Algorithms And Experimental Research For Near-field Acoustic Holography

Nearfield acoustic holography (NAH) is a powerful tool for identifying noise sources and visualizing acoustic field. By multiplying the inverse of the calculated vibro-acoustic transfer matrix and the measured acoustic pressure vector on the hologram surface, such acoustic quantities as acoustic pressure, particle velocity and acoustic intensity at any point in three-dimensional acoustic field and acoustic power on arbitrary surface can be reconstructed. In the past twenty years, the technique have achieve many progresses in itself, and its implementation algorithms mainly consist of spatial transform of sound field (STSF), boundary element method (BEM) and Helmholtz equation least-square method (HELS). In this paper, Based on the implementation and enhancement of the STSF-based NAH, designed a microphone array used in the experiment NAH frame and sheet metal through exciting experiments STSF algorithm was validated. Then, the NAH basic algorithm of based on STSF is used in noise source identification of fault simulation test bench, the experiment results demonstrate the effectiveness of NAH in noise source identification and point out the drawbacks in the application. In this paper, the main content include following aspects:(1) The background of NAH technology development is presented firstly. The motivation is to get out some novel methods based on the research status.(2) Based on the NAH technology of STSF, to address the key problems in the technology. The special functions and separation of variables are used to derive the theoretical formulation of plane NAH, analyzed the error and discussed implementation of numerical algorithms.(3) Based on NAH measurement, according to analyze the measurement processes, measuring instruments and measuring devices, a microphone array frame which use to NAH experiment is designed. And the sheet metal exciting experiments demonstrate the effectiveness of STSF algorithm. (4) The NAH basic algorithm of based on STSF is used in noise source identification of fault simulation test bench, the experiment results demonstrate the effectiveness of NAH in noise source identification and point out the drawbacks in the application.(5) Concluded the full text and pointed out the subject of further study.