Comparison of aerodynamic models for horizontal axis wind turbine blades accounting for curved tip shapes

Curved tip extensions are among the rotor innovation concepts that can contribute to higher performance and lower cost of horizontal axis wind turbines. One key drivers exploit their advantages is use accurate efficient computational aerodynamic models during design stage. The present work gives an overview different state-of-the-art models. following tools were employed, in descending order complexity: (i) a blade-resolved Navier Stokes solver, (ii) lifting line model, (iii) vortex-based method coupling near-wake model with far-wake (iv) two implementations widely used blade element momentum (BEM), without radial induction. predictions codes compared when simulating baseline geometry reference turbine extension designs relatively large sweep angle and/or dihedral angle. Four load cases selected for this comparison, cover several aspects modeling: steady power curve, pitch step, extreme operating gust impact, standstill deep stall. study highlighted limitations BEM-based formulations capture trends attributed introduction curvature at tip. This was true even using induction submodel. rest methods showed good agreement most studied cases. An exception configuration, as Navier-Stokes solver only code able highly unsteady effects