Computational Considerations for the Prediction of Stall Flutter

Abstract

A solver has been developed within the OpenFoam framework to compute large amplitude motion of two-dimensional rigid configurations. The results obtained with this code were successfully validated on rigid airfoils at static and dynamic conditions, as well as correlated with experimental data and numerical solutions from similar unsteady solvers. The results demonstrated that while current computational methods are able to predict the self-sustained oscillations characterizing a pitch-dominated stall flutter, including energy transfer, improvements are needed. The influence of grid, temporal integration, turbulence modeling, and flow equations is examined for the stall flutter starting solution of dynamic stall. Nomenclaturestream Mach number N Grid size in number of cells N ref Reference grid size in number of cells N sub−iters Number of sub-iterations per time step Re Reynolds number t Time, seconds T Period of cycle, seconds V ∞ Free stream velocity, m/s α Angle of attack, degrees α 0 Mean angle of attack, degrees α 1 Amplitude of angle of attack, degrees ω Frequency of oscillation, radians/second