Bill,
Thanks for your response! What is the best instrument to use to measure the
LOX flow directly? You mention cavitating venturis, but it seems like those
are more for flow restriction rather than actual measurement.
Could we measure the pressure delta across the injector and use that to
find the mass flow rate? Or should we get an instrument that can measure
the flow rate directly?
Brett
On Sat, Jan 30, 2021 at 1:05 PM William Claybaugh <wclaybaugh2@xxxxxxxxx>
wrote:
Brett:
If you are using a cavitating venturi to control the Lox flow
then—excepting start-up and shutdown—the flow rate is fixed. Thus
measuring initial and final mass in the tank is sufficient. Given boiloff
issues w/ Lox, measuring the tank mass in real time could in theory allow
you confirm the flow rate that the venturi allows.
However, all the connections to the Lox tank act as spring masses with
varying rates and make the mass measurement exercise fraught w/
assumption. Sometimes directly measuring the desired metric really is
simplest.
Bill
On Sat, Jan 30, 2021 at 12:01 PM Brett Coles <brettcoles@xxxxxxxxx> wrote:
Hi all,
I know I ask a lot of questions, but you're the best resource I have.
For our hybrid project, we were going to measure the mass flow rate of
the LOX by constantly weighing the propellant tank with a load cell. I
thought we would be able to account for the variation caused by the
pressurization of the stainless tubing, but I have heard that it will be
extremely difficult or impossible. Will we be able to measure the mass flow
rate that way, or will we need to choose a different method?
If we need to choose a different method, what options do we have? I would
like to use a venturi, but I have heard that they don't work well for LOX.
We can't really afford a turbine flow meter either.
Alternatively, we are taking pressure measurements on both sides of our
injector. If we characterize the injector well, could we use that
differential pressure to determine the mass flow rate?
Thanks,
Brett