Aerodynamic calculation of the performance of horizontal axis wind turbines and comparison with experimental results

Abstract

The aerodynamic forces over wind turbines are calculated by the strip theory and by the vortex theory, and their results compared with experiments. The induced velocities calculated by the strip theory are taken as the first iteration of the vortex method. The vortex position and strength in the wake are estimated from semiempirical considerations. Tests are carried out in a wind tunnel, where however the Reynolds numbers are so small that there is no data available for the lift and drag coefficients, which therefore have to be estimated. The comparison with experiments is very good for the values of the power, but not so good for the induced velocity. Although both theories give similar results, the vortex theory gives a better approximation.