I first ran into this too many years ago in engineering statics. A head or
column of liquid exerts a pressure per unit area only
dependant on how high the column and the density of the liquid. No
calculus involved to calculate the pressure at the bottom if the density can be
considered incompressible such as fuel or water, but not air if the column is
very tall. Now if we wish to calculate the total force on a dam or a container
that has a vertical component, then we need calculus to be able compute the
force. Do not have a neat analogy at the moment to explain it better.
One thing that grabbed me was to calculate the force exerted on a dam is
that you only need the dimensions of the dam and density of the liquid, ie it is
independent of how far or how much water is backed.
If we build a dam that backs a tremendous amount of water and now build a
second dam just upstream of it, the force on the first one will not feel any
change. Now if we pump all the water from upstream of the 2nd dam, the
downstream or original dam will still not feel any difference, but the 2nd
dam will now feel the same force in the opposite direction. Hope this might
clear the muddy water a little :>)
Back to original question of where to dump the return fuel. I doubt if the
pressure at the fuel injection point will be changed as a function of where you
put it back in the tank. This assumes the regulator does not hit a limit of
travel.
Bernie Kerr, 6A sold :>( Hopefully 9A rotary flying soon.
----- Original Message -----
Sent: Friday, February 13, 2004 6:23
PM
Subject: [FlyRotary] Re: EFI Fuel
Pressure
----- Original Message -----
From: <echristley@nc.rr.com>
To: "Rotary
motors in aircraft" <flyrotary@lancaironline.net>
Sent:
Friday, February 13, 2004 3:29 PM
Subject: [FlyRotary] Re: EFI Fuel
Pressure
Snip
> Actually, the rest of the feul will exert some
extra force on the column,
but it requires calculus to figure it out and it
won't be much.
>
I must have been playing hooky the day they
taught that. Could you explain
that just a little more? It
doesn't correspond to my learnin and
experience.
Bob
Darrah
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