How slow can it go?

[12AX7]

If one were to use a "big enough" motor and use the "ideal" (size,strengh,number and placement) magnets,  and at the same time put aside the issues of  "weight-size-cogging".  Has anyone already head down this trail?   And if someone has, anyword back from them?  (oh,  I see I forgot to mention "ideal copper coils")

Paddle wheel driven I'm hoping the constant torque will negate cogging as an issue?

Mounted on the river bank, the gen would be shaft driven.  Wheel on a "floating" structure.  

YES  I know I've left out a few minor details. (and been around long enough to know that the devil is lurking there).

Wheel about 12 to 16 ft. di.   Paddles   somewhere around 21 in wide and 32 in tall.

River depth min about 24 inches, I'm making a wild guess that average is 28.

The bottom of the river drops about 18 inches in a about 4 feet.   (yeah, lots of abouts).

At the "chosen" location with the river at it's normal low, the current is still fairly strong.  During high water you had better have on a life vest (and I had better have more than one spare sump pump).

What do I expect to get out of it?   Heck, it's fun already!

ps.    this river gets mighty hard in the winter months.  

[TomW]

12;

 600, 1200, 2400 KW

I can only hope you meant W not KW for the power out. 2,400 KW would be about 3,000 horsepower input to produce with no losses.

Just thought I should ask if you really meant KW?

Cheers.

TomW

[DanG]

Some formulas and examples:

Undershot wheel

  http://tinyurl.com/zmagu

Weir Gate Flow Test

  http://tinyurl.com/ze3n6

Axle Horsepower Calculation

  http://tinyurl.com/zwbgj

Not an advertisement for their plans, just good pictures and ideas

-

[willib]

wow , i knew there was a relationship between weir width and depth of water over the weir.

thanks ..

there ia a stream nearby with a flow of 546 cfm ,if weir width is  five feet wide , it might be more, the water over the weir is 8".

it drops five or six feet into a tidal basin ..

[MelTx]

        I wonder if you could make the gen site away from the stream some.And use a ram pump or maybe several rams, to pump water to a holding tank and use that water to power the mill.That way the mill would not be in the spring run off path..

                                               MelTx

[Titantornado]

I'm just playing with thoughts here, and I'm certainly no expert on the subject. (heck, you may have figured out my thinking for yourself already)

OK, on axial flux alternator thinking, turning a 16 foot water wheel at 18 RPM, if magnets were attached at that distance, would provide the same velocity as a 12 inch rotor with 12 2" disk magnets turning 350 RPM, of course the waterwheel would need 240 magnets to obtain the same spacing.  12 ft dia wheel at 18 RPM with 180 magnets is equal to 260 RPM on the 12 inch rotor. On another thought, mearly raising wheel speed by only 2 RPM on the 12 ft, it's then comparable to 500 RPM on a 12 in rotor.  Good speeds, but expensive magnet investment.

But with that size, it gives you all kinds of room for a stator. And no need for a full round stator. Say just make one that covers 1/4 of the wheel.  All kinds of wiring configurations can be arranged with many coils to work best for your needs.

I think you're considering using the flow of water under the wheel to turn it, yes?  I'm not sure how much torque that would provide for a given load, but my thinking would be to dump water into it (say at perhaps 2/3 the wheel height) might work much better.   Paddles would need to be changed to troughs like an old gristmill.   You mentioned the stream drops 18" in 4 feet.  How far upstream do you got to go to get 10 foot above the stream at your generator location?  If you can get that rise in reasonable distance, I think it might be worth running a channel or large pipe(s).  This method would also supply a constant RPM, unlike current flow, and give you easy ability to control/stop flow.

[12AX7]

Hello Tom

Yes I do mean KW.   600kw  1.2 MW and 2.4 MW  @ 24, 22, and 18 RPM.

There is a company out there that claims these specs.

I posted those numbers as a "hook"  Kinda an eye grabber I thought!

