REFLECTOR: Scoops

[Al Gietzen]

Subject: Re: REFLECTOR: Scoops

The total inlet area into the cowl through NACA scoops is 80.5 sq/"   

Kurt;

I meant, what is the inlet area to the coolant radiators; not including the
second NACA on the top. How thick are the cores?  What is the fin density?
Am I boring everybody yet?

  

I plan on having the "suction slot" just aft of the oil pan calculated into
the area. 

I'll be surprised if you don't end up with an oil cooler.  The pan surface
is not very effective (especially on the inside), is relatively small, and
the delta T is not very large after the air has gone through the radiator.
But, hey; I'm used to dealing with the rotary where a bunch of heat goes
into the oil.  

 

I have seen a couple different methods for calculating the ratio of exit to
inlet. What I have not seen is a method specifically for NACA inlets. Too
much pressure, and the air will just flow by them.  Too little (probably
rare) and the pressure recovery efficiency will decline or not work at all.
Any input on that?  Then one must add in the expansion from heat transfer as
well as exhaust expansion.  Interesting problems, but this stuff sure is
fun. 

The volume expansion due to heating is directly proportional to the change
in absolute temp (degrees K or R, Charles Law); so only 15 - 20% for the
cooling air.  Because of the friction and expansion losses of not having an
appropriate exit duct from the rads, I'd use an area ratio of at least 1.5 -
1.6.  If you have a good exit duct; maybe 1.2 - 1.3.  And of course ideally
we would have adjustable air flow for temp control (something for the next
project).  

 

Yes, indeed - ain't we got fun!  (Or is it anxiety?)

 

Best,

 

Al

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www.tvbf.org/mailman/private/reflector/attachments/20041203/5b235940/attachment.html