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Message
The curves that start at zero and rise as the
square of the flow with data points are measured flow rates through an
'individual' radiator core [measured both cores, they behaved the same]. I will
be running the cores in parallel, so the curve near the 'real rad test' is a
calculated curve that is the sum of two individual cores.
I then plumbed the two evaporator cores into the
flow loop, and got a single point with pressure drop and flow rate for the two
in parallel. Here is the plumbing setup. You have to look hard to see that they
really are plumbed in parallel, but they are.
Bill Schertz
KIS Cruiser # 4045
----- Original Message -----
Sent: Wednesday, October 20, 2004 11:35
PM
Subject: [FlyRotary] Re: nylon
EWP's
Bill;
Good stuff.
The flow curve shown for my dyno
run, http://members.cox.net/alg3/Dynamometer%20test%20report.htm
is pumping through the
engine and through the large radiator of the facility. I think the pump
on my 20B is geared about 1:1 with the e-shaft. For the same RPMs, my
data correlate reasonably well with yours at 0 backpressure across the
radiator.
Are the core drops for
evaporator cores? What is the “Real rad test” data point on the
chart? Ron Davis Racing gave me a pressure drop of 2.25 psi at 20 gpm
for the rad I got from them. Griffin did
not provide any pressure drop data on the rad they made for me that goes in
the wing root, but based on the configuration I’m sure it is higher. I’m
guessing that my two rads in parallel will get me out close to 40 gpm at 5600
rpm, which is pretty much on my design point.
Now if I just knew what the
actual air-side flow was going to be . . .
Al
Subject:
[FlyRotary] Re: nylon EWP's
A year or so ago I posted a graph
of measured 13-B water pump performance. I am enclosing it again with this
post. Several points to be made:
1. The water pump is on the
engine, so the pressure indicated on the Y axis is the pressure that is left
over to push the water through the radiator cores.
2. The measurements were made with
3 different size pulleys, to vary the water pump
speed.
3. At no flow, the pressure on the
Y axis is the maximum pressure that the pump can supply. At zero pressure, max
flow, all the available head pressure from the pump is taken up by the
pressure drop through the block, and there is no more pressure to force water
through the radiator.
4. Looking at the charts, you can
see that at a flow of 20 gpm, the pressure drop across the core is 5 psi, at
33 gpm the drop across the core is 8.5 psi, and at 44 gpm, the drop across the
core is 19 psi.
At a later date, Barny located the
full flow (no pressure) and zero flow (max pressure) points for the
Meziere pump. Dead head pressure was 10 psi, and full flow was ~55gpm. These
numbers did NOT have the pressure drop across the core included.
Tomorrow I will forward a graph with this information overlayed on this
chart.
Based on these TESTS, and
the CLAIMED performance (by the manufacturer) of the EWP, I calculate that you
can get ~ 20gpm max through an engine core combination. If you need more you
will start to have heat extraction problems.
Bill Schertz
KIS Cruiser #
4045
-- Original Message -----
Sent:
Wednesday, October 20,
2004 1:45
PM
Subject:
[FlyRotary] Re: nylon EWP's
Subject:
[FlyRotary] nylon EWP's
I'd
like to hear some more comments about nylon vs. AL EWP's. should I be
satisfied with "well, Leon uses them" and ask
no more? the nylon pumps seem light enough, 2 lbs., that they could be
supported simply by their rubber hoses, which should make a good
vibration damper. (I don't really know who Leon is, although I get
the impression his word rates right up there with Tracy's) the nylon ones
only push 20 gpm, whereas the AL claim 37 gpm.
I have no idea what my 20B will require. I would be using 2 in
series.
Two in series
may not give much more flow than one; depending on the back pressure vs
the pressure at which those flows are based. If those pumps are rated flow
at 0 pressure, it is likely that even the AL one is
marginal.
I’ve done the
math on the 20B. The flow requirements depends on the cooling system
design (obviously); but if you were to design for a sort of optimum system
for an aircraft, you’d like to have 20 – 30 F temp drop around the loop
when you are running about 85% power, say, 220 HP. So for a 50/50
EG/water mix, and 25F delta T; that says 39.5 gpm. For pure water
the number is 28.5 gpm
The only real
data I have on my pump is from the dyno runs. That showed 43 gpm at
5000; 48 at 6000. That is without a thermostat, and on a large
capacity system with presumably relatively low back pressure. 25-30%
less with a thermostat. Unfortunately, I don’t know what it is on
the airplane.
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