CFD modeling of vertical-axis wind turbine wake interaction

Abstract

Since wind turbines placed in wind farms need to minimize their footprint on the ground, the effects of the wake must be considered. Placement optimization, turbine spacing, and direction of rotation are known to affect the performance of vertical-axis wind turbines (VAWTs). However, rigorous numerical modeling methodologies that investigate the influence of these characteristics are lacking, especially in the case of large wind turbines. The goal of this study is to analyze turbine configurations that might enhance the power production of VAWT farms using two-dimensional CFD models based on the Star CCM+ package. The novelty of this work is to analyze wind farm configurations for very large turbines. This is important because large turbines are much more performant than small turbines and have a high power coefficient. Results show that CFD simulations adequately capture the performance of wind turbines in farms with multiple VAWTs. In general, if a second rotor is spaced more than 10 turbine diameters downstream of the first rotor, the effect of the wake is less significant. Furthermore, a specific farm configuration with five VAWTs is investigated and shows a 20% increase in power output compared with the same number of turbines operating in isolation.