Innovative Measurement of Airframe Noise Sources

The technical need in the solicitation calls for ldquo;Innovative source identification techniques for airframe noise sources, such as landing gear and high lift systems. This should also include turbulence details related to flow-induced noise typical of separated flow regions, vortices, shear layers, etc.rdquo;nbsp;In the proposed work, an innovative technique for identifying noise sources and measuring the acoustic spectra and effective source turbulence length scales of noise-creating flows in wind tunnel testing will be developed from TRL 3 to TRL 5. It uses standard microphone phased arrays. The method is especially well suited the weak, extended source with partial coherence, such as trailing edge noise and other airframe noise components. The method has exceptional dynamic range, which should make it possible to measure many sources in wind tunnels that cannot be measured today due to background noise. The method operates effectively looking though a wind tunnel shear layer, which also distinguishes it from other methods at high frequency. Its computation speed is at least one order of magnitude better than competing methods. It is designed to be seamlessly incorporated within larger acquisition and processing systems in use at NASA facilities. nbsp;It applies well to landing gear and high lift systems.