It's been a fun couple of weeks. We finished up
Matt's 15' wind turbine, made good progress on a similar 14, or 15' diameter (not sure yet) wind turbine, and we started a building an experimental hydro electric plant with our freind and neighbor Scott. He's the same fellow who built the
Rooster wind turbine. Scott lives near the creek. While he could run a lot of pipe and probably get 10' or more of head, the goal is to run this year round... and keep it simple. So the feed pipe will be 4" diameter, and he'll not be taking the whole creek, so the machine needs to run off about 3' - 4' head. Considering the low head, and simplicity - we decided to
try building along the lines of a
Banki (or Michell) turbine. We'll see how it goes, it may run as well or better as a simple overshot wheel. The goal is to make everything very adjustable so that we can experiment. Scott used to have something similar, a squirrel cage blower - hooked via a V belt to a tape drive motor in the same location where we'll be trying this. It was good for about 15-20 watts, 24/7... year round. Not bad! Were hoping perhaps to get double that, I think the belt cost him, and I think the squirrel cage blower was far from ideal. He also had problems with the bearings in the motor, and keeping belt tension just "perfect"....
We figured 4" diameter conduit would be good to use for the "paddles" in the wheel - and for the back side of the nozzel so we could connect PVC to it.
We quartered the conduit on a bandsaw and then cut them into 10" long pieces (The wheel is 10" wide)
We cutout two 12" diameter steel disks (from the base of a dead Onan generator set). The wheel is 12" diameter. In the background you can see the "paddles".
We made a template, and glued it to one of the disks, and punched the locations of all the holes, and the "edges" of the paddles - and then we drilled small holes so that we could properly locate the position, and the angle of the paddles. The wheel is also to be drilled out to fit what we believe is the wheel hub off a dodge truck, but were not really quite sure...
Here the wheel is partially assembled. This part was tricky, keeping everything square and such.
There it is pretty much finished up, along with bits of the frame which are being welded together, and the wheel hub.
Thats where we left off last Monday. It's starting to take shape anyhow! The nozzel is bent from a single piece of sheet metal with sides welded on it - and 4" conduit in the back.
The magnet rotors are on 11" diameter Dodge?? brake disks. We used 1 X 2 X 1/2 NdFeB Blocks in this machine. I made a plywood template to lay them out. This is almost identical to the rotors in Hugh's Wind Turbine plans.
Pictured above is the stator before casting, we made all the connections on the inside diameter... it looks nicer that way! The stator was a bit of a shot in the dark. I figure it'll turn pretty slow with only 3' of head, so I was shooting for a cutin (12 Volts) at about 40 rpm. The coils are wound from #17 wire, 125 turns each. We'll bring out 6 leads so we can choose from Star, or Delta. The back magnet rotor will also have 3 jacking screws so that we can easily adjust the airgap to either load up, or lessen the load on the wheel, and hopefully all this will allow us to reasonably match the alternator to the wheel and the water resource. We'll see!
Thats where it sits for now! Very nearly finished.. a couple of things yet to do. The nozzel will have a plate added so we can narrow it down a bit if the water flow is too low. We'll probably paint it, and we'll probably make a shroud that keeps water off the bearing and the alternator. I guessed pretty well on the cutin speed - right now, through the rectifiers we get about 12.5 volts at 50 rpm, but I can still take up nearly 1/4" in the airgap, so that could be improved, my guess is it will come in right at about 40 rpm. The whole thing is fun.. it is a shot in dark really - we don't really know what were doing here and have no experience. There is a lot of guessing at work... a bit of intuition, and hopefully a bit of good luck! We'll be quite happy if we see 30 watts or so. Hopefully on Monday we'll test it.
