| T O P I C R E V I E W |
| hillbilly |
Posted - 27/06/2007 : 15:02:57
Anyone building or thinking about building the above might be interested in this article :-
www.prod.sandia.gov/cgi-bin/techlib/access-control.pl/1976/760131.pdf
There seem to be lots of plans and info on Savonius turbines but little actual research. This article fills that gap. I have built a turbine using this info (5 foot diameter approx), and it will rotate in winds I can hardly feel. Though I must add that at present for various reasons I have not got around to pulling power of it. In high winds (I live up a mountain) the turbine is awesome (frightning even) and I look forward to fitting a generator. |
| 10 L A T E S T R E P L I E S (Newest First) |
| johnj |
Posted - 13/04/2008 : 07:50:06
quote:
Originally posted by BushWhacker
Well Johnj, I wouldn't be too worried about your tower buckling. ;-)
As for the bearings being mentioned, I'd look into incorporating a conical (or thrust) bearing, You get the best of both worlds that way with both vertical and horizontal support. A really light duty (rear wheel drive, Datsun B-210?) car axle and bearing ought to be plenty of strength. If you go heavy duty the friction losses can start to really add up.
Everything should be made as simple as possible, but not one bit simpler. - Albert Einstein
I think youre right about my tower! This bearing I use is from a farm wagon, double conical roller bearings, as you suggest.
I tried measuring the resistanse to turn it. Came up with something like 15watt. So I decided to put 3 sets of wings on top, in stead of 2. Hope it will spin when the alternator is on.
Here is how to adjust your alternator for a smaller wt:
http://www.fieldlines.com/story/2007/9/1/7921/49961
Cheers, j |
| johnj |
Posted - 13/04/2008 : 07:40:51
quote:
Originally posted by chris_psmith
I think the savonius can be outperformed my the benesh and possibly easier to make, report on taking a benesh to the next steps available on:
http://www.energy.ca.gov/2005publications/CEC-500-2005-084/CEC-500-2005-084.PDF
Benesh describes how to create the calcs for the blade profile in a number of his patents.
Regards
Chris
Chris, I agree with you, except for the name of the man. I thought he is called Hamid Rahai. I got mine up in the wind. It moves with hardly any wind, and its totally quiet. Quiet is one of the main reasons for me to choose vawt. Other ones being ease of manufacture and slow turning.
Cheers, j |
| BushWhacker |
Posted - 13/04/2008 : 00:31:20
Well Johnj, I wouldn't be too worried about your tower buckling. ;-)
As for the bearings being mentioned, I'd look into incorporating a conical (or thrust) bearing, You get the best of both worlds that way with both vertical and horizontal support. A really light duty (rear wheel drive, Datsun B-210?) car axle and bearing ought to be plenty of strength. If you go heavy duty the friction losses can start to really add up.
Everything should be made as simple as possible, but not one bit simpler. - Albert Einstein |
| johnj |
Posted - 12/04/2008 : 20:25:59
Hello there, I am trying to build one of these too. Got it spinning with one set of wings, (just to keep spirits high), two more sets to come. Cant seem to post pics, try here: tryhttp://www.thebackshed.com/Windmill/FORUM1/forum_posts.asp?TID=980&PN=1
or search for "rahai" at http://www.fieldlines.com/story/2008/3/13/131110/393
comments welcome,
Cheers, j |
| hillbilly |
Posted - 18/01/2008 : 09:04:51
Excellent link, thanks Chris.
The blade profile reminded me of something, then I remembered a post that discussed rotating advert signs, very similar, so if you can "aquire" a sign, cut down the middle and hey presto an embryo Benesh VAWT including the bracket with some tinkering.
Another advantage of the VAWT is that it is relatively easy to experiment with generators since they should be accesable. Even if its mounted on a pole, by running a shaft down the middle of the pole to ground level, the genny can be mounted there since the VAWT shaft is vertical anyway no gears needed.
Regards
Hillbilly |
| chris_psmith |
Posted - 17/01/2008 : 19:22:45
Hillbilly,
Had some time so got the links to the detail of the benesh blade patents:
Simple Benesh profile patent: http://www.google.com/patents?id=x6YfAAAAEBAJ&dq=5,494,407
Best Benesh profile with good description of geometry construction: http://www.google.com/patents?id=fZMxAAAAEBAJ&dq=4,830,570
Less wacky total idea with Benesh blade construction: http://www.google.com/patents?id=fZMxAAAAEBAJ&dq=4,830,570
One point I would make about VAWT vs HAWT is for the beginner it is probably less likely that you will cause any damage with baldes flying off a VAWT that a HAWT, one of the things that appealed to me!
Regards
Chris |
| hillbilly |
Posted - 17/01/2008 : 11:37:39
Thanks for the Benesh link Chris, very interesting. Might try that construction when I get the time ??.
David,with regard to iceing, that could be a problem since at least on my current VAWT, whilst there is no wind it could collect water/snow and when the wind starts up give initial balance problems, then fling the ice off as it speeds up ?. I do have drain holes but they may ice up. I don't think it would be an issue if its rotating, at least in my area.
PS - there are hills in Wales.
Very interested in a recent post by Del, using the inards of a washing machine for a VAWT, saves a lot of construction and could be a good start for trying the Benesh approach.
An opinion I would like to share, though I know most won't agree. I think that the VAWT approach is a far easier start point for newcomers to learn the basics of windpower than a HAWT. As I have discovered the real problems with windpower are the systems "downstream" of the actual power head (windmill)e.g converting the power to useful energy and evening out the peaks and troughs, plus acually using it in the home. A VAWT in my opinion is easier to construct and develope useful power without the complications of furling, cable twisting, towers etc, though it may not be as efficient as HAWT ?? results should be faster, and enthusiasum sustained. |
| chris_psmith |
Posted - 13/01/2008 : 09:22:48
I think the savonius can be outperformed my the benesh and possibly easier to make, report on taking a benesh to the next steps available on:
http://www.energy.ca.gov/2005publications/CEC-500-2005-084/CEC-500-2005-084.PDF
Benesh describes how to create the calcs for the blade profile in a number of his patents.
Regards
Chris |
| davidautrey |
Posted - 12/01/2008 : 15:14:21
Just signed up, hi all, this is the latest, most recent activity I've seen while lurking savonius type systems. I'm curious too. But have dial up.
Hillbilly, hey, I thought you were in Arkansas at first, I guess all you guys are in the UK? I'm in Texas.
Do any of the sites you're using for these savonius' have issues with icing? Couple weeks back I was in the Abilene area and had a chunk of ice hit the ground next to me, whew, rim ice off a power line from a few meters up... I'm sure the big boys out there use heated leading edges or something, not sure what a good idea for this issue would be concerning a savonius. bearings and balncing issues are big questions for me.
But the savonius is my choice, deal with the contraption flat footed, no tower. good low end tourque. would lend itself well to compressing air. Hillbilly's coment about the RPM fear factor too, I'm chicken as well. Five foot unit, that is of some consiquence, could take you for a ride.
My goal for this year is a unit from fifty five gallon drums. Just like gotwind, got the issue of other projects.
I've booked marked ya'll and will check back about once a month. |
| gotwind |
Posted - 27/06/2007 : 17:26:54
Hi Hillbilly.
Looks very interesting, dial up users please note, it is a 2.7 Mb download.
I have put my VAWT generator on hold for a while, been busy with the Orange charger project and a few more large companies have also approached me.
I will revisit it one day, although I do believe there efficiency is considerably less than a horizontal gen.
Ben
The Futures Green - Getwind of it. |
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