Al Gietzen wrote:

Paul and all;

I haven't responded to the postings related to my rad installation as I have
been traveling.  However; I appreciate the input.  The limited perspective
of a couple of photos don't tell the story, but the main points raised are
valid ones; a) the space downstream from the radiator; b)the potential for
an eddie in the inlet diffuser (and the possible eddie that recirculates
through the radiator), c) the shape of the inlet scoop, and, d) the effects
of the boundary layer.  I have considered all of these previously in the
light of the sometimes conflicting requirements, and will reconsider them
some again in light of the comments; and when the concept is actually flown.

amount of diffusion is required for each case.  I suggest some reasonable
lip radii and a splitter to separate the boundary layer.

Meanwhile; the boundary layer effects remain the one that concerns me the
most; and Jeff; could you please tell me more about what a boundary layer
"splitter" is, and what it would look like.

Al

Jeff Spitzer wrote:

A splitter is nothing but a plate of some type positioned just forward of
the inlet to make sure that the boundary layer on the adjacent fuse/wing
cannot be ingested into the scoop.  The most obvious examples are many jet
engine inlets.  The F-4, A-4, F-18 (C/D not E/F) are three that immediately
come to mind.  In each case the splitter should be no longer than necessary
to sheild the inlet but not form a large boundary layer itself from excess
length.  The jet fighters often have suction holes on the splitter to
eliminate the splitter boundary layer.  Once the air is diverted/sheilded
you  must do something with the air.  The result is usually some sort of
wedge shape between the splitter and adjacent structure to force the air to
move sideways out from under the scoop (usually as the scoop turns inboard
and passes through the notch of the V-wedge)  Your situation is a problem.

I'm guessing that your radiators are long and skinny in a spanwise manner.
That means that your inlet will also be long and skinny.  That makes the
splitter a problem.  Once you've installed the splitter there's no "nice"
way to get the air out from under your long skinny duct.  I have the same
problem on my airplane design.  I decided to take the air from the splitter
and feed it into the engine intake.  The fact that it's boundary layer air
is of no consequence to my turbo motor, I'll turn up the boost if I want
more power.  The nice thing is I can calculate how big to make the splitter
area and know that it will be effective without adding the drag of a
"not-nice" wedge when the scoop is too wide.  You need to come up with a
similar solution.  You need to figure out how to collect and dump the
boudary layer air without causing additional drag.  Good luck.

Jeff Spitzer

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