摘要
在激波区使用自适应壁对跨声速翼型上的激波/边界层干扰进行控制,可改变机翼的气动性能。这种被动控制可通过在翼型的激波区开一凹腔,其上覆盖一弹性橡胶膜柔壁来实现。本文给出用N-S方程数值模拟这一自适应控制翼型的跨声速粘性绕流,提出了一个适用于本特殊情况(物面边界局部地区在求解过程中有变化)的处理办法。并探讨了自适应柔壁对当代跨声速翼型绕流的影响。
The performance of transonic airfoil can be changed with the shock/boundary layer interaction controlled by an adaptive surface in the shock region. This passive control can be. realized by making a cavity on the airfoil and covering it with an elastic rubber membrane wall.The 2-D Reynolds-averaged compressible unsteady full Navier-Stokes equations is solved using the Beam-Warming scheme with Baldwin-Lo-max turbulent model. A method is proposed which can treat this special case (with the local surface boundary adaptively changed by the flow field around airfoil), and a procedure is described which allows the computation of transonic viscous flow over the adaptive airfoil using N-S equation. The influence of the adaptive wall on the flow field over a modern transonic airfoil has been investigated.Since we use the time marching method to get the steady result, the main difficult in the present case is the treatmenl of the membrane wall boundary which changes its shape as the solution proceeds. Deflections of the flexible wall as function of the pressure over it can be found by the mechanics of materials. We proposed a method of locally changing grids to avoid the global interpolation. Since the grid spaces grow exponentially from the surface in the normal direction, we use a linear relation which means deformation of grids dies out exponentially. The converging time is saved considerably to get accurate solutions following the above treatment. The locally changed grids maintain the good quality of the original grids. The calculated results show that compared with the case without control, a strong shock splits into two weak shocks and the lift increase a little with the adaptive control case. That the adaptive control case has a smaller wake means less losses and the total drag decrease more than three percent
出处
《空气动力学学报》
CSCD
北大核心
1993年第2期129-135,共7页
Acta Aerodynamica Sinica
关键词
激波
边界层干扰
跨音速分离
shock/boundary interaction, passive control, supercritical airfoil, transonic separated flow.
