On 23 Oct 2007 at 20:53, Randall wrote:
> oddly enough, some fan makers do say to turn the blades around
> when configuring as a pusher instead of a puller...
> Apparently their fans are more efficient
> when turning in a particular direction.
There are reasons why this could be true. IIRC (and I'm not going to
go look right now) my Spitfire's fan, an electric Lucas, I think,
yellow plastic, has blades which are curved. Reversing the fan
wouldn't change the air direction but it would change whether the
concave or convex side of the blade faced the oncoming air. There is
also the matter of whether the motor is in front or behind, for
example in a region of less or more turbulence. There are enough
degrees of freedom in a physical setup like this that no single
"rule" is going to predict how it behaves. So we can't say a priori
that either way is the best. But if the manufacturer says so, then
they probably know something about it as a system.
--
Jim Muller
jimmuller@rcn.com
'80 Spitfire, '70 GT6+
--
Version: 7.5.503 / Virus Database: 269.15.8/1089 - Release Date: 10/23/2007
7:39 PM
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