High Frequency Surface Pressure, Shear Stress and Heat Flux Measurements for High Temperature Applications

Lambda Instruments, Inc., in cooperation with Virginia Tech and Pratt & Whitney, propose to investigate the feasibility of developing ultra high-temperature, high-frequency sapphire optical fiber-based sensors for next generation hypersonic vehicle sensors and wind tunnel testing programs up to 3600 ºF. The capability to accurately measure the surface pressure, skin friction, and temperature gradient imposed on a body subjected to high speed flow is a vital first step toward improving the performance of future hypersonic vehicles. Although real-time determination of these parameters has been an on-going challenge since the early days of flight, only in the last 15 years has attention shifted to hypersonic conditions due to sensor advancements in miniaturization, sensitivity, and mounting techniques. Accurate measurements of aerodynamic heating is a major concern at hypersonic speeds. Temperature sensors used to monitor the thermal profile can also give insight into determining the peak in a shock interaction region or the boundary layer transition. Finally, current air-breathing hypersonic vehicles integrate airframe and engine. The entire fore body of a scramjet vehicle's underside, for example, may be used as an external inlet to provide flow at the perfect condition to the engine. Failure to accurately know or predict surface conditions can lead to engine failure or catastrophic vehicle structural failure.