Author Topic: Lenz2 test machine complete (Read 8282 times)

windstuffnow · « **on:** October 20, 2005, 06:56:00 PM »

This is the machine that will be going to the wind tunnel. It's been a real "stinker" and hasn't performed as well as the original or the 2x3. The only thing that is different is the way I made the trailing edge. I was thinking the open edge may be creating some drag and decided to clean it up. The aluminum is folded and pressed into the stringer and sealed in the front of the stringer. I'm now thinking the dirty edge of the others is working as a "flap" to some extent.

This also changed the wing angle that it seems to perform the best. I plan to run it in 5 mph increments from 10 to 30 mph and take output readings from this. As well, I want to change wing angles from 0 deg to 20 deg in increments of 5 at a wind speed of 15 mph and record output. Below shows the alternator its mounted on...

<BR<p>
This morning I took the mounting plate to the test facility to make sure that it would fit their bolt pattern and to find the size of bolts required to mount it. They had the small machine running ( open-loop ). Had the opportunity to walk around the machine and see its components in operation. They were testing the pressure in front and behind a round cylinder. I'm not sure what wind speed they were testing but it sounded like it was darn near max of the machine ( about 170 mph ).

It will be about 2 more weeks before I can get mine in to play with, they had the larger tunnel calibrated for testing different wing shapes at high speeds...

I've decided I have to own one ( at least a homebuilt unit that I can afford ). After having the opportunity to get a close up look at how they operate, as well as many hours this week reading documents on wind tunnel design, I think I can make one with a reasonable amount of accuracy ( far superior to what I now have ). I'm not concerned with winds over 30 mph, this should reduce the power requirement considerably.

I have 5 - 30 inch barn fans available ( have to take them out of the barn ) or a 64 inch ground adjustable propellor. The prop will handle 65 hp and produce a thrust of over 600 lbs but I think I can make the 30 mph wind with a 2hp 130V dc motor that I've been saving for the right project along with the speed controller. Sounds like a fun project... just need some lumber and honey comb plastic !

Just what I need... another project !

.

Ungrounded Lightning Rod · « **Reply #1 on:** October 20, 2005, 02:25:18 PM »

Looks like you've got a lot of obstruction to laminar flow on the inside of the airfoil's curve. The red supporting member looks like it is square-edged rather than streamlined into the surface of the airfoil sheet (maybe even detached from it). And is the short end folded at a right angle?

I'd expect a significant amount of airflow along the inside of those airfoils as well as the outside, so discontinuities that break laminar flow there could hurt you.

Ungrounded Lightning Rod · « **Reply #2 on:** October 20, 2005, 02:27:23 PM »

I'd expect a significant amount of airflow along the inside of those airfoils as well as the outside, so discontinuities that break laminar flow there could hurt you.

Just realize you could check that by mounting a little drag spinner on the mounting bolt at the center of the circular part of the rib.

rotornuts · « **Reply #3 on:** October 20, 2005, 05:44:16 PM »

Hi Ed, there is only two things I can see that you did differently, the trailing edge as you pointed out and the center rib.

Since a picture is worth a thousand words(plus the added text).

Maybe?

Mike

monte350c · « **Reply #4 on:** October 20, 2005, 05:50:35 PM »

Hi Ed,

I've been lurking away in the background on this story. Wow it looks pretty exciting.

Now that you know the mounting configuration for the tunnel, can you make an adapter for your original 2 x 3 unit and take it along just for fun?

I would think just about any general aviation prop and engine would create a sufficient draft for a homebrew wind tunnel. If you used the honeycomb you could probably straighten up the breeze enough to be useful too.

Good luck with the tests!

Ted.

electrondady1 · « **Reply #5 on:** October 20, 2005, 06:25:43 PM »

ed you know i'm a real fan . i think both your alternators and vawts are cuting edge.

but if you have made changes that are affecting performance, you might want to do a little rethink as to wether this is the unit you want to test. if the changes were made to aid you in doing quick modifications while in the windtunnel, thats understandable. if they are cosmetic ?

i don't have the tech. mike has but i also went into my douments to check out the changes.

just hopeing you can put your best foot forward in the windtunnel. (well actually i'm hoping you blow the doors off the record for a vawt)

good luck! shawn

electrondady1 · « **Reply #6 on:** October 20, 2005, 06:29:20 PM »

and, is it too early to book time in your wind tunnel!

iFred · « **Reply #7 on:** October 20, 2005, 07:28:27 PM »

Hi Ed, As always, excellent work!

Got a quick question. What is the major reasons of building a lenz or vwat versus a standard hwat? I thought that the vwats had the problem of self start. They had low torque, where high speed but no real power. Does the lenz vwat change this?

Thanks and good luck!

hiker · « **Reply #8 on:** October 20, 2005, 08:19:03 PM »

seems like you would get a lot of drag with that open design....

looks like it would have a lot of tork[but low speed]

with a closed design it seems you would get more speed but less tork..

just my thoughts ...........

Jerry · « **Reply #9 on:** October 20, 2005, 10:31:39 PM »

Hi Ed.

I have simular componets for my wind tunnel. my plan is to use 4, 2.5 HP 3050 rpm dc tredmill motors. I have 4, 24" heavy duty vent fan blades. Since I primaraly build 5ft or smaller machines I think this will be suficient blade area.

I'm going to build the tunnel on a 12ft trailer bed with a 7FTX7FT tunnel opening. Going to use ribbed metal roofing for the inside skin and thin wall concreat tube forms 4FT long mid way to straighten out the turbulance. I'll put some flaired doors on the exit for transport and larger machines.

I can vary the wind speed from 0 to ? with dc volts from 0 to?

