Al, what is the volume of your radiator core, not overall. I’m trying to fit about 5-600 cub”
Bulent

On 7/14/04 1:57 PM, "Al Gietzen" <ALVentures@cox.net> wrote:

Subject: [FlyRotary] New Scoop
 
Steve;
 
There are all kinds of things one could say about trying to make the scoop ideal, effective, low drag, etc; and then when you face the reality of fitting to your plane, you can’t do it.  So it’s what works for you.  I’ll add a few comments for whatever it’s worth.
 
The intake area of the scoop should be fine.
 
One would like to slow (expand) and turn the air entering the scoop in a manner that maintains surface attachment for max pressure recovery and minimum drag.  This takes a much longer scoop throat than you have.  The air entering will trip to turbulent at the abrupt corner behind the B.L dam.  This will result in poor flow and pressure distribution, with most of the air going toward the back of the scoop.  I don’t know what happens in your installation downstream from the actual scoop, but you might consider some internal baffles but get a more uniform distribution if the rad is close to the scoop.
 
The boundary layer dam that you have is high drag, and may be close enough to the entrance lip that backup of the B.L. flow will be ingested into the scoop – or it could result in some external diffusion (pressure recovery) and allow the scoop to work just fine.  The idea in the B.L. “bleed” is to try to divert that flow somewhere else, generally  off to the sides.  That would require a much more gradual diverter angle.
 
I made a much more gradual bend in the wall of my scoop (pic) attached.  Still, in doing flow tests, I found flow separation and turbulence which lead uneven flow distribution.  I added to baffles in the scoop get it fairly uniform.  It could be that some of the turbulence was a result of the test rig setup, although I thought I had a long enough duct from the blower to straighten things out.
 
The squared off internal corners will add frictional drag, but probably not significant in overall picture.
 
But, hey – try it. If it gives you the cooling you need, you’ve got 90% of the battle won.  If you feel you need to reduce drag, you can consider that at your leisure.
 
Al