My 1st VAWT failure!

[CmeBREW]

Hello friends,

     Thought I would share my first attempt at a VAWT rotor. Yes it failed horribly. It wouldn't even begin to turn in a strong wind!! Thought I would share this failure as an example of what not to do-- so try not to laugh TOO hard. I admit, I must of missed the WHOLE basic principle here! After the Vawtman shared that one website recently, I grew curious and so thus tried to see if I could get one to at least spin mounted to this little alternator I had already made. The alternator has zero cogging and spins mega easy.

I didn't put much time into this though---  I tried to mimic the 'DELTA1' at this website:

http://www.pacwind.net/#deltaII

It is purdy to look at-- almost like art.(ha) -At first I tried the 3 blades. They are the basic straight airfoil  profile.(made from a 2x4) -Leading edge goes the same direction. The blades are 2 feet long each, and the diameter is 32 inches.





Everything is balanced fairly well. I used 3 angle steel pieces to hold the blades on the 3 arms.





I tried moving the blades both directions and every angle conceivable. Still no spin in a wind. Evidently, the blades look like they oppose each other for the most part. I can't figure out how this could work. The air drag would be murder since the blades seem to always oppose each other all the time!  I also tried only 2 blades to see if that would make a difference.  ....It didn't.  







I really wasn't trying to generate electricity with this experiment since that is really a high rpm HAWT alternator. I was simply trying to make a VAWT rotor spin to see how it would work. I guess its back to the books! Any reasons or ideas why this attempt failed miserably, ,would be appreciated.  I know there is an enormous amount of info. on these VAWTS here, so I will keep researching. I know these things are suppose to be complex. I thought I might get lucky.  ....I wasn't.  

Nevertheless, I do like the looks of those VAWTs though----if only I could get one to spin!!

[vawtman]

Welcome to my early days.It acts just like weathervane doesnt it?

 I thought i would get lucky also.Many attempts later i got it.

 With a 6in chord and the profile shaped for the rotation you will be off and running.You cant have a flat inner profile.You could try just carving out the inside of your current blades.

 Even the slightest drag will hamper a small turbine like that.

 Have fun and hang in there.When she gets going you will be amazed.

 Mark

[windstuffnow]

  I had my share of failures with the little Darrieus models myself.   I had built several models with no real success.  It dawned on me one day, something I had read over and over again but apparently didn't sink in, that the darrieus doesn't self start reliably.  I took one of my models out in the wind, wrapped a rope around it and gave it a pull start.  I do believe I soiled myself when it took off, scared the heck out of me.   It started running when the rope released but it sounded like a turbo kicked in, the rpm went up so fast I thought for sure it was going to blow.

  Your blades probably aren't ideal, usually a teardrop shape is best but I've had a couple with more of a prop profile that ran pretty well.  Before you give up, set the blade angle to 0 ( zero ) and give it a pull start when its in the wind. Pull it hard to get some speed on it.  Make sure all the bolts are tight!  If she does start stand clear of the blades, they can be very dangerous.  Typically you need to get the blades running at a TSR of 2 or more to get it going and you'll know when it caught the lift guaranteed!

.

[vawtman]

Ed maybe the poster will do what i mentioned and find how easy they start.

 Goodness its been 2yrs and still nobody believes me.No pull ropes needed

 Glad we got a good experimenter here that may follow through and not give up.

[CmeBREW]

Thanks guys for the quick response and advice!

I will certainly do what you BOTH say. I will carve out the inner part of the blades. I have seen a diagram of such a profile. I also have seen a diagram of the 'teardrop' shape also. I will  certainly make a set like that also later. Pine is so easy to work. I have some equipment that makes it quicker. (tablesaw, fixed joiner, routers, etc.)

In fact, if you look at one of the photos in my post, you will see the shape of the blade profile is not quite right yet. I simply used a 1" router bit to shape the leading edge of the blades. It is easy and quick. However, I was in a hurry today to get this up to try since the winds here today were 20-30 mph! I will sand the profile down correctly tomorrow.

I also twirled the rotor by hand (probably 200rpm or so) many times, but it simply would not take off and keep spinning! I will try the rope thing too tomorrow. But I thought these  VAWTs only go under 300rpm anyway??  We'll see what happens.

So I quess even though a couple of the blades oppose each other, what happens after it starts spinning fast enough, is make like a vortex and the fluid (air) keep it spinning without the opposite blade drag?

I will keep on experimenting with these. They are fun and complex -and it would be nice to have these all over the place sitting on 10 or 15 foot poles. (with no guy wires!)

