Lenz2 pushing over 450 watts

[windstuffnow]

   We've got a heck of a blow going through.   Last night and today the winds have been 20-45 pretty consistant.  Watching the amp meter peg 30 amps this afternoon I decided to lock it down.  Shorted the leads and it helped but not by much.  Slowed the machine down a bit so I went up on the roof to stop it and lock the rotor.   I got it stopped fine when the wind died down to around 20 or so... then a gust came through, it took everything I had to hold the rotor.   The alternator was never meant to exceed 250 watts and it certainly was no match for the turbine when shorted.   It would still spin up to 350+ rpm although it slowed down very quickly when the wind subsided a bit.  

  I also found my static balance was only good to around 400 rpm and it made quite a vibration through the house running over 500 at times.  I stated before that I thought the dirty wings would help to possibly self furl the machine by stalling the wings... well I was dead wrong.   After calculating the efficiency of the wings (alternator losses etc removed ) they only dropped to around 28%.   Definately needs a sub-system to control it in extreem conditions.

  Mother nature is testing my engineering skills as well, the roof mounted Lenz is not attatched to the roof in any way... yep it's just sittin' there.  I calculated it would take a 70mph wind or better to get it down and so far... knock on wood... it hasn't budged.  

  Sure wish I knew what to do with all this extra energy !?!!!

Exciting day

.

[monte350c]

Very nice Ed,

I'm curious - is it still a drag machine, or has this thing started to 'fly'?

You mentioned before that it seemed happy producing power at around .8 or so.

Another question - does it oil-can when the wind gets stronger or is it pretty quiet?

Again great work and look forward to the continuing saga!

Ted.

[windstuffnow]

  Hi Ted,

    It's a combination of lift/drag .  The alternator keeps it at around a TSR of .8 in normal winds.  As far as noise... none - nada except when it reaches an rpm of around 400, actually not noisy just creates a vibration through the house.  I'll have to give it a better balance job later.

    .  

[dinges]

Makes you wonder,

Why can't the wind always blow like that :-)

But even in such big winds your turbine 'only' does 400-500RPM. I've got a small genny that I intended to be used as a VAWT (neighbours, turbulence, etc) but it needs 33RPM to give one volt (33RPM/V in star-connection). So 450 RPM for 14V....

I noticed that your coffee-can 'VAWT' rotated at only 700RPM; a bigger version, as I would need for my genny, turns ofcourse much slower...). My genny was build to put out max 50-60W (10W being the normal expected value).

Hmm, I still like the VAWT idea for my genny; even better after your story :-) but it'll need either a new stator (this is already the 2nd one; first one had 65turns/coil; current one 130turns/coil; should I go to 250turns/coil?!) or a solid-state voltage inverter (4-8V to 13.8V; shouldn't be too hard with all those current voltage-converter ICs (free ones, like the Maxim MAX724 & MAX726). Think I'll go that last route.

Ed, your story just made my mind up: it's going to be a VAWT!

Now, to start reading up on those blades... or for that matter, on designing VAWTs; am afraid all my knowledge deals with HAWTs.

Ed, looks like you've found another follower. From now on, you'll be my guru! (or at least till I find another, better one ;-)

Peter,

The Netherlands.

[ghurd]

Hi Ed,

"Sure wish I knew what to do with all this extra energy"

What would be the gain of connecting to a 24 or 48V battery bank?

G-

[windstuffnow]

  I'd hardly call myself a "guru", I'm still learning like the rest of us.  The stator I'm using is basically a dual rotor identical to my 500 watt kit ( 8 inch magnet discs ) 12 pole/9 coil layout.  The stator is 1/4" thick wound with #18 wire, 47 turns per coil wired in star.  It runs about 7 rpm per volt which for the 3x4 unit is a bit fast.  It was designed for a 2 ft diameter unit but I figured the 3ft would overrun a bit, which it does.  The magnets I used are the 1/4" wedge magnets ( on my site - builders corner ).  

   The wings are scaleable:  width = 1.875 x diameter, length is .4 x diameter.  Basically a C with a tail C__ . The angle I'm running with this one is 9 degrees of the chord line ( positive )(99 degrees from the arm its mounted on).  The chord line is center of the C to the tip of the tail or trailing edge.   I'm working on another set of wings which enhances the downwind capture as well as cleans up the upwind side.  Also, one more modification that isn't in the pictures is the addition of a winglet.  This was added to both ends of the wing to keep the air flowing over the wings.  

Lots of fun!

.

[dinges]

Thanks for the technical data!

One more quickie: do you think it's possible to use a, say, 10W (50W max) genny of 33 RPM/V with a VAWT? Perhaps 1.5ft diameter? About 350RPM in a 12.5MPH wind? Just guessing here.. Is there a 'magic' ratio for VAWT diameter:length? Or does diameter determine RPMs, while length can be adjusted for powermatching?

