for Automotive Air Induction & Exhaust Systems Fabiano Bet - - PowerPoint PPT Presentation

Approaches for Acoustics Simulation for Automotive Air Induction & Exhaust Systems

Fabiano Bet Gerald Seider Simon Bless

Vienna, 18 March, 2014

Consulting, Engineering Services & Virtual Test Center

• Simulation and Analysis of

complex fluid flow and heat transfer systems for engineering and industrial applications

• Virtual Performance Testing

for automotive accessory units

InDesA GmbH  Carl-Zeiss-Ring 19a  D-85737 Ismaning  Phone +49 (89) 552 7978-10  Fax +49 (89) 552 7978-29  www.InDesA.de

Company Profile

1D System Analysis

GT-SUITE

3D CFD/CHT Analysis

STAR Global Conference Vienna, 18.03.2014 page 3

Acoustics Simulation for Automotive Systems Introduction

From engine Driving noise Body vibrations Mechanic and wheel noise

Aeroacoustics:

“…branch of acoustics that studies noise generation via fluid motion or aerodynamic forces interaction…” (source: Wikipedia)

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Acoustics Simulation for Automotive Systems Introduction

Noise generation via fluid motion:

e.g. Blowing in a bottle

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Acoustics Simulation for Automotive Systems Introduction

Noise Transmission:

e.g. Speaking into a loudhailer

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Acoustics Simulation for Automotive Systems Overview

1. Design of a high frequency broad band resonator for an engine air induction system 2. Simulation of exhaust sound pressure level for different tail pipe designs.

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Acoustics Simulation for Automotive Systems

air box

w/o filter

air intake (open, echoic) to compressor

HHR

*) random signal with constant power spectral density (intensity)

Simplified Air Intake System

white noise*) speaker

Acoustic resonators and dampers

• air box
• Helmholtz resonator (HHR)
• broad band resonance chambers

resonance chambers

Virtual Transmission Loss Test Bench

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Acoustics Simulation for Automotive Systems Signal Processing and Analysis

signal analyzer

GT-SUITE attenuated frequencies

• FFT
• noise reduction
• insertion loss
• transmission loss

pressure sensors

STAR Global Conference Vienna, 18.03.2014 page 9

Acoustics Simulation for Automotive Systems Transmission Loss Analysis for Air Box

• <700Hz, broad band attenuation due to expansion

in air box

• > 1000 Hz narrow band attenuation due to

reflections in airbox

air box

alternative air box connection

higher order response

 

STAR Global Conference Vienna, 18.03.2014 page 10

Acoustics Simulation for Automotive Systems Transmission Loss for Air Box & HRR

HRR

• Helmholtz Resonator is used to attenuate specific frequencies (here: 80Hz)
• to build broad band high frequency resonator reflections of airbox are used.

Resonator chambers must be added to fill the gaps. … fill the gaps for broad band attenuation

HRR

Helmholtz Resonator (HRR)

air box design II

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Acoustics Simulation for Automotive Systems Transmission Loss for 1st Chamber

chamber response frequency: 1320 Hz

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Acoustics Simulation for Automotive Systems Transmission Loss for 2nd Chamber

chamber response frequency: ~2050 Hz higher order response

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Acoustics Simulation for Automotive Systems Transmission Loss for 3rd Chamber

chamber response frequency: ~2600 Hz

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Acoustics Simulation for Automotive Systems Transmission Loss of Broad Band Resonator

• 3 chamber broad band resonator in

combination with airbox reflections

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Acoustics Simulation for Automotive Systems

• 2.78E-16

0.02 0.04 0.06 0.08 0.1 0.12 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00

Amplitude x/x_ref

1320 Hz 2050 Hz 2600 Hz

Wave Analysis for 90° Bent

inner pressure sensors

0.02 0.04 0.06 0.08 0.1 0.12 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00

Amplitude x/x_ref

1320 Hz 2050 Hz 2600 Hz

• uter pressure

sensors x FFT outer pressure sensors FFT inner pressure sensors

• higher amplitudes occur at outer radius, thus more

effective for chamber connection.

• high frequency resonators can be shifted to position

where amplitudes are highest.

• inner radius is less effective for chamber connection

STAR Global Conference Vienna, 18.03.2014 page 16

Acoustics Simulation for Automotive Systems Splitter Baffle in 90° Bent as Resonator

splitter wall

phase shift through different path lengths and wave cancellation when maxima meet minima at the end of splitter baffle

STAR Global Conference Vienna, 18.03.2014 page 17

Acoustics Simulation for Automotive Systems Overview

1. Design of a high frequency broad band resonator for an engine air induction system 2. Simulation of exhaust sound pressure level for different tail pipe designs.

STAR Global Conference Vienna, 18.03.2014 page 18

Acoustics Simulation for Automotive Systems Different tail pipe design

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Acoustics Simulation for Automotive Systems Different tail pipe design

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Acoustics Simulation for Automotive Systems Different tail pipe design

0,5 m 0,3 m Microphone Case #1 Case #2

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Acoustics Simulation for Automotive Systems Different tail pipe design

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Acoustics Simulation for Automotive Systems Outlook

Driving trough Simulation (coming soon) …thanks for Your attention!