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.