Abstract: The sparatated flow structure of an NACA 0015 airfoil performing the constant-rate pitching motion is studied by numerically solving N-S equations in vorticity-stream function form. ADI method is used for solving the vorticity equation and a direct method for Poisson equation is used for solving stream function equation. The computation correctly simulates the experimentally observed multiple-vortex structure on a pithching airfoil and, in addition, some new flow phenomena are revealed. Based on the calculated flow structure and existing data on measured aerodynamic forces, and by using the theory of vortictity dynamics, the mechanism of high-lift generation on the pitching airfoil is studied, and some ideas about it are provided.

Key words: airfoil, pitching, separated flow, N-S equations, numerical calculation