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
I just thought of something. Maybe you don't have to weld it up.
Just cut the core tubes off and let them dump into a bucket. Some sort
of gasket and small tank could be used on the coolant inlet end of the
core tubes. Figuring the coolant pressure drop on the core might be
a problem.
Paul Lamar
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