I have a few questions for you Francois concerning your coolant flow
requirements.
At what HP level is the specified 53 gallons per minute required?
How was that determined?
I assume you are using a stock Mazda water pump?
If so do you have flow rate data as a function of water pump RPM?
Were any test run on the effect on the coolant flow using less
than dash 16 diameter hose?
Paul Lamar
Hello Paul,
You put your finger on a sore spot: there is indeed a gross mistake in
our data sheet: we need a 50kw (170,000 BTU/h) oil cooler, the oil flow
to the cooler should be 66 l/mn (17.5 gal/mn), and we now use dash 12
hoses for oil. The mistake came from measurements done at our partner
Fribourg University of Applied Sciences before I spun off the project
and took over the management of MRE, so I don't know the reasons of the
screw-up. We also had to redesign the oil collector to reduce head
loss, but the problem is now solved.
The water pump is our own design, not Mazda's. It pumps 200 l/mn (53
gal/mn) at full continuous power (200 hp and 5650 engine RPM). We have
a flow rate chart for our design but, as far as I know not for Mazda's.
We are using hoses of 21.33 mm inner diameter in the aircraft (it's been
purchased in the US by ERAU, I don't know what the standard is). Simple
head loss calculations show that dash 16 (19.5mm inner diameter) hoses
would be ok, but not much below. We have not experimented further
because water cooling was never a problem as we have ample flow and had
a big 86 kW heat exchanger on the bench. We'll see how it goes in the
plane as our partner for heat exchangers has been less liberal with his
design.
Best regards,
Francois Badoux
Bill Schertz and I did some work with the stock pump and found that 53 gallons
was generally a very good output with the stock pump. Vance built a pump dyno
and we found that about 2 HP was required to drive the stock pump. The valve
simulates the pressure drop through a heat exchanger. I am still working on
measuring the actual pressure drops throughout a real system. Your data and
our data is tracking pretty good so far.
Paul Lamar
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