Dan Ruggirello wrote:

I should have sent this pic along with the others.  This overall velocity plot of perry2

shows the

high pressure in front of the inlet causing boundary layer separation problems.  If there

was

no oil cooler to obstruct the flow through the duct, I don't think you would see this

problem.

Wait a minute, that's the answer - remove the oil cooler!  ;-)

I forgot to ask about the space above the inlet between the inlet and the strake.  How is

this

configured?  I ran two cases - one where flow is assumed to be unobstructed to simulate a

faired

3D surface where flow would slip around it and another where flow was not allowed to pass
through.  The latter case is worse for boundary layer separation.

Dan

Dan:

Thanks for doing all this, it is interesting.  To answer your question, there is a one inch
thick leading edge airfoil shape between the oil cooler inlet duct and the bottom of the
strake. If you were looking upward through the duct and it was transparent or downward
through the strake and it was transparent that is what you would see.

I took some pressure measurements with an airspeed indicator some time ago, before my most
recent mods.  It showed pressure on the inlet was lower than at the exit!  This did not make
sense to me but I'm sure it was accurate: later I made the inlet bigger and cooling got
worse!  I think I originally had reverse flow and making the inlet bigger made the flow
stop.  Then I did some things to try to get flow out the exit so things would be working as
they should in the right direction. Your simulations seem to show that even though it is a
big snoot 5 x 5 inlet the air really just wants to go around it.

Perry

I agree Perry. That could be for one of two reasons. A. The scoop is not far
enough down to be out of the boundary layer. B. the pressure is too high
on the back side of the oil cooler reflecting through the cooler all
the way forward to the scoop entrance.

Paul Lamar
 
The AirCraft Rotary Engine NewsLetter.  Powered by Linux.
ACRE NL web site. http://home.earthlink.net/~rotaryeng/            
Copyright 1998-2002 All world wide rights reserved.