Ultrasonic Thermometry for Embedded Measurements in Hypersonic Vehicles

The proposed sensor development effort leverages the nonintrusive and remote interrogation capabilities of ultrasonic pulse-echo technology to measure skin temperatures in hypersonic applications, both in test facilities and eventually during flight. A focus is placed on the most challenging surface materials, ceramic/carbon fiber-based shells, but the approach is extensible to materials of all types including metals and ablative materials. The sensing modality is based on the temperature-dependence of the speed of sound through a material and is fast, limited only by that sound propagation speed through the material and the conduction rate of heat into the skin itself. Also, the tool is able to process signals from multiple interfaces at different depths, including intrinsic surfaces such as near and far surfaces of the skin material, or surfaces engineered into the probe, yielding multi-depth temperature measurements. Thus, the system is capable of ~10’s kHz response and temperature depth-profiling for the calculation of heat transfer. The Phase I project will demonstrate proof of principle on relevant geometries, materials, and temperatures for the hypersonic scramjet application, while Phase II will be dedicated to system ruggedization and automation for actual hypersonic test beds and flight platforms.