Numerical Simulation Methods Of Unsteady Flow Field For Oscillating Airfoil

Based on unsteady Euler and N-S equations, moving grid method, field velocity method anddynamic approximate boundary method are used to simulate transonic flow, dynamic light stall anddynamic deep stall of NACA0012airfoil.The finite-volume method is applied, and the dual-time stepping for multistage schemes is usedfor time marching. Detached eddy simulation (DES) model based on Spalat-Allmaras One-Equationturbulence model is employed to simulate turbulent flows. The initial grid is C-type grid. An elasticdeformation grid method is used to solve the moving boundary problem. On fixed grids, field velocitymethod with viscous flux correction and dynamic approximate boundary method are used to simulatepitching movement of an airfoil.Calculated lift coefficient and moment coefficient based on the moving grid method and fieldvelocity method are in good agreement with the experiment data. Tne field velocity method is able tosimulate the unsteady prccess of the light stall and deep stall effectively, which will save computationtime. Moving mesh method is able to capture the actual flow field information better than fieldvelocity method.At small angle of attack, the results calculated by dynamic approximate boundary method is ingood agreement with the experiment data, but on transonic flow, moment coefficient is very differentfrom the experimental data. Because there is error of surface pressure coefficient distribution near theshock wav.