Shock-tunnel flow visualization with a high-speed schlieren and laser holographic interferometry system

An optical system upgrade was recently carried out in the NASA HYPULSE facility operated by GASL. The upgrade was part of a major facility enhancement that added a reflected-shock-tunnel operating mode to complement the existing shockexpansion tunnel mode. New high-speed, multiframe schlieren and improved laser holographic interferometry subsystems were designed and installed. The current visualization system provides several new functions, such as rapid interchange from one subsystem to the other and access to several different test-section windows. The quick system turn-around function and the multi-frame schlieren capability enable shocktunnel flow visualization to become a low cost, routine operation providing crucial insight into the steady and unsteady behavior of test article flow. Results of a recent HYPULSE study on a generic scramjet engine at Mach 7 flight simulation conditions are described.