Interactions Of Shock Waves With A Sphere AndArrayed Spheres

Abstract

This paper deals with the results of experimental and numerical studies of shock wave interaction with a single sphere and arrayed spheres. An 80 mm dia. sphere suspended vertically along the centerline of a 300 mm x 300 mm vertical shock tube was loaded with a planar shock wave at a shock Mach number of 1.2 in air. Unsteady drag forces working on the sphere were measured with two accelerometers installed inside it. The measured result was compared with that of numerical simulation solving the Navier-Stokes equations, which agreed well with experiment. It wais found that a maximum drag force appeared at the time instance slightly after the transition of the reflected shock wave from regular to Mach reflection and a negative drag force was created only for a very short duration of time when the transmitting shock wave merged at the rear stagnation point of the sphere. The shock/arrayed spheres interaction was experimentally investigated in a 60 mm x 150 mm diaphragmless shock tube. The process of the interaction was visualized sequentially by using double exposure holographic interferometry. Due to the three-dimensional distributions of arrayed spheres the shock wave attenuation was much more pronounced than in arrayed cylinders.