VISPeR: Vehicle integral simulation for pass-by noise reduction (an innovative step towards low noise traffic emissions)

• Unité de recherche: PCRD EU
• Numéro de projet: 00.0468
• Titre du projet anglais: VISPeR: Vehicle integral simulation for pass-by noise reduction (an innovative step towards low noise traffic emissions)

Mots-clé (Anglais)

Pass-by noise; benchmark of numerical methods; raytracing; IFEM; model of the engine cavity

Autre Numéro de projet (Anglais)

EU project number: G3RD-CT-2000-00288

Programme de recherche (Anglais)

EU-programme: 5. Frame Research Programme - 1.3.3 Land transport and marine technologies

Description succincte (Anglais)

See abstract

Partenaires et organisations internationales (Anglais)

Coordinator: AVL List GmbH (A)

Résumé des résultats (Abstract) (Anglais)

Pass-by noise of vehicl~s is an important environmental issue. A method allowing its entire or partial numerical prediction would help minimising exterior noise and could be used as a design tool for
noise sources and treatment configurations. In the VIS PeR project, RlETER is involved in developing a numerical method to represent noise radiated outside the engine compartment and underfloor with special emphasis on optimisation of the sound package. RIETER is participating in a benchmark of numerical methodologies and in measurements for validation purposes. RlETER is also supporting partners with supply of acoustic materials and their acoustic properties calculated with the proprietary software SISAB. The study is performed for a passenger car.
Pass-by noise has a relevant spectral content up to around 3kHz, so a large frequency band has to be covered by the predictive method. A split of the frequency range between a typical LF method (like BEM) and a HF calculation (like ray tracing) is possible. A benchmark of existing numerical methodologies, possibly candidates for the representation of the engine compartment and the underbody has been carried out in close collaboration with CRF. RIETER' s contribution consisted in numerical testing of some methods (raytracing, FEM/BEM, FEM/lFEM), with respect to calculation time and memory requirements. Conclusions on applicability and CPU time have been driven from
the first benchmarking of numerical methodologies on a small box: BEM and FEM/IFEM remained as interesting techniques for the low frequency domain and ray tracing for the high frequency range.
The quality of the results is evaluated through comparison of measurement and simulation. For the experimental validation, RlETER built the simplified mock-up of an engine cavity, provided
treatement materials and participated to the measurement campain at CRF. Treatment materials have been characterized and material models created.
Numerical models for IFEM f~r all treatment cases (bare, withsi~ple foam material, with real trim parts) have been created and some modeling guidelines deduced. Calculations for the bare case show reasonable results and calculation time. Comparisons of calculation times between IFEM Sysnoise and IFEM with ACTRAN are foreseen.
A raytracing model of the engine cavity mock-up has been created and calculations are on-going. A study on the influence of various modeling parameters has been performed.

Références bases de données (Anglais)

Swiss Database: Euro-DB of the
State Secretariat for Education and Research
Hallwylstrasse 4
CH-3003 Berne, Switzerland
Tel. [phone]
Swiss Project-Number: 00.0468