Rotors of Vertical-Axial Wind Turbines Assembled in Bearings and Aerodynamic Characteristics of a Blade with Unclosed Wing Profile

Abstract

In world practice, traditional blades used in high-speed wind turbines, both horizontal-axial and vertical-axial, have a wing-shaped profile. However, for horizontal-axial wind turbines, blades with such a profile have a fairly narrow range of operating values of the angle of attack of the incoming air flow and a low value of the moment of pulling from place. As for vertical-axial wind turbines, the self-starting of the rotor with wing blades is completely absent and additional devices are needed to start the rotor into operation. In order to ensure the self-starting of the rotor and the operation of the wind turbine at high and low wind speeds, a new shape of the blade profile was developed, called non-closed wing profile. The concept of the development is that the blade should have a configuration in which the pulling force is involved at the beginning of the movement, and then, with the establishing of the movement, a lifting force would arise, which acquires a prevailing character in the operating mode. The article presents the results of experimental studies of the aerodynamic characteristics of the developed non-closed wing blades. One of the results obtained is to determine the effect of the thickness of the blade profile on the range of values of subcritical angles of attack of the incoming air flow and the differences between the nature and range of changes in the coefficients of lifting force and pulling force in a traditional wing blade and a blade with a non-closed wing profile. Studies of the rotor model of a vertical-axial wind turbine with non-closed wing blades have confirmed the presence of its self-starting and operability even at low wind speeds.