Tom, there is no way I'd expect to achive or approch those numbers.

(at least not on my first attempt!)  

I also understand to get that kinda power at those speeds the torque required must be mind boggling.

Just looking to take a few baby steps...  

Thanks for the repley!

[12AX7]

99y

I've been reading and looking at formulas..  numbers.. theories and laws.

Some of them don't always agree with others.

It wasn't that long ago when people thought wind power (electrial generators) would never "fly".

Also, the common belief is that hydroelectric generation requires "Head"  The higher the falls and more water..   the more power is there.   That I'm sure is true.

Now their (the big boys) out there dropping generators (driven by props or modified turbins) into rivers,  using tidal currents.  

If you haven't already,  check out Verdant Power.

I know this sounds like a pretty poor plan,  but I'm thinking ..  "build it, and it will turn".  

Dam the numbers and..   full speed ahead!

[12AX7]

Willib

Go for it!

The reason I come to this site are the members.

Most all share the wind,  and in their own ways..  in the process of having fun they capture power.  

I to have wind, (been known to break some myself).    At my location I would need a tower a few hundred feet tall to clear a near by ridge.  When I was a younger man I enjoyed crawling up my 40ft. tower to work on my amature anntenas.  But that was a while back.  

I live along side a river so that's the best route for me.

I've never found another site that "dabbles" so much in home made power.

If there was a site that focused on home hydro I suppose I'd be spending my time there.  But this place is close,  real close!  

[12AX7]

Mel

The local DNR would swoop down on me like the bird flu.

High water (flooding conditions)  should not be an issue for me.

I hope to "float" the wheel.   and by a line drive shaft the gen would be at a "safe" hight located on the bank.

[12AX7]

Titantorado

I had been thinking of axial,  but due to the size and concern for bearing play at such extream DI. I've kinda  (for now) decided to go with a motor conversion.

The Wheel DI. maybe around 14feet but the gen at it's location would have a limited turning radius.

Not that it's in my plans,  but imagine a rotor that's the size of a 55 gal drum?

For now  (subject to change)  the idea for the paddles would be the halves of 55 gal drums (cut and mounted verticaly)

And yes,  it would be a "undershot" wheel.

The paddles would be made from plastic drums.

[roddy]

I have two streams one low head/shallow but massive year round. and a small contributing steam that seasonally produces 300 gpm with at least 20' of head available, I can just about do whatever I want to the small stream but hate to spend large $$$ on commercial units. the large stream I will have to float, suspend, "covertly divert" the water or something. so I am thinking exactly along the same lines as you with the barrels. I even thought of a floating raft/paddlewheel design. check out Farm Show Magazine, the compilation was a great $30 or so. anyway they had a guy pumping water for his cattle with one of these homemade rigs turning a water pump sending water to a holding pond... keeps me up at night..good luck and keep us posted. Thropton energy services also does a "floater", looks pretty neat

roddy

[wildbill hickup]

Just a couple of thoughts. Wouldn't it be easier to include your generator, be it conversion or axle on your float and string a well protected elevated cable to the bank than try and use a mechanical, flexable "shaft" to transfer power to shore. A cable would seem to be more forgiving during rapid waterline changes say in the spring and after heavy rains, and could be suspended "up" out of the way of floating debree. You could place a short pole on the float and another on the shore with a eyelet to run your cable though, somesort of spring loaded spool (haven't thought that one out yet, to early) could then play out cable as water rises and retract it as water level falls, keeping cable from sagging. If your gennie was producing high enough voltage the cable going to shore could be kept at a reasonable size and then power could be transformed or steped down on shore. An axle flux design with Large magnets mounted directly on waterwheel and large stator(as mentioned in another reply)with big coils could produce sugnificant power and would be expandable as needed by adding more coils to the stator, whereas a conversion is somewhat more limited by the fisical size of the housing.

