THEORETICAL AND EXPERIMENTAL ASPECTS OF ACOUSTIC MODELING OF ENGINE EXHAUST SYSTEMS WITH APPLICATIONS TO A VACUUM PUMP

摘要

The engine exhaust system was modeled as a lumped source-muffler-terminations system. An expression for the predicted sound pressure was derived in terms of the source and termination impedances, and the muffler geometry. The developed prediction scheme is very efficient from computation point of view. Also, the predicted sound pressure can be calculated without computing the source pressure or the source velocity although these quantities can be calculated if necessary. The formulation was verified through a series of experiments. The source impedance was measured using the direct method. Sound pressure level measurements for the prediction scheme were made for several source-muffler and source-straight pipe combinations. In all cases, correlation of the experimental results and those predicted by the developed expressions was good.