NUMERICAL INVESTIGATION OF UNSTEADY TRANSITIONAL FLOW OVER OSCILLATING AIRFOIL

A numerical investigation of unsteady transitional flow over an oscillating NACA 0012 airfoil at a Reynolds number of 44,000 and reduced frequency of 0.2 is carried our and the results are compared with experimental data. The Navier-Stokes equations defined on arbitrary Lagrangian-Eulerian coordinates are solved by a time-accurate finite volume method that incorporates an incremental pressure equation for the conservation of mass. The transitional turbulence field is described by multiple-time-scale turbulence equations. The numerical method successfully predicts the large dynamic stall vortex (DSV) and the trailing edge vortex (TEV) that are periodically generated by the oscillating airfoil. The numerical results shore that the transition from laminar to turbulent state and relaminarization occur widely in time and in space. The calculated streaklines and the ensemble-averaged velocity profiles are in good agreement with the measured data.