. 21: Velocity Vectors at 80% at 20° Outlet Angle

Fig. 22: Velocity Vector at 80% at 30° Outlet Angle

Fig. 23: Velocity Vector at 80% at 38.3° Outlet Angle



Fig (26) Velocity Streamlines at 20° Outlet Angle


Fig (28) Velocity Streamlines at 38.3° Outlet Angle



Above results are showing plots for various fluid properties

related to different outlet angles of blade. Also after

reviewing all outputs we can conclude that at 40° outlet

angle the impeller performance is better than existing




impeller of pump. Numerically we got best efficiency at 50°

but from velocity streamline images we conclude that flow

become turbulent over blade as the angle increase beyond

40° that causes chances of cavitation. Now we will perform

analysis of impeller with stationary domain, whole domain

will take for analysis at 40° angle and then result will be

calculated and compare with the existing cooling pump

impeller with blade outlet angle 38.3°.

REFERENCES

[1] M.H. Shojaee Fard, F.A. Boyaghchi “Studies on the

influence of various blade outlet angles in a centrifugal

pump when handling viscous fluids” American journal

of applied sciences 4(9) :2007 ,ISSN 1546 – 9239, 718-

724

[2] ZHU Bing, CHEN Hong-xun, “CAVITATING

SUPPRESSION OF LOW SPECIFIC SPEED

CENTRIFUGAL PUMP WITH GAP DRAINAGE

BLADES” journal of hydrodynamics(science direct)

2012, DOI: 10.1016/S1001-6058(11)60297-7,

24(5):729-736

[3] B. Jafarzadeh ,*, A. Hajari , M.M. Alishahi , M.H.

Akbari , “The flow simulation of a low-specific-speed

high-speed centrifugal pump” applied mathematical

modeling 35(2011), 242-249

[4] Zhang Jinfeng, Yuan Shouqi, Fu Yuedeng，Yuan

Jianping “Influence Of Splitter Blades On The Total

Flow Field Of A Low-Specific Centrifugal Pump”

Technology and Research Center of Fluid Machinery

Engineering Jiangsu University, Zhenjiang

[5] Lamloumi Hedi, Kanfoudi Hatem, Zgolli Ridha,

“Numerical Flow Simulation in a Centrifugal Pump”

International Renewable Energy Congress November 5-

7, 2010 – Sousse, Tunisia

[6] Rodrigo Lima Kagami , Edson Luiz Zaparoli , Cláudia

Regina de Andrade “CFD analysis of automotive

centrifugal pump” 14th Brazilian Congress of Thermal

Sciences and Engineering , October18-22, 2012, Rio de

Janeiro, RJ, Brazil

[7] Tayfun E. Tezduyar.(1999). “CFD methods for three-

dimensional computation of complex flow problems”

Journal of Wind Engineering and Industrial

Aerodynamics 81 (1999) 97-116

[8] Marcus Vinı´cius C. Alves, Jader R. Barbosa Jr.*,

Alvaro T. Prata.(2012) “Analytical and CFD modeling

of the fluid flow in aneccentric-tube centrifugal oil

pump for hermetic compressors” international journal

of refrigeration xxx (2012) 1-11

[9] D. Gosman.(1998). “Developments In Industrial

Computational Fluid Dynamics” Institution of

Chemical Engineers Trans IChemE, Vol 76, Part A,

February 1998

[10] Jose Caridad1, Miguel Asuaje, Frank Kenyery1, Andrés

Tremante1, Orlando Aguillón1.(2008).

“Characterization of a centrifugal pump impeller under

two-phase flow conditions” Journal of Petroleum

Science and Engineering 63 (2008) 18–22

[11] K.W Cheah*, T.S. Lee, and S.H Winoto, 7th ASEAN

ANSYS Conference “Unsteady Fluid Flow Study in a

Centrifugal Pump by CFD Method” Biopolis,

Singapore 30th and 31st October 2008

[12] Bhavik M.Patel, Ashish J. Modi,Prof. (Dr.) Pravin P.

Rathod “Analysis Of Engine Cooling Waterpump Of

Car & Significance Of Its Geometry” International

Association For Engineering And Management

Education (IAEME), India

[13] S R Shah, S V Jain, V J Lakhera, 37th National & 4th

International Conference on Fluid Mechanics and Fluid

Power “CFD BASED FLOW ANALYSIS OF

CENTRIFUGAL PUMP” December 16-18, 2010, IIT

Madras, Chennai, India.

[14] R. K. Bansal, Fluid Mechanics, Laxmi Publication

2008.

Optimization of Cooling Water Pump By Changing Impeller ... · PDF fileOptimization of Cooling...

Documents

Transcript of Optimization of Cooling Water Pump By Changing Impeller ... · PDF fileOptimization of Cooling...