ACOUSTIC ATTENUATION PERFORMANCE OF CIRCULAR EXPANSION CHAMBERS WITH SINGLE-INLET AND DOUBLE-OUTLET

Expansion chambers with single-inlet and double-outlet provide desirable broadband acoustic attenuation similar to simple (single inlet/outlet) chambers and reduce the flow noise and back pressure in exhaust systems. The present study develops a three-dimensional analytical approach to determine the transmission loss of circular expansion chambers with single-inlet and double-outlet, which couples the continuity conditions of the acoustic pressure and particle velocity at the inlet and outlets with the orthogonality relations of Fourier–Bessel functions. The analytical results are compared with the boundary element predictions. The acoustic attenuation of the expansion chambers with single-inlet and double-outlet is then investigated in detail as a function of the chamber length and the locations of inlet and outlets.