Magnus Effect

[fepps]

Hi All,

While going through my files looking for something else, I came across these two articles about Magnus Effect wind turbines. Maybe this will be of interest?
I have more material including patents, etc, if people want more.

Fred

[Adriaan Kragten]

The biggest problem to use a spinning Magnus rotor as a wind turbine blade is that the drag/lift ratio is much higher than for a normal airfoil. For a fast running 3-bladed rotor with a design tip speed ratio of 6 you need a Cd/Cl ratio of maximal 0.03 to get a high maximum Cp (see my publc report KD 35 figure 4.7). The Cd/Cl ratio for a Magnus rotor is much higher and so Magnus rotors can only be used for wind turbine rotors with a rather low design tip speed ratio. A ship with two Magnus rotors was built by Flettner and he crossed the Atlantic ocean already in 1925. He also proposed to build a wind turbine with Magnus rotors but I don't know if this was really done.

Another problem is that the rotor has to spin rather fast. So you need a complex mechanism to drive the rotors and this also requires a certain amount of power which reduces the nett power which is generated by the rotor. So it is much easier to use a real airfoil than a Magnus rotor.

[Mary B]

I remember Popular Mechanics (yes I read it, I was not a typical girl... I did 160mph down the drag strip in a car I built LOL) in the 70's pushed Flettner sails for cargo ships... and it was tested. Bearing life was horrible under the sail...

[fepps]

Hi All,

I know next to nothing about the subject.. just an information packrat...

Fred