The Acoustic Fields Reconstruction Based On The Acoustic Radiation Modes And Its Application

The paper introduces the acoustic fields reconstruction method based on the acoustic radiation modes. The acoustic radiation modes constitute a set of independent basis functions defined on the vibrating surface and describe the radiation patterns of multi-pole. The field distribution modes constitute a set of independent basis functions defined on the radiation field and describe the distribution patterns of multi-pole radiation. The radiation from the vibrating surface can be uniquely expressed in terms of the acoustic radiation modes and the field distribution modes. For reconstruction of acoustic fields, the key is to determine the expansion coefficients. At N measurement points in the acoustic field, measuring the acoustic information, the expansion coefficients can be determined. Once the expansion coefficients are obtained, the whole acoustic fields can be reconstructed.For the spherical sound source which radiate sound to the whole space, the reconstruction is implemented. Through carrying on acoustic fields reconstruction to the orthogonal spherical wave source, this paper discusses the acoustic radiation modes of sphere acoustic source and the spheric harmonic Function have one-to-one corresponding relations, they have the same inherit, and both of them manifeste the radiation patterns of multi-pole . For the radiation of complicated source, A vibrating piston set in the side of a rigid sphere is adopted in the numerical simulation for verifying the algorithms, the regularization method is used to guarantee the accuracy of the reconstruction. When the flare angle of vibration piston on the sphere increases gradually, the directivity which is radiated by piston is not obvious gradually, and the accuracy of reconstruction is getting better and better.As to the application of the reconstruction based on the acoustic radiation modes, this paper has made some preliminary discussion, mainly on the use of sound source identification and the estimation of acoustical power. In view of sound source identification based on acoustic fields reconstruction, this paper attempts identify the sound source by reconstructing surface acoustic pressure. After the simulation and visualization processing, the method is simple and feasible. By using the acoustic fields reconstruction based on the acoustic radiation modes, the method for calculating acoustic power radiated at medium and low-frequency is proposed. Taking the panel source for an example, emulation results are given. Some factors affecting the accuracy are discussed, the stability of the method is discussed, and the engineering measurement method is compared with the method of the method of the acoustic field reconstruction. It is found that through the near field measurements, the rich far-field information can be obtained, and the method for calculating acoustic power have enough accuracy and good stability.