SHARDA MOTOR INDUSTRIES LTD.Research & Development

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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

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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

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Thank You

www.shardamotor.com