An improved tip-loss correction based on vortex code results

Standard blade element momentum(BEM) codes use Prandtl’s tip-loss correction which relies on simplified vortex theory under the assumption of optimal operating condition and no wake expansion. A new tip-loss correction for implementation in BEM codes has been developed using a lifting-line code to account for the effect of wake expansion, roll-up and distortion under any operating conditions.

A database of tip-loss corrections is established for further use in BEM codes. Using this model a more physical representation of the flow and hence a better assessment of the performance of the turbine by BEM codes is expected.