Optical Instruments for Non-Intrusive Off-Body Measurements in Hypersonic Flight Experiments

ABSTRACT: Under this Small Business Technology Transfer (STTR) program, Innovative Technology Applications Company (ITAC), LLC and the University of Notre Dame (UND) are working to develop new optical instruments that will enable nonintrusive, off-body measurements of flow parameters in hypersonic flight. The two concepts under development by the ITAC/UND team and described in this proposal involve, first, the employment of a thermal-tufting technique for real-time determination of three-dimensional velocity components, and second, the use of innovative aero-optic techniques for determining spatially-resolved fluctuating flow properties. The thermal-tufting technique will be designed to be packaged and implemented in the form of an air-data probe that would provide measurements of 3-components of velocity, angle of attack, sideslip angle, and Mach number, and which would most likely be placed near the vehicle nose where the shock is expected to be relatively steady owing to laminar flow in the initial leading-edge boundary layer. The aero-optic instrument will consist of a wavefront sensor and other optical components that will most likely be situated further downstream on the test vehicle, and designed to determine flow transition and turbulence in the vehicle boundary layer. BENEFIT: The proposed instruments will provide capabilities of real-time determination of three-dimensional velocity components and other spatially-resolved fluctuating flow properties which will lead to improved understanding of high-speed flows around hypersonic vehicles. This kind of fluid-mechanic understanding cannot be obtained from ground-test and CFD efforts alone, since ground-test facilities are not capable of achieving all points in the flight envelope of realistic vehicle designs, while CFD results require validation data. The proposed non-intrusive, optical instruments will aid in the design and development of safer and more reliable systems, and will be suited for the flight-test environment where space and installation options are limited.