Acoustic Shear Stress Sensor for Flight Research

Nielsen Engineering & Research (NEAR) is proposing to develop a robust, nonintrusive aerodynamic shear stress sensor for use in aircraft flight testing. This sensor is based on technology developed by NEAR under a previous SBIR contract. In the proposed Phase I contract, NEAR will take this established sensor concept and refine it to create an instrument which can withstand the rigors of the flight test environment. Numerical simulations, analysis, and laboratory experiments will be used to 1) advance the design of the transducers and electronics to permit accurate shear stress measurements up to 100 Pascals, 2) improve the correlation algorithm to account for large variations in speed of sound, density, and viscosity, and 3) environmentally harden the sensor to withstand the temperature, pressure, and atmospheric conditions encountered in flight. The resulting Phase I sensor design will be evaluated through environmental and wind tunnel testing. Results from this research effort will be used to develop a second generation prototype in the Phase II contract. Wind tunnel results from this second prototype will then be used to further refine the design and to generate the final sensor which ultimately will be flight-tested towards the end of the Phase II effort.