Three-dimensional shock wave distortion in shock-square vortex loop interaction

• This study focuses on the three-dimensional shock wave distortion and propagation.
• A square vortex loop emitted from a square nozzle impinges on a planar shock wave.
• The planar shock wave transforms into either a concave or convex distorted shape.
• The concave shaped shock wave results in shock wave focusing.
• The shock wave is locally focused along the axis of the nozzle corner.

Understanding of the three-dimensional shock wave-vortex loop interaction phenomena plays a key role in noise reduction. This study focuses on the three-dimensional shock wave distortion and propagation phenomena in a near-field supersonic jet. Shock-square vortex loop interaction was experimentally investigated in a square cross-sectional open-end shock wave generating tube at an incident shock Mach number of 1.39 ± 0.05. A square vortex loop impinged on a reflected shock wave from a wall located in front of the nozzle end. The planar reflected shock wave transforms into either a concave or convex distorted shape due to the opposing high-speed flow emitted from the nozzle corner. The convex shaped shock wave scatters towards the outside of the vortex loop, whereas the concave one converges towards the centre of the vortex loop. The concave shaped shock wave results in shock wave focusing. In shock-square vortex loop interaction, the shock wave is locally focused along the axis of the nozzle corner.