Aerodynamic performance enhancement analysis of horizontal axis wind turbines using a passive flow control method via split blade

Abstract

Horizontal axis wind turbines (HAWTs) are being widely used for green energy generation. Hence, aerodynamic performance enhancement of these machines is a key point for their overall performances. This paper numerically investigates effects of a passive flow control method on aerodynamic performance of a HAWT by splitting its blades along the span. First, 2-D simulations are conducted on S809 airfoil in order to study effects of split width and Reynolds. Later, original blade (without split) and two split blades are simulated, and effects of split location on power coefficient, low speed shaft torque and flow patterns are investigated at different tip speed ratios. The results reveal that for an attached flow, torque value are sensitively dependent upon split location and injected flow angle. This is because injected flow triggers an early separation and reduces aerodynamic performance. For a partially separated case, results show that split location may impose either positive or negative effects on torque generation. Finally, for highly separated/stall situations, blade aerodynamic performance becomes less sensitive to the location of split. Also, torque per unit span analysis shows that as tip speed ratio decreases the split part of the blade generates a higher share of the total power.