Thanks for your reply Richard.
We can not assume 2.5cm filled height, no.
There are holes on the bottom of the tube, to let etchant in, and if there
is more etchant in the tube than the OD of this ring of holes it will flow
out again there.
I assumed 1cm of etchant "skin" inside the tube, which probably is a
rather high estimate.
A bar is fixed, the athmosphere isn't, i think the atmhosphere is off by a
small bit but it not important for the estimation here.
Did you also try 6000RPM? i got approx. 1Bar with 6000RPM and 1cm "skin".
I found calculators on the web for lab centrifuges and they seem to agree.
I don't know how many rpm a pipe this diamter can take, and what sort of
motor power one would require.
> Maybe the outflow of the fluid is the result of it moving tangentially
> at 2.6 mps, not because it's squirting out under pressure.
> It kind of makes sense if you look at the numbers.
> I wish I remembered half of what I've forgotten in fluid mechanics, I
> could understand it better and give a better explanation.
> As far a nozzles go, in the US, Home Despot has started carrying 1/2 and
> 1/4 inch irrigation equipment, mass produced plastic (not sure what
> kind), with all sorts of nozzles - mist, 45, 90 180 and 360 sprayers,
> all for 5 for two dollars kind of prices. They screw right into 1/4
> inch tubing, and are made to screw into the side of 1/2 inch tube. If
> you are interested, and can't get it over there (I hope the EU is not as
> obsessive about their lawns as we are), I'd be willing to mail you an
> assortment. I think that USPS has an international 3 day for less than
> $20, and these things don't weigh much.
> LMK
> Thanks
> Richard.
I think you may be right there and the rotational speed is contributing.
I was already considering that. I was wondering which direction the
nozzels would be best, straight outwards or maybe angled towards the
tangent, i dunno. It seems straight is easiest.
I appreciate your offer with the home depot nozzles, but i'm not very sure
they would be suitable. Generally irrigation nozzles create a big amount
of mist, and ideally i would have "fan" type nozzles.
If someone had built a sprayer and the nozzles are known to work, there
would be no question, but this way the chances that they are useless in
the end for some reason are high.
I will have some time again today to try around with the nozzles, i have
rigged up the static pressure test i described. I know it may not reflect
true spray pattern when turning but better than nothing. I have looked at
photos of industrial fan nozzles and one type seems to be a staight round
hole with a small slit milled in the front. i can try that. Also, a single
nozzle leaves something like a 4mm "ring" in the bucket, so if i space
even round nozzles at 2mm it cold work. that would be 250 holes total and
i'm not sure if the sprayer can supply that much.
Another worry is how to glue the lexan tank. I may just use silicone which
i know how to use, but there might be better methods. I have made the
supplier send me some scraps so i can try a few things beforehand... Let
me know if any of you have experience with working Lexan/polycarbonate
please.
thanks
ST