Lenz2 wind tunnel tests are done

[windstuffnow]

  Well, after 3 days and a total of an hour tunnel time all is confirmed.  First a couple shots of the tunnel.   First one has the turbine set up and ready to go.   The second gives you an idea of how massive this thing is...

  The tunnel is a closed loop which goes outside the building all the way around to the back side and re-enters the building.  Everything is computer controlled... quite impressive.

  We dialed it in to match the output of my tunnel and I found I was 1/2 mph off in my readings ( to the good I might add ;o) ).  

  There were several tests done using windspeed and pressure.   Most of the calculating they did because, to be quite honest, I had no idea what they were doing.  When they were calculating pressure before and after I was lost... The windspeeds were calculated from inches of water which they said is more accurate.   And lastly the tests were performed by measuring ft/sec.

   So here are the numbers for how well the Lenz2 converts wind energy to mechanical energy.  Firstly a refresher of the unit that was being tested...  it stands 2ft x 2ft ( 4 sq ft total area ).  I haven't changed the wings to the new version but there are winglets added to this unit.   I wanted to get data on the original wings before proceeding.

   Here we go... I'm going to keep it in mph since it's common to all of us and easy to understand...

.  7.38 mph starts charging  2.25 watts

.  10.85 mph 41%     10.56 watts  

.  13.53 mph 38.9%   19.46 watts

.  15.61 mph 30.5%   23.39 watts

.  18.88 mph 31.4%   42.7 watts

Overall average of 35.45%

The efficiency is based on total area of the turbine from total power in the wind.  If you factor in the Betz theory then the efficiency of the total possible that is extractable then it would look like this...

.  10.85 mph 68.8%

.  13.53 mph 65.3%

.  15.61 mph 51.1%

.  18.88 mph 52.8%

or an overall average of 59.5% of total possible.

I shot the entire session on video tape but it will be awhile before I can cut some clips from it.  I'm going to go over it several times before I start pulling parts out.   I came up with several ideas to improve it during the whole experience.   It's definately been a fun and challenging journey !  I see another 30-40% of un extracted energy... I doubt it'll ever match betz but I'll bet I can get a few more watts out of it !

As I suspected the efficiency starts dropping in higher winds so the next wing change will hold the efficiency longer before dropping off although I still want to maintain a high lift/ dirty design to help control it in higher winds.  The data gathered from the roof mounted unit tells me it doesn't drop the efficiency fast enough which could be controlled by a more efficient alternator now that I know what it's capable of.

Lots of fun !  And the fun continues...

.

[Bruce S]

Ed-

   Let me say W O W!!!

All those extra hours seemed to be paying off in watts <_>.

Question: Did they have wow/flutter, and vibration sensors inside the tube? I'd like to know the what the sound level were along with the vibration frequencies were at the different speeds.

Keep it up!!

Bruce S

[Jon Miller]

windstuffnow

I would like to say well done that looks to be a lot of fun and must be even more intresting when your there.  

How will you go around increasing the efficiency during higher winds?  

[jmk]

  Ed the sientist! awesome! I recal you were going to a test facility, but I dont remember where. Is it U of M? How close can you put these to oneanother. How many are you going to line up. It would be neet to see a fence row decorated with kool looking ornaments. If you can put them close enough, you could put a diferant color bulb on each one for Christmas decorations. LOL! I was just kidding,but now that I think of it. It might not be a bad idea.    

[windstuffnow]

   First off a more efficient alternator would help considerably.  Changing the wing design slightly should maintain a better efficiency through a better range of wind.  I'm hesitant to make any major changes at this point but some small mods can make a big difference.

We'll see where it goes from here.  

.

[windstuffnow]

  Hi Bruce,

    I'm not sure if they did, I really didn't want to get to involved with the "bells and whistles" because it was expensive enough for the basics.   For the most part, my roof mounted unit makes little to no noise in average winds.  You can hear a mild "growl" while its charging but nothing I'd call a problem.  The only real problem I've had with it so far is that my "static" balance job wasn't as good as I thought and in high winds it has a very distinctive vibration that echo's through the house.  Since the alternator on that one isn't super efficient it tends to overpower it even when shorted.   So a better alternator and absolutely a better balance job would cure the problem.

.

[wayne]

Hi Ed

I must say I am always impressed with your test. Nice job and hope you carry it further. My small 12 inch is finally ready for a test and on ceiling fan motor, and finally found the problem with my 2 foot one. hope to put together again tonight and test indoors, if all looks good then on van. will post pics later.

Wayne

[johnlm]

Ed,

Am I correct to assume that the power levels are real dc (ac?) power into a resistive load and not power into a battery?  Your results are impressive.

John

[windstuffnow]

  It is DC going into a battery with a load.

.

