3D and finite-wing effects on the shock-buffet instability mechanism

A study of the transonic shock-buffet flow instability phenomena is presented. Reynolds-averaged Navier-Stokes simulations of four wing configurations are conducted at sock-buffet flow conditions. The simulated configurations include finite, infinite, straight and swept 3D wing models. Based on the results, the effects of 3D flow and wing finiteness on the shock-buffet phenomena characteristics are identified. The shock motion typical frequencies, amplitudes, periodicity, continuity and harmoniza- tion characteristics are found to be affected by the studied effects. Nevertheless, the instability fundamental mechanism was shown to remain similar to its 2D nature. It was indicated that the previously suggested necessary criteria for shock-buffet onset in terms of shock position and flow separations remained relevant for the studied configu- rations. Swept wings with a tip chord that is parallel to the root chord were found less likely to experience shock-buffet compared to similar wings with rotated tip planes. Two unsteady phenomena which are characterized by typical frequencies which are considerably higher than the shock-buffet typical frequencies were observed in this study.