A wind farm consisting of two turbines - The combined influence of turbine spacing and rotational direction

Abstract

Large-eddy simulations are conducted to investigate the impact of an actual decrease in turbine spacing on the wake structure for a small wind park consisting of two wind turbines in a row with a given rotor diameter D. A systematic variation of the inflow conditions (near-neutral and veering inflow) and the rotational direction of the rotors (clockwise and counterclockwise) provides an initial overview of the atmospheric flow fields in the wakes of both turbines. Whereas a smaller turbine spacing under near-neutral conditions results in a decrease of the streamwise flow component and an increase of turbulence, the situation is much more complicated under veering inflow. If a clockwise (counterclockwise) rotating turbine interacts with a Northern Hemispheric Ekman spiral, the combination of a rotor-induced v-component, which reduces (slightly amplifies) the meridional inflow velocity component, leads to a weakening (slight intensification) of this meridional wind in the vicinity of the downwind rotor.