AERODYNAMIC INTERFERENCE BETWEEN TWO DARRIEUS WIND TURBINES.

The effect of aerodynamic interference on the performance of two curved-blade, Darrieus-type, vertical-axis wind turbines has been calculated using a vortex/lifting-line aerodynamic model. The turbines have a tower-to-tower separation distance of 1. 5 turbine diameters, with the line of turbine centers varying with respect to the ambient wind direction. The effects of freestream turbulence were neglected. For the cases examined, the calculations showed that the downwind turbine power decrement 1) was significant only when the line of turbine centers was coincident with the ambient wind direction, 2) increased with increasing tip-speed ratio, and 3) is due more to induced-flow angularities downstream than to speed deficits near the downstream turbine.