二维涡轮叶栅流场的直接数值模拟

采用高精度有限差分格式求解非定常N-S方程组,对低雷诺数下二维涡轮叶栅流动进行了直接数值模拟,计算了雷诺数为10000,VKI涡轮叶栅在0°,8°以及-8°攻角下的流场,对涡轮叶栅非定常流动机理做了初步的探讨。计算结果表明:在叶栅尾缘处,逆时针方向和顺时针方向的主涡交替在壁面产生,并和主流相互作用产生二次涡,而当二次涡与主流连通发生掺混时,将引起主涡被分割并从叶片表面脱落;攻角在一定范围内的变化对VKI涡轮叶片表面边界层发展影响不明显。文中还对尾迹区的统计量特性和速度亏损特性等进行了研究。

Direct Numerical Flow Simulation in a Two-Dimensional Turbine Cascade

Using high order finite difference scheme,a Direct Numerical Simulation (DNS) of vortex shedding in a two-dimensional VKI turbine cascade has been carried out.The Reynolds number is 10 000,and the angles of attack are 0 deg,8 deg and -8 deg.The mechanism of unsteady flow in turbine cascade was investigated.Numerical results indicate that,near cascade trailing edge region,clockwise and anticlockwise primary vortices generate alternately from the surface.Secondary vortices form at the interactions of primary vortices and main flow.When secondary vortices mix with the main flow,primary vortices are divided and shedded from trailing edge.The changes of incidence in a certain range have no prominent influences on the development of blade boundary layer.The statistical characteristics and velocity defect characteristics in the wake region are also analyzed.