|
|
Really impressed with your scientific approach Al. I can't remember what
type of plane you have, but for the Cozy, my cooling was dominated by
dead air near rear of plane. That boundary layer gets thick back there.
So I duct taped two pieces of aluminum angle to the air brake and Bam!
All cooling issues disappeared. I do like Ed's suggestions. Sorry not
much help, but couldn't let it go without saying how impressed I was with
your method. Must have been tough to start cutting on your duct.
You know, I also liked Ernests blower and yarn approach. I wonder if that
would help?
-al wick
Cozy IV powered by Turbo Subaru 3.0R with variable valve lift and cam
timing.
Artificial intelligence in cockpit, N9032U 240+ hours from Portland,
Oregon
Glass panel design, Subaru install, Prop construct, Risk assessment info:
http://www.maddyhome.com/canardpages/pages/alwick/index.html
On Thu, 12 Jul 2007 21:02:32 -0800 "Al Gietzen" <ALVentures@cox.net>
writes:
> OK, all you aerodynamicists; heres the scoop what I did and what
> I
> measured;
> (Pressures measured in inches of water.)
> 1 sealed the strake/wing crack in front of exit fairing - - No
> effect
> 2 Installed Gurney flap at back edge of exit fairing (see photo 1)
> Very
> little effect.
> 3 Set up manometer to get some pressures. (photo 2)
> 4 Dynamic pressure in front of scoop, ½ from surface (photo 3) --
> 9.5 at
> 160 mph. Nothing wrong with that. Free stream away from surface
> would be a
> bit over 12.
> 5 Static pressure ½ from face of core 3 Ό (end of tube was
> pointing
> slightly away from direction of flow at about 60 degrees to the
> flow; flow
> velocity is pretty low)
> 6 Static pressure just behind the core --- 0
> 7 Static pressure at behind exit fairing, Ύ from surface (photo
> 4) Ύ
> 8 - Installed VGs about 2 1/2 ft in front he exit fairing - No
> noticeable
> effect.
>
> So .. . plenty of dynamic pressure in front of scoop and only 3 Ό
> pressure
> in front of the cooler core. This would suggest that the scoop/duct
> isnt
> working.
>
> Photo 5 is a reasonably accurate x-section of the scoop and duct.
> Shaping
> was limited because duct entrance is right behind the spar, and by
> the
> limited thickness of the wing root. I'm just guessing that the
> somewhat
> abrupt curvature of the upper wall at the entrance is causing flow
> separation, turbulence; and whatever.
>
> You'll also note in photo 4 that I had cut the center section of the
> exit
> fairing to allow exit further forward - that didn't help. I also
> did soap
> drops on the surface which way air was going both in front of; on
> top of;
> and behind the fairing. In all places the flow was relatively
> straight
> back. I'm also guessing that there isn't much chance of developing
> a
> greater negative pressure at the exit; but, hey, whatever works
>
> All I need to know is a simple fix:-)
>
> Al
>
>
>
>
-al wick
Cozy IV powered by Turbo Subaru 3.0R with variable valve lift and cam
timing.
Artificial intelligence in cockpit, N9032U 240+ hours from Portland,
Oregon
Glass panel design, Subaru install, Prop construct, Risk assessment info:
http://www.maddyhome.com/canardpages/pages/alwick/index.html
|
|