I don't know if tomorrow's winds will be good like todays, but I will try these things and get back real soon.  -thanks friends!

 

[windstuffnow]

  I was talking about the standard Darrieus model which it looks like he's trying to duplicate.  Your wing design will start on it's own and because of the shape it's self regulating to a certain degree.  

  I think there are alot of misconceptions of the darrieus and how it runs.  I've thought of building another one to run some video on how they normally run and perform. They are facinating turbines but can be very dangerous if built incorrectly.

.

[windstuffnow]

  The size you described in your post would run about 1200 rpm + in a 20mph wind with no load and would require a pull start of around 400-500 rpm to get over the hump.  Make sure the structure will handle the rpm before you pull it and have a way to control it when/if it takes off.  Shorting the wires on the motor would most likely stall the blades.  If the motor will run connected to a battery you could use that as the starter.  Be careful!  If the blade weighs 1 lb , at 1200 rpm it will be the equivilant of a 650lb weight at the point of release.

.

[thefinis]

I would recommend trying a drag style vawt. They are fairly easy and seem to spin almost no matter how you build them. The lift based vawts are more complicated as you are finding out. Yours is not self starting so it needs to be spun up like Ed has said. It could be done with a drag starter(S rotor) if sized right or with a cam to change the angle of the blades as they follow the circle into and out of the wind or by using power input from somewhere else. Mark built a wing design  which seems to have some drag built into it so it is self starting. Mark wish you could finish testing so I can see how my results on your wings compare. I have not had much luck with big models of the lift only vawts. Why I can get a square milk carton split at the corners with the sides flared out(you kind of squish it down so the sides go out) to spin so well so easy still baffles me.

My suggestions would be bigger wings and an attack angle of 6-12 degrees 8 is a good starting point and more blades. More blades might get it to the self starting point. On the small turbines any friction can be the straw that broke the camel's back so make sure it spins as freely as possible. Ed sometimes takes the seals off his bearings to help reduce drag friction. Anthony @ Integener was fond of saying build a lift vawt for low tsr with big wide blades.

Good luck and keep trying

Finis

[vawtman]

Hi Ed

 Its pretty much the same thing with the hawt only the blades wont fly has far.LOL

 His current solidity is <1 and sure it will be a burner just like skinney blades on the hawt.But it is small.

 My current thinking is a solidity ~.3 like my little guy that can survive anything and has.

 I never tried to selfstart such a narrow chord with so few blades.

 So you may be right on the start characteristics i guess we will see if curving the foil helps him.

[tecker]

turn the foil to the inside take 1 1/4 pvc cut in half put it on the leading edge and it should start. Lift to the center and drag the outside.

[CmeBREW]

Ok guys--been working on this crazy thing all day. Thanks for the advice folks--keep it coming! (i,m gonna need it)

Sadly, the winds today suck compared to yesterday. Only 0-10mph occasional breeze.  

I sawed out the inside of each blade with my table saw. But rather than make it a smooth curve, I made it come to a sharp 3/8" groove for the wind to help it start better. It seems thats the way the 'Delta1' is, exept it has it on both sides of each blade.  

So, I tried it and it did move alittle but nothing earthshatering.

I then read Tecker's idea of putting the PVC on, and so I did that next----What the heck. Exept I didn't flip the blade over like he said. (lift in center/ drag on outside)

I will try that next later in the week. I was afraid if I flipped it over the mount holes would make the blades more crooked. I used inch and a half PVC. Heres the pics:





The inside curve is not as graceful as Vawtman suggested, since I wanted a SHARP edge to catch the wind good. (at least that was my logic)  I sanded it smoother than the picture. I also finished a more correct airfoil shape as you can see. I figured that the 2 blade has less initial opposing blade drag than the 3 blade.





Here you can see the PVC. The wind catches the outside AND the inside of the blade. You can see the 3/8" sharp groove plus the PVC plastic. So the total inside catching edge is a little over a half and inch. Now the blades do self-start in a bout a 10mph breeze. But it only goes about 30 rpm. I twirled it as fast as I could, but the low breeze did not take it off. Maybe when there is more wind it will. The location is horrible.





I also turned the blades a bit at more of a angle, and that did help it to start turning. One VERY important thing I learned is that the whole thing has to be exactly straight up and down, not at all crooked. Yesterday, it was not plum or staight up in all directions. It is nearly impossible to begin to start if it slightly leans one way or the other. It is difficult to do this, the way I have it mounted--and I don't have a level that will fit inbetween the blades horizonally.

