Browsing by Subject "Wind turbines -- Mathematical models"
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Item A vortex model for the vertical axis wind turbine(Texas Tech University, 1988-08) Brownlee, Baron GeneVarious methods have been developed to predict the performance and aerodynamic loads of the Darrieus vertical axis wind turbine. The most accurate of these is the vortex method developed by Strickland (1981). As implemented in the program, VDART (Vortex method for the DARrieus Turbine), the vortex method proved to be uneconomical because of the large computation times required for convergence to a solution. In the present study, significant savings in computation time are achieved by assuming that the wake convection velocity can be determined at the time of vortex generation. A new program, VDART-TURBO, has been developed using this time saving assumption. Both two-and three-dimensional versions have been successfully implemented. The two-dimensional version, VDART2T, has been successful in reproducing both experimental and computational results achieved by Strickland (1979,1981). The three-dimensional version, VDART3T, is presently in the advanced stages of development, and promises to be highly effective in reducing computational time, while maintaining an acceptable degree of accuracy.Item A vortex model of the Darrieus turbine(Texas Tech University, 1978-12) Nguyen, Thong V.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.