An investigation of in‐field blockage effects in closely spaced lateral wind farm configurations

A method of increasing the performance of wind farms has been established by limiting the lateral separation between neighbouring wind turbines. The close proximity of the wind turbines creates a beneficial in‐field blockage effect that results in a core of increased speed that is accelerated through the gap between the turbines. A preceding study indicated that the performance of three wind turbines can be increased by over 10% with tip‐to‐tip separation of 0.5 diameters (D) compared with the power output of the respective turbines in isolation. A corresponding flow‐mapping study has been completed in the current work using a single‐normal hot‐wire anemometer to characterize the increased flow speed through a narrow lateral gap, leading to the observation of a region of increased speed that occurs between 0D and 2.5D downstream of the gap between laterally spaced wind turbines. The experimental results were confirmed by conducting a series of computational simulations with the generalized unsteady vortex particle discrete vortex method code. The simulations were conducted with three rotors arranged in five different configurations, and the increase in power generated by the multi‐rotor configurations closely followed the observed experimental trends. The closely spaced lateral wind turbine configurations may have the ability to increase the annual capacity factor of wind farms while reducing wind farm land use requirements. Copyright © 2014 John Wiley & Sons, Ltd.