立楔诱导高超声速分离流动的被动控制研究

双模态超燃冲压发动机由于压力扰动可能发生不起动现象,造成推力严重下降,对飞行稳定性与飞行安全具有很强的破坏性.不起动初始阶段主要受到激波与边界层相互作用引起的流动分离影响,希望通过控制分离达到改善流动的目的.采用5阶特征型WENO(weighted essentially non-oscillator)格式与3阶TVD(total variation diminishing)型Runge-Kutta(R-K)格式的高精度数值方法,求解三维Navier-Stokes(N-S)方程,研究与分析了凸起物和被动吹吸两种被动控制方法对激波与边界层相互作用导致的高超声速流动分离现象的控制效果.结果表明:凸起物通过诱导流向涡形成,改变空间压力分布,减弱二次分离,影响分离结构;吹吸方式的被动控制技术通过平衡分离区与再附区之间的高低压差,降低逆压梯度,使压力分布与分离区域发生改变.

Two attempts of passive control methods on hypersonic flow separation induced by a fin

Dual-mode scramjet engine may suffer unstart because of a large enough upstream or downstream pressure disturbance.Unstart would dramatically reduce the thrust and could compromise the stability and safety of the vehicles,so it is necessary and important to investigate the effective control methods.Fifth-order characteristic-wise weighted essentially non-oscillatory (WENO) scheme and third-order total variation diminishing (TVD) Runge-Kutta (R-K) method were applied to solve the three-dimensional Navier-Stokes (N-S) equations,to explore two passive control methods using trips and passive suck/blow respectively,and to explore corresponding control effect on the hypersonic flow separation caused by shock wave/boundary layer interaction induced by a fin.The results show that the vortex in flow direction induced by trips affects the flow separation structures evidently.The second separation and reattachment lines almost disappear.Control method employing passive suck/blow balances the pressure between the separation and reattachment areas and reduces the pressure gradient which depresses the separation structures.