NOISE REDUCTION OF TWO WHEELER BY REDESIGNING …...Bajaj pulsar two wheeler by redesigning a spiral...

http://www.iaeme.com/IJMET/index.asp 1996 [email protected]

International Journal of Mechanical Engineering and Technology (IJMET)

Volume 10, Issue 01, January 2019, pp. 1996-2010, Article ID: IJMET_10_01_195

Available online at http://www.iaeme.com/ijmet/issues.asp?JType=IJMET&VType=10&IType=1

ISSN Print: 0976-6340 and ISSN Online: 0976-6359

© IAEME Publication Scopus Indexed

NOISE REDUCTION OF TWO WHEELER BY

REDESIGNING SPIRAL RESONATOR &

PERFORATED TUBE

Raghuram Pradhan, Sukumar Puhan and M. Sreenivasan

(Professor, Department of Mechanical Engineering, Pace IT&S, Ongole, A.P, India)

ABSTRACT

Background: In this study, the Component of normal exhaust system such as

muffler or silencer shell, perforated tube, spiral resonator design have been carried

out by SOLIDWORKS and a Finite Element Approach have presented for modeling

and analysis of muffler noise developed at different locations as well as temperature

distribution over silencer. The main objective of this study was to simulate and

investigate the performance of a general muffler by simulation and experimental

technique.

Methods: In order to minimize two-wheeler noise, testing were carried out in a

Bajaj pulsar two wheeler by redesigning a spiral resonator andperforator tube which

is capable of attenuating noise level by about 7 dBA (Decibels).

Results: The results obtained from simulation that as the distance increases from

inlet of silencer the sound pressure level decreases gradually.

Conclusions: Obtained results shows a significance decrease of sound pressure

level about 7 dBA from existing silencer to new designed silencer

Keywords: ANSYS-FLUENT, CFD & FEA, Mesh Controls,Noise Reduction,

Perforated Tube, Spiral Resonator and SOLIDWORKS etc..

Cite this Article: Raghuram Pradhan, Sukumar Puhan and M. Sreenivasan, Noise

Reduction of Two Wheeler by Redesigning Spiral Resonator & Perforated Tube,

International Journal of Mechanical Engineering and Technology, 10(1), 2019, pp.

1996-2010.

http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=10&IType=1

1. BACKGROUND

I.C. Engines are equipped with an exhaust muffler or silencer, to suppress the acoustic pulse

generated by the combustion process. A high intensity pressure wave generated by

combustion inside the engine cylinder which propagates along the exhaust pipe and

to attenuate this airborne noise of the engine sound reducer called muffler uses to decrease the

velocity of the exhaust gases and either absorbs sound waves or cancel them by interference

with reflected waves coming from the same source. Internal combustion engines are a major

https://www.merriam-webster.com/dictionary/attenuate



source of noise pollution after industries. Noise is an environmental pollutant with recognized

impacts on the psychological and physiological health of humans. Noise pollution made by

engines turns into a crucial concern when used in residential areas or areas where noise

creates hazard. Countries like India two-wheelers are becoming increasingly prevalent as a

means of transportation. If noise level of more than 80 dBA (decibels) is harmful for human

being. Mufflers have been developed over the last ninety years based on electro- acoustic

analogies and experimental trial and error. G. W. Stewart (1922) used electro – acoustic

analogies in deriving the basic theory and design of acoustic filters. Later D. D. Diviset

al.(1954) published results of a systematic study on mufflers. Igarashi et al. (1958) calculated

the transmission characteristics of mufflers using equivalent electrical circuits. A.V Sreenath

and L. Munjal (1970) gave expression for the attenuation of mufflers using the transfer matrix

approach . The expression they developed was based on the velocity ration concept.

Later,againL.Mujal(1975) modified this approach to include the convective effects due to

flow . C. I .J. Younget al.(1975) used the finite element method to predict four-pole

parameters and then the transmission loss of complex shaped mufflers for the case of no flow.

