Quote:
Originally posted by GTA
I base this on the fact that its a lot easier to drill smaller holes than it is to mill narrower channels.
My thought is that an adaption of this design for very powerfull pumps would be for example 1mm holes, very very close together at say 2mm deep, and 0.25mm jets. Huge water velocity into the holes, and a HUGE amount of turbulence circulating over what is essentially a very thin base.
What are your thoughts on this? I'm still toying with the idea of a huge pump, 30 PSI or more, just to test, as I have found a tool hire shop that will hire out for £20 per day a four stage electrical pump that produces a 50 metre head.
Obviously noisy as hell, and enormous, but It would be nice to see what sort of effect power like that would have on a design.
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There are a few factors to consider with this design.
A nice one is that as the holes/jets drop down in size, the total orifice area drops down by a quadratic factor, but the number of holes also increases quadratically, so it all balances out. I really think that the jet diameter should be half of the hole diameter, but that's just my thoughts on the matter. It's an attempt to balance volumetric flow/velocity and the need to get the jet to reach the bottom of the well.
Making the base too thin (thinner than about 3mm with all the holes) means that the base will start to flex under mounting pressure. The basic honeycombing between the holes assists in strength, but once we start getting down close to 2mm thick or less you'll have to solve the issue of base flex, potentially easily solved by having support posts, but then, how to make?
Third issue is that high velocity water will gradually eat away and erode the copper. This is not something I have a lot of experience in, but very high velocity water is often used to cut metal. Not that I think that we're anything near those levels, but over a few months of high pressure jetting will we find that the block starts to leak out of the base as the jets bore their way into the remaining metal?
Use a 50m head height pump may result in issues with frictional heating. Forcing largish volumes of water through narrow holes is going to generate heat, along with the heat that the pump itself is dumping into the water. How to get rid of that heat? For a 50m pressure head pump pushing through a mass of little holes, the amount of frictional heat generated is going to be quite large is my guess. Think of pumping up a car tyre and how hot the pump head gets. That's just with 30PSI (~20m pressure head) and a low viscosity gas (air). Think of it this way. If the pump is providing 200W of pumping power, but after passing through the jet holes it loses 100W of pumping power just forcing through those holes, then the missing 100W is being converted into heat energy.