Experimental Investigation on the Unsteadiness in Shock Wave/Boundary Layer Interaction

The unsteadiness of Shock Wave/Boundary Layer Interaction (SWBLI) generated by the two-dimensional compression ramps in hypersonic flow was investigated. The experiments were carried out in a Mach-6 low-noise wind tunnel under three different unit Reynolds number. The flow structures of 22◦ compression ramp were quantitatively analyzed by schlieren images. Through the measurements of the wall fluctuating pressure, the high-frequency unsteadiness with a characteristic frequency about 320 KHz is found in interaction regions by the Power Spectrum Density analysis and the influence area of this unsteadiness expands when the ramp angle increases. The results also show that the stronger adverse pressure gradient caused by the higher unit Reynolds number under the same ramp angle lead to the greater unsteadiness. Finally, the nonlinearity of the shock/boundary layer interaction is verified by bicoherence analysis.