2-D Numerical Analysis of a VAWT Wind Farm for Different Configurations

Abstract

With the global focus on exploring more efficient and cost effective wind energy based power generation techniques, vertical axis wind turbines (VAWT) have emerged as a good option at small house hold scale. For large built-up area units having combined roof such as residential blocks etc., possibility of having a clustering of small VAWT as a wind farm is quite attractive; albeit very little is available in literature from CFD analysis perspective. This paper presents a novel 2D CFD analysis of a 2.75m diameter vertical axis wind turbine (VAWT) in a farm configuration. An urban area roof top scenario with a favorable and an adverse VAWT array configuration is analyzed. Further, the effect of variation of interturbine distance is also studied for these configurations. Each turbine consists of three vertically aligned NACA0022 turbine blades separated apart by an angle of 120o. Each turbine has a chord length of 0.23m. The initial results presented in this paper correspond to the freestream velocity of 12 m/sec with a tip speed ratio (TSR) variation from 1 to 4. Interesting results are obtained from the present research for both favorable and adverse configurations. A von Karman type vortex shedding is observed in the wake of all the VAWT configurations considered. For the adverse configuration (I-type configuration in which the VAWT’s are in tandem), the performance of downwind VAWT reduces drastically. With the increase in their mutual separation distance along the flow direction, the performance drop recovers. However, still the performance is lower than a single VAWT. Whereas, for the favorable configuration (T-type configuration in which the VAWT’s are staggered), the performance of the downwind VAWT increases and is higher than a single VAWT. The performance improvement decreases with the increase in their mutual separation distance.