Can Dan analyze this?  It is a pusher LEZ, this is a very

approximate

drawing of my oil cooler installation.  I've probably tried a dozen
different things over the years and oil still doesn't cool very

well.

The exit on top of the cowl is now basically open, just several

"fixed

cowl flaps" at a 45 degree angle.

Perry

Perry, what is the distance from the scoop opening to the leading

edge of

the strake? That will have a strong effect on the boundary layer

thickness

and consequently the simulation. Perhaps you should redraw it to

scale.

Paul Lamar

Perry Mick wrote:

It is about one inch and I did draw it to scale, but from memory.

Strake

is about 10" thick. Inlet opening is 5" x 5".

Still need the horizontal distance from the opening to the leading edge

of the strake.

Very important to see if the P51 type boundary layer bypass is working.
Also the airflow over the top of the strake should be included.

Paul Lamar

My estimate was only off by a factor of two.  It is four feet from the

leading edge of the

strake to the inlet, the strake is swept back at about 60 degrees

changing to a sweep of

about 45 degrees at that point.

Perry

We will have to ignore the 3D flow around the swept back leading edge for

now.

The boundary layer thickness is also a function of the angle of attack so
Dan, please run  0 and  5 degrees. Dan will need IGES drawings for both
cases Perry. Does your cad program output IGES?

Paul Lamar

Dan Ruggirello wrote:

Sure, I can get a model of that going.  Any idea what the percent open area
of an oil cooler is?  The IGES really helps getting the model built faster.
Looks like DXF will work too though.

Yesterday I ran a model with larger boundary conditions as you suggested and
it seemed to help.  I would have sent you the results but I accidently
deleted them ;-)  But I am re-running it.  I have a couple questions out to
the developers in Spain specifically about their algorithm option for
boundary layer slip to simulate boundary layers that are thinner than the
smallest element size.  The manual is at the sourceforge website in pdf
format.  I can read spanish (though not well), and find the manual very
basic with little detailed information.  I contacted the developer yesterday
and he was very helpful - just have a few more questions to work out with
him. Lucky for me, he speaks english!

Dan

 
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.