Most important would be the powermatching; I can match the voltage (either solid-state, with transformers or a complete new stator).

Peter,

The Netherlands.

[windstuffnow]

  Diameter is the function of speed, like a skater with their arms out turning slowly and speeds up when they pull thier arms in.  Power is in the area the turbine.  The two test units seem to produce about 5 watts per sq ft in a 15 mph wind ( fairly close between the two ).  

  Finding the speed at which it would run would be:

windspeed x 88 / ( diameter x 3.1415) x .8

the 88 simply converts mph to ft/min and the .8 is the TSR which it seems to deliver the best power ( which is still under investigation ).

So a 1.5 ft diameter in a 12.5mph wind would be...

12.5 x 88 / (1.5 x3.1415)x .8 = 186 rpm

After that it's a matter of matching the alternator/generator to the power of the machine.  

.

 

[dinges]

Thanks!

Just what the doctor ordered. Will play around with some figures to see what might be the best approach; smaller diameter (1 foot) or voltage conversion/new stator.

Peter,

The Netherlands.

[Chagrin]

Diameter is a function of speed, but this is not at all like a figure skater -- that's the moment of inertia and would only apply to HAWTs if you're talking about the acceleration/de-acceleration of the HAWT.

Minor nitpick. I'll go back into lurking now.

[electrondady1]

wow! ed, i was jealus when i thought your machine topped out at 200 rpm, 500! what a little monster youve created!

 it must have been exciting(high adreniline ) when you realized shorting the coils wouldn't stop it.

 what are you thoughts on adding a second alternator at the top pin. the latest desigh iv'e been sketching could accomidate one?

[windstuffnow]

  Thats actually a neat idea electron.  You could actually have the second one wired so the cut in speed would be considerably higher than the smaller one.

  We very seldom have winds like that, possibly 5 or 6 times a year.  It might be more cost effective to design a single alternator that would be much more efficient.

  It certainly gives you a good idea of some of the obsticals that have to be overcome for the VAWT units.  Had that been a 6ft diameter x 12 ft tall unit working well in low winds there would be no way to stop something like that unless there had been a system in place.

  If you've ever shorted an alternator and tried turning it by hand, even a small one, you realize the amount of force it would take to make it spin at 300 rpm, the little turbine made it look easy... to easy.  More to think about before the big one goes up !

.

[phil b]

Sounds like you may need to consider adding a disk brake below the magnet rotor.

[hvirtane]

Your machine seems to be really good.

I think that with some development

it will have about the same power as

propeller type HAWTs.

Excellent, indeed.

Could you, please publish a small

drawing giving the dimensions?

I've been planning (, but had not yet

time yet to start making it)

a bit different VAWT machine,

with skewed wings.

My plan is to make most of the pieces

of metal tubes.

The general layout of the machine.

A draft how to make it.

The tower can be used as a tent, too.

A picture of a small scale model.

What do you think?

- Hannu

[dinges]

Hi Ed,

Changed my mind again; don't think the little genny will be a VAWT after all (at least, not this one).

Am I mistaken in concluding that there would be quite a bit of experimenting involved in getting one to work (blade angle, e.g.)? After reading about your succeses and failures, I realize that this is still a highly experimental setup; think I'll wait until the dust settles a bit :-)

Seriously, I don't think this is the best design for me (I've never carved a prop), this is my first windgenny.

BTW, when reading your stories, the same questions keep popping up (power, efficiency, technical dimensions). I guess that an update to your VAWT-webpage could solve most of these recurring questions; also a matter of efficiency :-)

Looking forward to whatever will be next up your sleeve,

Peter,

The Netherlands.

[monte350c]

Hi Ed,

Something like this? Either spring loaded in the furled position, or with a linkage to command it in or out.

Probably better to have it fully 'in' until rpm needed it...

I can't wait to see larger versions!

Ted

[windstuffnow]

  Hi Peter,

    I believe I've covered all those questions, look through my diary on the Lenz turbine.  In any case, build what you feel comfortable with that's usually the best way to learn.

Most of all.... have fun doing it !

.

[windstuffnow]

Hi Ted,

   I need a bit of an explanation of what you have there.   Not sure I understand the mechanism....

.

[monte350c]

Sorry Ed,

For some reason that pic got a lot bigger when I posted it!

Anyhow, the view is looking straight down at the end of one of the wings.

There could be a rod running the length of the inside of the wing, that's going to act as a pivot point. It would pass through your wing ribs, close to the skin, on the inside of the wing.

