Search Results

The emitted noise of an exhaust system is divided into three different kinds of noise: Tailpipe noise, noise transmitted through the hanger into the cabin and surface radiated noise. This paper deals with the surface radiated noise which becomes more and more unmasked as the radiated sound power of other sources, e.g. of the tailpipe, decreases. Noise sources, the transfer path and the radiation of a structure are presented. A method for calculating and optimizing a structure with FEA (finite element analysis) is also part of this paper. An exhaust system is a complex dynamical system. Global eigenfrequencies of a whole exhaust system are below 200 Hz. A muffler moves then in rigid body motion and the radiated sound power is subjective not relevant. The main sound power is transferred through the hanger to the underbody. At higher frequencies the acoustical effects appear more local and are more effective in noise radiation.