Numerical investigation of a novel contra-rotating vertical axis wind turbine

Abstract

Darrieus H-rotor has gained much interest in the last few decades as among the reliable devices for wind energy conversion techniques for their relatively simple structure and aerodynamic performance. This study presents a numerical investigation of a novel vertical axis wind turbine (VAWT) with a contra-rotating concept. The aim is to reveal the effectiveness of this concept on enhancing the performance of the turbine as it has yet to be applied to a VAWT system. The simulations were performed using three-dimensional computational fluid dynamics (CFD) models based on K-omega shear stress transport (SST) turbulence model. This computational study covers a wide range of simulation work including a parametric study based on the axial distance between the two rotors and rotor aspect ratio. It was found that the new concept works more efficiently and therefore the performance of the turbine has been improved significantly. The system was capable of producing more than double of torque coefficient compared to a single-rotor system of a similar type. The results also indicate that smaller axial distance tends to enhance the performance output of the system relatively better compared to a larger distance. In terms of rotor aspect ratio, bigger aspect ratio generated the highest amount of power.