Numerical Investigation on J-Shaped Straight-Bladed Darrieus Vertical Axis Wind Turbines Equipped with Gurney Flaps

This study provides a numerical investigation about J-shaped straight-bladed Darrieus vertical axis wind turbines equipped with outboard, inboard, and two-sided Gurney flap (GF). The performance of the turbines is examined for different GF heights and tip speed ratios (TSRs). The aerodynamic analysis is carried out using power curves, vorticity field, and pressure field surrounding the wind turbine. The results indicate that employing the inboard GF effectively enhances the turbine's performance by harnessing the drag force in the desired direction and postponing the flow separation up to 14 degrees of azimuth angle. The inboard GF with a height of 0.75% chord length exhibits the best performance among the GFs, showing an increase in output power at higher TSRs up to 12.35%. Conversely, the use of outboard and two-sided GFs of any height cannot improve the turbine efficiency.