Computational flow field analysis of a vertical axis wind turbine

Abstract

The present work has used Computational Fluid Dynamics (CFD) to obtain the flow field characteristics of a novel Vertical Axis Wind Turbine (VAWT). The turbine used in this study features a multi blade design where both a stator and rotor blade array is used. The computational model is three-dimensional and contains full-scale turbine geometry measuring 2.0m in diameter and 1m in height. The pressure field across the wind turbine has been computed for operating conditions of λ=0 and λ=0.4 where it is shown to be non-uniform. The velocity field across the turbine has been obtained at λ=0 and λ=0.4 and has highlighted the presence of a jet flow passing through the central core of the turbine as it exits the rotor assembly. It is evident that under dynamic conditions and due to the direction of this jet flow a strong flow interaction occurs with the downstream rotor blades. This interaction results in rotor blades 5, 6 and 7 generating an opposing torque that acts against the direction of motion. Furthermore, it is noticed that rotor blades 10, 11, 12 and 1 contribute to the majority of overall rotor torque, which is a characteristic of this machines design. Key words Vertical axis wind turbine, CFD, flow field.