Quasi-Steady Analysis of a Small Wind Rotor with Swept Blades

Abstract

It is well known that wind power generation addresses the energy needs of small and remote populations as one of the alternatives to petroleum-based energy’s greenhouse effect. Although there are several publications on rotor design and performance analysis, more should be written about the starting of wind turbines, mainly the small ones, where starting can be a big issue. The present paper evaluates the impact of the swept blade angle on the aerodynamic torque, thrust force, and minimal wind speed required to start the operation of a compact horizontal-axis wind turbine. It presents a novel investigation of the influence of swept rotor blades on the starting performance of a turbine drivetrain. The methodology uses the blade element moment theory coupled to Newton’s second law, in which Palmgren’s extended approach is employed. When the proposed methodology is compared to the experimental data available in the literature, it exhibits good agreement. However, when the wind turbine starts to run, the results show that swept blades do not always enhance the torque coefficient or reduce the thrust force as indicated in some scientific papers. For backward-swept blades, the maximum value decreases 4.0%. Similar behavior is found in thrust force for forward-swept blades. Therefore, more study is required to evaluate many blade foils in several operational environments to confirm this statement.