Windstuffs educational turbine outputs

[rotornuts]

Well I'm sorta settled in  Edmonton and I'm getting an itch. I built a small 12" wireframe maple blade and it's spinning away right now but I want to put the single blade thing away for now. Now I'd like to build a three blade employing some things I think I learned during the maple blade experiment but I can only go about 30" so it will be too small for a conversion and I'd rather not be at the mercy of the quality of small motor I find. I'm thinking the alternator portion of Ed's educational unit may be a reasonable choice.

Only problem right now is I need to know the performance of that alt at different rpm's before I can do any serious blade design so do you have any info Ed? May not be a good choice but I know it will "work" well as your quality is impecable.

nuts

[41south]

I recently emailed Ed along these same lines. There seems to be a wide gulf of available designs for those that want to exeriment with something that will generate 50-100 watts (or even less) at 12v with a small blade size. I asked Ed if it would be possible to combine 2 of his kits and make it a dual rotor using the same stator. His reply is below..

  Hello Colin,

    The output would increase considerably, although, the wire used in the

kit isn't a size where it would take much punishment.  If it made an amp of

power (12 watts) for any extended period of time it would most likely

overheat.  The alternator was designed for a slower rpm to make about 3

volts in a 15 mph wind.  If you installed a prop with a TSR of around 6 you

could substantially reduce the amount of turns and increase the wire size to

get a more appropriate output.

I haven't yet come to any further conclusions on this. My copy of Hughs book arrived yesterday, so I'm hoping that may have some more answers. Good luck.

[windstuffnow]

 Hi Rotornuts,

    I really don't have any real specs on the little unit.  I basically designed it originally for voltage.  The original design was to be connected to a circuit that plugged into your RS232 port and the software monitored the voltage and sine waves of the 3 phase.  Mostly educational learning about alternators.  My guess is that it does a couple watts at 1100 rpm, about the equivilant of a 20 mph wind for the little turbine.  I've had a string of 40 led's connected to it and running. ( those tiny led's that come with a battery pack and you put them on christmas trees.. maybe 1/2 watt or so) and a single Bright red led going quite nicely on it.  

  Not sure what your looking for as far as power but I'm betting its more than the little alternator makes.  You could use #28 wire in it and make up a mini dual rotor unit and probably get a good increase in output... could be fun.  If you opened up the slots a little you may be able to get some 25 wire in it... starting to make me think about another unnecessary project! hmmm...

Hav eFun

Windstuff Ed

[rotornuts]

Thanks alot for thwe response Ed. I was curious about it's output. I like the design and would like to have a reliable little alternator to test blade designs on. I'd also like to use it as a demo unit for how wind power works. I'm temporarily living in a townhouse and it's driving me, well, nuts! so I need to expand my horizons (and space) and see if I can start doing some demonstrations or something.

I'm not really concerned about large output but need to match a 30" units power potential so it sounds too low but could potentially be modified but I guess the question is if it's worth it.

I was thinking along the same lines as Colin above and possibly in a dual rotor configuration with some heavier wire? The diameter of 6" is just right so I'll give it some thought. I've always wanted to try the idea of a three rotor two stator design and your 6" stator would be absolutely perrfect for that.

Thanks again Ed

nuts

[ghurd]

I think I found a great motor for a mini conversion and blade test bed.

About 3.5x3.5", 24 slots, 5/16" D shaft, perfect for 1x1/2x1/8" neos.

IBM by Robbins & Myers, Japan bearings, 1/30th HP, new, just a nice motor.

(that one to break a half amp as is with 4 neos)

I'm going to try 6 mags, 3 coils per phase, 2 phases, using 12 slots.

There is room for 4 phases, but don't know if I can actually do it.

Looks like room for about 45-50 #20. (Math says 70 turns fit?)

Only $3.50!

Sounds like cheap entertainment.

Just add wire and a 6 pack of neos.

Anyway, if you have even the slightest interest, I'll dig up the store and part number.

I could email pics of the insides. (Someday I'll try to learn to post pics)

(and if anyone has a guesstamite of how many turns for 200RPM cut in, that would be great too)

G-

[rotornuts]

keep us posted. It looks as though I'm looking to produce in the 50 - 75 watt range if I'm lucky. 5-6 amps in the 12 volt range.

[ghurd]

This is it.

http://www.herbach.com/Merchant2/merchant.mv?Screen=PROD&Store_Code=HAR&Product_Code=TM92MTR
2042%2FC&Category_Code=MTR

And the ends are interchangable.

Meaning I have 2 round ends flying now.

I bought a pile of them after I found one in my garage.

So I can screw up a rotor or windings and still have a fresh start

without starting from scratch on a 'different' motor.

A few posts said 24" dia should get 50W easy enought.

Do you think it is a pipe dream to get 50W out of it?

G-

[rotornuts]

I've always paid more attention to blades but if you halved the rpm on that motor and got the same efficiency as an alt as it does a motor then it seems you'd get around 30 watts so maybe? you got me thinking though I've got some old AC servo motors 1/30 hp that may work as a conversion, completely forgot about them as they were too small for what I wanted to do before.

Thanks for the reminder, I'm still searching for my info on available power in the wind . that will decide ultimately what I can expect at 30".

[PHinker]

Using some formulas from Hugh's Windpower Workshop book, it looks like you'll need alot of turns (500+) to get a 200 RPM cutin using 6 - 1"x1/2"x1/8" neos and 6 coils. My math might be off.  I would be most interested in what real testing shows since the spreadsheet I'm using to calculate this is a work in progress.

Paul

[monte350c]

Hi Rotornuts,

Here's an excerpt from a spreadsheet I did to calculate power vs. area. It's assumes 35% efficiency which is probably not that far from reality for a carefully carved set of blades.

This is in Excel format so you'll need it on your PC for this to work.

click here

Ted.

[ghurd]

With 4 mags and 2 'sets' coils 2 and 3 slots wide per leg, maybe 500 () turns per coil,

cut in is about 100~120.

But it has some problems, like big airgap, magnets are not quite wide enough for the way it is wound, etc.

The resistance is through the roof. 50 and 100 ohms.

It makes 50ma all the time. In some breese around 100ma.

In a real 'wind' it will pass 500ma.

Vopen has past 100V in good wind when a battery clip fell off.

With a 20" box fan blade.

Not sure if any of that is useful to you.

[rotornuts]

I don't have excel but thanks anyways ted

[Barnac]

Ted,

Verify your spreadsheet, in the RCF sheet, I think you should not multiply by 0.5 in your conversion to obtain cm from po. (all your RCF are halved).

Also it will be easier to simply convert directly from foot to cm. Since 1 foot = 30.48 cm just take $d$5 * 30.48 and your are all set.

I guess what you did was something like :

? cm = ? ft * 12po/ft *1 m/39.37po * 100 cm/m

Why * 0.5 if it's a strait radius unit conversion

barnac from Montreal QC  :-)

To make your prayers come true, you have to get off your knees...

[monte350c]

Oops!

The heading for that column should read DIAMETER in feet, not radius!

Thanks for pointing that out!

Ted.

[ADMIN]

Ed's alternator kicked butt at the http://www.kidwind.org/ seminar at NREL last weekend. Much better voltage than the DC motors they were using, and enough amperage for a pair of white LEDs at least -- tho we were shooting for voltage since kids always want to light something up for their project instead of just reading a meter. Michael from Kidwind.org is sending out one of Ed's kits to each participant in the seminar that wanted one! We don't know who will be first to mount it on a HAWT. The NREL folks were impressed, too. excellent to get the electrical side of wind power education going. ADMIN