Well there it is, that's enough thinkin for one day(wife says she smelled wood burning)((:-O)

Wildbill

[Drives]

MelTx:

I have done some work at this site.  It is a very interesting concept.

http://www.nypa.gov/facilities/blengil.htm

[12AX7]

Roddy,

I hope you follow up "some how".    How close are your locations?  Between the two locations of the "sites".     Could they share a common "storage system"?

How far to what ever "load" you wish to power?

20ft. drop?  yikes  L   and here I am... thinking I'm lucky with simple "water current".    

[12AX7]

Wildbill

I have to agree with you.  I too beleive the gen loated on/at the wheel would be the best route.  However there are a few minor points hanging me up.

If the gen were mounted on the wheel it's self, the diameter of the rotor has to be much less than the paddles or else...  it would be "swinging" though the water, and that can't be good.  

With the gen located on shore I'll have the "convenience" of working on my second.. third or..   however many version.  L

I know and lived under the KISS rule.   With that said, I think one needs tobe felxible in their thinking.   Meaning KISS may require lots more $$$$$$$  or time.. or unavailible experties.  

Also if one were to have a "junk yard" collection,  and a "knack" for duct tape..wire ties bailing wire...  

Some where on/in the piles I've a pair of universal joints.  There made of SS and are large enough to accomadate shafts greater than an inch.  The total (expected) vertical variation will be (about) three feet.  That's + and -  one and a half feet.

Your wife smells smoke?  THings can't be too bad, she's still speaking to you!  

Good firefighting...   and thanks for your reply!

any other suggestions..   I'm all ears!    

[roddy]

yeah, I could do a common storage system if I keep the voltage up to prevent excessive line loss. I don't know if it would be better though since the small creek is more seasonal and the best (deepest) part of the big creek is completely on the other side of the property about 500' away. I get fired up when I think about the potential there but this will be my first re project and hope to somehow start this summer. run busy 12v retail shop for the last 20 years, 2 kids, soccer, baseball, etc...not to mention new house/ 5acre yd that's never finished. We are buying the property opposite us on the small creek so I am waiting until it's ours before I even start on the small creek. maybe I'll post some pics and see if I get any ideas/input. I'm pretty good on building, but am a complete beginner on generation, learnin' fast though. Thanks for replying I'll definitely keep in touch

Roddy

[12AX7]

Hello Roddy

I understand it may be a bit early to ask, but....

Have you an idea on which path your leaning towards?

Water turbin?

Water wheel?

something else?

And how about the gen ?

Make your own?

axial..motor conversion...?

You mentioned high voltage due to the distance,  Been giving that alot of thought myself.  

I'm not [yet] calling mine a "re" project.  I'm just doing it for fun, and anything I happen to get out of it...  just more fun after it's done.

I've a large bay window that will give a "large view"  of what ever I end up with.

Meaning if it's ugly the boss will tie me to it like the old torture wheels you see in the movies.

Also..  the river happens to be a nice trout stream,  people walk into my yard to fish.  I enjoy watching others fish,  young familys with their kids.  SOme of them pretty young.   I've one grandson 5yrs..  and a set of twins  just a few weeks  old.  What ever I build will need to SAFE.  Plenty of fisher persons walk up and down the river.   I'll have to have to put up a sign..  something about grabbing their hooks and lines..  a "disclaimer" of some sorts.  L

Getting back to POWER..   There are LOTS of people in the know here..  Our problem is that their working under much tighter limits/rules.

Not saying we (I hope theres more than just the two of us)  haven't got our share of "issues".

Seeing that we're not planing on lifting our gens up a pole or tower,  Size and weight shouldn't be an issue.  {OR should it?}

WIth the water current constantly flowing, starting the gen from a dead stop shouldn't be an issue.   Does this mean that "cogging" shouldn't be an issue??  {or should it?}

The current speed variations between low/drought   high/flooding   can't be anything like...   winds 0 to 60 mph..  right?

