Numerical Simulations of Dynamic Stall for Wind Turbine Applications
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The current trend in wind energy is towards even slimmer rotor blades, as they combine aerodynamic efficiency with low weight, thus enabling further rotor growth. These blades require precise knowledge of aerodynamics for their design, as they are increasingly prone to aeroelastic effects, i.e. movement induced by aerodynamically imposed forces. One effect that has been insufficiently investigated in the design process of blades for wind turbines is the dynamic stall. In this present work, an attempt has been made to numerically simulate NREL S809 airfoil for wind turbine applications. The airfoil has been evaluated under static and dynamic conditions at a Reynolds number of 1e6. The airfoil has been studied with three different mean angles of attack of 8°, 14°, and 20°. A reduced frequency of 0.078 and an amplitude of 10° is imposed at a quarter chord position in a sinusoidal manner. Two equation eddy viscosity turbulence model “k-Omega SST” is used for static and kOmegaDDES turbulence model is used for dynamic conditions. The results are validated against the experimental data and show a reasonable agreement. The flow field around the airfoil in dynamic conditions is evaluated and presented in detail.
