Exploring the Complexities of Wind Turbine Wakes

November 24, 2010
November 2010

The aim of this research is to characterize the structure as well as the behavior of the turbulent flow around the turbine tips with emphasis on the vortical structures shed by the blades. Model wind turbines of different sizes (rotor diameters of 0.128 and 0.6m) are being used for this purpose.

The 0.6m-model wind turbine consists of a three-blade rotor attached to a magnetic particle brake that allows a highly controllable load on the wind turbine. The blades of the wind turbine have a length of 250 mm with total rotor diameter, including the rotor, of 630.5 mm. Each blade has a NACA 634-421 airfoil section with maximum chord length of 32 mm, at a distance of 11 mm from the blade base, and a minimum chord length of 9.5 mm at the blade tip.

A cross-wire anemometer and Particle Image Velocimetry (PIV) are being used to obtain single-point time-resolved statistics and averaged spatial statistics respectively at different locations downwind of the turbine. A general case of the flow around multiple wind turbines (as is found in a wind farm) will be also studied by considering a number of turbine layouts--both aligned and staggered farms will be considered, in addition to different inter-turbine spacing.
The high-resolution spatial and temporal information obtained in the laboratory experiments is being used to test and guide the development of improved parameterizations of wind turbines in high-resolution numerical models.