International Journal of Research in Advanced Technology - IJORAT

Vol 2, Issue 3, MARCH 2016

All Rights Reserved © 2016 IJORAT 1

DESIGN AND ANALYSIS OF

HIGH EFFICIENT SOUND REDUCING

MUFFLER Arul Danie.J, Vignesh.V, Leo Martin.C, Kiran Krishnan.M

Panimalar Institute of Technology, Chennai.

Abstract: A pollutant of concern to the mankind is the exhaust noise in the internal combustion engine. However

this noise can be reduced sufficiently by means of a well-designed muffler. This design and development will help to

reduce the noise level, but at the same time the performance of the engine won’t be hampered by the back pressure

caused by the muffler. Noise control has become one of the most vital problems in present-day manufacture

including motor-car manufacture. Introduction of new technological processes, growth of power and speed of

technical equipment result in high-level noise man is constantly exposed to. Creation of new types of industrial and

automobiles with pre-set speed, power and load parameters is often accompanied by the increase of general noise

level and the expansion of sound oscillation spectrum. This project is mainly attention to design a muffler to reduce

the noise and back pressure.

Keywords: silencer -exhaust– muffler- noise – pollution- efficiency.

I. INTRODUCTION

The muffler is defined as a device for reducing the amount of

noise emitted by a machine. To reduce the exhaust noise, the

engine exhaust is connected via exhaust pipe to silencer called

muffler. The silencer makes a major contribution to exhaust

noise reduction. Internal combustion engines are typically

equipped with an exhaust muffler to suppress the acoustic

pulse generated by the combustion process. All internal

combustion engines produce noise, some more or less than the

others. The intensity and magnitude of the noise will vary

greatly depending upon engine type i.e. naturally aspirated or

turbocharged, horse power developed, means of scavenging,

type of fuel used, number of cycles whether two cycle or four

cycle engine etc. Sound is simply a vibration that spreads as a

wave through air. This vibration, or pulses of high and low

are pressure, move through the air at the rate of a mile in five-

seconds on the average – commonly referred to as “the speed

of sound.”

Fig.1 Constructive Interference

Fig.2 Destructive Interference

II. PROJECT DESCRIPTION

There is plenty of documentation on how sound waves

move and the way that sound waves move through mufflers,

but we can describe how formulas are used in locating the

chambers and tubes inside a muffler. Channels and chambers

inside a muffler are there for a reason. Certain sound

frequencies are eliminated and others are allowed to pass

through. Honestly, the most impressive thing that others

identify in an automobile right away is the sound that your

bike makes. Formulas used in targeting specific sound

frequencies are generally based on the number of cylinders of

the engine and the cylinder firing rate of the engine that an

engineer is designing a muffler for. Internal design depends

on space. Both the amount of space that is available in the

platform and the volume of the muffler required for the

engine size and rpm are important in calculating where

channels and baffles go. Each type of muffler has its

owndesign formulas and physics framework to adhere to

when designing a muffler for a new application.

International Journal of Research in Advanced Technology - IJORAT

Vol 2, Issue 3, MARCH 2016

All Rights Reserved © 2016 IJORAT 2

A. Project description and methodology

The Muffler design is done using the design software

CATIA developed by Dassault Systems’.

Fig 3 Wireframe figure

The design is done using various work benches in CATIA

such as Part design, Generative sheet metal design and

drafting workbenches. Many tools were used in this process.

Fig. 43D Part

The drafting part was done using draft workbench in catia and

the measurements are accurately described as seen in the

figure below

Fig.5 Draft

B. Gas Welding Process

Oxyacetylene gas welding is commonly used to permanently

join mild steel. A mixture of oxygen and acetylene, burns as

an intense / focussed flame, at approximately 3,500 degrees

centigrade. When the flame comes in contact with steel, it

melts the surface forming a molten pool, allowing welding to

take place. Oxyacetylene can also be used for brazing, bronze

welding, forging / shaping metal and cutting.

This type of welding is suitable for the prefabrication of steel

sheet, tubes and plates.

Gas Welding is a welding process utilizing heat of the flame

from a welding torch. The torch mixes a fuel gas

with Oxygen in the proper ratio and flow rate providing

combustion process at a required temperature. The hot flame

fuses the edges of the welded parts, which are joined together

forming a weld after Solidification.

The flame temperature is determined by a type of the fuel gas

and proportion of oxygen in the combustion mixture: 4500°F

- 6300°F (2500°C - 3500°C). Depending on the proportion of

the fuel gas and oxygen in the combustion mixture, the flame

may be chemically neutral (stoichiometric content of the

gases), oxidizing (excess of oxygen), carburizing.

Gas Welding equipment:

Fuel gas cylinder with pressure regulator;

Oxygen cylinder with pressure regulator;

Welding torch;

Blue oxygen hose;

Red fuel gas hose;

Trolley for transportation of the gas cylinders.

