Author Topic: Need some help. Large verticals. (Read 2232 times)

Henry Swayze · « **on:** February 06, 2006, 10:45:37 PM »

I have been studding not build anything yet. I am attracted to the simplicity of doing a straight bladed vertical 2 or 3 bladed machine driving a PM generator to do grid net metering. I aiming to produce enough power for our home and for recharging a hybrid car as well. My average wind speeds are modest... 10 -12 MPH so the machine will have to be perhaps 15'H X 18'W. (Thanks to the H-Rotor Calculator)

Questions:

How do I come up with an airfoil profile for 2 blade machine?

How do I predict RPM?

Should I consider three blades and will that tend to increase RPMs?

Is higher RPMs something I should avoid in this scale machine?

And lastly (for the moment) What prototypes must I build and at what scale?

I am good in wood, comfortable with composites, have no welding experience but understand basic mechanical design and can do rigging and guying.

Any thoughts or resources would be appreciated.

vawtman · « **Reply #1 on:** February 06, 2006, 04:08:48 PM »

Henry.I think your getting a little over your head here.Build a 8x8 first and you will understand the forces your dealing with.I posted pics and blade design a while back.You should be able to open up my files.

georgeodjungle · « **Reply #2 on:** February 06, 2006, 10:02:46 PM »

i agree with vawtman, start small.

how much power do you need?

or how much are you using now?

& no matter how lame hybrids are you don't plug them in.

you could turn off the generator before you get home, like 1/2 hour?

but it will drain the batteries deeper.

ie...shorten the life.

any way there's lots of good stuff here.

just search the board.

they are vary powerful,

my s rotor crainks out great power in low wind.

oztules · « **Reply #3 on:** February 07, 2006, 02:29:55 AM »

vawtman, I too would like to view your files, but unfortunately you have saved them in a format and size that precludes me from learning from your experience. On this tiny island, I'm flat out getting 1 kbs (yes one), and the size of your files would take me around ten hours to download... and then no guarantee that I could read them..(mozilla can only tell me they are some form of octet stream)

Are you able to save them in a jpeg 30-40 kb (not the 2.3meg ones you have at the moment). I tried to download one of your pics, but after getting an inch of sky after about ten minuites, the line dropped out.( I did get Mark_s_Wind_Thingie_002.jpg)

I would like very much to see your exploits, and perhaps emulate them as I have a soft spot for vawts, and a wind reservoir to boot.

oztules

thefinis · « **Reply #4 on:** February 07, 2006, 03:37:49 AM »

Keep studying friend. There are many great projects listed here and many good authors here. One not from here that I personally like is The Wind Power Book by Jack Park it is easy reading and has most of the math and terminology in smiple enoungh terms for a beginnner to understand. There are many excellent books on wind out there that have the tools to build the tools to make wind work.

Wind may be free but the ability to use it isn't cheap or easy. There are two main paths to reach the stage of harvesting the wind. One is to just buy your way in with a manufactured turbine and control system. The other is time, sweat equity and elbow grease mixed with a lot of math, reading and luck. Start small and work your way up is excellent advice.

A straight bladed lift based vawt isn't simple when you start dealing with the forces involved.

Finis

vawtman · « **Reply #5 on:** February 07, 2006, 06:55:02 AM »

Oztules,Ill see what I can do.I havent mastered the pic thing yet.Sorry

wind4Reg · « **Reply #6 on:** February 07, 2006, 02:40:51 PM »

Hi Henry, WOW! that would be a big turbine. I will try to provide answers to some of your questions, I am sure my answers will be debated by others on the board, but what the heck here goes:

How do I come up with an airfoil profile for 2 blade machine?

Take a look at the profiles manufacturers of straight bladed VAWTs have built. They have done the research to determine what profiles will give the best overall performance. IMHO I'd go with a fat symetrical profile of around NACA 0018. Others recommend cambered profiles, just remember the curvature of the camber should match the circumference of the rotor path, so that will affect your choice of airfoil. One guy on this board recommends super slim profiles and not only super slim, but doubled. In one wind power book I have it says that using the fatter profiles for VAWTs helps the turbine self start easier.