Yes, The thing rotates extremely easy by hand. It has ball bearings, plus the grease in the bearings are thinned with oil. There are no seals. Tomorrow is suppose to be more windy. (10-20).  So something may hit the fan tomorrow. We will see.

-Thanks for all the help folks!! Preciate it.

ED:, your estimate that each of my blades weighed 1 lb was WAY off. They each actually weigh 1.15 lb.  --=Also, How in the world am I suppose to wrap a rope around this thing to spin start it, if the blades hang down like they do?! If you pull it, the blades hit the rope.

I was standing there with the rope, but could not figure it out. I quess i could use a rubber band and 'slingshot' the thing off!!

[vawtman]

Hi Brew heres a pic of my fishfoil has i call it since i thought of it while icefishing.Im sure there is a number for it.

 Starts spinning in almost nothing and people sometimes ask me why its spinning.My opinion is that you need to keep the diameter and height the same or a higher diameter if needed.

 Any ?s im here.

[windstuffnow]

  I think you went backward from the original.  I don't think the new one will create much lift if any at all.  The additions to the blades created alot of drag which in the end will hold them back.

  In order to extract power from the wind you either have to generate lift or capture the wind as drag or utilize both.  There is a fine line between the two where drag cancels out lift and you end up with a spinny thing that doesn't make any power.  

  A drag machine will capture energy on the downwind side only up to the point where the blade and wind are at the same speed.  Once they are running at the same speed there is no more power being extracted and it's just a spinny thing.  In order for a drag machine to extract power the blade must run slower than the wind while loaded.  Ideally, a tsr of 0.33 or 1/3 the windspeed for peak extraction.  

  A lift machine is quite a bit different.  The upwind blade is actually doing most of the work up to a certain speed.  Remember the downwind blade is going faster than the wind so there is no extraction taking place.  After a TSR of 2 the downwind blades starts seeing a little bit of lift and as it increases in speed all the blades will add something to output power although lower and at varying degrees.  A Tsr of 4 or higher is best for a VAWT lift machine for all the blades to be interacting to the extraction.  

  A drag machine runs slow with high torque, a lift machine runs very fast with low torque.   You can combine the two using both lift and drag as long as it runs below a TSR of 1 while loaded.  

  I used to have a bunch of drawings for a darrieus machine, I'll see if I can locate them and you can decide which way you want to go.

.  

[windstuffnow]

  I found my files and also a web site that give a very good analysis of a darrieus machine as well as some good plans to build one.

http://windturbine-analysis.netfirms.com/

  Great site for learning about the lift type verticals!

.

[CmeBREW]

Vawtman;  

     Interesting profile. I think i am beginning to understand.  That blade of yourn looks quite wide. Looks like 12 inches wide!. No wonder it starts so nice. I could make blades similar to that fairly easy with a 2x6. Thanks for sharing that picture. I'm learning some good tricks with the table saw and joiner to do it quicker and easier. So I wonder if 2 blades are better or worse than 3 blades?  Or if 4 blades better than 2?  

I quess the reasoning is the same as for the HAWTS; more blades means easier take-offs, but suffer more drag and less top rpm.(&less power)  I do want a fairly low wind VAWT is my goal. I know the output is lower--but thats fine. I also like Tecker's PVC idea. At least it can spin slowly now in one direction. Later in the week I will see how 3" PVC wings work, if the 1.5" isn't enough.

ED: Thanks for the link and help. Will check it out. Yes I am just beginning to experiment with these, and so I don't know that much about them yet.

These are very interesting machines. Cant' wait to see it go! If it does anything tomorrow, I will speak of it. -Thanks all.

[vawtman]

Its 24in wide and the curved profile pretty much forces it to start.Amazing torque thus my alt problems.But fun

 The blades will hit a point depending on solidity where they just keep spinning and no wind inside other than little pulses.COOL

 Ive built 2 more blades for it.Will be up in time just need to redesign the tower,rotor for the alt and raise it up.

 Lots to do yet.

 With pvc on the leading edge it wont be good because of the little vorticies traveling behind(drag).Seems almost like eddy currents in a alt.

 My thoughts and i'll shutup now

[tecker]

Ok I'll ramble through a general vawt cycle as I see it . Here's the classic sail tack

 

  you can see a logical drag form from the sail tacking .

 If the wind approaches from 0 degrees north the drag cycle is possible from around 0degrees to around 160 degrees maybe  more with a foil adjustment.

 180 to 360 the blade must employ some lift or mechanical advantage to reach the cam over at 0degrees with the least amount of drag

From Eds link on Darius

 

 Assuming the wind from the north the teardrop drags a good portion of the cycle from slightly past 0 to maybe around 200 degrees .

