Dynamic Stall of a Pitching Airfoil: Comparative Study with ONERA and OpenFOAM

Dynamic stall is an inevitable complex flow phenomenon in rotorcrafts, wind turbines, supermaneuverable aircrafts and flapping- wings. Although experimental studies on dynamic stall pose difficulties, a great interest lies in understanding and mitigating its effects. Researchers opted for computational techniques and empirical/semi-empirical models for predicting the aerodynamic loads under dynamic stall conditions. The current study aims to understand the dynamic stall of an airfoil exhibiting pitching motion through numerical simulations and ONERA’s semi-empirical model. The numerical simulations are carried out for different reduced frequencies of range κ = 0.03, 0.05, 0.1 and Reynolds numbers Re =  \(3\, \times \,10^{4}\) , \(3\, \times \,10^{5}\) , \(3\, \times \,10^{6}\) . An open-source computational fluid dynamics software, OpenFOAM is used for the simulations, and the results are compared with experimental data and the ONERA model. The features of dynamic stall are examined effectively, and the results correlate well against the experimental data. With the decrease in Reynolds number, an increase in lift-curve slope is observed during the onset of dynamic stall.