Numerical Investigation of Co-flow Jet Effects on Dynamic Stall of a Thick Airfoil

Dynamic stall is a phenomenon which appears due to the vortex shedding on the oscillating wing section at high angles of attack. Occurrence of the dynamic stall causes a severe decrease in the lift force and huge increase in the drag force. The Co-Flow Jet (CFJ) is one of the active flow controls to prevent this phenomenon. In this paper, the effect of this active flow control on the NACA 0025 airfoil for different Reynolds numbers is investigated. For numerical solution of the fluid flow, the Reynolds-averaged Navier-Stokes equations in two-dimensional, incompressible, and unsteady form with the SST-k-ω turbulence model is solved using an in-house computer code. The developed code is validated with the previous experiment data, and a fairly good agreement is observed. In order to investigate the effects of the CFJ, three different momentum coefficients of 0.05, 0.07 and 0.08 and five Reynolds numbers of 5×104, 7.5×104, 105, 1.5×105, and 3×105 are studied. It is found in the examined cases that the baseline airfoil in the Reynolds numbers of 105 and lower has different behavior compared to the higher Reynolds numbers; while in order to eliminate the dynamic stall, it requires more jet momentum of 0.08, while for the higher investigated Reynolds numbers, by applying the jet momentum of 0.07, the dynamic stall is completely eliminated.