A.K.M.Mohumuddin (2005) did experimental study of noise and back pressure for silencer

design characteristics. The main objective of this study was to find the relationship between

the back pressure and the noise level. He concludes that the relationship between the noise

and the back pressure is inversely proportional. S.N.Y.Gerges et al. (2005) paper implies the

basic formulation of the Transfer Matrix Method (TMM) to predict the Transmission Loss of

muffler elements has been summarized. Experimental measurements were carried out for

different muffler configurations and compared to the numerical results obtained from TMM.

It was observed that in general a good agreement is obtained between the experimental and

numerical results. Reza Kashani et al.(2011) approach were based on adding tuned acoustic

damping to the combustion environment. By incorporating in-situ adjustability into acoustic

damping devices, they can change their mechanical attributes, e.g., mass and/or stiffness, and

adapt themselves in a semi-active manner to the varying instability frequency. Takashi

Yasuda(2013) studied on an automobile muffler with the acoustic characteristic of low-pass

filter and Helmholtz resonator. Based on the typical structure, a muffler with an

interconnecting hole on the tail pipe was proposed to improve its acoustic performance.

Acoustic performances of the proposed muffler were studied experimentally and theoretically

in frequency and time domain. Results showed that the specimen muffler had attenuation

performances of low-pass filter and Helmholtz resonator when an interconnecting hole was

designed on the tail pipe.The paper of Vishal Vaidya et al. (2014), emphasizes the role of

resonator on transmission loss in air intake system and its sound pressure level reduction.

Jigar H. Chaudhari (2014) speaks on the various types of mufflers and design of exhaust

system belonging engine has been studied. The object of this study is choosing muffler design

which one reduces a large amount of noise level and back pressure of engine. In designing,

there are various parameters which has to take in to the consideration. These parameters affect

the muffler efficiency. Absorptive muffler design uses only absorption of the sound wave to

reduce the noise level without disturbing the exhaust gas pressure. Ehsan Sabah M et

al.(2013) were conducted an experimental test for noise attenuation in gasoline engine with

different Types of mufflers. Compares between three different types of an exhaust muffler for

noise attenuation of single cylinder four stroke air-cooled gasoline engine. A set of

conclusions achieved about the effect of the mufflers chamber's expansion ratio, chambers

length, and wall thickness. Sound attenuation of 12.5, 15 and 16 dBA is achieved with, multi-

chamber reactive Muffler, concentric-tube resonator muffler and combined reactive and

dissipative muffler. Wei-Hong Tan et al.(2013) conducted an expansion chamber muffler with

the use of a micro-perforated panel (MPP) to improved acoustic performance. The result

showed that the performance of this muffler with an 80mm air cavity depth improved by

http://proceedings.asmedigitalcollection.asme.org/solr/searchresults.aspx?author=Reza+Kashani&q=Reza+Kashani

Noise Reduction of Two Wheeler by Redesigning Spiral Resonator & Perforated Tube


75%.At the same time they found that, the noise level was reduced by 20 dBA for the

frequency band of 125Hz to 4000Hz of the engine running at 3000±200 rpm. Bin Li1et

al.(2013) experimented a novel and practical acoustic energy harvesting mechanism to harvest

traveling sound at low audible frequency is introduced and studied both experimentally and

numerically. The acoustic energy harvester in this study contains a quarter-wavelength

straight tube resonator with Lead Zirconate Titanate (PZT) piezoelectric cantilever plates

placed inside the tube. M. L. Munjal (2013) development of long strand fibrous materials that

can be used in hot exhaust systems without binders has led to the use of combination mufflers

in exhaust systems. Breakthroughs have been achieved in the prediction and control of

breakout noise from the elliptical and circular muffler shell as well as the end plates of typical

mufflers.Yu, X et al.(2015) A muffler in the exhaust system of an internal combustion engine

reduces its power and increases fuel consumption. Jesus Madrigal et al.(2017)uses transfer

matrix method to calculate the frequency dependence of the transmission of longitudinal

elastic waves for a layered structure where the specific acoustic impedance of the layers with

odd numbering follows a Gaussian distribution, while the inserted even layers have the same

impedance as the propagation medium

2. DIMENSIONS AND DESIGN OF MODELS BY SOLIDWORKS

The SOLIDWORKS ® CAD Software is a Mechanical Design Automation application that

lets designers quickly sketch out ideas, experiment with features and dimensions, and produce

models and detailed drawings.

