If somebody has a minivan or pickup truck and wants a project we
could use some simple data on air flow through rad cores as a function
of air pressure. Take an old leaking junkyard rad core and band saw it
down
to a one foot square. Build a plywood box around it to serve
as a intake duct. Leave the back side open and accessible. Install
the duct and core in the open side door or 10 inches over the cab with
a 2 X 4 frame. Use a simple water manometer to measure the
air pressure on the face and the back side of the of the core
in a 3 inch grid pattern. Get one of those hand held digital wind speed
meters and do a survey in a 3 inch grid pattern on the back side of the
core. Run the van or truck at several known speeds such as 70, 80,
90 and 100. Should not take long so you should be able to find a
road some place that you can get up to one hundred briefly.
This should give us some points on a curve that we can extrapolate up to
say 120 MPH. Record the air temp and altitude when you do this.
This air side data is only half of the info we need on a specific core
but it is a start.
It would take a very powerful fan indeed to get 100 MPH slip
stream. Perhaps a tied down aircraft might also do the trick
but I kind of doubt it.
The same rig can be used to test different inlet duct shapes to maximize
the air pressure on the face of the core.
Paul Lamar
Paul,
I don't think you need to do the driving test. I'm planning to use a big
vacuum cleaner motor with a throttle valve downstream of the sample radiator
section. All we need to do is create pressure, not a tremendous amount of
flow. I want to see what the air is doing after the diffuser, design of the
diffuser is a separate matter. I'm shooting for about 36 lb/ft^2 of pressure
ahead of the cooler, which is all that is available if you consider about
120kt climb and .8 for the diffuser efficiency. By the time the air has
been through the diffuser it should be moving fairly slow. A small section
of radiator should not be that hard to test. If you use a propane fired coil
and a calibrated pump to supply hot water, add a couple thermometers,
monometers, and we can size these things not just guess. I'm hoping I can
throw something together next weekend. It's going to be field expediant for
sure, nothing fancy, (read, duct tape, silicone and PVC) but the data will
be good. What I really need is a sample of one of the griffin radiator cores
or some other common radiator core that we will be likely to use in a plane.
If somebody has a damaged aluminum radiator let me know. I could test 2 row,
2 row cross flow, and 4 row, just for comparisons sake. What I need to know
now is the flow rate that the mazda water pump puts out so I can calibrate
the flow of water.
Monty
Sounds good Monty. I guess we don't need a whole square foot of core.
What size test core do you have in mind? Welding it up to pass
hot fluid through it sounds like the hard part. Do you think long
and skinny will be a problem on the air side? Leaking or damaged rads
can be had at the junkyard for near nothing.
The 13B pump is about 35 gallons per minute as I recall.
I have a 5 HP industrial vacuums. I guess I could hold the
three inch diameter air outlet hose against my Howe rad and see what
kind of pressure it will generate. I also have stock 2nd gen
RX7 and Ford cores.
Can't do this till next week as we are off to Hawaii for a few days.
Robin's Uncle, John Rauschkolb, is a Pearl Harbor survivor and we have
been invited for a big 50 year reunion get together.
Paul Lamar
Go get 'em, Monty. Good man. Nice to see someone take the
initiative and go and do the experiments. Best of luck with the
experimental rig, could be a bit of hassle getting it all set up.
Bill Freeman
Long EZ builder & pilot
BSME, MSME
EAA Technical Counselor
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