Development of the Exhaust Systems Radiation Noise Simulation Technology

The purpose of this paper is to present a Finite Element method able to simulate and predict exhaust radiation noise. The simulation takes into account fluid flow pulsation, aeroacoustic noise sources; flow induced structural vibration as well as noise radiation in the far field. All those phenomena are directly calculated in a fully coupled manner. By applying measured values at the model inflow, accurate radiation noise from the exhaust system is obtained. Locations of noise sources as well as mechanisms of noise generation are clarified. The method enables the investigation of exhaust noise radiation at early development stages. The use of semiconductor pressure sensors with 1-MHz sampling as well as Laser Doppler Velocimetry contributed greatly to the measurement accuracy required for the definition of inflow conditions.