<VV> Re: fan, motor and belt efficiencies links

[djtcz at comcast.net]

> Subject: Re: Re:Mo' Fanz 
> To: virtualvairs at corvair.org 
> Message-ID: <42EFB8B0.52A6F275 at earthlink.net> 
> Content-Type: text/plain; charset=us-ascii 
> 
> Padgett wrote: 
> > 
> > ... the amount of air you move. How much power that takes depends 
> > on the design of the fan (and curves/spirals are better than 
> > straight lines). 
> 
> Ahh, Padgett -- Spal says the straight blades are more efficient 
> and the curvy spiral blades are for noise reduction ... 
> 
> Bill 
> 
> 
> ******************************************* 
The following links talk about some of this -
The usual centrifugal fan or blower discharges at a single point.  I'd guess the Corvair dual lobed "8" discharge might have slightly different rules.
Operating on a non-optimum portion of "the curve" can cost way more than the 10% or so efficiency separating the different types, thus fan matching might have bigger gains than picking one ny the vane shape.  And yeah, the price of lower efficiency is hotter air.
http://www.mtprog.com/briefingnotes/images/fan%20characteristics%20curve.JPG

http://www.engineeringtoolbox.com/fans-efficiency-power-consumption-37_197.html
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"Centrifugal fans with backward curved blades are generally more efficient than the other two blade configurations. "
http://ianrpubs.unl.edu/farmbuildings/g1243.htm

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"The ideal inlet airflow condition is one that allows air to enter axially and uniformly without spin in either direction. The ideal connection would include up to 10 diameters of straight duct leading to the fan inlet, depending on the air velocity. "
http://www.hpac.com/member/feature/2004/0404/0404brooks.htm#spinning

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The highest-efficiency centrifugal fans use airfoil or backward-curved impeller blades 
http://www.wisconsinpublicservice.com/farm/eba_32.asp