Abstract: For separation controlling in hypersonic turbulence flow, flat plate/roughness element interaction is studied with large eddy simulation (LES). Unsteady flow characteristics behind roughness element are analyzed. Flow stability is investigated with roughness element flow field in different height and diameter conditions. Simulation indicates that intensity inverse pressure grads are generated due to roughness element interaction in hypersonic boundary flow. In high free shear layer, inconsistent stable characteristic is influenced by height of roughness element:Short cylinder roughness element interact with flat plate boundary layer induces shock wave/boundary layer interaction and produces a free shear layer, while free shear layer is stable downstream. However, free shear layer induce by long cylinder roughness element is instable. It evolves into K-H vortex in stream-wise. On the other hand, average friction coefficient and heat-flux coefficient on flat surface interacted by roughness element are lower behind roughness element(k=1.0δ), which could be applied in anti-heat and anti-drag of aircraft inlet.

Key words: turbulence, transition, roughness element, shock wave/boundary layer interaction, large eddy simulation