A vortex model of the Darrieus turbine

Abstract

An aerodynamic performance prediction model for the Darrieus turbinehas been constructed. The primary purpose was to allow reasonableprediction of aerodynamic blade forces and moments to be made. Previousaerodynamic models based on simple momentum principles are inadequatefor predicting blade loading. In addition, accurate overall performancepredictions for large tip to wind speed ratios cannot be made withthe simple momentum models. Detailed prediction of the near wakestructure is also within the capability of the present model.Results were obtained from the present vortex model for the one-,two- and three-bladed rotors operating at various tip to wind speedratios to study the effect of number of blades and tip to wind speedratios on the rotor performance. Power coefficients predicted bythe present vortex model were compared to the vortex model due toFanucci and the simple momentum or "strip theory". In addition, experimentalresults were used to compare with predictions obtained from the analyticalmodel in an attempt to validate the analytical model.