叶栅内定常及非定常粘性流动数值模拟

NUMERICAL SIMULATION OF STEADY AND UNSTEADY VISCOUS FLOWS IN CASCADES

本文给出了一个模拟叶栅内准三维定常和非定常粘性流动的数值方法。对于定常流动，采用ＴＶＤ Ｌａｘ－Ｗｅｎｄｒｏｆｆ格式和代数湍流模型求解雷诺平均Ｎａｖｉｅｒ－Ｓｔｏｋｅｓ方程，使用当地时间步长和多网格技术使计算加速收敛到定常状态；对于非定常流动，使用双时间步长和全隐式离散，采用与求解定常流动相似的多网格方法求解隐式离散方程。文中给出了ＶＫＩ透平叶栅内的定常流结果和１．５级透平叶栅内的非定常数值结果。

A numerical method for the simulation of quasi-3D steady and unsteady viscous flows in cascades has been presented. For steady flow simulation, the TVD Lax-Wendroff scheme is used to solve the Reynolds-averaged Navier-Stokes equations and the eddy viscosity is estimated by using an algebraic turbulence model. Local time-step and multigrid algorithm are applied to speed up the convergence to a steady state; For unsteady flow simulation, dual time-step and implicit discretization are adopted and the implicit discretization equations are solved by using the multigrid algorithm similar to that of steady flow simulation. Numerical results of steady flow in the VKI gas turbine cascade and unsteady flow in a 1.5 stage steam turbine are presented.