Verification of Numerical Acoustic Radiation Predictions 891171

An experimental verification study was done of the numerical predictions of sound radiation from an automotive valve cover. The valve cover was mounted on the floor of a semi-anechoic chamber with a mechanical shaker attached to the inside of the cover. Transfer functions between the excitation force and the surface motion of the cover surfaces and the radiated sound pressure were measured. The surface motion of the valve cover was input to a numerical radiation prediction program which was used to predict the acoustic radiation using both the Helmholtz integral equation and the Rayleigh integral equation. The predicted and measured sound pressure levels were compared at 25 field points. The verification study showed that the Helmholtz integral equation prediction is good at all locations for this frequency band. The Rayleigh integral equation predictions were reasonable at some frequencies at some points but are not good in general.