2.1. Design of spiral Resonator

Diameter of a spiral resonator, d = 70 mm, Diameter of mandrel, dm= 25 mm

Thickness of spiral profile, g = 3 mm, Lead of Spiral turn, s = 100 mm



Figure 1 Basic dimensions of Spiral resonator

2.2. Design of Chamber Separator:

Major Diameter of the chamber separator disk = 68 mm, Minor Diameter of the chamber

separator disk

= 30 mm, Thickness of disc = 10 mm, Number of discs = 2



Figure 2 Basic dimensions of Chamber Separator.

2.3. Design of Perforated Tube

Internal Diameter = 70 mm, Diameter of the perforated holes = 8 mm

External Diameter = 72 mm, Length of the tube = 400 mm

Figure3 Design of Exhaust Perforated Tube



Figure 4 Design of Exhaust Perforated Tube

2.4. Design of silencer shell

Diameter = 80 mm, Thickness=4mm, Length of the tube = 400 mm

Figure 5 Design of Silencer



Figure 6 Design of Perforated Tube

2.5. Design of Plate

External Diameter = 84 mm, Internal Diameter = 30 mm, Thickness = 4 mm

Figure 7 Design of Plate

3. COMPUTATIONAL FLUID DYNAMICS & FLOW ANALYSIS

Computational Fluid Dynamics also generally called CFD is an important branch of fluid

mechanics and it uses numerical methods and algorithms to analyse and solve fluid flow

problems. It has become popular since the previous methods, experimental and theoretical are

either very expensive, time consuming, or involve too much labour. In CFD, computers are

used to solve the algorithms that define and analyse the fluid flow. Due to the increase in the

computational capabilities over time and better numerical solving methods, most experimental

and theoretical work has been done using CFD. It is not only cost effective but it helps one

analyse and simulate complex geometries, heat transfer, and shock waves in a fluid flow. It

also helps solve partial differential equations (PDE) of any order in a fluid flow. This mainly

helps analyse the internal or external fluid flow. The use of CFD has become increasingly

popular in branches of engineering such as Aerospace to study the interaction of the



propellers or rotors with aircraft fuselage, Mechanical to obtain temperature distribution of a

mixing manifold, Bio-medical engineering to study the respiratory and circulatory systems.

Figure 8 Processes of CFD and FEA

4. FEA SOFTWARE

There are many FEA software’s available in the market. Some of them mostly used in

Industry are ANSYS, ANSYS WORKBENCH, MSC NASTRAN and ABACUS.Apply Mesh

Controls/Preview Mesh: Meshing is the process in which geometry is spatially discretized

into elements and nodes. This mesh along with material properties is used to mathematically

represent the stiffness and mass distribution of your structure. Model is automatically meshed

at solve time. The default element size is determined based on a number of factors including

the overall model size, the proximity of other topologies, body curvature, and the complexity

of the feature. If necessary, the fineness of the mesh is adjusted up to four times (eight times



for an assembly) to achieve a successful mesh. If desired, preview of the mesh is available

before solving. Mesh Controls: When in Simulation, your part or multi body part is

automatically meshed at solve time. The default element size is determined based on the size

of the bounding box, which is the smallest box that the part or assembly will fit in, as well as

the proximity of other topologies, body curvature, and the complexity of the feature. If

