Author Topic: 3 Blade VWAT Test Over  (Read 2466 times)

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taylorp035

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3 Blade VWAT Test Over
« on: June 22, 2010, 05:20:01 PM »
Today I decided to see if my 3 bladed Savonius was going to work at all, because the winds were a nice 20 mph and relatively constant.  So I put the windmill on top of my ladder and hooked up the bridge rectifier and my nicd cells to charge.  No load voltage was about 5 volts in a good gust, maybe 25 mph.  Amperage came out to a peak 0f 0.58 amps @ ~1.33 volts.  Cut in was maybe 15 mph +.

The design seems to be very inefficient in terms of the blades.  Granted, my motor has a lot of friction, but even when it got going, there was very little torque.  It may be possible that the 3rd blade blocks too much wind.

Design flaw #2 maybe be the idea of using the benesh shape for the blades.  I think there is a lot of air resistance coming up wind.
 
I think I will do much better with a 6ft blade set that starts up in low wind speeds than a VAWT.  Plus, the windswept area was fairly small with the VAWT (20" x 24").

So in conclusion, if anyone wants to build a VAWT, don't do what I did  :)  I think it is certainly possibly, but for your time and money, a normal 3 HAWT will be much better.

Here is a picture from last month:



« Last Edit: June 22, 2010, 05:21:51 PM by taylorp035 »

REdiculous

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Re: 3 Blade VWAT Test Over
« Reply #1 on: June 23, 2010, 03:10:03 AM »
Try a Lenz2 next..? Maybe 5' blades and a 3-ish foot diameter? I wouldn't put all the weight up top tho...

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..imagine the angled parts attach near the center and replace the straight lines on either side w/ a proper blade...3 blades. I think something like that would put less stress on the bearings and it could be more worthwhile....bigger is better too.

Too bad it didn't work as planned - at least it looks good though! later :)
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Harold in CR

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Re: 3 Blade VWAT Test Over
« Reply #2 on: June 23, 2010, 08:27:29 AM »

 I've seen these built by splitting metal Drums in half, length wise. Use 3 drums for max torque and wind catch ability. Mounted on Plywood discs and front car rotor hubs.  Used to be the 30 gallon grease drums were easy to find.

electrondady1

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Re: 3 Blade VWAT Test Over
« Reply #3 on: June 23, 2010, 09:43:59 AM »
taylor if you still have the interest, dismantle what you have and use two of the wings to form a traditional benesh.
see what sort of difference that makes.

even the most enthusiastic vertical axis builder will plead no contest when it comes to output comparisons with a hawt.

the path i'm taking is to make them look as pretty as possible ,
accept there inefficiencies, and just build more of them.




lohearth

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Re: 3 Blade VWAT Test Over
« Reply #4 on: June 23, 2010, 12:07:38 PM »
I think Tecker had some luck with a 3 blade savonius using steel drums mounted on 2 ceiling fan conversions (one upper and one lower).http://www.youtube.com/watch?v=ZquIlH1XLJg


Ungrounded Lightning Rod

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Re: 3 Blade VWAT Test Over
« Reply #5 on: June 23, 2010, 04:44:03 PM »
taylor if you still have the interest, dismantle what you have and use two of the wings to form a traditional benesh.
see what sort of difference that makes.

Agree with that.  These have a benesh-like profile but the three-blade configuration doesn't hand off the air stream from one blade to another.  That's a big loss.

Alternatively, go with a squirrel-cage of many cylinder segments with an empty center.  That hands off the airflow from one side to the other more as free wind than as an attached airstream.  (Saw a house along the CA coast that had a big merry-go-round squirrel-cage of 55-gal drum segments covering the garage roof, some years back.  Don't know what happened to it.)

taylorp035

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Re: 3 Blade VWAT Test Over
« Reply #6 on: June 24, 2010, 01:37:32 PM »
Yeah, I think going to a 2 blade set up would be a good and worthwhile test (and easy one at that :) ).  We will see how much motivation I have today...

wind4Reg2

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Re: 3 Blade VWAT Test Over
« Reply #7 on: August 19, 2010, 07:48:32 AM »
I hope you try the 2 blade configuration and let us know the difference it made.
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