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Forum Index : Windmills : Why Not In Reverse?

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Kamak
Senior Member

Joined: 13/04/2021
Location: Canada
Posts: 150
Posted: 02:50pm 04 May 2021
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Why not, (as I've actually read somewhere) make the turbine rotor blades and nacelle offset of the tower bearing, and downwind. making the rotor blade leading edge on the backside (the face between the rotor and the nacelle). This way, there might not be a need for a tailfin, and the rotor will always tack naturally to the wind direction, due to its center of gravity being offset from the tower bearing? Also, use some form of viscous, or eddy current drag/clutch to smooth out, reduce fast changes in directional correct.
Edited 2021-05-05 03:27 by Kamak
 
kitestrings
Senior Member

Joined: 23/04/2014
Location: United States
Posts: 102
Posted: 08:55pm 05 May 2021
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This too has been done.  The Proven is one example... Enertech is another.  It seems simple, but there are some trade-offs (always, right).  It requires much of the weight of the turbine to be cantilevered away from the tower, so if it is of any size it can be a structural consideration.  And, believe it or not, they can get stuck in a position 180 degs. to the wind.

Then there is tower shadow.  The wind is now going through the tower to get to the blades which cause uneven loading on the rotor, and possible noise.

You also still have the speed protection considerations.  Unchanged in your barking proposal, but this would rule out side furling.  The Proven's actually had a "coning" rotor design for speed control.
 
kitestrings
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Joined: 23/04/2014
Location: United States
Posts: 102
Posted: 09:00pm 05 May 2021
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Oh yes, and more recently, the Skystream I believe is a downwind design.
 
Kamak
Senior Member

Joined: 13/04/2021
Location: Canada
Posts: 150
Posted: 03:58am 06 May 2021
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  kitestrings said  Then there is tower shadow.  The wind is now going through the tower to get to the blades which cause uneven loading on the rotor, and possible noise.


Ah yeah, I never thought about the tower interference.

Shape the tower profile like this.



Just from the nacelle down to the length equalling the rotor's radius. More like a skirt of fabricated sheet metal that goes over the tower, and yaws with the turbine, as it follows the wind direction. Making the air pass around the profile with more laminar flow.
Edited 2021-05-07 12:51 by Kamak
 
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