This paper discusses how the different design parameters of an exhaust system influence the sound quality of the tailpipe noise. This investigation is primarily based on simulation and proved by measurements. The requirements of a calculation tool are presented in the first part. An accurate prediction of the firing frequency and a few harmonies is usually sufficient for calculating the overall sound pressure level precisely enough to compare it against the legal noise level - as long as flow noise is not the main sound source. However, taking sound quality into account, the software has to consider the roughness created by sub-harmonies, creation of flow noise and the interaction between flow and sound. Examples are shown of measured data and of data generated with an acoustic prediction tool developed in-house. In the second part an overview is given about different parameters influencing the sound quality of the tailpipe noise: the geometry of the manifold in terms of final harmonic distribution, the different exhaust components, and the tailpipe itself. The effects of dynamic flow noise can now be predicted - essential for cases where this dominates the overall sound pressure level.
Sound design of exhaust systems
Tonentwurf von Abgassystemen
2005
9 Seiten, 8 Bilder
Aufsatz (Konferenz)
Englisch
Principal exhaust system design parameters to improve exhaust sound impression.
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