Hi Richard:
It is nice now that a lot of the gamers and power PC users want to run
silent cooling systems in their machines. Many of the PC fan mfgs rate
airflow as well as noise in dB. Silenx utilizes the same blade modeling
algorithms previously used for SSBN Boomer propellors. Quietest fans
I've ever seen.
Curt
Richard Knoppow wrote:
----- Original Message ----- From: "TC Dailey" <daileyservi...@qwest.net>
To: <drakelist@zerobeat.net>
Sent: Tuesday, August 23, 2011 11:38 AM
Subject: [Drakelist] Cooling Fans
In the "for what it's worth" department - I used to hold a muffin fan
ATOP my SB-220 and SB-200, with a pair of toothpicks. It made NO
permanent holes, held the fan where it did some good, AND I had it
"sucking out", as opposed to "blowing in". Any physics or
fluid-mechanics guy will tell you that when you compress a fluid
(like air), it heats up (albiet, in this case - very slightly), a
negative pressure [sic] tends to lower the temp - whatever works for
you, but my fans PULL - they don't PUSH.
Tom - W0EAJ
Having a sucking fan on top takes advantage of the normal flow of
the heated air due to convection. It also does not blow heated air
over the rest of the chassis. Since the amount of air to be moved is
not great a low speed fan works fine. Mounting on the back of the
final cage works fine despite the theoretical advantage of top
mounting (I've tried it).
The size of the fan and design of the blades and its speed
determine the volume of air it moves and also the amount of back
pressure it can work against. Both are not critical at all here.
However, the _noise_ a fan makes also depends on size, speed, and
blade shape. For the same volume of air a small fan must run faster.
Some miniature fans are nearly sirens, they are necessary for some
applications but not for cooling fairly large vacuum tube gear so a
much quieter fan can be used.
I suppose one could devise a physics lab problem of determining
both compressional heating and the heating due to frictional forces on
the flowing air. That would require measuring a _lot_ of parameters.
While this is silly here there are engineering applications where such
things _do_ need to be calculated.
--
Richard Knoppow
Los Angeles
WB6KBL
dickb...@ix.netcom.com
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