Gurney Flaps Design_Passive Flow Control
Gurney Flap Design:
VAWT aerodynamic performance is enhanced by redesigning the blades using a Gurney Flap (GF) as passive flow control technique
It enhance turbine efficiency by using a passive flow control technique where no energy needed to control the separation of the boundary layer.
Symmetrical NACA 0015 airfoil selected to be as turbine blade and a gurney flap is added in three different configurations as following:
- Symmetrical gurney flap at the blade trailing edge on both pressure and suction side.
- Gurney flap on pressure side upstream the trailing edge.
- Gurney flap as on configuration #2 with inward dimple.
In previous studies, these three configurations showed a better aerodynamic performance in terms of lift increase and delay of the onset stall.
Rotor Tall (m)
Swept Area (m2)
Overall Height (m)
Bianchini et al  studied numerically three configurations of gurney flaps and they obtained power enhancements about 20% for some configurations. Other CFD study conducted by Shukla et al.  on different Airfoils presented that the configuration of using a combination of inward dimples and gurney flap achieved the best values of drag coefficient (CL) of 1.133 at angle of attack 12o. This was for NACA 0015 airfoil.
- Bianchini, Alessandro & Balduzzi, Francesco & Di Rosa, Daniele & Ferrara, Giovanni. (2019). On the use of Gurney Flaps for the aerodynamic performance augmentation of Darrieus wind turbines. Energy Conversion and Management. 184. 402-415. 10.1016/j.enconman.2019.01.068.
- Shukla V, Kaviti AK. Performance evaluation of profile modifications on straight-bladed vertical axis wind turbine by energy and Spalart Allmaras models. Energy 2017;126:766e95