[windstuffnow]

  Looking forward to hearing your results on the small ones.   I built a 10 inch diameter x 12 inch tall one to play around with, I haven't built an alternator for it yet but I'm looking for a fairly consistant 4 watts from it for another project...

  I had similar problems as you did with this little one, where it wanted to bobble back and forth before starting.  I changed the wing angle and it starts right up in a very mild breeze now.  I think the smaller ones could use a bit more wing area, they don't make alot of power to begin with and have a bit more to overcome than the larger ones ( bearing grease ).  

  Gotta put my toys back in the toybox for a while and get back to work...  The next Lenz2 is going to be extreemly facinating...

.

[electrondady1]

congratulations ed,  looks like all your work has been worth while.those seem like very good numbers especially in low winds. how does your machine stack up compared to props or darius types?

 your personal wind tunnel should be kind of handy, quick test results on every modification.

[pyong]

Hi windstuff

I've been following your progress with interest!!

Well done with the tunnel test, the numbers look good!

2 questions please..

A. What was the sq section size of the tunnel the turbine was placed in?

B. Were tunnel blockages taken into consideration when working the numbers?

Cheers

Pyong

[monte350c]

Hi Ed,

Good numbers and a good looking test!

I'm impressed by the performance of the Lenz2 - and equally impressed by the very small error in the measurements in your own tunnel. If nothing else it was worth it to validate your wind tunnel.

Now you can put various designs to the test in your own back yard and be confident in the numbers.

Well done all around.

Ted.

[electrondady1]

when you refer to a more efficient alt. are you thinking of a unit that will have a lower cut in speed? some thing that will produce more induced drag(a brake) at higher speeds?just curious as to what design changes you would make when building an alternator specificly for your lens2.

[windstuffnow]

  Hi Pyong,

    The tunnel test section is 3ft tall x 4 ft wide.   The professor, Dr. Liu, worked out the details on blockage and these were added to the final calculations.   For the most part I watched and learned.  They wanted to disassemble the unit and run the wings through a series of lift/drag tests at various wind speeds, I would have loved to let them do it but my budget would only allow the basics.

    I did, however, study the balance beam mounted below the unit the wings are attatched to and it appears a smaller less technical ( computer controlled ) balance and measure system could be used for this.   I'd like to build one for my tunnel and play with some measurements.  The mechanics of the beam is quite simple and as long as everything is balanced the measurements should come out reasonably accurate.  Another toy to play with...

.

[windstuffnow]

   The alternators I built for the small one and the rooftop were meant to produce about 250-300 watts maximum.  They drop to 50% efficiency at around 200 watts.   By building an alternator that is more efficient ( less resistance ) it would increase the load on the turbine in all windspeeds.  This, of course, has to be matched as closely as possible to the turbines output.  I don't think its quite as critical as it is with the HAWT which relies on speed to achieve lift.  I think an alternator that will maintain a 50% efficiency at around 400 watts would work fine with the 3 x 4 unit but that has yet to be worked out, it may suffer in lower winds if its to efficient... we'll see!

.

[nothing to lose]

Wow.

 Your comming along pretty good on this. Can't wait to see what you do next.

[wayne]

Hi Ed

My little 12 inch worked great the first time, just hard time with 2 foot one. Had to play with the dia. Here is a pic of a ceiling fan rewound and hope to get a few watts from the little one. Its -28 here so might just hide in basement and try different things with the 2 foot one. Thought of cutting some foam blocks and playing with center. We see what trouble I get into.

Wayne

[wayne]

opps

[Ungrounded Lightning Rod]

.  7.38 mph starts charging  2.25 watts

.  10.85 mph 41%     10.56 watts  

.  13.53 mph 38.9%   19.46 watts

.  15.61 mph 30.5%   23.39 watts

.  18.88 mph 31.4%   42.7 watts

Overall average of 35.45%

[factoring in Betz]

.  10.85 mph 68.8%

.  13.53 mph 65.3%

.  15.61 mph 51.1%

.  18.88 mph 52.8%

or an overall average of 59.5% of total possible.

1) If I read this correctly you're comparing energy

delivered as electricity to energy extractable from

the wind, right?  So your alternator inefficiencies

are included, rather than measuring the efficiency

of the rotor alone?

2) Also you've got the alternator's loading controlling

the speed of the rotor, rather than running several tests

at each wind speed with the rotor running at a range of

speeds, to find the max power point.  So a smarter load

might be able to extract more power yet, but you don't

know what the desired curve would be.

Right?

If 1 is true you've gotten even the best claims

for the sandia savonius design beaten by more than

a factor of your charging system's efficiency.

(Even if you were measuring ONLY the rotor you've

beaten the Sandia Savonius claims of 37%.  Cool!)

(You might be "cheating" by using lift to decellerate

air a little way out from your blades, making your

effective cross-section a bit wider than the physical

one.  But this is good.  B-) )

[ghurd]

might be "cheating"

I wondered if it was related somehow to "the geese fly in a 'V' because its easier" concepts.

