Modeled airfoil aerodynamics predicts optimal vertical-axis wind turbine performance

Horizontal-axis wind turbines, currently the most common version used for wind energy production, work best in places where winds blow around 30 miles per hour continuously. Vertical-axis wind turbines, or VAWTs, on the other hand, have a main rotor shaft positioned transverse to the wind. This means they can utilize wind from any direction without the active system required by the horizontal-axis turbines in order to follow the wind direction. They can also operate in moderately low wind conditions (around 11 miles per hour), allowing more widespread use. VAWTs do still suffer limitations, such as trouble self-starting. One VAWT design called the geosphere overcomes this difficulty using a s1210 type of airfoil. This type of turbine blade is highly cambered to promote self-starting.

A model presented in the Journal of Renewable and Sustainable Energy can predict the aerodynamic performance of these s1210 blades through a full 360 degrees of angle of attack. Accurate modeling of the aerodynamic forces is necessary for optimizing energy production of the geosphere design. The authors found the airfoils received the highest thrust contribution between 0 to 30 degrees and 180 to 300 degrees. They tested their model with experimental results from wind-tunnel measurements, finding it closely approximates the airfoils’ performance and outperforms previous models applied to the s1210 blades.

By providing a way to accurately predict lift and drag characteristics of the airfoil for all incident angles, this model facilitates spacing of the airfoils around the vertical axis to get the most thrust, optimizing performance and energy production. Geosphere VAWTs could be used in remote applications with low wind speeds, like at agriculture farms, small airports, or in areas disconnected from the power grid by a disaster. The researchers plan to verify their design by adding this model to a larger model that will predict how much power the geosphere design will be able to produce overall.

Source: “A new 360° airfoil model for predicting airfoil thrust potential in vertical-axis wind turbine designs,” by D. Blake Stringer, Paul Hartman, Dakota W. Bunner, and Michael R. Fisch, Journal of Renewable and Sustainable Energy (2018). The article can be accessed at https://doi.org/10.1063/1.5011207 .