Experimental comparison of shock buffet on unswept and 10-deg swept wings

Shock wave oscillations and surface flow fields on unswept-wing and 10 deg swept-wing models were experimentally investigated in a two-dimensional transonic wind tunnel facility to clarify the effects of wing sweep on the shock buffet phenomena. High-speed shadowgraph imaging, oil flow, and unsteady pressure-sensitive paint (PSP) techniques were used to visualize the shock oscillation over the models, surface stream lines, and the surface pressure distributions, respectively. Shock waves oscillated periodically on both models under specific flow conditions, but the oscillation frequency for the 10-deg swept wing was 1.4 times higher than that for the unswept wing. A spectral analysis and a mode decomposition analysis of PSP data for the 10 deg swept-wing model showed that higher-frequency shock oscillation developed mainly on the outboard wing, where a complicated 3D surface flow structure was formed. We confirmed that the wing sweep angle is an important factor affecting characteristic Strouhal number of shock buffet according to the present data and the results of previous studies. Graphical abstract