Low head undershot waterwheel blade idea

[keithturtle]

I have only about 1 metre of head I can tap in my creek, flow is around 2 cubic feet per second, estimated.   Would an waterwheel with blades of this configuration do any good?   I can pinch the flow down to 18" wide for increased velocity. Probably just wasting my time with that lame a resource

Turtle, all wet

[XXLRay]

In my opinion you should just stick to the poncelet design: http://en.wikipedia.org/wiki/Water_wheel

[ghurd]

Might have better luck using the term 'breastshot'.

To me, 'undershot' usually means no head at all.
G-

[Kwazai]

I always wondered if something the reverse of the water ladder would do any good in a case like this.

http://www.fao.org/docrep/010/ah810e/AH810E06.htm

fig. 52 is a pump (what if used as a driven wheel(turbine)?)

Mike

[keithturtle]

Yes on two counts, the ponceleot design's advantages are indeed what I had as a goal.  The breastshot is the best way to describe this design.

The water ladder as a driven device might work with more flow, but 2 CFS is mighty low flow.

Thanks for all the input- now to get accurate flow numbers

Turtle

[keithturtle]

OK, then, I visited the site after 2" of rain in 18 hrs, to get a feel for the high-flow conditions.   Very promising; took lots of pics and video to study, and once I shoot elevations I'll be able to make an informed decision on this project.  A muskrat swimming by reminded me of the presence of wildlife and the need for fish ladders; how much flow will the fish ladder take away from the turbine?  I suppose the muskrat can climb the rocks to the other side... 

Turtle, in the water

[hydrosun]

Your 2 cubic feet second and meter head could produce 270 watts ......if you use all the flow and have a system that is 50% efficient. Any hydro system needs to leave some flow in the stream. In a small stream it may just require a leaky weir that lets out some water before the intake pipe. Or it is an outlet that is lower than the intake. The shorter the water diversion is the less impact the hydro has on the wildlife of the stream. Fish are adapted to different stream flows and go from pool to pool. As long as your weir is short enough they will get over it.  Or like you said a series of pools like a ladder so they can get over it. As far as how much water it takes, it wouldn't be a large amount because the important thing is to have the series of pools full with some fresh water replacement.
With a variable stream flow you will have to decide if your system will take one small amount of water that is available for most of the year or have a system that can handle a wide range of flows but will be bigger and costlier with a lower level of maximum utility. It depends on if you can match the variable amount of power with the need to use that power. For instance if the flow is larger in the winter you could use the additional power for heating. But that may be of a lower value than a little power all the time and not worth the extra expense of a larger system.  It is one thing to maximize the output of a hydro but in costlier per watt low head especially it is important to look at the value of the power to see if it makes sense to make the investment for larger systems.
Chris

[keithturtle]

OK, then, a bit of good news; I did a cross-section profile and velocity study, and found the stable wet-weather resource to be just under 16 cubic feet per second, or around 7000 gpm.   I see this creek running like this often, and it gives me pause for consideration regarding the actual wheel design.

I realize (I think) that the bucket size  and shape (Poncelet) works within a fairly narrow flow range, like, if it's too big for the available water, it'll really lose efficiency.  Conversely, it needs to be big enough to handle this wet-weather flow potential and not let it go to waste.   After watching these guys and their gate approach

http://www.waterwheelfactory.com/Hester.htm

I come away with the distinct feeling that I can make a wheel with a bucket that has a partition in it, and the flow can be valved / directed to one side, or the other, or both, depending on the creek level.   I ran the numbers and 5000 gpm down 3' will net a cool 1.2 kW after losses.  Now that's something to splash around about, I would think.

Here's a pic of three turtle island submerged after a 2" rain.   This gave me a sense of where to place the wheel to avoid damage.  The study was done with the creek running stable and clear, about 2' lower than shown here.

I wonder, am I all wet?

Turtle

[Lowhead]

Are you in a place where it freezes?  I don't know much about wheels but I see the one you posted is stainless.  I have heard that is a problem in freezing climates and you are better off with wood.

