Savonius turbines are one of the simplest turbines. Aerodynamically, they are drag-type devices, consisting of two
or three blades (vertical – half cylinders). A two blades savonius wind turbine would look like an "S" letter shape in cross
section (figure 1).
The savonius wind turbine works due to the difference in forces exert on each blade. The lower blade (the concave
half to the wind direction) caught the air wind and forces the blade to rotate around its central vertical shaft. Whereas, the
upper blade (the convex half to wind direction) hits the blade and causes the air wind to be deflected sideway around it.