Comparison between two-dimensional and three-dimensional computational fluid dynamics techniques for two straight-bladed vertical-axis wind turbines in inline arrangement

Abstract

This study is dedicated to drawing a comparison between two- and three-dimensional approach capabilities for the simulation of two similar rotors placed in three inline (or tandem) arrangements. This arrangement is generally recognized as the worst-case scenario for the downwind rotor considering the vortices and disorders produced by the upwind rotor. The rotor in question with the diameter of 2.5 m is made up of three NACA0015 blades with the chord length and span size equal to 0.4 and 3 m, respectively. Based on the authors’ previous works, the [Formula: see text] shear stress transport model was selected for this comparative study. According to the results, there is an appreciable deviation in the aerodynamic performance of the upwind rotor predicted by the two-dimensional and three-dimensional simulation techniques. There is no tangible difference between the two-dimensional and three-dimensional results in terms of the averaged power output for the downwind rotor. However, the study of flow field employing different means like vortex structures, axial velocity, and even torque variation indicates that the two-dimensional approach is unable to achieve realistic and reliable output data. The introduced “pillar effect” regarding the dimensional limitations of the two-dimensional approach, which affects the vorticity shape and its dissipation, is plausible evidence for this discrepancy.