Aerodynamics

A simulation tool has been developed to predict the aerodynamics of a vertical axis wind turbine. The goal was to better understand how a vertical axis turbine captures energy from the wind and thus be able to improve performance by optimizing turbine design.

Aerodynamic flows are complex and must in many cases be solved numerically. When the aerodynamics is simulated for the vertical-axis turbines, three different methods are generally used: the stream tube model, vortex models and finite element/volume method. Research at Uppsala University, focuses on the first two models.

The stream tube model allows for most rapidly numerically solution as it does not contain a time-dependent flow. The velocity field is approximated only on the turbine blades. Thanks to its speed, this model can be used to simulate the flow in three dimensions. It allows simulations of varying wind speed of the turbine area, and the impact of the blade support arms.

Studies of how various turbines affect each other must instead use the vortex method which is somewhat more complex. Vortex simulations are preferably done in two dimensions as these require more computational power. Higher power can be obtain for individual turbines if they are placed close to each other in a line while the flow direction is perpendicular to this line, according to simulations with the vortex method.

The model developed at Uppsala University can be used in the design of an H-rotor to optimize efficacy and/or minimize material-loads. With the help of wind statistics from a given location, the most optimal design for a turbine can be calculated iteratively.

For more information on aerodynamics of wind power plants, please contact Anders Goude.