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.