A Nearfield Acoustic Holography Based on the Mapping Relationship Between Patterns on Surfaces of Structure and Hologram

摘要

A nearfield acoustic holography method based on the mapping relationship between patterns on the surfaces of structure and hologram is proposed. The approach is to seek explicit descriptions of the mapping relationship between velocity patterns on the boundary and pressure patterns on the field, and design a proper experimental setup for obtaining the participant coefficients of the pressure patterns on the hologram surface. The mapping relationship adopted in this work is built on the fundamental solution of Helmholtz equation in spherical coordinates. The advantageous is twofold. Firstly, the patterns making the mapping relationship on the structure and hologram surfaces are analytical, which supplies an analytical way to determine the number and position of microphones for accurate patterns recognition on the hologram surface. Secondly, the inverse numerical operation to reconstruct the boundary velocity based on the measured acoustic signals is avoided by a substitution of evaluation of participant coefficients on the hologram surface and applying the analytical mapping relationship to the structure surface, which alleviates error amplification. The approach is validated by numerical examples.