Acoustic attenuation performance of circular expansion chambers with offset inlet/outlet: II. Comparison with experimental and computational studies

This is the second of two papers investigating the acoustic attenuation performance of asymmetric, circular expansion chambers with respect to the chamber length and the relative location of the offset inlet/outlet. Three approaches;ire employed to determine the transmission loss: (1) the three-dimensional analytical approach developed by the authors in a companion paper (Selamet and Ji, 1998, Journal of Sound and Vibration 213, 601-617) [1]; (2) the three-dimensional computational solution based on the boundary element method; and (3) experiments on an extended impedance tube set-up with expansion chambers fabricated with fixed inlet, outlet, and chamber diameters, varying chamber length to diameter ratios, and varying offset locations of the inlet and outlet. The results from the three approaches are shown to agree well. The effect of geometry, particularly that of the offset angles of the asymmetric configurations, on the multidimensional wave propagation and acoustic attenuation performance is discussed in detail. (C) 1998 Academic Press Limited.