Performance Analysis of Hybrid Vertical Axis Wind Turbine in Low Wind Velocity Regions Using CFD

Abstract

There is a significant contribution of the wind energy to total renewable energy consumption. In vertical axis wind turbines (VAWTs), most of the experimental works are done on the Darrieus VAWT or Savonius VAWT alone. However, the experimental results cannot capture all the aerodynamic characteristics of the turbine. Therefore, computational analysis is the most powerful tool for reducing the time and cost of experimental analysis in this type of research. Recently, research on hybrid wind turbines is attaining popularity because such coaxial arrangements exhibit the improved efficiency and the better self-starting capability as compared to individual Darrieus or Savonius turbines. In this present study, firstly, a wind dataset was collected for different seasons and heights (above ground level) to get the average wind speed as an inlet boundary condition. Then two-dimensional simulation was performed on the considered hybrid VAWT using ANSYS Fluent. The steady analysis shows that the static torque is low at 90° azimuthal angle for the hybrid VAWT at different heights in all cases. For various tip speed ratios, flow visualization through a hybrid turbine showed that vortex generation is lower at the high tip speed ratio (TSR) as compared to the low TSR. At TSR = 2.5, all attachment angles achieve the highest power coefficients, which decline with increase in the attachment angles. Among all the operating conditions, the TSR = 2.5 and the 0° attachment angle revealed the optimal power coefficient value of 0.33.