 Ed's big  modification drags hard slightly past  0 to 100 degrees approximately and the foil drags 100 to around 200 with the leading edge creating a lift pressure that increases with Rpm

  Vman's trailing edge is somewhat like an aileron or an elevator forcing the blade to turn inward and concaved inner area drags hard from 90 to 200 degrees with the topside dragging hard from 0 to 90 .

 Improving the vawt Is a function of increasing drag 0 to 200 degrees and overcomming the parasitic upwind vector from 200 to 360 assuming the wind from 0 degrees north

 The big plus for a Vawt is not having to turn the unit into the wind and not having to

manage the wire down the tower.

  hope this opens discussion

[vawtman]

Hi Tech

 Ive been looking at your drawings for a couple days and totally dont undestand the first one.

 The second one seems to me that a straight airfoil will have start problems has well has performance overall.

 What is an aileron?

 I think one could engineer these things to death and have.

[vawtman]

Mark wish you could finish testing.

 Im not sure of your results.Was this when they were at 13ft or did you bring them in like i mentioned.If not im not even gonna try the wide diameter your losing to much that way.

 My opinion

 

[tecker]

  Put your foil out the window at 10mph and I'll bet it tries to turn sideways instead of fly straight . Just a guess  I have been laboring over all the designs looking for a power start for a Vawt . I want a come up with a solid unit that dosen't need a lot of maintainence and a Vawt seems to fit that bill .  The sailing principles give some method to set a lot of weight in motion . The Aircraft analogy is a little vague but the wing moves when you raise or lower the trailing edge.

[windstuffnow]

  Vman, the first diagram is for a sail boat and how it tracks in the wind, showing the wing placement for lift or drag.  The second simply shows how to use vector math to calculate lift on the wings in various places of rotation.

  An aileron is a device used to control an airplane.  Hangs off the back of a wing to control wing angle and turns.   Did know than an airplane can only go up and down, it can't turn...

  If you look at STOL (Short take off and landing ) aircraft you'll get a better idea of the wing shapes that have very high lift.  My wings are designed around a very dirty "D" cell but generate alot of lift in very low winds.  When I was designing ultralight and experimental aircraft we built a wing similar but a bit cleaner, 28ft wing span would lift 500 lbs in a 20 mph wind.  It was dirty enough you could point the nose at the ground when landing and not gain alot of speed, bleed off the excess speed and land it in about a 100 ft patch.  Turn around and lift off in a 25ft run and climb like a homesick angel.  

  The downwind drag aspect of my wings were designed around shapes that have the highest drag (Cd), combining the open shape and forming a high lift wing was simply a natural combination.  Where the air detatches itself from the wing to the point drag takes over is a very short distance.  ( Remember the upwind video with only one wing attatched and with the wing at 180 degrees from the wind at a dead stop would fly directly into the wind and accelerate? )  Its still in my files.

  Anyway, your wing is (appears to be) a derivitive of a STOL wing shape, very similar to what the 747 jets have on take off or landing.  Some use drooped ailerons in the rear or slats in the leading edge or both to form a very dirty high lift shape ( also flaps to really deform the wing ).  So without any prior aerodynamics background you did good!  Now its time finish the alternator for the beast!

.

[hvirtane]

Hi,

this is a very good discussion indeed.

There are in production some vawts, too and these designs will certainly improve over the years. Ed's 'Lenz turbine' looks very promising.

CmeBREW: I think that you should follow the way of vman, you seem to have tools to make new blades quickly.

Some quite good knowledge is available here:

http://www.me.dal.ca/~dp_03_7/

- Hannu

[thefinis]

Did not post my results as they seemed way off of what I was expecting. I am lazy. Would rather see your results on an 8 ft than do it myself. I didn't miss you posting them did I? If there was a large enough difference between what I saw and yours then trying them at 8ft would move up on my list. With the heavy sq tubing and sheet metal skin I just never redid the supports to rehang them for an 8 ft diameter. When I get a 30 ft tilt tower so I can stand on the ground to attach a turbine may try them again at an 8 ft diameter. They are too heavy(due to me using sheet metal vs al skin of yours) to make it worthwhile for me and a friend to stand on makeshift scaffolding 6-10 ft up to attach to the test tower. After trying several other designs finally came to the conclusion that I was really too low in gusty turbulent conditions for very good test results too.

Ed's Lenz2 wings at only 4 ft high tore up the mountings which made my day(was wanting something that powerful) so I have been working on a bigger and better setup since then.