How do I predict RPM?

The RPM will depend on several factors. I know that this is a non-answer, but it really does depend. The average windspeed at your site, how efficient your turbine is, what the cutin speed is of your generator is, etc. Ballpark ~ 20 - 500 RPM, If I had to hazard a guess I'd say maybe 100 RPM for a well designed unit your size, remember this is just a guess off the top of my head and you will need to do the math, might be faster or slower.

Should I consider three blades and will that tend to increase RPMs?

I have been looking into the 3 vs 2 blades myself as well but not to increase RPMs. 2 blades will be faster than 3, however the reason I have been looking at 3 is because of overall turbine stability throughout the entire revolution of the rotor and I've heard rumors that 3 blades self start in lower windspeeds than do 2 blades. I have yet to test this but plan to before my final design is done on my H-Rotor.

Is higher RPMs something I should avoid in this scale machine?

I guess the question is how high is higher RPMs? As you increase the RPMs you increase the strain and stress on your turbine, so basically it has to be designed to withstand higher RPMs than your typical running RPM so that it can withstand storm winds. Plus you will need a huge braking system on a turbine this large, you don't want that thing overspeeding. So again there is a lot of math i,e engineering involved with a turbine this size to ensure it is safe.

What prototypes must I build and at what scale?

If it were me I would build a scale model at least 1/3 the size of your final turbine. At 1/3 the size you should be able to understand the forces at play in the H-Rotor VAWTs. I have built a scale model of my turbine and I don't regret doing it. In fact I am thinking real strong about building more scale models before building the large one because I still have some unanswered questions that need to be answered before I would feel I could safely put up a large unit.

I can tell you from my first model and from the research I have done what the two main weaknesses are with H-Rotor VAWTs.

The attachment points where the blades attach to the main crossarm. The blades will try to twist themselves off the crossarm at the attachment point. Extra care has to be taken to ensure that these attachment points are strong enough.
The main bearing is subjected to extreme forces and has been the failure point of many large sized commercial units. My model also experienced problems in this area since I didn't make the shaft that attaches to the main bearing heavy enough in my first model and this was eventually it's downfall.

My advice is to build the model and set it up so you can try different blade shapes/profiles and if you build the hub right you can try different number of blades so that you can determine for yourself what configuration works best in your area.

Best of luck, let us know how you make out,

wind4Reg

vawtman · « **Reply #7 on:** February 07, 2006, 03:48:41 PM »

I changed them to bitmap whatever that is.Come up real quick on mine.Let me know if its better.

vawtman · « **Reply #8 on:** February 07, 2006, 04:55:39 PM »

Good job Reg,I agree with the blade profile and have tested.The thin double bladed design is more for decoration than power.Im thinking airfoil vawt one third that size is all he needs.Hows your project going?

oztules · « **Reply #9 on:** February 08, 2006, 03:47:06 AM »

i'm desperatly sorry vawtman, i can still only find your original files in your file section. Am I looking for them in the wrong place. the current files in your files folder are still huge and of a type .... what type are they ( blade profile etc)

there are several jpg (also whoppers except for one)

I'm either lost or.....well yes lost

sorry....tules

vawtman · « **Reply #10 on:** February 08, 2006, 06:51:08 AM »

Im more lost than you.Ill seek professional advice.

wind4Reg · « **Reply #11 on:** February 08, 2006, 07:08:40 AM »

Hi vawtman, my project is going painfully slow. There are a lot of demands on my time right now with work and work at home. I recently built an addition on my house so I am trying to get that finished too, plus I was running a side business besides my 40+ hour per week regular job and I am in the process of shutting down that side business.