With (compared to wind turbins) an almost constant speed, should/could one build a more efficent gen?

and.. if I may ask    what is a 12v retail store?

[roddy]

I don't know which I'll get around to first, if the land deal goes through I'll probably lean toward the small stream 1st. I've studied overshot a little and read about all the mfgs of the commercial units, even talked to a few. apparently this stream has the potential in the winter mos. to produce up to 1kw that's a lot of power 24 hours per day  so it could potentially payback if done right. I've read about a Banki if homemade, sounds pretty good/easy. I had thought perhaps a rewound alternator if a hobby, but been reading about these homemade pm units and they look like more fun than the turbine itself...hmmm. Thought I'd get a few books including Hugh Piggot's and at least learn what I'm doing before I DO it. Even then it might just be better to get a Harris. The little stream is already dammed in a way, it essentially opposite a hill/mountain range in a National forest. there are two 150 acre fields joining together in a ditch, going under a blacktop rd which sits on about a 5ft.tall culvert(sp?). the culvert has about a 2' drop where the water hits the "creek" there are various drops and blockages before it enters the large creek which as big as a river behind my house. from the culvert there is around 20' of drop. I don't know whether it would be better to dam it up about 150-200' downstream and put the penstock under the dam, allowing better flow control and look beautiful as well or capture the fall out of the culvert and pipe it to a turbine. I can follow most of the logic, but can't understand why there isn't adequate pressure right at the culvert since the water is flowing downhill anyway and already channeled.

 On the big creek, I'm thinking raft with paddlewheel style turbine (banki?) and belt driven alternator, or homemade pm. it would be relatively easy to build, and I have several large trees to tie off the raft to. this would also let me move the whole thing to different parts of the creek to see where power is greatest.

I agree with you that this can't be as bad as raising a tower and worrying about varying windspeed can it?? (famous last words??) We own a shop that started out as a Car stereo store, even won a national title. still do that but also do truck/ car accessories as well as cellular/paging, and other whatever sells enterprises over the years. It's a living, been a good one. dunno perhaps I'm just trying to make up for all the wasted natural resources I've helped promote the waste of when I was younger, now I can't quit because we have to eat.. maybe it's just a new hobby.. I also don't have a very favorable view of world affairs and crisis handling in the world. I'd like to always be able to keep heat fans, fridges/freezers and some lights going no matter what. if you want I'll try to send you the article on the homemade paddle wheel/raft/pump project I mentioned. we've got the whole CDrom on the way.  sorry for the length, just neat to talk to someone who doesn't think I've lost my mind.

Roddy

[12AX7]

Hello Roddy!

ah,  that's not that long of a post!  

Lost your mind?    You don't think it's been wash down stream?   L

Not too many have the ability to "alter" the rivers/streams..

my vote..   would be to make due with what you have..   I've learned not to screw around with women, or mother nature!  

As far as  your location is concerned...  a pic is worth lots of words.

Yeah,  I know..   not showing any pics myself...

still shopping for a digital camera (I'm still a 35mm type person)

This site (I think)  even though most everyone are 'flapping in the wind'.

and their focus is to make it work for them...  is the best place for "us"  hydromaniacs to seek help.

if there is power in a breeze..   there has to be GOBs (sp?) more in a modest river/stream current.

Some of the hydro sites I've visited...  talk about the energy in a "cubic meter" of water (in a stream)  But, I haven't seen anything in their math.. that takes into account the "cohesive" force of the flowing water on the six sides of that "sample" of one cubic meter..

People say if your doing hydro you need head.    I'm thinking thats .. doo doo.

Ever watch an old steamship move up river?   just paddles..   no..  damns..  just..  "grunt.. grunt.. grunt.."   POWER and low speed torque.  

Hang in there Roddy...   like ya said..  someday the power just might go out..   and who wants to sit in the dark?

the wind blows...    and water flows...   use what ya got!

[roddy]

ditto it all, I will get some pics of the sites when I get time tho and definitely send it to you.