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A combined sound field reconstruction method for non-cylindrical rotative surfaces based on statistically optimal cylindrical near-field acoustic holography and multipoint Helmholtz equation least square

For the sound field reconstruction of non-cylindrical rotative surfaces, current near-field acoustic holography (NAH) methods have relatively poor applicability and low accuracy. To overcome the problem, a combined sound field reconstruction method is proposed. First, an improved multipoint Helmholtz equation least square (HELS) method is proposed, which is more applicable to reconstruct the sound field with an aspect ratio larger than 1. Second, based on single criterion traversing method (SCTM), an improved double criterion traversing method (DCTM) is proposed to determine the optimal truncation order, and reduce the reconstruction error of multipoint HELS. Third, with the sound pressure measured on the holographic surface, the sound pressure on the transitional surface is reconstructed using statistically optimal cylindrical near-field acoustic holography (SOCNAH), and the sound pressure on the reconstruction surface is reconstructed using multipoint HELS. Finally, typical numerical case studies and experimental studies on a test bed are carried out, which validate that the combined method can obviously improve the accuracy and robustness of sound field reconstruction for non-cylindrical rotative surfaces, and thus provide reliable evidences for noise monitoring and control of mechanical systems.