So hopefully I can get these things cleared off my plate shortly and I will be able to focus more on getting my turbine constructed and up. The side business seemed like a good idea at the time, but what a time sucker. I also have 2 other projects on the go, one is building a fully suspended off-road go-kart, I have the frame 95% completed and have the engine, and the other is my S10 truck project. The S10 is a 97 and it needs some work. I am very tempted to convert it to electric since it is an ideal candidate, 4cyl, 5 spd, regular cab, 2wd, shortbox, needs an electronic fuel pump ($585 ridicous price), and it is even white in color like the electric ones GM made. I was even considering the possibility of swappable battery packs between my wind system and the electric truck. All this takes time and money though so right now I am slowly collecting the materials needed for my wind turbine. I'll post the updates.

ttyl

wind4Reg

IntegEner · « **Reply #12 on:** February 08, 2006, 08:10:09 AM »

Bob Lynette, who was the CEO of Flowind Corp., the company that made all the Darrieuses in CA back in the '80s, suggested to me on the phone one day that I call them "verticals" (easier to say) than "vertical axis wind turbines". Progress is measured in such small steps.

No one, however, told me that the wind energy industry was so intent on producing windpower that it forgot to take the simple parasitic (profile) drag of the blades of every kind of wind turbine into account - even to this day. It is never mentioned but by only a few, including myself. The "verticals" see much more of it than the "horizontals" do for the same size rotor since the blades are entirely out on the rotor periphery and they run upwind part of the time and so have generally been unable to match their performance.

The other problem with them, of course, is that everyone assumes too much from their blade swept areas, as if to say that they are equivalent to the blade swept areas of the horizontals. They are not. All wind turbine blades (except for the drag machines, for those who favor these) extract energy from only the component of the wind velocity perpendicular to their motion of the blades that they see. For the horizontals yawed into the wind, this is all of it. But for the verticals, the perpendicular component varies from 100% at dead center to 0% out near the edges on the right and the left, with partial amounts in between. The physical reality of this prompts a calculation and the calculation yields a factor of 66.7%. So the verticals' blade swept areas are only 66.7% as efficient overall as those of the horizontals (ignoring some debate over just how efficient the horizontals' swept areas are). In other words, their rotors must be 50% larger in swept area to match the output of the horizontals - even before considering the greater drag they see mentioned above.

So everyone is welcome to make their own verticals, which seem simpler and easier to make in large rotor diameters and blade lengths, but remember that they have these difficulties to consider in doing so.

Other thoughts come to mind but it would suffice here to just direct everyone with interest in this to go look at the IntegEner-W website - www.integener.com - for more information. It was recently substantially upgraded, also, for those who have visited it before.

The homongous (and fragile in strong winds) 15' x 18' rotor size mentioned in the post would theoretically yield, using the above factor, 14.7 kws. in 30 mph winds but it is safer to say 7.5 kws. in 24 mph winds. Compare this to the Bergeys with just 10' long blades. The 8' x 8' rotor size also mentioned would yield about 3.5 kws. and 1.78 kws. respectively. Many take into account a "real world" factor on top of all these of some 50% or so for electrical and "other" inefficiencies to come out to what can be expected.

The retail store at which the microrotator seen on the website is located says "the wind is our friend" in their advertising and it certainly can be. But it will demand some respect from even the best. More "power", as they say, to you.

Anthony C.

IntegEner-W

www.integener.com

vawtman · « **Reply #13 on:** February 08, 2006, 05:41:11 PM »

Oztules,Wind4reg shrinked them for me.Try the ones with sm in front.Hope this helps.

oztules · « **Reply #14 on:** February 08, 2006, 06:43:53 PM »

and now we are found..... saved by another vawt devotee.. Thanks for your efforts vawtman.

wind4reg...just what the doctor ordered thanks very much, i can now see vawtmans exploits,

vawtman · « **Reply #15 on:** February 08, 2006, 07:05:04 PM »

Im glad you could see them.Where are you from?That was my first attempt at photos.Kinda like my first attempt at vawts.Large but slow.

oztules · « **Reply #16 on:** February 08, 2006, 09:37:55 PM »

Vawtman I'm from Flinders Island Australia latitude 40.00.

