CFD simulation of horizontal axis wind turbine rotor with fitted guide ring

Abstract

Horizontal Axis Wind Turbines (HAWT’s) has losses due to the axial free stream wind velocity converting into radial and tangential velocity as it moves through the rotating rotor. By fitting a guide ring to the hub some of these losses could be recovered. Computational Fluid Dynamics (CFD) simulations were carried out on a conventional HAWT rotor, and a similar rotor fitted with a guide ring. The purpose of the guide ring is to direct the axial free stream velocity onto the rotor. Simulations were conducted at 0.5 m/s and 1 m/s free stream velocities. Water was used as the fluid for simulation as future experimental verification will be conducted in a water tunnel. Guide rings were placed at 15 % and 20 % of the rotor radius, to investigate the effect on rotor efficiency. Investigative CFD results showed that a guide ring placed at 15 % increased the rotor efficiency with 24 % at peak power coefficient rotor Tip Speed Ratio (TSR) for 1 m/s free stream velocity. A guide ring placed at 20 % increase the efficiency with 1 % at peak power coefficient rotor TSR for 1 m/s free stream velocity. This implies, that precise positioning of a guide ring to the hub can produce a significant increase in the efficiency. These investigative results justify further research for HAWT’s fitted with guide rings and their placement.