This innovation consists of developing in-flow microphone enclosures (acoustic probes) that will have negligible self-noise over a wide range of free-stream and operational conditions.The goals are to provide probes that are superior to any existing ones because they are (1) less sensitive to free-stream turbulence, (2) easy to manufacture, (3) effective over a wide range of Reynolds numbers and Mach numbers, and (4) insensitive to angle of attack and yaw.The acoustic probes will be usefulfor measuring acoustic signals and determining noise-source locations in wind tunnels, on aircraft, in engine inlets, and in air-conditioning ducts.The probe designs will rely on a knowledge of aeroacoustic principles that relate probe self noise to probe aerodynamic characteristics.The aerodynamic design of the probes will be carried out by modifying an existing computer program for solving the full Navier-Stokes equations to serve as an iterative design-tool. Commercial Applications:There is a wide range of opportunities for pursuing the commercial development of the probes after the completion of Phase IIwhen there will be a well validated design.There are both government and non-government markets for quiet acoustic probes that are effective in high-speed turbulent flows.Manufacturers of acoustical testing and measuring equipment have, for a number of years, marketed special microphone "nose cones" and "slit probes" that decrease turbulence-induced noise in high- speed flows.However, the quiet microphone enclosures to be developed in Phases I and II of this project should provide much better performance than the commercially available probes.In addition, the simpler designs of the new probes should make them less costly to manufacture.With those advantages there is a good opportunity to break into the special market niche. In addition to a large civilian market, there is potentially a large market for the probes for use on military weapons systems, such as the Army BAT, if the probes turn out to be significantly better than existing ones.
