Transonic Flow Field Analysis of a Free Flight Capsule using Ballistic Range

The free-flight test of the capsule has been performed using a ballistic range at a Mach number of between 0.77 and 1.52 to visualize a flow field around a capsule. The test models are Hayabusa capsule models whose diameters are 15 mm and 3 mm, and the Schlieren method is used for flow visualization. The characteristics of the flow around the capsule with the 15mm capsule model were investigated using the time-averaged flow field and instantaneous field images. Then, Dynamic Mode Decomposition analysis of the flow field was conducted, it was found that the recompression shock wave and the large fluctuation of the wake are dominant structures in the capsule flow at a Mach number of 1.0. Furthermore, the recompression shock wave fluctuated at Strouhal number of O(0.01) with the 3 mm capsule model test, which indicated that the fluctuation of the recompression shock wave is caused by the local shock wave generated from the free shear layer in the recirculation region.