Energy-Harvesting Performance of Twin-Rotor Vertical-Axis Wind Turbines with Phase Interference Under Different Solidities

Abstract

This paper aims to investigate the aerodynamic variation patterns of twin-rotor vertical-axis wind turbines (TR-VAWTs) considering phase interference under different solidities, and to reveal the interactive mechanism between solidity, phase interference, and aerodynamic loads of TR-VAWTs. This paper first establishes a phase interference aerodynamic analysis model for TR-VAWTs based on two-dimensional computational fluid dynamics (CFD) methods. Secondly, experimental results are used to verify the accuracy of the numerical model. Finally, the variation patterns of aerodynamic forces and wake characteristics of TR-VAWTs under different parameters (solidity, initial phase angle) are explored. The results show that: (1) Each turbine of the side-by-side TR-VAWTs exhibits an increase in the energy utilization coefficient (CP) in comparison with a single rotor. (2) The phase angle exhibits similar influence patterns on the efficiency of TR-VAWTs with different solidities. As the phase angle varies within the range of 30° to 60°, the efficiencies of rotor 1 and rotor 2 under medium-to-high tip speed ratios are both improved, while within the range of 60° to 90°, the efficiencies of each rotor generally decrease. (3) When TR-VAWTs with different solidities are at intermediate phase angles (90° for two blades, 60° for three blades, and 45° for four blades), the efficiencies of each rotor are basically consistent, which is conducive to power transmission. (4) If the intermediate phase angle is adopted as the reference configuration, the pressure influence on the turbines is minimized, which can not only make the power output more balanced but also improve the wake characteristics to a certain extent.

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