Another experiment today: a vertical axis wind rotor (VAWT, not yet a turbine), between two Sharp rotors side by side. Wind speed about 5-7 m/s.
Getting the whole thing started was very difficult because of the bending. Once started, things improve and a rotation of 380 rpm (6 m/s at the tip of the blade) was able to stabilize until the wind weakened, which is better than during previous tests however at a higher wind speed. This was not enough to achieve a TSR allowing the Sharp rotors to produce lift and fly.
We probably don’t have the aerodynamic problems of interference between the two types of rotors, but we must take into account the size of the assembly and the mechanical difficulties. One can imagine that a large device will need to include several cable drive transmissions in order to mitigate bending.
In front of my fan, my current VAWT rotates at 6 m/s, i.e. a TSR of 2. While the Sharp rotor rotates at approximately 1.73 m/s, i.e. a TSR of 0.575. Things get worse for my VAWT when the wind gets stronger while they get better for Sharp rotors, as long as they are not associated with this VAWT in some way.
The rpm is counted at idle (0.25) with the help of adhesive tapes:
