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Smart Drive Oil Barrel Undershot Waterwheel
MattM:
A dam doesn't need to block the main flow. You just need a bypass at a higher level. The bypass is essentially a non-invasive stream flow, so eels won't be cut off.
But why use round pipe to mismatch your rectangular bucket surface facing the water? Marine-grade plywood should hold up a few seasons. Build your bypass out of wood.
bmannz:
Hey boys, thanks for the comments,
George, the large plastic pipe sounds like a PITA, I have also considered large bore concrete and steel, I spent a bit of time on the eco innovation / powerspout calculators playing around with different pipe configurations and an open trough is the best for me but a trough is going to create its own issues
I have access to an endless supply of 60L and 200L drums and was wondering about creating my own pipe, funnily enough my barrel man at Ruakaka is selling exactly this at the moment - not load bearing worth a damn but set it deep enough and your all good. My run will be around 300m so trade me (NZ eBay) is my friend right now!
Matt, during my research phase, I came to the understanding that a dam is a structure where the water usually goes underneath in a pipe and a weir is a structure where the water goes over the top
Remembering that my flow is super variable (dry to 47 cumecs) and basically no head, I am thinking a low weir is the only way to satisfy all 4 points above, any sort of dam will be either empty or overflowing - or perhaps I misunderstood your post?
as for shape mismatch, a ply section will fix that, I've seen a few examples online of how they look.
bmannz:
This is how the lay shaft turned out:
The lowest ratio I could get was 50:1, but even that was to high and the wheel is currently stalled so I'm going to change the small end from a 9 or 10 tooth to a sprocket carrier and aim for 25:1 overall
MattM:
I was thinking you had a more substantial flow to draw energy from. You have only one flow, not really a diversion off a stream. With so little flow and so little elevation delta, it might make sense to run two gennies. Maybe switch from your F&P in high water and run a scooter motor at low flow. The F&P probably has the mass to spin only with the highest flow.
I have the same problem with my crick. No mass or drop most of the year. I'm not going to try to generate that one or two days a year the rain from hell gives it flood stage.
george65:
Don't know if it's at all applicable here re a dam, But, I was looking at a property a couple of years back that had a small stream running through it. Was told it ran all year but was pretty much only a small flow till it rained then it was a gusher.
Always wanting to do a MH setup, I thought about building a dam that open and closed as the flow I was seeing was pretty much useless. Not much chance of elevation but plenty of room to back the water up.
My idea was to have a dam with an automated gate. The gate would close till the water built up to sufficient level and then would trip a float switch which would open the gate and the water would flow in sufficent volume to be put to useful generation. Could easily control it with an arduino and some float switches to open and close. When the water was flowing as in after or during rain, the thing would run constantly. When the flow got too low, it would shut down and save up the water till there was the set level and off it would go again. Seems to me that short runs even just once or twice a day would in the end yeild more power than the piddly flow that was normal and still be able to run hard and handle the much better flow with rain.
You may be able to back the water up a little at least to do this. May be the easiest way to get some work out of what you have while still allowing for when there is a lot better flow.
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