A joint comprehensive validation activity on the structured numerical method elsA and the hybrid numerical method TAU was conducted with respect to dynamic stall applications. To improve two-dimensional prediction, the influence of several factors on the dynamic stall prediction was investigated. The validation was performed for three deep dynamic stall test cases of the rotor blade airfoil OA209 against experimental data from two-dimensional pitching airfoil experiments, covering low-speed and high-speed conditions. The requirements for spatial discretization and for temporal resolution in elsA and TAU are shown. The impact of turbulence modeling is discussed for a variety of turbulence models ranging from one-equation Spalart-Allmaras-type models to state-of-the-art, seven-equation Reynolds stress models. The influence of the prediction of laminar/turbulent boundary layer transition on the numerical dynamic stall simulation is described. Results of both numerical methods are compared to allow conclusions to be drawn with respect to an improved prediction of dynamic stall.
Nomenclatureb span, m c chord, m c d , c d drag coefficient, difference in drag coefficient c l , c l lift coefficient, difference in lift coefficient c m , c m pitching moment coefficient, difference in pitching moment coefficient f frequency, Hz M Mach number r radius, m Re Reynolds number s, s LE , s max cell size, cell size at airfoil leading-edge, maximum cell size, m T period, s v ∞ freestream velocity, m/s x, y coordinates, m y + normalized wall distance α, α angle of attack, difference in angle of attack, deg t timestep, s ω * reduced frequency, ω * = 2πfc/v ∞
