terry5732 wrote:So basically , they just added more blades.
Why did the common windmills of 80 years ago used for pumping water have like 50 blades and ultra high tech ones of today have two or three?
Terry and Jonathan, with over 20 years experience with large generators I feel that I can speak freely.
First the many blade windmill went by the wayside, with the exception of a small DC generator to feed batteries it's usage is limited. Yes it works for pumping water but not AC generators. The preferred speed for a 60 cycle system is around 80 RPM. and must be held constant.
With multiple blades, they effect each other by being in the wake of the previous. THey also have a tendency to set up a resonant vibration which eventually fatigues the metal.
Todays consensus is that two with a maximum of three blades is the most productive and cost effective. These are also limited in radius due to resonant frequencies. In a strong wind they are designed to feather or shut down to prevent over speeding. Two to three blade develope a more even torque that must be maintained to produce the 60 cycle current used he in the West while the European countries use 50 cycle.
One must consider that any electrical production attached to the grid must produce not only the same cycles but be in phase.
Ralph
