Modeling and investigation of combined darrieus and vane design vertical axis wind turbine

Abstract

Wind energy is one of the potential sources of renewable energy because of its abundance in the atmosphere. It is available in different scales of high, medium and low-velocity ranges. Wind power is a major source of sustainable energy, which can be harvested by Horizontal Axis Wind Turbines (HAWTs) and Vertical Axis Wind Turbines (VAWTs). VAWT can be used in low wind speed regimes for performing various small-scale functions ranging from electrifying a building’s equipment. In this thesis, the performance of a newly designed vertical axis wind turbine for application in urban areas is presented. The proposed new design is a combination of vane type rotor and a vertical straight-bladed Darrieus rotor (NACA 0012 airfoil) on the same axis. This design combines the advantages of both designs while attempting to reduce the disadvantages. The vane type rotor creates high torque and is self-starting even at low wind speed but with a relatively low-efficiency rating. The Darrieus rotor has poor performance on selfstarting rotor but has much higher efficiency than the vane type rotor. The combination of the two rotors, vane type and straight-bladed Darrieus airfoil NACA 0012 increases the total power of the turbine at lower wind speeds. A combination of Vertical Axis Wind Turbine (VAWT) rotors was designed and tested in a subsonic wind tunnel. The proposed new combined design increases the turbine output power in low wind speed areas of above 4 m/s while solving the low starting torque problem for a Darrieus wind turbine. The results showed that the new design could achieve the highest power coefficient of 𝐶𝑝 = 0. 24 for a vane type wind turbine at wind velocity of 6 m/s and tip speed ratio 𝜆 = 0.223. In addition, the power coefficient for the combined designed wind turbine increased to 𝐶𝑝 = 0. 3925 at the same wind velocity of 6 m/s and at a tip speed ratio 𝜆 = 0. 75.