Flow visualisation of a normal shock impinging over a rounded contour bump in a Mach 1.3 free-stream

Area of Science:

• Fluid Dynamics
• Aerodynamics
• Shock Wave Phenomena

Background:

• Understanding shock wave interactions with surface geometries is crucial for supersonic and hypersonic vehicle design.
• Previous studies have explored shock wave impingement, but detailed visualization of instantaneous flow structures remains challenging.

Purpose of the Study:

• To visualize and analyze the instantaneous streamwise and spanwise flow patterns of a normal shock wave impinging on a rounded contour bump.
• To investigate the influence of the shock wave's impingement location on flow structures and shock wave configurations.

Main Methods:

• Experimental investigation using a Mach 1.3 free-stream.
• Employing a transparent shock generator for real-time image capture.
• Utilizing multi-colored fluorescent oil-flow visualization to highlight complex flow features.

Main Results:

• The rounded contour bump fragmented the normal shock wave into lambda-shaped structures.
• Flow patterns and shock structures were highly dependent on the shock wave's impingement location.
• The impingement location influenced the size and formation of spanwise counter-rotating vortices downstream of the bump crest.

Conclusions:

• The study confirms that the impingement location is a critical parameter for shock wave-boundary layer interaction over bumps.
• Transparent shock generators are recommended for accurate visualization in shock impingement studies.
• The terminating shock can distort surface flow visualizations, necessitating careful interpretation.