Hybrid Experimental - Numerical Method to Predict Far Field Noise of HVAC Unit.

摘要

A hybrid method based on both experimental measurements and simulations to assess the sound pressure level emitted by an HVAC unit in far field is described The measurement consists in the acquisition of sound pressure level in the near field all around the HVAC unit. Also, to validate and evaluate the accuracy of the method, some measurements are done in far field. The simulation starts by the extraction of the pellicular modes and their radiation to retrieve the transfer function with each near field microphone. Thanks to the inverse method, the participation factor of each mode can then be calculated using a least mean square method. The excitation pattern of the pellicular surface can be generated and the solution can be reconstructed at the far filed microphones location. A Thikhonov regularization is also investigated and applied to improve the accuracy of the prediction. Finally, sensitivity study on various parameters (like grid size, number of pellicular modes to consider, Thikhonov parameter value,..) is performed. The conclusion is such hybrid method is adequate to predict sound pressure level of HVAC unit in far field using near field pressure measurement.