Vertical axis wind turbine

Abstract

Increasing demand for energy in recent years has seen a rise in development of alternative energy sources. Wind being one of the most abundant and easily available sources is an excellent alternative to conventional energy sources. Vertical Axis Wind Turbines (VAWT's) are of two type's viz. Darrieus (lift based) and Savonius (drag based). The problem associated with Darrieus is the lack of self-starting while the Savonius has a low efficiency. In order to overcome these flaws, an innovative design has been created by incorporating both the types into one single unique structure not tested before. In this design, the Darrieus blades are helically twisted to get even torque distribution. The Savonius blades are of half drum type and at the center of the assembly. This unique design allows the use Savonius as a method of self-starting the wind turbine which the Darrieus cannot achieve on its own. There are 3 Darrieus blades placed circumferentially and 2 Savonius couples attached perpendicular to each other along the shaft. The cross-section of the Darrieus blades is of NACA-4415. The objective is to eliminate the need for external motors for self-starting purposes and study the performance of the model. The testing of the model was carried out for different wind velocities. Initially the Darrieus and Savonius blades were tested independently and then the new model which combines the two designs was tested.