CFD Analysis for Optimization of Vertical Axis Wind Turbine Farms

Vertical Axis Wind Turbines (VAWT) have gained more importance due to their compactness, adaptability and ease of installation. However, the efficiency of VAWT is much lesser than that of Horizontal Axis Wind Turbine (HAWT). Substantial research is going on to improve the efficiency of VAWT. One of the most effective methods of improving the efficiency of VAWT is to operate them on a farm rather than isolated turbines. This project deals with determining the most effective layout for a VAWT based on average performance coefficient increase when operated in a farm configuration. In order to find the optimized layout of VAWT, 2D URANS (Unsteady Reynolds Averaged Navier Stokes) CFD simulation were performed in STAR CCM+ software. Validation of the CFD simulation was done by simulating a rotor in isolation and its blade torque profile was compared to the results of published research. The validation of results proved that the blade torque profiles agree with similar studies. A new methodology has been proposed using a sliding mesh and volume controlled polyhedral meshing approach. The CPU hours for simulating 17 complete revolutions (30 seconds of flow time) of a rotor in isolation was approximately 3.5 hours (11th Gen Intel(R) Core (TM) i9-11900K @ 3.50GHz, 3504 MHz, 8 Core, 16 Logical Processor). It is also found that the current study reduces the computational time to a great extent without compromising on the accuracy. This makes the proposed methodology computationally inexpensive and faster. After validation, various configurations were simulated to identify the best possible layout for a VAWT farm. From the results the staggered configurations using a 5-rotor system proved to be the most efficient one. An increase in power output of up to 47% was observed for the same type of configuration. The V-shaped configuration consisting of five rotors yielded an increase in power output of 43%. The computational time increases exponentially as the number of rotors in the system increases. The fluid physics and mechanism which led to the increase in power output was also examined