Finis

[thefinis]

Ed's Lenz2 wings at only 4 ft high

That should read 4 ft tall(they were a 4 x 13 turbine)

Finis

[vawtman]

Finis

 Your not lazy you must have worked very hard on them turbines and continue too.

 If anyones lazy i am.I just keep staring at the alt and not gaining much but once i get a thought ill tear into it.Trying to come up with a testbed for it.

 That must have been a bugger wrapping that sheet metal or did you do it in pieces like i did?

 My blades are around 13lbs apiece.

 Good luck and have fun with your projects.

[vawtman]

Hi Ed

 Thanks for all the info and your right im sorta aerodynamically challenged.Thus the looking at a fish in a ice shanty.

 My dads not though hes a retired pilot/plane mechanic and now works for the gov doing crash investigations and he thought it would work.

 So on we go.

 Thanks

[CmeBREW]

Thanks guys--Very interesting discussion in deed. That decent wind didn't come until today, so I had to wait till now to do alterations. They were about upto 10-12mph occasional gusts I guess.

Yes, ED was right, the PVC changes did not help my cause. I was just trying to switch to a drag machine temporararily to see something spin. But it only turned very slowly. Clearly, the resistance (drag) on the left side was almost exactly the same on the right side. Only a small tornado dropping straight down on top of it would have got it spinning. I even tried the 3" PVC:





It didn't improve at all needless to say. Looks cool though, doesn't it!

Nevertheless, I proceeded on to something else.(Hopefully better!)






I wondered why this direction wouldn't work. This is super obvious though, I'm sure its been tried countless times. But I would think that this method would be MUCH better than the other VAWT method with the blades vertical. Because the blades don't oppose each other. I don't have much angle on this example--only 8-10 degrees.

However, if I redesigned the blades for a wider, steeper angle, it might just take off. Right now, it only goes very slow in a 12mph gust. I love the look of it even better, since it is VERY unnoticable when the blades would turn.

Does anyone know of this VAWT method operating correctly. It looks VERY promising to me. If it doesn't work, I think I will make blades like Vawtman showed--only out of 2x6s and 4 blades instead of only 3.




Or I wonder if I shouldn't flip it over so the lift goes upward just like a helicophter or airplane. Or what about 6 or 8 blades?   Comments???

Nevertheless, If ALL ELSE FAILS, I also rigged it to make quite a nice 6 foot diameter HAWT turbine. It was going over 300rpm in a 12mph breeze!! Pretty cool. Goes way easier than my 4 footer!





Keep the info coming friends--I might just grasp something and make something that works!!  Gotta admit, these VAWTS are fascinating and look really neat!  Thanks.

[vawtman]

Oh Goodness

 Keep Thinkin my freind.

 If you want yard art you got it.But must say i had that thought thinking the blades would lift the wind from underneath somehow..Didnt work.But at least i couldnt say i didnt try like your trying.

 Carry on my wayward son

[Lumberjack]

a small s rotor in the center should have enough torque to get things going.

[CmeBREW]

Yeah, you're right. I know there is almost no wind surface area, but My wild dream is that it might somehow create a vortex, and the wind would keep hold of, and keep feeding the vortex. There would be very little drag in this theory so that it would reach very high rpms. For real though, Once, I took a common box fan (on the high setting) and held it horizontally like that and smoke was underneith it---and I could see this cool vortex it was making. THAT is the crazy idea. I think I will hook it to a running 600rpm treadmill motor (hooked to my 12v batt) and see if it can keep itself going in a good wind.  Its a very good bet it will not. You get these things in your head and you got to try them! However, I will continue to make and learn about the already proven VAWTs though.     --Bottom line,,,I'm having fun!!  -Thanks Pop!

[windstuffnow]

  The Hawt type Vawt doesn't have a chance to catch any wind.  If you put the airfoils upward into a V shape it will fly like the darrieus.  Below shows one I put together experimenting with the idea...

  It wouldn't self start but would run with a push.  I didn't take it any farther to see if it would actually make any power.  The non-self starting through me in a different direction.

  Keep up the good work and keep thinking... an idea that will work is just around the corner!

[gizmo]

This is a idea I wanted to try, sort of a modified Lenz2, but this time using a closed pipe.



The hope is it will run faster than TSR 1. Uses smaller wings to swept diameter than the Lenz. Would be easy to make.

Glenn

[windstuffnow]

  That would be a simple one to build and test Glenn!  Not doubt it would spin.  I'll have to check my PVC pile for scraps... ;o)

.