Andy

[keithturtle]

Yeah, the heat transfer thing with steel would be bad in our area; I think that the little power-pal turbine would have the advantage in freezing areas, for even wood could have problems in Ohio.    There is something similar to the power pal but on a larger scale just to the north of my site http://www.bearsmill.com/history.html but thay don't mention their hydropower on the website.  The turbine house (not at the main mill) shields from the cold

Turtle, still contemplating

[keithturtle]

OK, then, I am moving forward with this project and will have just under 4 feet of head to work with, still a minimum flow of two cubic feet per second.   I stumbled across this Nautilus design called the NIADE for very low head installations [see attached].   It's basically a reaction turbine at a slant to maximise the draft tube draw.

The penstrock is 15 inch HDPE pipe and the tailrace will be open channel at least for now.

Turtle

[document opens in MS word]

[hydrosun]

if you are thinking of buying the nautilus Niade, I hope you have deep pockets.
chris

[keithturtle]

Not purchasing it, just using that slanted draft tube idea to make the most of my shallow differential.  Still contemplating the runner design, though some sort of vortex created in the penstock and directed toward the runner and its guide vanes seems to be in order.

By virtue of the slant mount,  a decent swirl could be easily preserved on the way to the runner.  It is all below high waterlevel, so the chamber will remain flooded

The dam is about a third done.

Turtle, still at it

[keithturtle]

OK, then, 6 months later the dam is no longer one-third done.  Big storms washed out most of what I had started, so I had to drop back and punt.  More concrete and less wood on the way.

In the meantime I got a simple breastshot waterwheel assembled out of 18" fabricated angle rings and blades of 1/3 circumference sch 35 8" PVC drain pipe.  The PVC mounting brackets allow a pivot to adjust pitch, and jacking rods will be attached behind the blade to the ring [not shown].  I intend to make a trickle of power with this whilst I tackle the construction of the reaction wheel and draft tube.

Don't know why I couldn't get a decent picture... 1" shaft on pillow block bearings, mostly all scrap pieces except the rings

Progress, albeit slow, like the turtle

Turtle, still at it

[machinemaker]

Thanks for the update. I spent some time yesterday down in our creek. We moved in this spring and I have watched our creek go from flooding to now a trickle. We have maybe 4 feet of head over the width of our property. I think part of the flow issue is that just upstream of our land the creek is dammed with a huge beaver dam that has a pond of about 1-2 acres. I think that this pond saturates a lot of the soil around the flood plain area that are soggy for the first couple hundred feet down stream. This make this area an over grown jungle of brush or wet areas of skunk cabbage. I want to rent a back hoe and rebuild the creek crossing area at the bottom end of the property and thought that I might try to dig a drainage ditch below the beaver dam on both sides of the creek to reclaim both some land and to get more flow. Any thoughts?

Also any good dam design guidelines or resources?
kent

[thirteen]

You might have to get the beavers (none paying renters) trapped and removed. The longest dam ever built is suppose to be in Canada and it was built by beavers. Watch out for your nieghbors complaining you are disturbing the creek eco system.

[bj]

  For info, it's in Wood Buffalo Park, northern Alberta.

[machinemaker]

I have no problems with the beavers, they are just doing what is natural. The first beaver dam is about 60' upstream of our property. The person who owns the land upstream likes the beavers and wet lands they have created and the owner has had several other ponds dug to enhance the wild life in the area. It is a several hundred acre farm that is owned by an hunter who lives several hours away and rents the fields out to a local farmer. Part of my idea for damming the stream at the upsteam edge of our land is to not just provide some microhydro potential, but to also create some fish and water fowl habitate. Part of this area was where the past owner of our land used to dump trash. Doing some work there would also clean up the broken glass and metal that was dumped there.

[loadstone]

Hey Keithturtle,

Looks good keep it up till its finished. The only thing I would change would be to move the pillow blocks to the front and place a hinge or pivot in the back so that the height of the wheel can be adjusted to accommodate the different water height in your area. Low head can be compensated for by making the paddles as catch basins (and obviously that would mean wider) that change the system from using flow to using the waters weight. Then reduction gears can do the rest, finally attached to the shaft of your generator.....but, it sounds like you are well underway to a good system.

Good Luck

Jon

[keithturtle]

I have a pitch jacking rod for each end of the blade, can adjust probably 30* each way.   Will need to make a curved catch-bucket for the inner part of the blade, ala Poncelet design to capture much of the force.

The whole thing goes in a cage that will float up and away as needed for high flow, not shown.  Got the frame, not final on the scheme yet.

Still have a long way to go, and hope to get the barrier done before the slow flies

Thanks for the pointers

Turtle, still at it