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I recently saw a wind turbine that I'm trying to identify the type or category of.

turbine view 1 turbine view 2 turbine view 3

Basically, the turbine looks like two squirrel cage fans mounted side by side on a fairly tall ~40' pole.

The blades of the turbines rotate along the horizontal axis of turbine. Essentially, they work like paddle-wheels of a steamboat. There are shrouds in front of the blades to direct the airflow, which obscures the view of the blades themselves.

turbine rotation called out
Note, rotational direction may be in the opposite direction of what's drawn.

I'd like to know name of the type or category of this type of wind turbine as I would like to research it some more. Most of the images and types I was able to find so far have been the "windmill" style turbine with a central housing and 3 or 4 blades coming off of the center.

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The design looks like a Savonius turbine, but horizontally mounted, instead of the typical vertical mounting that you see with this design. I'm really not sure why this would be mounted this way either, as one of the key benefits of the Savonius design is that it's never not facing the wind.

The bottom of the Wikipedia article mentions that the horizontal mounting could be used to keep the turbine aloft if it's not rigidly supported, because the rotation will generate lift. However, this does have a rigid support, so I'm not sure what the thinking is behind the orientation.

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  • $\begingroup$ Thanks for the insight. I believe the direction of the turbines can change. So either the pole they are mounted on rotates or the hub connecting the turbines to the pole can rotate. I think that's why they are mounted horizontally, but it may also be a zoning restriction. $\endgroup$ – user16 Apr 17 '15 at 15:57
  • $\begingroup$ Yes, and that's true for plenty of horizontal-axis turbines, but then you've got a motor in there to rotate them towards the wind, and probably some type of sensor to determine which direction it needs to point. Vertical mounting doesn't need any of that. $\endgroup$ – Trevor Archibald Apr 17 '15 at 16:01
  • $\begingroup$ It looks like the pivot is slightly offset so it will automatically turn into the wind... $\endgroup$ – Floris Apr 17 '15 at 22:50
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It is a Savonius Turbine. This page provides additional information about Savonius turbines:

A Savonius is a type of vertical axis wind turbine (VAWT) generator invented in 1922 by Sigurd Johannes Savonius from Finland....

The Savonius is a drag-type VAWT which operates in the same way as a cup anemometer....

Savonius wind turbines typically only have an efficiency of around 15% - i.e. just 15% of the wind energy hitting the rotor is turned into rotational mechanical energy....

Savonius turbines do not scale well to kW sizes, but for a small project they are typically the easiest and cheapest wind turbine generators to build yourself.

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    $\begingroup$ To give some context to the 15% number, Betz's law states that the maximum possibly efficiency of a wind turbine is only 57%. 15% still isn't great, but it's closer to 1/4 of what it could be, rather than 1/7. $\endgroup$ – Trevor Archibald Apr 17 '15 at 16:42

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