Abstract

This paper presents an extended Kirchhoff integral formulation for predicting sound radiation from an arbitrarily vibrating structure moving along an infinite baffle. In deriving this integral formulation, the effect of sound reflection from the baffle is taken into account by using the image source theory. Moreover, the effect of source convection motion and that of interaction between motion-induced turbulence and the vibrating surface on the resulting acoustic pressure field are incorporated in the formulation. As an example, this formulation is used to simulate sound radiation from a full-size vehicle driving on an infinite solid ground at various speeds. Sinusoidal forces are assumed to excite the vehicle on its four tires. Vibration responses due to these excitations are calculated using finite element method. Once the normal component of the surface velocity is specified, the radiated acoustic pressure field is obtained numerically using boundary element method. The results show that the effect of source convection motion becomes obvious when the Mach number exceeds 0.1, or equivalently, when a vehicle drives at a speed of 70 mph or higher.

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