Acoustic radiation prediction of a compressor housing from three-dimensional experimental spatial dynamics modeling

Abstract An application of experimental spatial dynamics modeling (ESDM) is demonstrated for predicting the sound radiation from a vibrating structure based on experimental velocity response data. A scanning laser Doppler vibrometer (LDV) is used to measure velocity at thousands of locations on the surface of the radiating structure. Velocity measurements are acquired from multiple laser positions where the position and orientation of the LDV relative to the structure are determined. A weighted least-squares discrete finite element formulation is used to solve for the complex-valued continuous three-dimensional velocity response field on the surface of the structure from the experimental data for a single frequency. The velocity field solution on the surface provides the necessary boundary values input into a finite element/boundary element acoustic code for predicting acoustic radiation. This experimental-numerical noise prediction technique was demonstrated on the housing of an operational reciprocating Freon compressor. The technique was verified by comparing measured and predicted acoustic responses. This is the first time an experimental three-dimensional spatial dynamics model has been linked directly to the acoustic analysis of complex structures. The capability to make in-the-field vibration measurements, solve for the complex-valued continuous three-dimensional velocity response field, and predict the acoustic response from the same test is a novel approach and a major contribution of this work.