[Amps] Blower noise

[Roger (K8RI)]

That might be an answer, or a major problem.  I believe the fan noise 
from the squirrel cage blower, is air flow, turbulence, and a resonance 
related to the number of blades the impeller speed, and possibly changes 
to back pressure related to turbulence and air density which changes 
with air temp.

In the computer world they have come up with 140mm, low RPM fans with a 
very low noise signature at less than 20 to 25 db.  They can run as much 
as 70 cu ft per min IIRC and do it with surprising back pressure.  With 
a sealed system they can be used in a push pull configuration, although 
the P P configuration is not nearly as efficient as two in parallel.  I 
doubt they would be sufficient for a single or pair of 8877s.  OTOH,  
they might just work on a pair of 8877s runni8ng in parallel at the 
legal limit combined with a very low noise signature.  I leave that 
calculation to someone with a higher pay scale.

73

Roger  (K8RI)


On 8/12/2015 2:39 AM, Chris Wilson wrote:
>
> In the automotive world most belt driven engine (radiator) cooling
> fans these days have an asymmetric blade pattern for noise reduction.
> I have never seen this on other than an axial fan design. I wonder if
> it would work for a centrifugal fan?  2E0ILY
>
>


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