Prospects for development of wind turbines with orthogonal rotor

The experimental data obtained previously on the investigation of power characteristics and the possibility of the self-start of the Darrieus rotor are anlysed. These results are used at the design of new two-tier wind turbines with straight blades. The full-scale tests of two design variants showed the prospects for the development of wind turbines with the Darrieus rotor. At a reasonable design, they do not need any devices for the rotor orientation and start-up, are little sensitive to wind gusts and can have a high level of power characteristics, which is not inferior to the best samples of the units of propeller type. At present, the horizontal-axis wind turbines (WTs) of propeller type take the main position in the wind-power engineering. For such WTs, an immense experience in the design and operation was accumulated, and the latest achievements in science and technology are implemented in the advanced WT designs. A further improvement of the WT of propeller type is problematic, and there is a need in the search for alternate ways for the wind-power engineering development. The development of vertical-axis WTs with orthogonal rotor, in which the wind flow directed perpendicularly to the rotation axis, is the most promising way according to the estimates of specialists [1, 2]. Such WTs have appeared relatively recently. In 1929, Savonius proposed a rotor with S-shaped blades, and Darrieus proposed in 1931 a rotor with curved blades. In 1975, Masgrowe modified the Darrieus rotor by replacing the curved blades with straight blades. The torque on the Savonius rotor arises at the expense of a difference in drag forces on the S-shaped blades. The flow energy utilization coefficient for such a rotor does not exceed 20 %, which impedes its practical application. The mechanism of torque formation on the Darrieus ⎯ Masgrowe rotors is different. A pulsating flow similar to the flow around a flapping wing [3] acts on the rotating blades of these rotors. Such a flow creates the thrust forces on blades, which rotate the rotor. The flow energy utilization coefficient for orthogonal rotors with straight blades may be above 40 %, so it is no worse than the best horizontal-axis WTs of propeller type. The main peculiarity of orthogonal rotors is the independence of their functioning of the wind-flow direction. This enables a substantial simplification of the WT design by refusing the complex and low-reliable orientation systems needed for the WT of propeller type. Another important peculiarity of the orthogonal rotor with straight blades is a relatively low rate of its specific speed. The high-speed coefficient for such rotors