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Al, I have to say I'm in agreement w/ others. I think putting some VG's up near the leading edge [say 25% cord] would keep more energry down in that region. I would make them a bit larger than the standard vg's [ the little 't' shaped alum ones.. ~1/4 high] as I don't think you could have too large a vortex in that area. It may cost you 1-2knt but your cooling could easily double.
I can picture in my mind the low energy air going in that scoop and as soon as it's asked to turn the corner it just seperates and you'd get an eddy/reversed flow in the "B" location. Another thing a guy could do is get one of those lip stick cam's and use a type post w/ red yard on it, glue it to perpendicular to the wing about 6" ahead of the inlet and leave enough yard that it can reach right back to the face of the rad. Mount the cam down below the wing so it shoot's up into the duct.[or it might fit into the duct also.] This would give a good visual on what is going on??
I find this type of trouble shooting very intriguing.
Best
Jarrett Johnson
> Good ideas TJ. I agree that the upper wall shape is not good. Didn't
> concern myself that much about it originally because I had been
> assured that
> the negative pressure at the exit above the wing would take care
> of things.
> NOT!!!
>
>
>
> I think I would shape it such that there was no contraction of
> the area,
> because; based on past experience with scoops, where you do not have
> external diffusion to help you out, any contraction in the duct
> causes back
> pressure and air spilling around the scoop, especially if you are
> ingestingthe BL. Best if you can have continued expansion once
> past the entrance.
>
>
>
> Monty; you may well be right; it may take a combination. However,
> I did put
> VGs in front of the entrance, and it did not make a noticeable
> difference.They were only about 8" forward of the entrance because
> of the gear well
> that is there. I think I will try again with them further forward
> - on the
> gear door covers; and make them a bit taller this time.
>
>
>
> Al
>
>
>
> -----Original Message-----
> From: Rotary motors in aircraft [flyrotary@lancaironline.net] On
> Behalf Of Thomas Jakits
> Sent: Wednesday, July 18, 2007 4:26 PM
> To: Rotary motors in aircraft
> Subject: [FlyRotary] Re: Oil cooler inlet
>
>
>
> 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
> pushingtowards Ed's "pinched ducts" system :)
>
>
>
> Personally I would try some foam insert before I would mess with
> turningvanes. 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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