Influence of Off-body Energy Addition on an Oblique Shock Wave in a Supersonic Flow

It has been proposed that one way of reducing the sonic boom is to deposit energy upstream of the vehicle. A computational and experimental study has been carried out on the near-field flow around a wedge model placed in a Mach 2.4 wind tunnel, where a Nd:YAG laser beam is used to breakdown the air upstream of the wedge, leading to a hot spot of gas which interacts with the wedge oblique shock. These interactions are studied with the help of time-resolved Schlieren (using a MHz rate camera) and using four sequentially placed pressure sensors, located in the region of impingement of the oblique shock on the floor; here they measure the effect of the energy deposition on the shock-induced pressures on the floor. 2D Euler calculations are compared with the wind tunnel results. Both numerical and experimental results agree quite well in the relative pressure levels before and after the shock impingement position, and also in the qualitative behavior of the pressure levels as a function of time after the discharge. The presence of other extraneous shocks and also the well-developed, large, turbulent boundary layer on the tunnel floor hindered a further quantitative comparison of experimental and computational results.