- #1
DaveC426913
Gold Member
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I've been thinking about the wind turbine (horizontal turbine - like an airplane propellor.) that I pass on the way downtown and I'm realizing I've been taking for granted how it works.
Seems to me it's exactly opposite of an airplane wing. Rather than forward speed generating lift, you have lift generating forward speed. (It is the wind attacking the blade rather than the blade attacking the wind)
The wind hitting the blades should create lift on the downwind side, pulling the blade in a perpendicular direction.
But it seems to me, the blades have an awfully high angle of attack - they are almost flat in the plane of the rotor, yet the wind's angle of attack is parallel to the axis. The result is that the blades attack the wind at a 45+ degree angle. Also, it seesm to me, as the wind picks up, the rotors move faster, which means they partially cancel the effectiveness of the oncoming wind. You'd want to raise the angle of attack to compensate, rather than lower it, like you would in a plane as speed increases.
Seems to me it's exactly opposite of an airplane wing. Rather than forward speed generating lift, you have lift generating forward speed. (It is the wind attacking the blade rather than the blade attacking the wind)
The wind hitting the blades should create lift on the downwind side, pulling the blade in a perpendicular direction.
But it seems to me, the blades have an awfully high angle of attack - they are almost flat in the plane of the rotor, yet the wind's angle of attack is parallel to the axis. The result is that the blades attack the wind at a 45+ degree angle. Also, it seesm to me, as the wind picks up, the rotors move faster, which means they partially cancel the effectiveness of the oncoming wind. You'd want to raise the angle of attack to compensate, rather than lower it, like you would in a plane as speed increases.
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