Fast Response Heat Flux Sensors and Efficient Data Reduction Methodology for Hypersonic Wind Tunnels

Accurate knowledge of heat flux is critical in assessing the design, performance, and survivability of hypersonic flight vehicles. Despite decades of research and testing, much is still unknown regarding hypersonic instabilities and transition mechanisms that define the state of the boundary layer. While the existence of these features is known, the ability to accurately measure them remains a challenge. In Phase II, the heat flux sensors and efficient data reduction methodology will be developed and demonstrated in a representative hypersonic flow environment. An improved semiconductor temperature gage will be manufactured that is specifically tailored to the heat flux sensor application. Both the indirect and direct sensor designs will be pursued while improvements are made in their manufacturing process. The sensors will undergo NIST-traceable static and dynamic calibrations to demonstrate the sensor frequency response, precision, and accuracy. The experimental campaign in the small-scale hypersonic wind tunnel will be expanded. The focus of the data-algorithm development will be on the experiment-based calibration of the model parameters and a scheme for resolving the second-mode fluctuations using an adaptive reconstruction strategy. The program will conclude with a demonstration in a USAF hypersonic facility.