Jeff Spitzer wrote:

Wschertz@aol.com wrote:

If the Pumps are plumbed in parallel (with check valves), then the pressure
will be the same with either one or two pumps running, ignoring second

order

effects due to a slightly increased flow rate.

If the pumps are plumbed in series (ala Jeff's sketch), then the pressures
add.

Bill schertz

Not true.  The pressure is controlled by the regulator not the pumps.  The
pumps output an amount of fuel directly related to the pressure they "see".
 The regulator has a variable orifice area to control pressure.  If you
force more fluid through the regulator the orifice must open.  This is the
situation with two pumps in parallel.  Both pumps "see" the same pressure
and pump the normal amount of flow.  The regulator must open to pass
"double" flow.  if the regualtor is big enough then no problem.  If the
regualtor is not big enough then pressure will go up.  If the pumps are in
series then they "share" the pressure load.  They each supply about half
the pressure.  that means that each pump "sees" about half the pressure and
pump slightly more than if they saw full pressure.  the result is that the
regulator must pass much less flow increase for pumps is series then pumps
in parallel.

Jeff Spitzer

The Aircraft Rotary Engine Newsletter.              Powered by Linux.

http://home.earthlink.net/~rotaryeng/            http://www.linux.org