Design and numerical study of the integration of omnidirectional shroud with vertical axis wind turbine

Abstract

The integration of a vertical axis wind turbine (VAWT) with the novel omni-directional shroud is proposed. It consists of the upper wall, lower wall and an array of 5 guide-vanes. Wind from all directions is collected radially from a larger area and the geometry of omni-directional shroud creates a venturi effect to increase the wind speed before entering the wind turbine. Guide-vanes aid to channel wind to better angles-of-attack of the turbine blades. Hence, self-starting behavior of the VAWT and the coefficient of power improve. The system was investigated numerically by simulating the wind flow over the omni-directional shroud with a single bladed NACA 0015 airfoil VAWT. In this 2D simulation, the shear stress transport (SST) k-Ȧ turbulence model with the sliding mesh method was used with the tip speed ratio of 5.1 for the wind turbine. The result was verified by re-simulating the experiment published by the Sandia National Laboratories. The result shows that the torque coefficient of the VAWT was increased up to 287% as compared to the bare VAWT. This system improves the performance of the VAWT and it has a great potential to be sited in urban areas for onsite and grid-connected power generation.