GREEN SOLUTION OF THE ACOUSTIC-WAVE EQUATION FOR A CIRCULAR EXPANSION CHAMBER WITH ARBITRARY LOCATIONS OF INLET, OUTLET PORT, AND TERMINATION IMPEDANCE

Abstract

The acoustic characteristics of a circular expansion chamber whose inlet and outlet are situated on arbitrary locations of the chamber, i.e., the side wall or the face of the chamber, are analyzed based on the Green's function of a chamber with homogeneous boundary conditions. The Green's function is found by considering the boundary condition of the walls as rigid except at the location of the source, which is assumed to be a uniform volumetric acoustic source. The complete solution that determines the sound pressure distribution, intensity, and sound power pattern inside of the chamber are found. The solutions are compared with those based on the modal expansion techniques for the aforementioned cases. To verify the solutions, experiments were also performed, which determines the transmission loss of the expansion chamber. Side-inlet/side-outlet, face-inlet/side-outlet chambers were tested. A two-microphone method was used to accurately determine the transmission losses of the chambers. The Green's solutions are verified by comparison with the experimental results and the solutions based on the modal expansion techniques.