Then attached to the rod there could be say four short struts (the thin lines leading away from the rod), these would hold a flat slat (represented by the heavy black line on the diagram)

The furled position is shown by the solid black lines.

The activated position is shown by the dotted blue lines.

The idea being that by positioning the strut like this, it would be subject to centrifugal force. That could be countered by a spring which would let the slat pivot out into the oncoming wind at a predetermined rpm. Or the three slats could be connected by a linkage and commanded out when needed.

Here's another sketch which hopefully will be a bit clearer...

1. st view, looking at a wing as it would be sitting on the bench, with the open side facing up.
   
2. nd view, looking in from the end of a wing, running position, slat furled.
   
3. rd view, looking in from the end as before, slat deployed.
   
   

Ted.

[Bruce S]

Hello Ted;

 I too have been following Eds VAWT with quite a bit of interest, since here in the city I cannot put up a nice big HAWT.

Correct me if I'm wrong but your design looks very much like the spring advances for car distributors.

This would be an interesting way to make the "wings" swings out and begin acting like big brakes to slow the machine back down.

Seems the only hard part would be to get the spring load just right for a set speed.

Am I way off base here?

Thoughts?

Bruce S

[monte350c]

Hi Bruce,

That's the exact idea.

There are a couple of design considerations (of course - there always is!)

It would be good if the slats stayed completely furled until needed to avoid mucking up the aerodynamics of the inside of the wing.

Also when the braking is needed the slat will need to overcome the apparent headwind as it extends.

So either a clever over-center kind of spring linkage, or a system of control rods, one out each strut, leading down the center tube of the unit with an actuator would work. The linkage idea may not be so bad since it would give the option of a manual furling of the unit. It wouldn't stop it completely of course, but make it easier.

Ted.

[electrondady1]

 first, i believe teds illustration is 180deg. out of whack, the 1/2 round nose of ed's wings are on the outside(thats the most intrieging aspect).

the lenz turbine is so simple and responsive i think it would be a shame to glome on a furling mechanism .

purhaps i am mistaken but i think ed was more concerned with melting his stator than the wings breaking up.

[windstuffnow]

  Ok, I get it now Ted.  That would probably work fairly well as long as, like bruce said, you get the spring tensions dialed in.   There may be some "flutter" problems to work out as it changes from up wind to downwind.  On the upwind side the wind will try to force it back in its pocket where down wind it will force it back out.  This might tend to slow it down but also enhance the drag torque on the downwind side. Another problem is maintaining balance as one may be out farther than the other creating a heck of a vibration while furling.  Might take some more thought... interesting idea.

  My thought was to use the wings in the same form, spring loaded on a central pivot.  This in turn would end up doing the same thing and eventually enhancing the drag torque.  My idea wouldn't work.  If it were reversed, pulling the trailing edge toward the center of the machine, might stall the upwind wing but still offer a large area on the downwind side.

  Probably the simplest way would be to design a much more efficient alternator and utilize it as part of the control.  Fine for the smaller ones but the large unit might take a bit more to keep it at bay.   A large one could be built inside a silo and raise it or lower it in and out of the silo to adjust the power you need in a given wind or simply put it completely away.  That would be quite an engineering challenge...

  We have another group of storms blowing through today and tonight and tomorrow, so I should have the opportunity to experiment with some small quick ideas.  

.

[electrondady1]

you know i've been thinking about silos as a windmill platform for a few years now . i think it's great your sorting out a way to utilize yours! one of those whinches from an off road truck could probably be made to provide the lift and controlled desent. and don't forget, it would be sweet to have a little elevator to get up there.

[Bruce S]

Ed;

   How about the idea of using a high wind genn to make use of them even used as a braking system. I'm thinking one that is designed just for high winds.

This unit would not be engaged unless there was the possibility if high winds and could be used as a braking system that would withstand a lot of heat instead of smoking the 200 RPM unit.

Going out on a limb here, but I'm thinking that one built around a brake rotor style would act as a type of flywheel effect to smooth out the pulses in low and designed for high winds and as an added energy grabber in those up coming mill destroying winds that could also if shorting it for braking would hold up to the heat.

Much better than trying to climb up on a roof and stop it in 35+ winds.

This would of course because of the added mass raise the startup speed.

Thoughts?

Bruce S

 

[cyplesma]

another option would be to have a set of spring loaded vanes around the genny that open and close based on wind spin.

As the wind blows harder it pushes a set of blades/levers that close the vanes, so in 30 mph winds or higher the vanes could completely close or use a limiter (bolt) to maybe keep the vanes open at least an inch no matter how fast the wind blows. use sprigs to reopen the blades as the wind speed lowers.

