Paul,
When I did the diffusers for our tank at Masten, I did a design that had
several approximately radial tapered slots (wider at the outlet than the
inlet) to act as a real diffuser. I think I used some tables in Blevins for
guidelines on angles and such. Just doing radial holes helps by not having
a big coherent jet going straight down into the liquid, but the tapered
slots If Done Right™ can help convert dynamic pressure back into static
pressure efficiently. Sounds like for what you were trying to do, the
drilled holes are probably good enough, but if you ever want to do anything
fancier, you might be able to do that style of tapered holes using a wire
EDM or a taper drill set.
Food for thought,
~Jon
On Thu, Apr 5, 2018 at 3:19 PM, Paul Mueller <paul.mueller.iii@xxxxxxxxx>
wrote:
We modified the male boss fitting that threaded into the female boss
fitting on our tank, so that we didn't need to get inside the tank to
modify it (we didn't build our tank). We welded a short tube to the "tank
end" of the male boss fitting, with the biggest diameter that could barely
clear the female boss threads when inserted into the tank. We then welded a
flat disk on the end of this tube to make it "blind," and then drilled 8
(if memory serves) radial holes around the circumference of the tube just
above the blind end. The number and size of the smaller holes were such
that it they were still much larger than the main pressurant flow
restriction in the upstream regulator. Sorry I don't have a picture to
better illustrate it.
Another "feature" of this was that the length of the tube determined the
fill level of the tank. We filled with LOX from the bottom and used the
pressurization port as a vent port as well. When LOX came out the vent, we
knew we were at the desired liquid level.
Paul M
On Wed, Apr 4, 2018 at 9:15 PM, Troy Prideaux <troy@xxxxxxxxxxxxxxxxxxxxx>
wrote:
Also worth mentioning is the late Charles Pooley’s pet idea of
introducing a thin layer of ice on top of the LOX to eliminate the
requirement for a diffuser and to theoretically provide a positive
insulation between the pressurant gas and LOX.
Troy
*From:* arocket-bounce@xxxxxxxxxxxxx [mailto:arocket-bounce@xxxxxxxxxxxxx]
*On Behalf Of *William Claybaugh
*Sent:* Thursday, 5 April 2018 12:33 PM
*To:* arocket@xxxxxxxxxxxxx
*Subject:* [AR] Re: PSAS LOX Tank Diffuser
Georges:
You want a machined aluminum disk, hollow in the center and with either
holes or slots cut in the sides. Weld it to the inside of the top tank dome
and separately weld a boss at the dome entrance for the nitrogen inlet. Gas
flows into the tank and then out the holes / slots and along the dome.
Obviously, after this assembly is welded into the tank assembly,
everything will have to be heat treated and then stretched and formed back
to a true cylinder.
Bill
On Wed, Apr 4, 2018 at 7:38 PM Georges Oates Larsen <g.mason@xxxxxxxxxx>
wrote:
Howdy, folks, Georges here from PSAS <http://psas.pdx.edu/> at Portland
State University!
I'm wondering if anybody knows anything about creating a diffuser for the
N2 entrance on a LOX tank. We're using the N2 to pressurize our LOX, and we
need a diffuser to make sure we don't end up with pressurized N2 mixing
into the LOX and getting pushed into our systems downstream.
Is anybody aware of any research articles or other sources out there
about the possible designs for this sort of thing? Possible
materials/important design points to make sure the thing actually works as
intended? Key hangups to be avoided?
Thank you,
-- Georges Oates Larsen