Author(s)

P. N. Liang

Abstract

Prediction of radiated noise from a fan over an absorbing surface Paul N. Liang Harley-Davidson Motor Company, USA Abstract A passby noise spectrum usually consists of the direct sound from a noise source and the reflected sound from the track surface as well. In this paper, a boundary element method (BEM) is used to model the direct sound from the source and the reflected sound from an infinite plane that has an impedance boundary condition. An image source combined with the reflection coefficient is added to the BE model so that there is no need to model the infinite plane. A series of tests is conducted to verify BEM predictions. A passby track covered with a ceramic wool blanket is used to simulate a strong absorbing surface. Introduction There are two types of passby tracks in the US: the ISO track and the SAE sealed asphalt track. The surface absorption of both tracks is nearly zero. After years of use, the surface absorption may change because of the dust coating, sno

Keywords