<VV> Fans/.my take

[Roger Gault]

Yes.
The Corvair fan has about 1/2 (or less) the efficiency of similarly shaped
pressure blower impellers.  A large part of that difference is almost
certainly related to the poor "scroll" design.  Of course, another factor in
the difference is that published fan curves are measured at the outlet of
the bare fan, while our "measurements" are for the whole fan system,
including the non-ideal path from the fan to the fins.  For example, I'm
suspicious that the "requirement" that the turkey roaster mate up with the
plug boots makes this area too tight to get the air turned efficiently.
Some improvement might be had in that area too, but my meat powered computer
can't handle the flow dynamics modeling and my wallet can't handle software
for my silicon based computer.  Maybe we can get Smitty to solve this
experimentally (that'll get me a private e-mail).  ;-)

Roger

PS:  I had a dream of building an iris like device to decrease the diameter
of the inlet hole.  The iris would be controlled by pressure inside the
turkey roaster, so that the pressure was limited to something like 8 in-H2O.
This would give about 90% of the max flow, but cap the hp requirement at
somewhere around 8 hp.  Still a lot, but better than 18+.  But, I'm way too
lazy to actually do this.

----- Original Message ----- 
From: "Chris & Bill Strickland" <lechevrier at earthlink.net>
To: <virtualvairs at corvair.org>
Sent: Thursday, August 02, 2007 8:52 PM
Subject: Re: <VV> Fans/.my take


> JVHR wrote:
>
> >The top shroud is the compressor  scroll. Just like a supercharger, the
> >scroll needs to be a tight clearance to  the compressor blades.
> >
>
> So, you engineer types, would changing the size / shape of the top
> shroud or the fan inlet opening, which was designed for the 1960 fan and
> never redesigned, improve the mag fan's efficiency?  Like with a smaller
> opening, could the fan or pulley be effectively changed in size?
>
> Thanks,
>
> Bill S
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