Effects of surface heat transfer on the dynamic stall performance of a pitching airfoil in turbulent flow

Abstract

The dynamic stall phenomenon has been extensively studied in literature. Despite various innovative interventions focused on understanding its behavior, there are few efforts to study the influence of heat transfer on the dynamic stall performance of pitching airfoils, particularly in turbulent flows. This work investigates the effects of surface temperature variations on the dynamic stall of a NACA 0012 pitching airfoil at Re = 135,000. The temperature difference between the airfoil surface and the freestream temperatures was ΔT= 50, 100, and 150 K. The flow field around the airfoil was simulated using the computational fluid dynamics, and solving the Navier-Stokes equations incorporated with the k-ω/SST turbulence model. After validating the thermo-fluid solver, the aerodynamic response of the pitching airfoil was analyzed under upper surface cooling (USC) and upper surface heating (USH). The results showed that despite changes in the surface temperature, the drag coefficient remained nearly unchanged in both cases. However, the lift coefficient increased in USC and decreased in USH. In USC, the aerodynamic performance improved as much as 6.2 % at ΔT = 150 K. However, it was not affected that much in USH by varying ΔT. The USC tended to keep the flow attached to the surface, increasing the skin friction drag and lowering the pressure drag. The local Reynolds number increased since the USC raised the airflow velocity over the airfoil. Conversely, USH led to opposite effects on the flow characteristics. Overall, unlike USH, USC improved the dynamic stall performance of the pitching airfoil in the turbulent flow. The findings indicate that the airfoil’s surface heat transfer can effectively manipulate the dynamic stall behavior, offering a promising strategy for dynamic stall control in aeronautical applications.