Numerical Modeling of Stall and Poststall Events of a Single Pitching Blade of a Cycloidal Rotor

Abstract

In the present work, a numerical study is carried out to compare the performance of seven turbulence models on a single pitching blade of cycloidal rotor operating in deep dynamic stall regime at moderate Reynolds number. The investigated turbulence models were: (i) kω-shear stress transport (SST), (ii) kω-SST with γ, (iii) transition SST (γ–Reθ), (iv) scale adaptive simulation (SAS), (v) SAS coupled with transition SST, (vi) SAS with γ, and (vii) detached eddy simulation (DES) coupled with transition kω-SST. The wake vortices evolution and shedding analysis are also carried out for the pitching blade. The performance of the investigated turbulence models is evaluated at various critical points on the hysterias loop of lift and drag coefficients. The predictions of the investigated turbulence models are in good agreement at lower angle of attack, i.e., αu ≤ 20 deg. The detailed quantitative analysis at critical points showed that the predictions of SAS and transition SST-SAS turbulence models are in better agreement with the experimental results as compared to the other investigated models. The wake vortices analysis and fast Fourier transport analysis showed that the wake vortex characteristics of a pitching blade are significantly different than those for the low amplitude oscillating blade at the higher reduced frequency.