CFD Analysis of Vertical Axis Wind Turbines in Close Proximity

This paper presents an analysis based on computational fluid dynamics of vertical axis wind turbines when placed in close proximity in a linear array. It has been noticed that VAWTs placed close to each other with counter rotation motions have a higher coefficient of power than a single turbine. This was termed the “coupled vortex effect”. Two mechanisms have been identified to cause this increase in efficiency: the stream tube contraction effect and the vortex effect. The first is due to the blockage effect from neighboring turbines while the later is related to the neighboring turbine acting as a vortex that induces an increased flow field. This paper analyzes each of these effects and studies the influence of the turbine size and the rotation speed. The change of torque on each blade due to these effects is investigated for two different sizes of wind turbines.