As wind turbine technology grows, larger and longer blades are needed to generate more energy. At the same time, the turbines need to remain structurally stable. Blades with increased thickness towards the center of the turbine address this problem but can also cause stalling.
Vortex generators are a proven technology for preventing stalling and improving performance in turbines. However, previous studies focused on individual cases of optimizing vortex generator parameters for specific turbine designs.
Im et al. created simulations to enhance any existing wind turbine using a vortex generator. They determined the best vortex generator designs based on the size of the turbine blades. They analyzed different cases according to the height and length of the vortex generator and used computational fluid dynamics analysis to determine which parameters most effectively delayed the stalling point.
“The vortex generated reduces the momentum thickness by mixing the energy inside and outside the boundary layer,” said author Heejeon Im. “Therefore, the vortex generator serves to stabilize the boundary layer, so that flow separation does not occur easily, and stalling becomes less likely.”
If the eddy current strength generated by the vortex generator is too large, the induced drag force greatly increases, making it essential to use a vortex generator of an appropriate shape and size.
When the vortex generators were applied to an example wind turbine design, the annual energy production increased by 2.6% on average at a low mean wind speed and 1.6% at a high mean wind speed.
Source: “Numerical analysis of the effect of vortex generator on inboard region of wind turbine blade,” by Heejeon Im, Seongkeon Kim, and Bumsuk Kim, Journal of Renewable and Sustainable Energy (2021). The article can be accessed at https://doi.org/10.1063/5.0065108.