C.CNC Machining

The CNC machine comprises of the computer in which the

program is fed for cutting of the metal of the job as per the

requirements. All the cutting processes that are to be carried

out and all the final dimensions are fed into the computer via

the program. The computer thus knows what exactly is to be

done and carries out all the cutting processes. CNC machine

works like the Robot, which has to be fed with the program

and it follows all your instructions.This way your machine

can keep on doing the fabrication works all the 24 hours of

the day without the need of much monitoring, of course you

will have to feed it with the program initially and supply the

required raw material.

III. EXPERIMENTAL WORK

A. Measuring Backpressure

International Journal of Research in Advanced Technology - IJORAT

Vol 2, Issue 3, MARCH 2016

All Rights Reserved © 2016 IJORAT 3

Exhaust backpressure is measured as the engine is operating

under full rated load and speed conditions. Either a water

manometer or a gauge measuring inches of water may be

used. Refer the below figure.

Fig.6 Backpressure Measuring Instrument

Backpressure is commonly caused by one or more of the

following factors

Exhaust pipe diameter too small.

Excessive number of sharp bends in the System.

Exhaust pipe too long.

Silencer resistance too high.

Table 1 EXISTING MUFFLER DATAS

Exhaust

flow

rate (Q)

Exhaust

Temperature(T)

Maximum

backpressure(∆P)

600

kg/hr

600 oc 500 mm of water

873

cfm 1112 F

19.69 inches of

water

B. Measuring Sound

Sound is measured using microphone and an Android

application Called Smart Tools. The sound test was done by

keeping the microphone 3 meters away from the muffler.

Fig.7 Sound Meter

Fig.8 Graph

IV.ANALYSIS

Fig.9 Design model of the exhaust system

International Journal of Research in Advanced Technology - IJORAT

Vol 2, Issue 3, MARCH 2016

All Rights Reserved © 2016 IJORAT 4

Fig.10 Meshing

Fig.11 Contours

Fig.12 Vectors

IV. COST ESTIMATION

Table 2. Cost estimation S.NO COMPONENT AMOUNT

1. Sheet Metal 500.00

2. Gas Welding 250.00

3. Smart Tools 150.00

4. CNC machining 200.00

5 Sponge 50.00

V. FINISHED PRODUCT The figure shown below is the finished muffler before being

fitted on the automobile.

Fig.13 Product

The Figure shown below is the muffler fitted in the two stroke

bike.

Fig.10 Fitted on bike

VI. CONCLUSION From the above discussions, the following conclusions can be

drawn:

1. The muffler is capable of attenuating noise by about 15 to

20 dBA.

2. The muffler is designed to attenuate both high and low

frequency noises.

3. There is a side branch resonator, which attenuates residual

low frequency noise.

4. There is an option of tuning the resonator, which makes the

muffler flexible to use with different engines.

5. The conventional design of side branch resonator

construction involves the resonator connected perpendicularly

to the tail pipe, but in the present design, the resonator is

parallel to the main body of the muffler. This makes the

muffler usable with engines having limited space.

6. The reactive portion of the muffler has been covered with a

layer of absorptive material which considerably decreases the

self-generated noise of the muffler.

7. The material used in the muffler is capable to withstand

temperature of higher order. The resonator works pretty well

between a sound frequency of 220 Hz and 330 Hz, so if the

residual frequency exceeds the range, the resonator becomes

largely ineffective.

International Journal of Research in Advanced Technology - IJORAT

Vol 2, Issue 3, MARCH 2016

All Rights Reserved © 2016 IJORAT 5

ACKNOWLEDGMENT

We would like to thank the staff members of Mechanical

department of our college for their support and guidance

throughout the project.

REFERENCES

1. Bell, L.H., 1982, Industrial Noise Control, Marcel Dekker,

Inc, New York. Lilly, J.J., “Engine Exhaust Noise

Control”, ASHRAE Technical Board 2.6.

2. Miers, S.A., and R.D. Chalgren, “Noise and Emission

Reduction”, SAE Technical Paper Series 2000-01-2573.

3. CORSA Performance, 2004, “Reflective Noise

Cancellation”, Power Pulse RSC Technology.

4. Crouse, W.H. and D.A. Anglin, 2003, Automotive

Mechanics, 10th Edition, McGraw-Hill, New York.

5. 5."Exhaust Muffler For Engines Muffler Patent". Google.

Retrieved 22 June 2014.

6. 6."Exhaust Theory". NSX Prime. Retrieved 22 June 2014.

7. 7."Spiral Turbo Specialties:". spiralturbobaffles.com.

Spiral Turbo Specialties. Retrieved 22 June 2014.

8. 8."Aero Turbine Series Performance Exhaust

Mufflers". pickupspecialties.com. Pickup Specialties.

Retrieved 22 June 2014.