necessary, the fineness of the mesh is adjusted up to four times (eight times for an assembly)

to achieve a successful mesh using the assembly's bounding box first, then the part's bounding

box in the second pass. Define Analysis Type: We can choose the analysis type based on the

loading conditions and the response we wish to calculate. For example, if natural frequencies

and mode shapes are to be calculated, would choose a modal analysis. There are several types

of analyses we can perform in Simulation. The primary differences are in the specific types of

loads that we apply and results that review. Establish Analysis Settings:Each analysis type

includes a group of analysis settings that allow defining various solution options customized

to the specific analysis type, such as large deflection for stress analysis.

5. ANALYSIS OF SILENCER

Figure 9 Meshing of silencer

6. PROBLEM SETUP AND SOLUTION

The mesh was checked. The analysis type was changed to density based type and the velocity

formulation was changed to absolute. Time was changed to transient state. Models and

location of receivers: Energy was set on position and viscous model selected is LES model.

Subgris scale model is Smagorinsky-Lily sub model. For enabling LES model in 2-D, a TUI

command is to be used. The command is (rpsetvsr’les2-d? #t). Ffowcs-Williams& Hawking’s

acoustics model is used. The source of sound and receivers are specified.

Direction Distance from Inlet (mm)

Y 100

Y 200

Y 350

Y 440

Y 18728

The receivers are placed at inlet of the silencer and the distances are mentioned are above.

This distance is selected so that the source becomes a point source and a distribution of

acoustic pressure level does not change with angle of measurement.

Materials: Air (ideal gas) as fluid and stainless steel as solid was selected from the fluent

database by clicking change/create.

Properties given for the used fluid are:

Density : ideal gas density

Specific heat : 1006 j/kg-K (constant)



Thermal conductivity : 0.0242 W/m-K (constant)

Viscosity : 1.7894e-05kg/m-s (constant)

Cell zone conditions

The interior of the nozzle is assigned as fluid. Different boundary conditions were applied

for different zones. The boundary conditions are below

Location Type of Boundary

Condition Value

Inlet Pressure-inlet 1500000pa

Outlet Pressure-outlet 0.0pa

Inlet Temperature 623 k

Solution methods: The solution methods were set as follows

1. Formulation =implicit

2. Flux type =Roe-FDS

3. Gradient=least square cell based

4. Flow=second order upwind

5. Transient formulation=second order implicit

Initialization

Hybrid initialization is done. Convergence criteria

The convergence criteria were set to 10-4

Run calculationTime step size = 1s

Number of time steps=500

Number of iterations per time step=500

7. EXPERIMENTAL SET-UP & PROCEDURE (METHODS)

The details of the experimental set up are presented in this chapter the alternations made to

the instrumentation are also described .The experimental setup is fabricated to fulfil the

objective of the present work. The various components of the experimental set up including

modification are presented in this chapter. The silencer existed and new designed silencer is

fixed to the bike in below. The experimental set-up consists of spiral resonator, perforated

tube diameter 700mm, chamber separator, divergent, perforated tube of diameter 30mm, and

cylinder shell. Before starting the engine, the existing silencer is separated from the engine.

The designed silencer is fitted correctly. Then the decibel meter is placed at distance of

1900mm. The engine is allowed to run for 1 minute , so that it can get steady conditions are

attained. The various steps involved in the setting of the experiments are explained below

1. The Experiments were carried out after installation of the silencer.

2. Precautions were taken, before starting the experiment.

3. Always the engine was started with no load condition

4. The readings such as decibels are to be noted at intervals.

5. After completion of test, the load on the engine was completely relieved, then the

engine was stopped. Finally the results were noted.



