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Hi all
cutting down, Marv!
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If someone suspects they might have
separated flow on an existing installation you might consider trying turbolator,
zig-zap or
even hockey tape to try to trip the flow early. Much like
the vortex generators added after the fact to wings. :::::::::::::::::
Here I would like to note something seemigly
unrelated, but I think it might be easy to test:
Some of the Canard Flyers may remember that there
were a lot complaints about the canards on the Vari-Eze and the Long-Ez - loose
lift in rain, become erratic on the lift.
One solution was vortex generators.
Another was sanding the canard from front to back -
in only one direction!! - with 400 sandpaper!!
One guy got rid of the vortex generators all
together, still no more problems in rain!
See attached doc.
(Credit goes to the people named in the doc. and
Ned Puffer for the Cozy Newsletter, from which this was copied!)
The same should be able to be used in ducts.
Slippery is not always what you want - a re-energized flow stays attached
longer!
Also:
Would it be a reasonable understanding, that the
flow will separate for lack of airspeed?
One reason for the expanding duct is to slow down
the air to be able to do some aork in the radiator. True increased pressure may
"help" seperation, but I would think if you keep the pressure lower with exhaust
augmentation you still will see separation once you get the airspeed below a
certain energy level. Like a wing will eventually stall, not for AOA, but lack
of airflow - you need a certain flow to keep the airstream attached to the
airfoil even at 0º AOA.....
Am I way off??
Thomas J.
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