Looks interesting. but I just gotta know-----------

Q1. does the profile's curvature (bend) follow the radius

q2. does the profile run at rightangles to the radius or at a fixed dergree from "square"

q3 have you tested it out with a load and do you have any figures yet

q4 how high and what chord

..........bloody stickybeaks these folks from downunder

i'm scratching around for a proven design for a vawt, don't khow which way to jump. Will build 1:3 scale first, but what to build? all the hawt enthusiasts have well documented paths to follow,and it is all ho hum. Vawts have a struggle about them, which appeals to me. I figure that the wind is free, if I need more power to make up for the less than desirable difference between hawt and vawt, i'll just make it bigger. For once in our lives the energy resource is free,.... we get to choose how much blood sweat and money we wish to waste to harness it.

I now live on an isolated island of less than 700 people, but i'm armed to the teeth with 50 lbs of #13 wire, 100 2x1/2 inch grade 45 neo's....and an itch that needs sctraching..... i gotta build something

oztules

vawtman · « **Reply #17 on:** February 09, 2006, 08:30:09 AM »

Ill reply around 4pm cst no time now.Im in wisconsin.U.S.

Henry Swayze · « **Reply #18 on:** February 09, 2006, 01:46:52 PM »

Sorry not to get back on the board sooner. My last three attempts to post went up in smoke. I think I have it mastered now.

I have purchased two of the books alluded to... Wind Power & Axial Flux Alternator Windmill Plans. Any other suggestions?

I will plan to build 1/3 or 1/4 first and test airfoils ahead of that. I appreciate that the forces get really large in a big machine.

Bigness: I think I am looking for 24KWH/day. I haven't worked out the electric assisted car piece or whether I am supplying other houses as well as my own. Our net metering law may allow group generation this year. I pay 16cents/KW off the grid now.

On the 2 blade 3 blade debate what do you think is going on with Lenz's newest model. Specs look very good. I don't understand the airfoil he is using. http://www.fieldlines.com/story/2005/10/20/18560/012 and http://www.windstuffnow.com/main/vawt.htm

On copping tried and true commercial air foils for verticals. How does one get that information. I am only aware of to companies working with verticals http://www.solwind.co.nz/vertical.htm and http://www.ug-contact.dp.ua/eng/ Know any more?

Any information on power out-put as one goes up in height. I am in hilly terrain with a mix of wooded and open. I sit near the top of a hill 200 feet high with woods blocking my best winter winds but not summer ones. I saw one chart estimating doubling wind speed at 1000 feet. What happens at 30', 60', 120'? I ordered a delta kite to do tests. Any other ideas?

On subject of 1000' have you looked at http://www.magenn.com/products.php I think I would hear from my neighbors.

vawtman · « **Reply #19 on:** February 09, 2006, 03:04:05 PM »

Bloody stickybeek thats cool,Q1-The curve of the blade is a pretty close match to the outer perimeter.That seems to be the key to easy startup,less than 5mph.No back and forth weathervane attitude and also must help to reach such high tsrs.Q2-The blades are mounted square with rotor.That one airfoil pic looke alittle distorted.Q3-I just finished a 5hp conversion and get 20v turning by hand and will test on the drillpress and figure what gearing.Ive Tried different devices to mimic a gen,the best was 24qt beer cooler hung from ac4ft cable fun watching it fly around.The blades are 8ft high wih a 2ft chord and 5.5 in thick.

wind4Reg · « **Reply #20 on:** February 09, 2006, 08:05:25 PM »

Hi Henry, you know I actually emailed Solwind and asked them a few questions about their turbines, but they never responded, so are they really tried and true? I don't know, could be, but they don't respond to email info requests anyway.

wind4Reg

Henry Swayze · « **Reply #21 on:** February 09, 2006, 08:20:51 PM »

They responded to me with email and attachments when I contacted me 6 months ago or so. I though they were to pricey so dug into home brew at that time. I suspect it is a small firm and it is summer there so may be out at shows.

