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SHARDA MOTOR INDUSTRIES LTD.Research & Development
Lets Do Great Things Together
An Alternative Acoustic Simulation Approach for
Exhaust Orifice Noise Optimization
Using GT POWER
AUTHORS:
Dr .S Rajadurai
HG Jo
Rajakumar
Gokul Raj
GT SUITE User Conference 2014 - India
13-10-2014
Lets Do Great Things Together
Contents
Introduction
Exhaust system validation process
Established acoustic development methods for exhaust
Alternative exhaust acoustic simulation method
Result comparison
Summary
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Introduction
Crucial parameter for achieving PASS BY NOISE norms
Cabin Interior & Exterior noise assessments
Subjective & Objective noise assessments
Engine performance
Tail pipe noise calculation with full engine model ,engine performance validation
Accuracy of Predicted results
Reduced Development Time
Reduced number of proto samples for testing , saves – cost & time
Exhaust Orifice Noise Significance
Simulation Requirement
GT POWER
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Acoustic Simulation Methodology
Acoustic Targets
Back Pressure Target
System Layout
Conceptual Design/Muffler Tuning Code
Acoustics & Back Pressure Result Evaluation
GT POST
Engine Modeling /Simulation
GTise
Engine Inputs
Engine Model
Component Modeling in
GEM 3D/GT Space Claim
Engine Bench TestingEngine Validation
& Establishing Result correlation
Result Review/Design Freeze
Design Fine Tuning
Inputs
Engine Test Bed
Noise testing in Anechoic chamber
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Muffler Conceptual Design
Acoustic & Back Pressure Simulation
Engine Bench test Validation
Noise Validation in Vehicle
Freeze Design
Acoustic & Back Pressure Targets
system Layout
Acoustic Development Flow Chart
Transfer function
Sound transmission loss
Insertion loss
Tail pipe Noise
Order analysis
Back Pressure
Inputs from clients
Linear acoustic analysisStandard Non Linear
Engine Simulation
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Disceritization
GT Space Claim GT GEM 3D
GTISE
Converting file types
Flow volume extraction
Building up solid models
Simplifying geometries etc..
Muffler internals
Disceritization
Absorption material etc..
Pre Processing
CAD file conversion
GTISE Component
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Established Acoustic Development Method For Exhaust
Sound Transmission Loss
Insertion Loss/ Tail pipe noise
Analysis
Noise Reduction &
Transfer Function
New Product
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Non Linear Engine Simulation
Over All Noise Level2nd Order 4th Order
1D Engine Model
Orifice Noise Result Validation
Throttle
body
Microphone
Muffler
assembly
Resonator
assembly
Catalytic
Converter
Exhaust
Manifold
Intake system
Engine
assembly
Acoustics simulation with full engine model
capturing exhaust acoustic characteristics
Engine performance analysis
Over all noise level, Order noise level ,
Insertion loss calculation
Back Pressure analysis etc..
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Sound Transmission Loss
Sound Transmission Loss Result
Sound Transmission Loss Template
Anechoic TerminationRigid Load
Speaker sound source
4 microphone impedance tube setup
Anechoic termination
Evaluation of individual components
Full system evaluation is not realistic
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Insertion Loss Analysis
Exhaust sound level with muffler Exhaust sound level without muffler
Insertion loss Simulation Setup
Insertion Loss - Noise level Difference between with and without muffler
Microphone
Microphone
LL
Insertion loss Graph
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Noise Reduction
Simulation Setup
NR Result
Speaker sound source
2 microphone impedance tube setup
Ambient condition
Individual component and full system evaluation
uncommonly used
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Intake System
Engine
GT - POWER
Exhaust Acoustic Result Validation
Muffler
EXHAUST SYSTEM
Over All Noise Level 2nd Order 4th Order
Validated Engine model
Orifice Noise Result Validation
6th Order Back pressure
Microphone
Exhaust parameters
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Acoustic Simulation without Engine
Acoustic parameters
End environment
template Microphone
Alternate acoustic simulation approach
Exhaust Layout
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Result Comparison
Orifice Noise level and back pressure values have reasonable correlation with measured result
Good correlation
between
two methods
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45°
Tailpipe Noise Measurement
Method 1: Prediction Using Engine Model Method 2: Prediction by Boundary Condition Method
Pressure
Temperature
Engine Out
Parameters
I
n
p
u
t
s
Mass flow
Summary
Kg/hr°Cbar
Alternate
Simulation method
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Conclusion
Linear simulation in GT Power allows quick performance evaluation of individual
exhaust components which has good correlation with measurement results
Non Linear simulation in GT produces realistic acoustic results for performing
exhaust performance validation
The boundary condition acoustic simulation approach needs only engine out acoustic parameters
as inputs which provides reasonable result in shortest time
The alternate simulation technique can be efficiently put forward into exhaust noise optimization
process to reduce the iterations done in non linear engine simulation
The final validation of the exhaust system is always recommended to carry out
in non linear engine models