Kyle,
I don't post here much either, but I noticed the common pressurant
system for both Fuel and Oxidizer and strongly suggest separate systems
(Tanks) for several reasons.
Personal experience launched the injector to an engine several hundred
feet when a common pressurant system allowed (yea, through check valves)
fuel into the lox dome.
A friend was charged $5k when some alcohol leaked back into the rented
LOx dewar.
These systems both had check valves and independent regulators like yours.
Disturbances in the feed system will at least be a little more decopled
with entirely independent pressurant feeds.
Now, an actual flying system may have all sorts of goofyness in it, but
for a baseline test stand, remove as many variables as possible initially.
Goodluck,
-Gar.
------------------------------
From: Kyle Meeuwsen <meeuwsen.engr@xxxxxxxxx>
Date: Tue, 19 Apr 2016 18:15:16 -0700
Subject: [AR] Portland State Aerospace Society
Hello All,
This is my first post and I hope I am doing it correctly...
I am with the Portland State Aerospace Society and we are developing our
first liquid engine test stand. This is a LOX and Ethanol system
pressurized by either Nitrogen or Helium depending on the quote back from
Praxair.
Below is a link to the Test Stand PID on Imgur. I am looking for either
approval or to discuss design concerns. Please note that the valve below
the LOX tank is cryo rated with a pneumatic actuator that is pressurized
by
two solenoids which are fed from the LOX pressurant line.
The senior design team before me also selected relief valves and solenoids
for venting on the top of the LOX tank that are not cryo rated. I have
concerns that heat transfer from the tank to the LOX might freeze these
components that are attached to the top of the LOX tank. I could attempt a
very shaky heat transfer analysis unless people know right away that these
components will freeze very quickly.
I am also still searching for filters and burst discs, and a way to safely
fill the LOX and Ethanol tank from a great distance away.
Also, any suggestions on how to purge the system of moisture prior to
testing would be greatly appreciated. I have been told to run hot
pressurant gas through the system for an extending period of time but I am
currently not in possession of a heat exchanger or an ample amount of
pressurant gas.
https://imgur.com/gallery/wVbtgUz
