Analytical evaluation of performance of a small scale horizontal axis wind turbine rotor blade

Abstract

Influence of downstream wake rotation ω, drag coefficient Cd and Prandtl’s tip losses Fi on the geometry and performance of rotor blade for a 2kW horizontal axis small scale wind turbine has been analytically analyzed. The objectives of the study are accomplished through Blade Element Momentum theory (BEMT). Analytical examination reveals that only the idealized blade exhibits maximum geometry and its performance closely follows Betz limit due to non-consideration of downstream wake rotation ω, drag coefficient Cd and Prandtl’s tip losses Fi. However, inclusion of the said losses drastically changes the blade shape and performance. The study showed that the average sectional chord ci and twist distribution θTi of the idealized blade reduced by 20.42% and 14.08% respectively and also the Coefficient of Power Cp of the idealized blade reduced nearly by 29.4% as a result of losses.