Dynamic Stall Simulations on a Pitching Finite Wing

Unsteady Reynolds-averaged Navier-Stokes computations were carried out on a pitching finite wing model using the finite volume solver DLR-TAU. The comparison with the experimental data reveals a good agreement, especially in the region of the first occurrence of stall. Discrepancies are observed in the blade tip region, where the flow in the numerical data shows a stronger separation along with larger hysteresis effects in contrast to the experiment. Additionally, the analysis of the flowfield reveals the existence of multiple dynamic stall cells over the span. The simulations with different pitching frequencies demonstrate a change in the topology of dynamic stall vortex formation in the spanwise direction. An investigation using turbulence transition modeling based on a gamma-Re-theta t approach demonstrated that small differences can be attributed to transition; nevertheless, these can give further insight into the physics of dynamic stall and improve the comparability with the experiment. A comparison with two-dimensional simulations shows strong similarities of the peak values in the sections where the vortex starts to evolve and, although the three-dimensional flow is strongly driven by spanwise flow, the impact on the aerodynamic loads is relatively low.