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Smart Drive Oil Barrel Undershot Waterwheel
bmannz:
DISASTER
George was right, 100:1 looked great on paper but the wheel only turned sporadically :(
The happy news is that with the setup as it is, I can simply swap my four sprockets to find a combination of ratios that do work
I know 10:1 makes too little power
I know 106:1 stalls the wheel
Think I will try for 25, 50 and 75 and see how they go
One thing has become obvious, in high flows a lot of the power is wasted so thinking about moving the wheel down the drain a bit and out of the main flow, piping to it to turn it into a breastshot to make use of the buckets and keep the downstream side of the buckets from creating drag.
Now to find a large quantity of cheap or free pipe around 500mm...
MattM:
Your power is going to be relative to velocity over time. Dropping (vertically moving) water is obviously moving faster than horizontal flowing water. But ultimately, if your generator is too big for your flow then it won't matter either way. Would a dam be potentially an option? Adding 24" of drop or more to the water could pay off dividends.
george65:
--- Quote from: bmannz on September 11, 2017, 03:06:18 PM ---
George was right, 100:1 looked great on paper but the wheel only turned sporadically :(
--- End quote ---
Was that with the generator hooked up or just the wheel turning an empty output shaft?
Go for the even money first and try 50:1. Still a lot of gearing but if the wheel moved at all at 100, 50 will tell you which if any way to go from there.
bmannz:
Cheers for the feedback guys,
Matt, I'm trying to avoid a dam if possible for four reasons:
1) this drains the neighbours farm and he's already told me he would like to lower it one day to get more usable farmland back (reduce the 5 hectare lake he has in winter)
2) letting aquaculture (eels in particular) migrate
3) avoided grief with the council
4) the flow can be enormous (47 cubic metres per sec) so high risk of destruction
I am thinking a very low weir (300mm) higher up and long run (300m) of large bore (300-500) mm pipe - just have to find the pipe!
George, that sporadic turning was under load, with it freewheeling the rpm is approx 75% faster than with the 10:1 and generator
I collected a bucket of sprockets yesterday so will pop them in this weekend and let you all know how I get along.
I think how this is going to play out is the wheel will stay here making only a fraction of the power it could until I can get the weir and pipe setup in place
george65:
--- Quote from: bmannz on September 13, 2017, 03:09:49 PM ---
I am thinking a very low weir (300mm) higher up and long run (300m) of large bore (300-500) mm pipe - just have to find the pipe!
--- End quote ---
I know Pipe size is exponential rather than linear for flow but perhaps you may find like I have in the past that using multiple smaller pipes does in fact work out cheaper than using one large one.
90mm here seems to be about the best value and most widely used so even maybe 4-5 runs of that or even 150mm could work out better than something harder and more expensive like 500mm.
Have you ever worked with large PVC Pipe? I have and it's a bitch. Firstly its heavy as hell due to the wall thickness. I was using pressure pipe which you'd probably want as well and it had at least a 5mm wall thickness. This makes it heavy. 2ndly, if you have to cut it, it's a big job more than one would realise. 9" grinders are the order of the day with that, not much else is big or fast enough. 3rd, Not that you would have to put in the bends and fittings I did, but even putting on an elbow on that big stuff is a multiple man job that requires an amount of planning. And check the prices of those fittings as well. Yeeesh!
And as for the cement..... Was going through 4L tins of the stuff like it was going out of style.
I think you will find that size pipe is anything BUT cheap and for the length you need..... Also just see if you can look at some to get a feel for handling it.
You are pretty much going to need machinery just to move the lengths round of that big stuff.
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