Direct numerical simulations of horizontal-axis wind turbine blade section by considering aeroelastic vibrations

Innovative wind power technologies have led to wind turbines with significantly longer and more flexible blade designs to meet the rise in green energy demands. Aeroelastic vibrations of large horizontal-axis wind turbines play a vital role in the aerodynamic performance of the turbine blades. Previous studies in the field of oscillating wind turbines were mostly focused on low-fidelity numerical simulations, and most of these analyses were performed over two-dimensional wind turbine blade sections. However, it is essential to perform a highly accurate numerical analysis over a mid-section of a wind turbine blade to capture all details of vorticities, flow separation, and pressure distribution on the surface of the blades by considering their flap-wise oscillations. In this study, high-order direct numerical simulation based on the spectral-hp element method is employed to capture all details of flow structure on the surface of NACA0012 wind turbine aerofoil for different angles of attack. The simulations were performed at Re=1.30×105, and the blades have harmonic oscillations at the Mach number of Ma∞=0.4. The results show that the flow separation point is significantly affected due to the vibrations. Flow separation occurs at X/C=0.580 over the stationary blade, while it happens much faster at X/C=0.172 on the surface of the oscillating airfoil. Flow detachment and reattachment due to the flap-wise oscillations is the main reason for faster separation and additional flow disturbance.