Savonius AWE kite?

[PierreB]

@dougselsam

It’s not too difficult to show on-paper, the limited Cp of a Savonius design. Since the working surfaces are traveling downwind at half the windspeed, you can expect about 1/4 of the power one would hope for, from this downwind-traveling, power-producing side. Then subtract the power used to push the upwind-traveling side into the wind, and you are probably down to between about 1/6th and 1/8th of the power available to the swept area. That agrees with the measured Cp’s we typically see of around 0.1 or less for Savonius.

@PierreB

Among other things, the S-shaped structure is characterized by the space between the two half-cylinders which allows air to circulate and also exert force on the other half-cylinder which returns upwind. This is shown on the diagrams.

A Savonius rotor without this space is not really a Savonius rotor. And perhaps a so high Cp of 0.3 can be explained with this feature when the realization and the proportions are suitable.

The figures mentioned on my comment above show the space between the blade.

In the following paper (figure 8), the values of power coefficient (Cp) reaches 0.3 for experimental data.

Energies | Free Full-Text | Experimental and Simulation Investigation of Performance of Scaled Model for a Rotor of a Savonius Wind Turbine