Figure 10 (A) Bike with Existing Silencer

Figure 10 (B) Bike with New Designed Silencer

8. RESULTS

8.1. The Temperature Distribution over Silencer

Figure 11 Temperature Distributions Over Silencer

8.2. The noise developed at different locations in the simulation areas follows



Figure 12(A) (SPL / St no) Receiver-1 Graph

Figure 12(B) (SPL / St no) Receiver-2 Graph

Figure 12(C)(SPL/St no) Receiver-3 Graph Figure 12(D)(SPL/Stno) Receiver-4 Graph



Figure 12(E)(SPL / St no)Receiver Graph

8.3. The noises developed at outlet in existing silencer areas follows

Figure 13(A)Decibels of existing silencer

Figure 13(B)Decibels of Experimental(New) Silencer



9. CONCLUSIONS

The results obtained from simulation(refer fig.12) are at 100mm distance from inlet of

silencer, the sound pressure level is 130.946dBA.From 200mm distance from inlet of silencer,

the sound pressure level is 100.643dBA. From 350mm distance from inlet of silencer, the

sound pressure level is 95.12dBA. From 440mm distance from inlet of silencer, the sound

pressure level is 84dBA. From 18728mm distance from inlet of silencer, the sound pressure

level is 73.24dBA.From result of simulation, it has been concluded that the silencer design

has the lowest sound pressure level of 73.24dBA is generatedexperimental testing for new

designed silencer is 1900mm distance from outlet of silencer , the sound pressure level is 69

dBA. From experimental test (refer fig.13), it was concluded that there is decrease of sound

pressure level about 7 dBA from existing silencer to new designed silencer.

10. FUTURE SCOPE

Future experiments can be done with the addition of glass wool to the silencer. Experiments

can be extended with addition of multi tubes with this new design. With above modification

this silencer can be fitted to the sports bike to test the sound level also. The future research of

sound transmission and absorption can be done with bio-based materials, wood plastic

composites and carbon name tubes (CNT) also.

REFERENCES

[1] G. W. Stewart , Acoustic waves filters, Physics Review 20, 1922, 528-551.

[2] D. D. Divis, Jr. G.M. Stokes, D. Morse, and G.L. Stevens, Theoretical and Experimental

Investigation of Muffler with Comments on Engine- Exhaust Muffler Design,1954,NACA

1192.

[3] J. Igarashi and M.Toyama, Aeronautical Research Institute, Fundamental of Acoustical

Silencers. University of Tokyo, 1958,Report no.339, 223- 241

[4] M. L. Munjal , A.V. Sreenath and M. V. Narasimhan .Velocity ratio in the analysis of

linear Dynamical System. Journal of sound and Vibration 26, 1970,173-191 .

[5] M. L. Munjal Velocity Ratio Cum Transfer Matrix Method for the Evaluation of Muffler

with Neon Flow .Journal of sound and Vibration 39, (1975), 105-119.

[6] C. I .J. Young and M. J. Crocker(1975).Prediction to Transmission loss in Mufflers by

Finite Element Method.Journal of Acoustical Society of America 57, 144-148.

[7] A.K.M. Mohumuddin, Mohd Rashidin Ideres and Shukari Mohad Hashim, Experimental

Study of Noise and Back Pressure For Silencer Design Characteristics, Journal Of Applied

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[8] S. N.Y. Gerges and R. Jordan, F. A. Thieme, J. L. Bento Coelho, J. P. Arenas ,Muffler

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[9] Reza Kashani and Jeff Monfort, Low-Frequency Thermoacoustic Instability Mitigation

Using Adaptive-Passive Acoustic Radiators. ASME 2011 Turbo Expo, Paper No.

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[10] Yasuda, T., Wu, C., Nakagawa, N., Nagamura, K. (2013).Studies on an automobile

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[11] Mr. Jigar H. Chaudhari, Muffler Design for Automotive Exhaust Noise Attenuation - A

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http://proceedings.asmedigitalcollection.asme.org/solr/searchresults.aspx?author=Jeff+Monfort&q=Jeff+Monfort



[12] Ehsan Sabah M. AL-Ameen, Experimental Test for Noise Attenuation in Gasoline Engine

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