Novel Kevlar-Walled Wind Tunnel for Aeroacoustic Testing of a Landing Gear

Abstract

which allowed aeroacoustic measurements to be carried out in the far field and in an environment with significantly less reflections. The model was a very faithful replica of the full-scale landing gear, designed to address the issues associated with low-fidelity models. A 63-element microphone phased array was used to locate the noise-source components of the landing gear from different streamwise positions, both in the near and far fields. The same landing-gear model was previously tested in the original hard-walled configuration of the tunnel with the same phased array mounted on the wall of the test section (i.e., near-field position). The new anechoic configuration of the Virginia Polytechnic Institute and State University wind tunnel offered a unique opportunity to directly compare data collected in hard-walled and semi-anechoic test sections, using the same landing-gear model and phased-array instrumentation. Through these tests, some of the limitations associated with testing in hard-walled wind tunnels were addressed. Nomenclature Cj = components of the steering vector d = distance from the array to the model f = frequency ffull-scale = full-scale frequency fmeasured = measured frequency k = wave number M = flow Mach number rj = distance traveled by an acoustic ray from the grid point with coordinates xn to array microphone j Rj = distance between the grid point with coordinates xn and array microphone j xn = coordinates of the grid point to which the array is being steered � = wavelength