Coupled Fluid-Structure Analysis for Exhaust System NVH 2014-01-0020

The purpose of this work is to analytically investigate automotive exhaust system noise generation and propagation phenomena. The turbulent exhaust gas flow interacts with the exhaust system structure, and as a result of this interaction, the structure vibrates and radiates noise. In the meantime, pressure wave becomes acoustic wave at its outlet. This study focuses on an exhaust system and carrying out transient fluid-structure analysis by using an explicit finite element solver that is capable of solving the Navier Stokes equations for turbulent, compressible viscous fluids as well as the field equations for solid structures in a fully coupled fashion. The time domain signals obtained from the transient analysis are post-processed to yield frequency domain data, sound pressure levels, noise source pattern as well as the selected acoustic field contour snapshots. The work involves evaluating different design proposals and comparing their corresponding sound pressure levels and acoustic fields. Good correlation has been obtained between the analytical results and the available test measurement data. The obtained results illustrated the design directions to achieve noise reduction and provided a better understanding of the root causes pertaining to the noise issue of a specific design configuration.