parafoil savonius-finally had some wind
By Kwazai, Section Wind Posted on Mon Jan 30, 2006 at 02:34:52 PM MST
so what overlap do I actually need?

I finally had some wind over the weekend where I could actually see what was going on. keep in mind that I am after a turbine that could be mounted at the top of a short solar chimney (greenhouse...)and that this is an hawt version of a vawt and would need to be mounted on a pivot as an hawt. pics to follow- the full radius foil runs somewhere around 100rpm (weather man said 21mph winds-but I'm heavily tree sheltered and it was gusty). the 1/3 diameter foil ran slower, started earlier and had the check valve collapse effect I would need with a chimney (smokejack aka DaVinci...). the best it would run was somewhere around 20rpm in forward gusty winds (backward winds-the foil would shut, then only fluctuations in the wind would make it run). I really am not sure what is best for this thing in terms of foil size for laminar wind velocities, but thought you might like to see the pics (this one is prettier than the last one and cheap too.) (this is radius length foil-1/3 diameter foil was just adding tape to seal it up in the center) (cigarrette smoke is laminar for about 6" from end of cigarrette-turbine just is spinning-runs wide open at point cigarrette smoke is entirely turbulent) L8r mike

parafoil savonius-finally had some wind | 9 comments (9 topical)

Re: parafoil savonius-finally had some wind (3.00 / 0) (#1) by ghurd on Mon Jan 30, 2006 at 08:33:21 AM MST

Looks like fun. The plastic isn't overly straight. What about thin tin like heating ducts. Maybe spin a little faster? One of my first ideas long before the internet, was a VAWT like that but parafoils on both sides of the spokes. Top and bottom.  Opening and closing. Might need a tiny bit of weight on the lower sail nearer the hub. Never did it. Ghurd.info

Re: parafoil savonius-finally had some wind (3.00 / 0) (#2) by Kwazai on Mon Jan 30, 2006 at 11:02:53 AM MST

my fab skills aren't the best and it was done rather quickly to see what it would do in the wind (I have little to none where I'm at). I would love to make one out of fiberglass, but then I'd lose the ability for it to snap shut when the chimney started leakingat the top. I'm not sure yet how to determine my minimum chimney height to run it, but am looking into it. Its still a very cheap turbine to build. I have three or four bicycle generators and will probably build one with a genny just to see if there's any power there (next time the wind blows...) L8r Mike [ Parent ]

Re: parafoil savonius-finally had some wind (3.00 / 0) (#8) by ghurd on Tue Jan 31, 2006 at 09:15:50 PM MST

I didn't intend any offence. (sounds different now than when I typed it, and it looks better than many of my 2 liter soda bottles, paneling and hot glue contraptions)  Sorry. I guess I mean if it was 'smoother', it may go faster. I planned plywood, but a bike rim overcomes some problems I considered, like how to get the heavy top parafoil to open. What about some kind of rotary displacement pump style chimney turbine?  The term escapes me right now, but like 2 gears, or some oil pumps. G- Ghurd.info [ Parent ]

Re: parafoil savonius-finally had some wind (3.00 / 0) (#3) by tecker on Mon Jan 30, 2006 at 03:52:20 PM MST

I like it .You might go for the cloth sail hem in some 1/4 " rope . hem up the perimeter and tie it off like a hooded sweat .

Re: parafoil savonius-finally had some wind (3.00 / 0) (#4) by stevesteve on Mon Jan 30, 2006 at 10:33:16 PM MST

Hi Mike, It is beautiful in it's simplicity. It reminds me a bit of the windmills in Cyprus: googled pic1 These have sails which can be 'reefed' i.e. rolled around the boom or spar as you would when sailing or you can run every other sail: googled pic2 Cheers, Steve

Re: parafoil savonius-finally had some wind (3.00 / 0) (#5) by Kwazai on Tue Jan 31, 2006 at 06:50:54 AM MST

I couldn't see the second pic-some access denied error. the first one is kinda cool. I've been wanting to make methane in a shed I've got-just don't want to store it and figured I could burn it in a chimney(short solar chimney problems...), problem with a chimney is when it leaks(not drawing a draft) it leaks from top and bottom-so this is not so much an exercise in turbine efficiency as it is in a one way only turbine(though somewhere along the line it would be nice to have it optimized...).This trubine would go at the top of the chimney. L8r Mike [ Parent ]

Re: parafoil savonius-finally had some wind (3.00 / 0) (#6) by hvirtane on Tue Jan 31, 2006 at 01:36:49 PM MST

Some pictures about Crete wind mills: http://www.wtamu.edu/research/aei/cdex/pump/image003.jpg http://www.experimentarium.dk/uk/naturvidenskab_og_teknik/schiolers/vindmoeller.html http://www.crete-homes.com/info/walks/walk02.jpg - Hannu

Re: parafoil savonius-finally had some wind (3.00 / 0) (#7) by wooferhound on Tue Jan 31, 2006 at 08:52:51 PM MST

Very simular to this story http://www.fieldlines.com/story/2005/2/9/154432/0686 W o o f -={(

Re: parafoil savonius-finally had some wind (3.00 / 0) (#9) by Kwazai on Wed Feb 01, 2006 at 06:24:54 AM MST

yea, that was me. This one is a lighter weight plastic. The first one I couldn't get enough airflow in my 10ft poly sheet chimney to raise the plastic foils up(even with mosquito candle).They were a 6mil plastic. This one is grocery bags. I am interested to see if the UV kills it before the wind does. A final version would probably use j-channel to hold the plastic on(instead of duct tape). As a savonius(drag type) turbine this one would need to be mounted on a pivot(hawt). I don't know what it actually takes to make it spin. This morning the light breeze (cigarrette smoke between 5 and 15 deg. from vertical would make it wiggle just a little- somewhere around 45 deg smoke from vertical it starts to move- at the point the smoke is horizontal turbulent from the end of the cigarrette it runs wide open----any idea what wind speeds those are (less than .25 m/s??). for my chimney(vawt) (probably gonna end up methane powered rather than solar) it would sit just above or just inside the top of the chimney. Only real plus to this ,rather than conventional bucket savonius ,is the airflow is all one way-it never has to fight the uphill side. In the gusty wind I had (no idea MPH-weather man said 21mph) it ran about 100rpm-would get there pretty quick(five ten seconds). I have video but it is a really huge file (.mpg). I have been looking into hot air balloons (www.overflite.com) and kite theory to see if there are any simple rules of thumb I could apply to it. (1/3 radius foil hgt???, etc.,1/3 diameter????). Curious thing to me was that when the wind was blowing gusty the wrong way, changes in the wind speed would pop the foil part way open and make it turn. anyway, L8r, Mike [ Parent ]

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