JK TAS Jerry

windstuffnow · « **Reply #10 on:** October 20, 2005, 11:10:36 PM »

It adds a little light when you look at them side by side like that. The large wing is 4 ft and the test unit is only 2ft. I'm not sure the center rib would make much difference since the span between the two are the same... I could certainly be wrong, it has to be something obvious like that. The original second version was made with PVC and sheet and worked very well with the extreem angle, the large one performed equally as well. Considerable visual differences in them. Now would be a good time to have some smoke in a wind tunnel to see how the air is flowing over the two wings.

I have a couple weeks to find the difference...

.

windstuffnow · « **Reply #11 on:** October 20, 2005, 11:25:26 PM »

Electron,

I don't think its a major problem by any means. On the worst run it made 0.69 amps at 13 volts and the wing adjustment it made 1 amp at 13.3 both in a 12.5 mph wind. The efficiency hasn't droped out of site but it's much lower than I had expected and the change in wing angle to get it to perform has really sent my mind searching. I'll be doing some minor mods to see if the dirty trailing edge is actually helping. If all else fails I'll build another set of wings for it just like the others.

It will be working good for the tunnel...

.

windstuffnow · « **Reply #12 on:** October 20, 2005, 11:30:01 PM »

Your making a BIG one Jerry ! Yikes I'm thinking of a test area of 3ft tall and 4 ft wide and maybe the entire unit being 16 ft long. I like to putz around with models ( keeps my playing costs down ).

Looking forward to seeing pictures of your unit when your done ! Sounds fun !

.

windstuffnow · « **Reply #13 on:** October 20, 2005, 11:34:34 PM »

Hey iFred haven't heard from you lately ! Glad to see your still around.

The VAWT is a pet project (long term) to come up with an efficiency close to that of an HAWT or better if its possible... I believe I done that or at the very least I'm getting real close.

.

tecker · « **Reply #14 on:** October 21, 2005, 01:51:57 AM »

Looks like your going to benefit from some top support . A rotating deflector on the approaching vector is what I'm working on now no data to offer though I'm trying to get the deflector to ride on the support frame .

tecker · « **Reply #15 on:** October 21, 2005, 02:05:09 AM »

Just as a side note on catching wind if has to have an exit to be effective the working cycle is followed by an eddy that has to be sucked out on the backside.

iFred · « **Reply #16 on:** October 21, 2005, 07:42:50 AM »

Still alive and kickin Ed!

I roam in here from time to time. Not so active as I was but alive.

Still building, still tinkering.

windstuffnow · « **Reply #17 on:** October 21, 2005, 12:45:44 PM »

It's basically a slow turning turbine and I've noticed no noticable noise from it. It's quieter than the wind flowing through the trees. I don't recommend mounting it on your roof as I did for testing purposes because you will get a mild rumble from the alternator. I don't have it mounted directly to my roof but I still hear a very mild hum when its charging.

.

hvirtane · « **Reply #18 on:** October 21, 2005, 05:29:48 PM »

It looks really good.

I hope that you will get

good testing results soon.

- Hannu

windstuffnow · « **Reply #19 on:** October 21, 2005, 06:29:38 PM »

Hi Hannu,

We'll know in a couple weeks if its good, bad or ...other...

.

motorhead2 · « **Reply #20 on:** October 22, 2005, 11:13:53 AM »

I think Ed is on the right track here for residential type turbines.As far as torque and low speed startup are concerned,I built a 8ftx8ft modified hbar.Blades are 2ft wide/6in thick.It starts in the slightest breeze and in a 10mph it spins around 60rpm and hard to stop with 2 hands on the shaft.The rotor and blades weigh over 100lbs.In 20+mph I tie it to a cement block on the ground and it can drag it in gusts.Its mounted on 2 8ft poles.

Norm · « **Reply #21 on:** October 23, 2005, 07:57:50 AM »

iFred....Do you still have a site? I couldn't

get to it last time I tried.

( :>) Norm.

Kwazai · « **Reply #22 on:** November 03, 2005, 11:46:09 AM »

I have been following the development of the lenz turbine eagerly. It appears to solve the startup problems of the darrieus type turbines and after having read about these-

http://www.aerotecture.com/

looks like it could have quite a few practical applications (just about any five story building). I'd be interested to see its low speed performance as an hawt.

Where I live there is little to no wind until you get about 65ft above the trees so low flow solar induced winds (rooftop or chimney) is what I have been looking at.

keep up the good work.

Mike

ozetrade · « **Reply #23 on:** November 06, 2005, 05:29:48 PM »

Hi Ed,

I'm building my own vawt similar
to your design Just a few questions.

Are you still designing the wings around these specs.

On the 2 x3 ft prototype, what was the startup force for the gennie?

You also stated that you got it dialed in at 9deg - 9deg to what?

Thanks from a devoted follower ,

Greg

jaybee · « **Reply #24 on:** November 08, 2005, 03:34:20 AM »

Something similar?

Link

dinges · « **Reply #25 on:** November 13, 2005, 03:36:33 PM »

I'm having the very same questions!

Plus: what RPMs to expect, how many coils on the stators (I assume the VAWTs turn more slowly than HAWTs) for, say 250RPM.

Ed says on the bottom of his website on his Lenz2 that he won't go into technical details, but I wish he would...

In the mean time, I'll regularly check out his experiments to see what results he has.

Building your own windtunnel; what's next... :-)

Peter,

The Netherlands.

spinner · « **Reply #26 on:** December 01, 2005, 07:56:54 AM »

limited experience so far suggests to me that sufficient torque is available ( for smaller gennys like mine, anyway....a 10 inch dual rotor) in a VAWT like the dualhelix, for example....

and gear ratio can provide speed BUT

being able to raise/lower the helix depending on windspeed and/or volt output just might be the missing factor?

News:

Author Topic: Lenz2 test machine complete (Read 8282 times)