Approaches for Acoustics Simulation for Automotive Air Induction & Exhaust Systems. Fabiano Bet Gerald Seider Simon Bless

Transcription

1 Approaches for Acoustics Simulation for Automotive Air Induction & Exhaust Systems Fabiano Bet Gerald Seider Simon Bless Vienna, 18 March, 2014

2 Company Profile 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 3D CFD/CHT Analysis GT-SUITE 1D System Analysis InDesA GmbH Carl-Zeiss-Ring 19a D Ismaning Phone +49 (89) Fax +49 (89)

3 page 3 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)

4 page 4 Introduction Noise generation via fluid motion: e.g. Blowing in a bottle

5 page 5 Introduction Noise Transmission: e.g. Speaking into a loudhailer

6 page 6 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.

7 page 7 Simplified Air Intake System Virtual Transmission Loss Test Bench air intake (open, echoic) resonance chambers air box w/o filter HHR Acoustic resonators and dampers air box Helmholtz resonator (HHR) to compressor broad band resonance chambers white noise*) speaker *) random signal with constant power spectral density (intensity)

8 page 8 Signal Processing and Analysis pressure sensors attenuated frequencies signal analyzer GT-SUITE FFT noise reduction insertion loss transmission loss

9 page 9 Transmission Loss Analysis for Air Box higher order response air box alternative air box connection <700Hz, broad band attenuation due to expansion in air box > 1000 Hz narrow band attenuation due to reflections in airbox

10 page 10 Transmission Loss for Air Box & HRR fill the gaps for broad band attenuation HRR HRR air box design II Helmholtz Resonator (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.

11 page 11 Transmission Loss for 1 st Chamber chamber response frequency: 1320 Hz

12 page 12 Transmission Loss for 2 nd Chamber chamber response frequency: ~2050 Hz higher order response

13 page 13 Transmission Loss for 3 rd Chamber chamber response frequency: ~2600 Hz

14 page 14 Transmission Loss of Broad Band Resonator 3 chamber broad band resonator in combination with airbox reflections

15 Amplitude Amplitude STAR page 15 Wave Analysis for 90 Bent 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 outer pressure sensors FFT outer pressure sensors x/x_ref 1320 Hz 2050 Hz 2600 Hz 0.12 FFT inner pressure sensors 0.1 inner pressure sensors x Hz 2050 Hz Hz -2.78E x/x_ref

16 page 16 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

17 page 17 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.

18 page 18 Different tail pipe design

19 page 19 Different tail pipe design

20 page 20 Different tail pipe design Microphone Case #1 0,5 m 0,3 m Case #2

21 page 21 Different tail pipe design

22 page 22 Outlook Driving trough Simulation (coming soon) thanks for Your attention!