Experimental investigation of unsteady shock oscillation by a forward-facing hemisphere at mach 3

Experimental and numerical investigation has been made to reveal the characteristic of shock wave pulsation in front of a hemi-spherical model at supersonic speeds more above Mach 2. Three types of measurements by; high-speed schlieren, pressure transducers, and pressure-sensitive paint, were employed to make the relation between shock pulsation and pressure distribution on the inner surface of the model clear. Three-dimensional numerical analysis has also been carried out on the flow field around the model by using compressible fluid analysis code FaSTAR, which was developed by JAXA. Comparison between the experimental results and the numerical one summarized that the shock wave pulsation with about 800 Hz was initiated by the small disturbances generated by the bow shock in front of the model and developed inside it. The development of the small disturbances depends on the geometric configuration of the rip of the model. A new geometrical configuration of supersonic parachute for planetary probes would be proposed to suppress shock pulsation at decent phase into the planet atmosphere.