Henry Swayze · « **Reply #22 on:** February 09, 2006, 08:27:35 PM »

Down loaded your small picture and looked at large ones before you shrank them. What inputs did you use to come up with your air foil? Do you have a profile with angle of attack you can share?
I think I picked up that you had a failure. If it was with this design what went?

oztules · « **Reply #23 on:** February 09, 2006, 10:31:46 PM »

well, looks like you have way more alternator than you will require. I'm guessing the diameter is around the 8feet, which gives us a figure (from windreg calc) of around 1.7kw @ 10m/s . Will be waiting with baited breath to hear your results.

The circumference of the front bulbous nose is 5.5" (i know it is not circular, but very rough approx to get the wire bones drawn up before getting line of best fit for an aerodynamically sound look) how long back have you carried this 5.5 before you start the inner radius to the trailing edge. looks 7 maybe 8 inches.

Do you have any idea at what revs you will be developing your cut in so as not to create blade stall, and a whole heap of other questions which you are not in a position to answer yet i guess untill you have it running under load......aaahhh the pain of waiting......

oztules

vawtman · « **Reply #24 on:** February 10, 2006, 07:10:59 AM »

That little 2ft turbine was my tester.I would cut different shapes and wrap them up.It seemed the more curve in the profile the better.We had some very strong winds here a couple months ago and I had it tied down with quarter inch cable.It tried so hard to start that it wrapped the cable so tight around the shaft that part of the cable is still inside the bearing and the 2x6 cracked.My final tower will be steel anyway.Ill mess with it when it warms up.Good luck with your project Henry.

vawtman · « **Reply #25 on:** February 10, 2006, 07:33:01 AM »

Oztules,Yes I have a lot of questions still to answer.I cant wait to get the gen on there and see how it performs in the calculator of Wind4regs.Its just been too cold.Im going to use heating elements instead of batteries.Can you get the pic of the airfoil shape?Good day you old stickybeek.Just kidding.Feel free to ask any questions.

Henry Swayze · « **Reply #26 on:** February 10, 2006, 10:35:28 AM »

Vawtman
Did you notice my new post at the top of the thread? Some airfoil quires for you.
thanks

vawtman · « **Reply #27 on:** February 10, 2006, 11:45:41 AM »

Henry I replied to #22 earlier was that it?

Henry Swayze · « **Reply #28 on:** February 10, 2006, 06:58:08 PM »

Thanks Mr Vertical
Yes your explanation was useful. If it is going to be trial and error development just trying to get a head start on it with an understanding of why one profile over another and angle of attack and its effects. Recommend any books or websites? Is you air foil a lift type? Is the three balded one of Linz also lift? http://www.fieldlines.com/story/2005/10/20/18560/012 and http://www.windstuffnow.com/main/vawt.htm

vawtman · « **Reply #29 on:** February 10, 2006, 08:17:25 PM »

Henry,This whole wind turbine thing is trial and error development,thats the fun part.If it was aperfect science I dont think we would be conversing here.My design of the airfoil came from the thought that airplanes dont fly in small circles like Vawts do.Thats the curved airfoil idea.I errored probably twenty times and looked pretty stupid to the neighbors.Now they peek through the trees watching.Aka mr vertical.Go out there any fly.Have fun.

Henry Swayze · « **Reply #30 on:** February 10, 2006, 09:01:17 PM »

Thanks Mr Vertical
Yes your explanation was useful. If it is going to be trial and error development just trying to get a head start on it with an understanding of why one profile over another and angle of attack and its effects. Recommend any books or websites? Is you air foil a lift type? Is the three balded one of Linz also lift? http://www.fieldlines.com/story/2005/10/20/18560/012 and http://www.windstuffnow.com/main/vawt.htm

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Author Topic: Need some help. Large verticals. (Read 2232 times)