New Method for Determination of Acoustic Signatures in Wind Tunnel Testing

"The acoustic signature generated by test articles in high speed wind tunnel tests is difficult to measure due to the high level of background noise created by the wind tunnel flow. A unique research program using microphone arrays is proposed to addressthis issue. The program combines experimental tests and analytical algorithm development to devise a system able to reject the undesirable wind tunnel noise and retain the noise generated by the test article. A generic model of an aircraft weapons bay willbe built and tested in a wind tunnel. The data collected from different microphone arrays will be analyzed using different source bearing and filtering algorithms to determine the optimum arrangement for the array and the processing algorithms.Individually, all algorithms exist and have been tested at the ASE FluiDyne Aero Test Laboratory and will provide the fundamental basis for the analysis tools. The use of these algorithms in proper combination provides the critical feature to the successof the program. A preliminary test program using a simple weapons bay model has been conducted which verifies the ability of this procedure to separate the wind tunnel noise from the model noise. The program will provide technology needed to accuratelydetermine and characterize noise sources in a wind tunnel. Potential applications include development testing of aircraft and automotive components and equipment in wind tunnels where the acoustic q