高超声速平板边界层/圆柱粗糙元非定常干扰

以高超声速表面湍流控制为应用背景,平板/粗糙元干扰流动为模型,采用大涡模拟方法研究粗糙元流场干扰作用机理.分析粗糙元外形特征对于流动稳定性影响,给出其引起的流动表面参数的变化规律.结果显示超声速边界层在粗糙元作用下产生强逆压梯度并发生分离,粗糙元高度对高位自由剪切层失稳有明显影响,低粗糙元干扰下游流动稳定性,而高粗糙元剪切层发生流向失稳,形成涡串结构;同时粗糙元干扰导致下游摩阻和热流系数较平板略低,可能应用在进气道降热和减阻中.

Unsteady Interaction on Flat Plate/Isolated Roughness Element in Hypersonic Flow

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.