Ok, take a close look at the fan.
1. There is an area in the center that produce no air. So the fins up against
that have no air flow.
2. Most of the air from the fan comes out around the blade tips. That is the
fastest moving part of the blades
and centrifugal force slings the air out in that direction as well. If you
set a fan in the open you will feel the
large quantity of air off to the side.
73
Bill wa4lav
________________________________________
From: Amps [amps-bounces@contesting.com] on behalf of Markku Oksanen
[markku.a.oksanen@kolumbus.fi]
Sent: Monday, February 17, 2014 5:38 PM
To: alan@g3xaq.net; amps@contesting.com
Subject: Re: [Amps] Force cooled heatsink aerodynamics
Hi
I have one of these heatsinks that have two 120 mm side by side and it is
with the air flow chamber.
The chamber is just an empty box about the thickness of the fans, in my case
perhaps 35-40 mm.
How exactly this helps I can only intuitively imagine, I would think that
having fan blades rotating very close to a dense cooling fan grid is not the
most efficient way of pushing air through.
My project is for a pair 1200 w freescale dual fets for HF, hopefully with
some headroom for reliability.
Markku
OH2RA /OG2A /WW1C
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