Don Dunbar wrote:

Hi again Paul,
You are right the water would run away if the pump is removed. This is how this pump is mounted at the sump level of the engine.
Don

I think you need the rad in there with the pump located at the top
of the the water level to get a meaningful simulation of the
cooling system.

As you can see by Bill's data the pressure drop through the core
is a significant effect as to how much water can be pumped.

BTW it appears from Bill's data that evap cores are unsuited
to centrifugal water pumps. Makes sense as evap cores are used
in air conditioning systems with positive displacement high pressure
piston pumps.

I never ceases to amaze me they don't work worse than they do :-)

Paul Lamar

A/C refrigeration coils (cores as most people say) are just that, coils of tubing arranged in a serpentine pattern.
Looking at one you can see that the flow is through a single tube from top, or in some cases from the bottom, but in a radiator the
flow is from a header tank on the end (or top) through all the tubes simultaneously, (existing, occurring, or done at the same general
time or at the same moment.).
consequently, the flow rate through a radiator is higher by far than through an evaporator coil.

Pumping type, centrifugal, piston rotary etc, has nothing to do with the flow rate of the coil.
In the evaporator coil the flow will be through the small tube all the way through the whole coil, but in the radiator it will flow
through all the tubes at the same time.
Heater coils would be better for flow rate than the evaporator coils, since most of them have header tanks like a radiator. This is
why water to air heat exchangers us header tanks instead of the serpentine configuration of the evaporator coils. These are called
cores in the trade, and the evaporators are called coils.
Royce

My point was centrifugal pumps can be stalled by too much back 
pressure and cavitate. A positive displacement pump will excessively 
load down the driving mechanism if the restriction is too high. In 
some cases an over loaded  positive displacement pump can shear the 
input shaft or do other damage to the mechanism. I have had it happen. 
I suspect that is the reason for the pressure relief valve on the rotary 
oil pump. I digress. In any event air conditioner *compressors* are 
designed to drive the fluid through the highly restrictive evap 
cores or coils.
 
Paul Lamar
 
The AirCraft Rotary Engine NewsLetter.  Powered by Linux.
ACRE NL web site. http://home.earthlink.net/~rotaryeng/            
Copyright 1998-2002 All world wide rights reserved.