Hi Al,
If a "full-strength" Streamline duct were tested under
the conditions of
9.5"H20 at the entranced to the inlet then at the
widest part of the duct
you should theoretically measure 9.5*.84 =
7.98.
Ed;
Perhaps you could
enlighten me on this. Where does the .84 come from? Is this static
pressure? I thought that as the air was expanded and slowed, dynamic
pressure was converted to static pressure and the value increased. You’ve
obviously studied this more than I.
Regarding your second sketch,
since you do have slower moving boundary layer air moving next to the skin of
the fuselage (and duct), the vane would probably help it turn around the
corner. However, you are still ingesting slower moving air with less
dynamic pressure to recover from it. It is my opinion (no experience or
hard data) that moving your inlet fuselage side of your inlet opening
approx 1 1/2 - 2"away from the fuselage would make an
improvement.
You are very right about
that. Actually in the location that it is, even an inch or less away
from the surface would make a big difference. Keep in mind that the
scoop is about 23” wide with about 1 ¼” opening. How do you get BL
diversion with that configuration? Of course this configuration began the way
it did because another Velocity
builder had put his standard aircraft oil cooler (for a Lyc) in the
same
location, and said it worked great without a scoop – just the differential
pressure above and below the wing was enough. Go
figure.
As I as looking over this diagram
more carefully (Winginstallation.jpg), it became apparent that it main point
was to show one duct installation with the inlet stand off (bottom one) and
the other without inlet stand off using a vane to assist the airflow.
So, one could draw the conclusion that you have a choice? either use
inlet stand-off OR using a vane.
FWIW
Where did that diagram come
from? Very interesting. I think that my scoop opening is large enough,
and the BL thin enough, that if I can get effective diffusion in the duct it
should work just fine.
Thanks for your input on
this.
Al
Thanks,
Al