[nothing to lose]

At first I thought this looked like something I have here, then I see there are outer coils and inner coils. Is this a rewind you did yourself and any specail cutting on the  stator?

 Mine has 2 sets of windings, both coils are right together offset by just a toothe or so.

 My lathe has not been set up here for a while, I need to turn the outer ring to mount the mags in still.

[wayne]

Its just a ceiling fan motor, here is a pick on the outside. Have not spun it up yet, but by hand get 3-4 volts.

Wayne

[nothing to lose]

In the study of wind and areodynamics, blades design and efficiency, turbulance etc...

We can learn alot from nature itself.

You do know that when geese fly in a V formation one side is longer than the other right. And of course I suppose you know why also.

There are more geese on that side

Ha ha, hee hee, hee haw.  Yep I think that is where I heard that I think , HEE Haw, with Buck Owens and Roy Clark

[windstuffnow]

  Those numbers are based on the shaft output of the turbine.   It actually outperforms my 6.5 ft HAWT in the same wind measuring watts per sq ft which I calculated to be about 38%.

  I wasn't set up to run it at various rpms at a given wind speed so it is possible it could go up or down by loading it differently.  

  Why do ducks fly in a V pattern?  Turbulance is created from the wing tips and travels out behind and down.   Nasty little eddy currents.  If the ducks flew below or behind another duck the rear duck would have to work twice as hard to keep up and as well would have a rough ride.  They know what their doing !  That's also why there is a hold on take off for a few minutes before the next plane departs.   You've seen some jets in the news crashing because of the wake turbulance... it will literally tear an airplane appart.  

.

[Ungrounded Lightning Rod]

Why do ducks fly in a V pattern?  Turbulance is created from the wing tips and travels out behind and down.   Nasty little eddy currents.  If the ducks flew below or behind another duck the rear duck would have to work twice as hard to keep up and as well would have a rough ride.  They know what their doing !

I had heard that aerodynamicists studying geese had found that each goose (except the one at the point) took advantage of a side-effect of the next forward goose's wake (the tip vortex?) to reduce its own expenditure of muscle energy to fly.  (That's also why the wing beats are synchronized in a phase-offset manner)  The leaders trade off from time to time.

The effect is also avialable to aircraft - though it invloves them flying dangerously close, too close for human pilots on a long flight.  There has been at least one proposal to build a pairable aircraft with electonic piloting to make use of this.

[Nando]

              F A N T A S T I C

[Old F]

Ed

Boy you  raised  quite a stir with your home brew  wind tunnel .

All most as much as two brothers  from Dayton  Ohio did with there's  :  )

Great work keep them flying the right or should I say Wright  way.

Have Fun

Old F

[windstuffnow]

  Funny you should say that... My home-made tunnel is based on the original Wright bro's tunnel only a bit larger...  I figured if they could get reasonably accurate readings from theirs I should be able to come close as well...

.

[ghurd]

Funny you should say that... Do you recall their propeller efficiency, and the propeller efficiency of a modern Cessna type aircraft?

Seems like the History Channel said 88% vs. 92%? Or there about?

Not bad for a century of progress, depending on how you look at it.

(I know a lot of the stuff on there is un-correct)

G-

[hiker]

same as my old motor conversion--i used harddrive mags and rewiered the outer coils.

the picture has some lighter wire in it -i sense  have rewired with thicker wire-

puts out over 20+ amps hooked to my old 5/8s hp gas engine-dosent really have to be running that fast at all..great little defusalater charger[single phase]

[nothing to lose]

Curious.

Had you thought about a junk trailer house as a large wind tunnel?

 I have been doing cleaning and repairs/demo work to a junk trailer house here to make into my shop. Get my lathe into the back room now and I can either put the wall back on or install a door

 (Darned truck with the lathe/mill in it won't start now, Lucky it's a boxed truck)

So anyway while working on stuff down there I got to thinking, would a gutted trailer house work for a wind tunnel? Remove inside walls, board up outside wall windows. This one is about 7-8' ceilings and 12' wide 65' long. If squared was wanted an 8' wide tunnel would leave nearly a 4' hallway beside it. Only need to build 1 wall, most of the materials already there when ripping out inside walls.

Just curious about it, I don't currantly have any wind tunnel plans, but if something like that would work farily easy often old trailer houses can be picked up for around $1,000 and moving costs. I could have bought another junk one a while back for $500 but did not want it then and no time to mess with getting it. Now I wish I had gotten it for parts, oh well.

Just thought I'd ask, maybe later you'll want a bigger tunnel like 8'x12'x70' and the thought might help a bit?

[hvirtane]

Really good.

Congratulations for

the really great job.

I've been silent for a while,

because of some problems of

Net connections; I had only

now the possibility to see

your results.

What about RPM?

How fast does the machine go?

- Hannu