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

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 GT-SUITE 3D CFD/CHT Analysis 1D System Analysis InDesA GmbH  Carl-Zeiss-Ring 19a  D-85737 Ismaning  Phone +49 (89) 552 7978-10  Fax +49 (89) 552 7978-29  www.InDesA.de

STAR Acoustics Simulation for Automotive Systems Global Conference Vienna, 18.03.2014 Introduction page 3 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)

STAR Acoustics Simulation for Automotive Systems Global Conference Vienna, 18.03.2014 Introduction page 4 Noise generation via fluid motion: e.g. Blowing in a bottle

STAR Acoustics Simulation for Automotive Systems Global Conference Vienna, 18.03.2014 Introduction page 5 Noise Transmission: e.g. Speaking into a loudhailer

STAR Acoustics Simulation for Automotive Systems Global Conference Vienna, 18.03.2014 Overview page 6 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 Acoustics Simulation for Automotive Systems Global Conference Vienna, 18.03.2014 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)

STAR Acoustics Simulation for Automotive Systems Global Conference Vienna, 18.03.2014 page 8 Signal Processing and Analysis pressure sensors signal analyzer GT-SUITE attenuated frequencies FFT  noise reduction  insertion loss  transmission loss 

STAR Acoustics Simulation for Automotive Systems Global Conference Vienna, 18.03.2014 page 9 Transmission Loss Analysis for Air Box higher order response  air box  alternative  <700Hz, broad band attenuation due to expansion air box in air box connection  > 1000 Hz narrow band attenuation due to reflections in airbox

STAR Acoustics Simulation for Automotive Systems Global Conference Vienna, 18.03.2014 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.

STAR Acoustics Simulation for Automotive Systems Global Conference Vienna, 18.03.2014 page 11 Transmission Loss for 1 st Chamber chamber response frequency: 1320 Hz

STAR Acoustics Simulation for Automotive Systems Global Conference Vienna, 18.03.2014 page 12 Transmission Loss for 2 nd Chamber chamber response frequency: ~2050 Hz higher order response

STAR Acoustics Simulation for Automotive Systems Global Conference Vienna, 18.03.2014 page 13 Transmission Loss for 3 rd Chamber chamber response frequency: ~2600 Hz

STAR Acoustics Simulation for Automotive Systems Global Conference Vienna, 18.03.2014 page 14 Transmission Loss of Broad Band Resonator  3 chamber broad band resonator in combination with airbox reflections

STAR Acoustics Simulation for Automotive Systems Global Conference Vienna, 18.03.2014 page 15 Wave Analysis for 90° Bent higher amplitudes occur at outer radius, thus more  FFT outer pressure sensors effective for chamber connection. 0.12 high frequency resonators can be shifted to position  0.1 where amplitudes are highest. Amplitude 0.08 inner radius is less effective for chamber connection  1320 Hz 0.06 2050 Hz 0.04 2600 Hz 0.02 outer pressure sensors 0 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 x/x_ref FFT inner pressure sensors 0.12 0.1 Amplitude 0.08 x inner pressure 1320 Hz 0.06 sensors 2050 Hz 0.04 2600 Hz 0.02 -2.78E-16 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 x/x_ref

STAR Acoustics Simulation for Automotive Systems Global Conference Vienna, 18.03.2014 page 16 Splitter Baffle in 90° Bent as Resonator phase shift through different path lengths and wave cancellation when maxima meet minima at the end of splitter baffle splitter wall

STAR Acoustics Simulation for Automotive Systems Global Conference Vienna, 18.03.2014 Overview page 17 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 Acoustics Simulation for Automotive Systems Global Conference Vienna, 18.03.2014 page 18 Different tail pipe design

STAR Acoustics Simulation for Automotive Systems Global Conference Vienna, 18.03.2014 page 19 Different tail pipe design

STAR Acoustics Simulation for Automotive Systems Global Conference Vienna, 18.03.2014 page 20 Different tail pipe design Microphone Case #1 0,5 m 0,3 m Case #2

STAR Acoustics Simulation for Automotive Systems Global Conference Vienna, 18.03.2014 page 21 Different tail pipe design

STAR Acoustics Simulation for Automotive Systems Global Conference Vienna, 18.03.2014 page 22 Outlook Driving trough Simulation (coming soon) …thanks for Your attention!