Pass-by noise synthesis from frequency domain exterior acoustic simulations

Zusammenfassung

The evolution of the Pass-by Noise regulation put Automotive OEMs under pressure to reduce the emitted noise from vehicles. To be able to decrease the emitted noise level while meeting other constraints such as weight, space or sound quality, OEMS and their suppliers have to come up with innovative solutions to reduce the different noise sources and study the noise propagation around the vehicle. The experimental study of the acoustic propagation around a complete vehicle during a pass-by noise event occurring late in the development process, the need for methods to investigate solutions to control the acoustic propagation around the vehicle arises. This paper presents a method for predicting a vehicle pass-by noise based on a Finite Element exterior acoustic calculation in the frequency domain. With an approach similar to what is proposed for experimental indoor pass-by noise measurement, the simulated pass-by noise is synthesized from multiple acoustic transfer functions between each noise source and a line of virtual microphones located 7.5m on the side of the vehicle. The method is demonstrated on a car model using Actran commercial software. The contribution from several noise sources to the pass-by noise is evaluated up to 2 kHz and expressed both in terms of sound pressure level and frequency content. Finally the performances and computational times are reported for integration in a design process.