CFD modelling and prototype testing of a Vertical Axis Wind Turbines in planetary cluster formation

This study aims to improve the applicability of Vertical Axis Wind Turbines (VAWTs) by investigating their feasibil-ity in a novel planetary cluster configuration by observing its effect on efficiency and overall power density. Computational Fluid Dynamics (CFD) simulations were carried out using a two-dimensional vertical axis wind turbine model in ANSYS Fluent 2020 R1. This software was used to solve the transient k-omega (SST) turbulence model. For the isolated VAWT the wind velocity, rotor radius and tip speed ratio were varied to find the optimum turbine performance at a given parameter. A peak efficiency of 34.05% was attained and equivalent configuration used as the "sun" turbine in the novel planetary design. The parametric study of the novel set up was conducted with the PCD (Pitch Circle Diameter) and oblique angular (phi) position of the smaller "planet" turbines being varied in relation to the "sun" turbine. The planetary system was then evaluated in terms of efficiency improvements against the isolated VAWT model. Use of the "planet" turbines resulted in power extraction from the free stream which in turn creates varying wind velocities and improved the efficiency of the central "sun" turbine. The optimal PCD was found to be 5D (3.75 m) and the optimum angular position of the "planets" was discovered at 30 degrees. Ultimately this gave a percentage increase of 1.01% from 33.04% to 34.05% when comparing the "sun" turbine of the planetary arrangement to the optimum isolated respectively. An average improvement of 4% over the range of tip speed ratios (TSR) was found. Lastly, a scale model of the isolated VAWT was constructed and tested through wind tunnel experiments. The characteristic curve correlation was found between the CFD and experimental results which allowed validation of the CFD models. (C) 2021 The Authors. Published by Elsevier Ltd.