[time-nuts] time-nuts Digest, Vol 79, Issue 31

[Bob Bownes]

Not to mention improvements in motor design. The brushless motors have
gotten better and the change to lighter plastics has put much less
burden on the bearings, which while they might not last as long, sure
are a lot quieter. One of the parameters you can use now to select
fans is the noise factor for a given cfm. Simply replacing the old,
loud fans in 3 or 4 pieces of test gear has really quieted things down
for me.

As you say, the big changes are in getting more air to move with less
turbulence at a lower rpm by changes in blade design. Probably a few
former submarine prop designers making money in their retirement. ;)


On Thu, Feb 10, 2011 at 9:38 PM, Hal Murray <hmurray at megapathdsl.net> wrote:
>
> richard at karlquist.com said:
>> I don't see why changing the operating voltage of the fan would make
>> bearings last longer, move more air, or make less noise, unless it allows
>> the fan to run at a different RPM.  Even then, more air and less noise would
>> seem to be mutually exclusive.
>
> Somewhere in the past 10-20 years, people started paying much more attention
> to how much noise fans make.  For a given amount of air, most modern fans are
> a lot quieter than old ones.
>
> I think one big step is to keep the support bars away from the fan blades and/or make them smaller.  There are probably some important details about the fan blade shape that I don't understand.
>
>
> --
> These are my opinions, not necessarily my employer's.  I hate spam.
>
>
>
>
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