D. Tsyplenkov1, A. Kolb1, O. Bobrov2, O. Nesterova1 & I. Borsch1
Purpose. to carry out the modeling of Savonius multi-blade rotor with different number of blades to determine torque value and its variation with time.
The main peculiarity of Savonius rotor consists in self-starting opportunity under the conditions of low wind speeds. Savonius rotor usually contains some blades (2…3); multi-blade ones are less common (4…8 and more). Blades may be located on a small distance from the rotation axis and also blades and rotation axis may be R spaced-apart.
It is known that torque produced by aerodynamic forces on each blade depends on blade projected area, arm of a pressure force, and resistivity factor of hemicylindrical blade [1]. Expressing projected area and arm of a pressure force of Savonius rotor by the angle between the wind direction and blade location we may obtain the torque depending on the angle mentioned in the first and second power, as well as on blade diameter, rotor height and diameter.
The calculations were carried out for wind wheels with 2, 3, 4, 6, 8, 12 and 16 blades. It was determined that for 12 and 16 blades the dead section occurs. As for each case (12 or 16 blades) the blades in some sectors do not form torque. In case of 12-blade wheel the sectors are 90º - 120º and 240º - 270º; in case of 16-blade wheel, 101.25º - 146.25º and 213.75º - 258.75º. The occurrence of dead section may be substantiated by the fact that the blades are screened by the precedent ones. This also results in fluctuating nature of the graph of relative torque.
The study was carried out as a part of students’ master thesis research.
Keywords: Savonius rotor, torque