[windstuffnow]

  There are probably an infinate amount of ways to cure the problem and some of the cures could get considerably complex using linkage, centrifugal forces etc. and as well could be quite simple such as reversing one wing ( although the mechanism to do that isn't simple).  Possibly look at it in a different way and use a separate system mounted on the protruding top or bottom shafts.  I don't think the small unit presents a problem as long as the alternator was efficient enough to keep it at bay up to a given wind.   A large unit,however, would need to have a "stop and lock" system in the event of extreem winds.  The lock would need to be out by the wings to keep the shaft loading down.  

  The overall problems of a large VAWT may be overcome by simply putting up an HAWT with a furling system and forget about it... ;o)  But where is the fun of that?

.

[nothing to lose]

"In any case, build what you feel comfortable with that's usually the best way to learn."

Speaking of which, I remember posts where you were kinda comfortable with stirling engines

 Did you get that machined one done, I remember a post with pictures, I think that was yours. If you have some links to sterlings feel free to e-mail them.

 I think it was you that got me interested in those also. Thanks.

I am looking into building more stuff this winter. How do you think this lenz is for ice and snow? What I been thinking about for a Hawt for a long time is cutting down 30gal plastic barrels. Probably just in half, 4 half barrel arms. Or would you think 1/4 would be better? Close to about 3' tall I geuss, maybe a little less. I do have at this time some floor shelving racks I can butcher. They are about 4' tall straight rectangular tubing, slots on one side.  I am thinking 4'/2 is 2 foot arms, maybe a 1/4 barrel would bolt in nicely with one straight metal bar on an auto hub spindle and bearing?

My goal would be to chain/belt or friction drive a DC motor I think.

4 Half plastic barrels as arms in the wind, 3' high ( using barrel top and bottom for mount points). Using the 4' long steel shelving metal I might get into 5-6' dia machine here 3' tall. Using car spindle/bearings/rotor for the base it should be strong. If using car parts I would also be able to use the brakes maybe?

How much power would you expect from something like that in normal lower winds, and would using a large DC motor like 180V 15amp provide enough power in decent or low winds yet be good for higher winds also? I need to use some of the DC motors I have here and this might be a good project for one.

Other question, would I be better to cut the barels shorter in height to like 1' or 2', or leave at max hight of 3' ??

[windstuffnow]

   The hybrid/twin cylinder isn't finished yet.  It's real close to completion but other projects have overshadowed it.  With winter comming on those projects will come back to life again.  I have a couple stirling projects for this winter.  

   I'm wondering about the ice and snow detail myself.  As long as its spinning the snow shouldn't be a problem.  Once it stops, and we get one of those very calm lake effect snow storms it may be a different story.  I'll find out this year how it will fair.

   I have some 55 gal cardboard storage containers that I've been thinking would convert to a lenz wing very nicely.  That size ( I believe their 24" in diameter ) would work nicely on an 128" diameter, just over 10ft and a wing length of 51".  The torque would be quite awsome and driving a large alternator shouldn't be a problem even through a redrive.  I only have enough drums to make it 6ft tall though.  The plastic drums would probably hold up better with less work making them weather resistant.

   You'll need to make the seam between the drum and tail piece very smooth.   Any disruption in air at that point will reduce performance.  One of my test machines had an edge where I seamed them together and it didn't work very well.  Once I smoothed out the seam it worked perfectly.

   Lots of fun!

.

[nothing to lose]

I also had/have too many things going when I have any time.

Try to have various project for various conditions. Warm and nice, work outside on a project. Rain, work indoors at old trailer. Cold work in house next to wood burner

 And I wonder why I can't find tools

Do you have a picture of this one?

 Wasn't sure if it's the one I saw before. Not sure what a tail piece is? Maybe not exactly what I though it was?

[ghurd]

Great job Ed!

I am sure there was a lot of work in a working model.

I just had to say it.

After all this talk, and it looks pretty easy, so I built one today. 2 hours.

Looks too simple NOT to work.

It is windy today.

With a hand spin it goes indoors for 10 seconds. Same outdoors.

Wind has no effect on it. At all.  If there is a balance, I sure found it!

Not big, (understatement of the year) 9" dia, 3" high. 0.1875^2'. And it is on a micro gennie, micro magnetic cogging, but no amps out.

And Ed, if you want to see a picture I'll post it.  I don't get embarassed easy.

G-

[windstuffnow]

  I'd like to see a picture of it, maybe I can see why it didn't work... It's pretty small for starters but no reason it wouldn't make a good spinner....

.

[windstuffnow]

  I believe I posted it last winter, one thing lead to another and it was put on the shelf until I had more time...

It's actually farther along than in the picture above.

The tail piece I refered to is the extension from the drum to the trailing edge forming the wing of the Lenz turbine.

.