Numerical Investigation of the Dynamic Stall at Low-Reynolds Number Flow over a S1210 Pitching Airfoil

The current numerical simulation is performed to investigate the behavior of the oscillating S1210 airfoil and study the effective parameters like the oscillation amplitude and the reduced frequency of the oscillation. Moreover, to investigate the dynamic stall phenomenon; flow structure and vortices propagation are discussed based on the velocity contours obtained from the numerical simulation. This 2-D transient simulation is at Re=135000 and SST k-ω turbulence model is utilized. Mesh study and time study were done to achieve the best number of the cells and the optimum value of the time step, respectively. Also, since there were no available identical experimental or numerical results for the S1210 airfoil, to validate the method of the simulation, a similar simulation was done by employing a NACA0012 airfoil and the outcomes were compared with the published data. It is observed that increasing the amplitude and reduced frequency of the oscillation will result in postponing the dynamic stall. It is revealed that increasing the amplitude from 10° to 20° causes the aerodynamic efficiency to be reduced by 48.2 percent. Furthermore, it is observed that 0.15 is the optimum value of the reduced frequency among the reduced frequencies equal to 0.1, 0.15 and 0.2. At the end of this study, the flow structure is shown, and it is concluded that the formation and movement of the low pressure vortices towards the TE (trailing edge) is the main reason of dynamic stall occurrence.