Abstract:

As a common structure in engineering, axisymmetric structures have attracted widespread attention in the engineering community for their acoustic simulation calculations. A method to comprehensively utilize the equivalent surface sound source and point sound source for predicting the acoustic radiation from axisymmetric structure is proposed. In response to the non-uniqueness of solutions for the traditional equivalent point sound sources at the corresponding Dirichlet characteristic frequency inside the structure and the high sensitivity to acoustic parameters, a surface sound source is arranged inside the structure for the matching operations of external sound field, while the point sound source is located inside the surface sound source to ensure the uniqueness of the solution. Based on the symmetry of the structure, the surface sound pressure and vibration velocity are expanded into Fourier series form according to the rotation angle, and the orthogonality between the series is utilized to establish the expression of various undetermined coefficients. An equation for the relationship between the equivalent source strength and the undetermined coefficients of Fourier series is established based on the principle of wave superposition, and the virtual area integral equation is transformed into a product form of the outer boundary integral and rotation angle integral of axisymmetric structure. The shape function is utilized to interpolate the outer boundary of the structure in order to obtain the transfer function between the surface sound pressure and vibration velocity of axisymmetric structure. The accuracy of the proposed method is demonstrated by comparing the results of the proposed method with those of traditional equivalent point sound source method, surface sound source method, and analytical method.

Key words: equivalent sound source, axial symmetry, wave superposition, characteristic frequency, acoustic radiation