Tweaking The Hydro Weir
I recently made a tiny modification (with a huge impact) to the hydro weir/sluice to address the imperfect alignment of the sluice and the capturing basin to which the penstock is attached via a shower drain fitting. I was losing a lot of the weir flow because of that mis-alignment which caused a lot of the water to wick back underneath the sluice when the creek flow was a little reduced. The clue to the need for this improvement was the noticeable belching of the water jet at the turbine nozzle a thousand feet downhill, indicating the system was sucking in some air. Normally the turbine is nearly inaudible from the rocking chair on the front porch of the cabin, but the system breaking wind was clearly audible.
With a piece of copper flashing I bent a liner for the sluice so that the complete channel of water would be directed onto the screen on top of the capturing basin rather than to the closest edge, which was causing the water loss for the system. I had intended to place the capturing basin directly under the end of the original sluice but there was a boulder in that precise spot, preventing me from getting the basin at exactly the right height (by about 1/2″ inch!). This was a minor thing but the improvement was noticeable immediately.
I’m thinking about making a new capturing basin as this one might not be deep enough, Given the weight of the 22 cubic feet of water in the penstock and the siphon function resulting from that 1400 lbs. of water, the flow of the system exhibited an intermittent air incursion into the flow, noticeable as a momentary gurgle at the turbine.
A new capturing tub needs to have the water level a couple inches higher than currently relative to the penstock intake. I might accomplish this easily by simply making a new tub with the shower drain fitting right at the bottom of the tub, or at least as low as I can get it, so the water level would be adequate for minimizing the vortex sucking in air. The space does not allow for a deeper setting for the tub as I mentioned earlier, but I also might make a wooden collection box so that it can be longer and lower in the water at the penstock intake.
Stay tuned.
Every time I read one of your water turbine posts I wish I had a stream near the house. If we ever relocate, that’ll be on the list.
a drip-edge/drip-cap avoid water going backward under the edge of a sill.
You might consider bending the edge of your copper sluice.
Sylvain
The real problem was that the bottom of the sluice was 1/2″ higher than the capturing basin because of the boulder underneath and can only abt the lip rather than rest above it. The copper sleeve elevated the water flow to just above the basin lip. When the water flows with higher velocity it is not such a big problem,