Jerry Hey wrote:

Kell, I have been looking at the NACA data in the pdf that was
referenced a few days ago.. First, it clearly states that in all
cases the curved diverging duct is the most efficient.  However, I do
wonder if the differences are significant.  Max pressure recovery for
parallel walls is .080.  For divergent straight wall it is .860 and
for curved divergent wall it is .865.  I have trouble translating
these numbers into real world reality (I am not an engineer) but the
differences seem slight to me.  It should be noted that for each of
the examples above max pressure recovery  required different width to
depth ratios.  The parallel walled inlet duct was best at a ratio of
1:1 while the Curved divergent wall duct was best at ratios between 3
and 5 to one.  So if you don't have much space you might be better
off with the parallel ramps.  Wait until the engineers on this list
respond before making up your mind.  I may have it all wrong.  Jerry

I must admit I did not read those papers as I left for Oregon and Washington
right after Bill suggested them. Which paper and what page Jerry?

If that is true and you have good velocity under there after you
do a velocity rake measurement survey the 1:1 sounds good as you can get
the required area of 100 square inches with an opening only 10 inches
wide. What was the ramp angle on the parallel opening?

Paul Lamar
 
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