On the Evolution of Double Shock Accelerated Elliptic Gas Cylinders

Abstract

The evolution of double elliptic heavygas (SF6) cylinders impacted by a planar shock wave is studied by highspeed camera diagnostics. The minor axes (b) of the elliptic cross sections are aligned perpendicular to the shock direction. While the cylinder dimensions are fixed, we adjust the centertocenter separation s between the cylinders. The resulting flow morphologies are visualized and the interaction between double cylinders is analyzed. When s/b = 4.0 or 3.0, the two elliptical cylinders roll up into two counterrotating vortex pairs and their interaction is weak. When s/b decreases to 2.0 or 1.2, due to strong interaction of the two inner vortices, the inner structure completely disappears and the flow morphology evolves into one countervortex pair. Compared with the s/b = 2.0 case, larger amount of baroclinic vorticity is produced in the s/b = 1.2 case, and the morphology is similar to the single elliptic cylinder case, with a second vortex phenomenon occurring at later times. As s/b increases, the extent of cylindercylinder interaction becomes weaker, and the integral height of double elliptic cylinders grows while the length decreases.