A vortex model of the Darrieus turbine
An aerodynamic performance prediction model for the Darrieus turbine has been constructed. The primary purpose was to allow reasonable prediction of aerodynamic blade forces and moments to be made. Previous aerodynamic models based on simple momentum principles are inadequate for predicting blade loading. In addition, accurate overall performance predictions for large tip to wind speed ratios cannot be made with the simple momentum models. Detailed prediction of the near wake structure 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 speed ratios to study the effect of number of blades and tip to wind speed ratios on the rotor performance. Power coefficients predicted by the present vortex model were compared to the vortex model due to Fanucci and the simple momentum or "strip theory". In addition, experimental results were used to compare with predictions obtained from the analytical model in an attempt to validate the analytical model.