Wind Turbine Blade Optimisation with Tip Loss Corrections

Tip loss corrections are a critical factor in blade element momentum theory when determining optimum blade shape for maximum power production. Using numerical and analytical optima, this paper compares the optimal tip shape using the classical tip loss correction of Glauert, a later refinement by de Vries and a new tip loss model of Shen et al. A semi-analytical solution was proposed to find the optimum rotor considering Shen's new tip loss model. However, whilst theory and numerical solution were in good agreement, the solution is highly questionable from an aerodynamic point of view. The de Vries tip loss correction was found to be most suitable correction for blade optimisation. However, the BEM calculations described herein suggest that any improvements in CP were typically 0.4% compared to analytical and numerical optima obtained ignoring tip losses.