Diagnostic Techniques for High Speed Flows

The U.S. Air Force Research Laboratory has determined that a need exists for new diagnostic instrumentation capable of obtaining quantitative flow data in large scale aerodynamic facilities without reliance on molecular or particle seeding. This Phase II Small Business Innovative Research proposal offers a new avenue for non-intrusive instrumentation based upon the application of ultra-fast laser technology to a class of optical diagnostic known as Flow Tagging Velocimetry, with particular emphasis on the high subsonic (Mach ~0.7) to moderate supersonic (Mach ~2-3) flow regimes. In Phase I experiments were successfully performed demonstrating all critical elements associated with our proposed enhancements to the oxygen-based flow tagging method known as RELIEF (Raman Excitation + Laser Induced Electronic Fluorescence). Phase II, building upon the results of Phase I, will focus on optimization of the optical technologies demonstrated in Phase I and delivery and integration of a complete ultra-fast flow tagging system to the AFRL Air Vehicles Directorate Trisonic Flow Facility. The instrumentation will be modular in design and will also be readily adaptable to other optical diagnostic methods, most notably Planar Imaging Velocimetry (PIV). The Phase II program will culminate in a sequence of velocity field measurements of the flow produced external to and within a transonic cavity model.