Color schlieren for hypersonic shock wave structures diagnosis

A non-invaded and high resolution color schlieren system was developed to diagnose the hypersonic flow field with complex shock wave structures, intensive shock interactions and different shock intensity. The key technique of color schlieren system is the color filter. A high sensitive color filter with 6 regions is designed. High speed color camera and synchronization technique are employed to meet the needs of high speed photography. Space and time resolution were brought up to 0.1mm and 1s, respectively. Experiments were performed in hypersonic shock tunnel with Mach 5.0 and 6.0. Regular reflection and Mach reflection generated by interaction of oblique shocks, and type IV shock interaction generated by oblique shock and bow shock were detected. Clear color schlieren images were obtained at the 3 conditions. The complex structures of the 3 kinds of shock interactions are disclosed, which proves that the color schlieren system was efficient and reliable. And it also supplies an alternate method in the diagnostics of hypersonic flow field.