Mailing List flyrotary@lancaironline.net Message #38513
From: Thomas Jakits <rotary.thjakits@gmail.com>
Subject: Re: [FlyRotary] Re: Oil cooler inlet
Date: Wed, 18 Jul 2007 19:43:13 -0500
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
One way to try this out is to use a sheet of alu (or fiberglass or similar), protect the edge AA with some duct tape ( or better: protect the cooler from the sheet) and tape the sheet at point BB, with some curve to it.
Nearly anything should be better that it is now. You also could to various tests and get successively more aggressive with the curvature. Once you see (hopefully good) results, we can brainstorm the exact coordinates for the permanent change...
 
I don't see how you would have a real problem with the air turning:
It is less than 45º, once the turn is made it opens to both sides AA and C, and there is no straight shot to the core from the direction of airflow before it has to turn.
I would assume the air will go fairly straight to the center of the core before the duct opens up...
 
I still belief that the wall B produces a load of eddies that block at least half of the cooler...
 
TJ

 
On 7/18/07, Thomas Jakits <rotary.thjakits@gmail.com> wrote:
Hi all,
 
please keep in mind that I am here only with theory at this time, also I am excomunicato from PL-heaven (maybe that counts for something?? :)).
 
What I gathered so far from the cooling discussions, I would try the following in this case:
 
a) any of the lines I have drawn into the sketch OC scoop-03
b) to add a little, make sure the intake lip has a smooth lip, with the biggest possible radius on the inside
c) IF your glass finish is "absolutely perfect" in front of the intake, I'd sand it with 400 or 360 in flow direction: mask of the area and only sand in one direction ( I would draw the block away from the intake...). The idea is to rough up the surface and create miniature vortex generators
if c) does nothing
d) Try out "real" vortex generators.
 
However, I believe (...if your sketch is sufficiently accurate) the most loss you see from "stall" in area B.
The red line is rather conservative (the first one I tried in paint :))
Bue and Magenta should get you fairly close to streamline. Magenta pushing towards Ed's "pinched ducts" system :) 
 
Personally I would try some foam insert before I would mess with turning vanes. AS your sketch looks you will not be done with a vane, as the air still slows too much because of the excessive retreat of the the upper duct wall....
 
Hope it helps!
Stand to be corrected!
 
TJ


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