Diagnostics of shock tube flows by laser interferometry

A laser differential interferometer with Wollaston prisms is utilized to measure the density change across a shock generated in a shock tube and a shock Mach number. The results of the incident shock, reflected shock, and contact surface show that the influence of the boundary layer on the side and end walls becomes large when the initial pressure in the test chamber is less than 1.0 kPa. It is also found for the case of air that a strong interaction of the reflected shock with the side-wall boundary layer takes place. It is concluded that this method is one of the most reliable techniques for gas dynamic investigations.