凸拐角附近激波与湍流边界层干扰的数值模拟研究

Numerical investigation of shock wave/boundary layer interactions near a convex corner

采用大涡模拟方法数值研究了来流马赫数Ma∞=3、雷诺数Reθ=2070的凸拐角附近激波与湍流边界层干扰问题。对于尖拐角和钝拐角两种情况,计算考察了激波入射到拐角下游时的流场结构、非定常分离流以及湍流统计特性。研究发现:尖拐角能够使流动产生局部集中的顺压梯度,导致壁面摩擦系数在拐角处出现峰值,因此分离点难以越过拐角向上游运动,而再附点发生前后运动。与尖拐角情况不同的是,钝拐角产生的局部顺压梯度不足以阻止分离点越过拐角,因此分离点和再附点都会发生运动。此外,尽管凸拐角产生的顺压梯度能抑制分离点附近的近壁小尺度涡结构,但在经过入射激波作用之后,近壁小尺度涡结构在再附点附近显著增强。

Large-eddy simulations have been conducted on the interaction of shock/turbulent boundary layer near a convex corner of inflow with Ma∞ =3 and Reθ=2070.Two typical convex corners,i.e.,the sharp and blunt corners,are considered.The geometrical effects of convex corner on the flow structures,unsteady separating flow,and turbulent statistical characteristics are analyzed systematically.For the sharp corner case,locally concentrated favorable pressure gradients are formed near the corner,where the wall friction coefficient obtains a high level.As a result,the separation point is fixed and thus unable to move cross the sharp corner,while the attachment point takes a front/back motion.However,for the blunt corner case,the separation point is not fixed at the corner because of the dispersed distribution of the favorable pressure gradient.As a consequence,both the separation and attachment points become to move front and back.Furthermore,the small scale vortical structures near the separation point are suppressed due to the presence of favorable pressure gradients near the convex corner,while enhanced greatly near the attachment point by the incident shock interaction.