Numerical analysis of the horizontal axis wind turbine with winglets

Abstract

The objective of this paper is to show numerically the aerodynamic effectiveness of winglets on the performance of a horizontal axis wind turbine (HAWT). The winglets used in this study are an inclined extension of the rotor blade. For the numerical analysis, a vortex lattice method with a free wake model was used, as the method can be applied to arbitrary blade shapes and the model needs no parameter based on empirical data about the wake geometry. Calculations were performed on the flow field of the rotor wake and the rotor performance, and results were compared between rotors with and without winglets. To examine the effects on the strength of blades, the flatwise bending moment was also calculated. A small installation angle of winglets causes a large increase in the power coefficient but a small increase in the flatwise bending moment compared with the blades with radially extended winglets.