Visualization of acoustic pressure fields radiated from a complex vibrating structure

Abstract

This paper presents visualization of acoustic pressures radiated from a complex vibrating structure using the Helmholtz equation least-squares (HELS) method [Z. Wang and S. F. Wu, J. Acoust. Soc. Am. 102, 2020–2032 (1997); 104, 2054–2060, (1998)]. The structure under consideration has the same shape and dimension as those of a full-size vehicle front end. Random noises are generated by an engine noise simulator that consists of many loudspeakers of different sizes. The radiated acoustic pressures are measured a certain distance away from the vehicle surface, which are then taken as the input to a computer model based on HELS formulations. Experiments are conducted in a 12 ft by 12 ft by 6.5 ft fully anechoic chamber at the Acoustics, Vibration, and Noise Control Laboratory of Wayne State University. The reconstructed acoustic pressures on vehicle surfaces and in the field are compared with the measured data. Also shown are comparisons of the reconstructed and measured acoustic pressure spectra at various locations on the vehicle back surface. Results show that good agreement can be obtained with relatively few expansion terms over the low- to midfrequency range. The accuracy of reconstruction, however, decreases with the increase of frequency as expected. [Work supported by NSF.]