Aerodynamic performance of wind turbines

This report summarizes the state-of-the-art of performance prediction methods for both horizontal and vertical axis wind turbines. Strip theory methods for horizontal axis wind turbines are evaluated for various tip loss models and occurrence of multiple solutions in strip theory analysis is discussed and illustrated. The performance of high-solidity turbines such as the Chalk design also are discussed. The configuration and performance of optimum horizontal axis wind turbines are addressed. Optimization schemes are developed and discussed and comparisons with the MOD-O rotor are made. Performance at off-design conditions is also examined. Performance prediction methods for vertical axis wind turbines are covered. The performance model for the Darrieus Rotor is developed. Multiple solutions are found to occur for Darrieus Rotors in the same manner as occurs for horizontal axis rotors. This flow model is compared to existing experimental data and shown to yield excellent agreement. An analytical model of the flow in a Savonius Rotor is presented. The flow model is shown to predict the essential features of flow in Savonius Rotors with consideration of viscous effects. (GRA)