That's very simplistic. What about changing the fan pitch? The duct
shape? Load-dependent speed?



Ivan Vegvary wrote:
wrote in message
...
My computer power supply fan is terribly noisy when I first turn it
on. After a few minutes it quiets down and is fine till the next time
I turn on the computer. Then I go in my barn and turn on an electric
heater and the fan in there is just as noisy, but it too quiets down
once the thing is running for a few minutes. Why do these small fan
motors do that? If a bearing was bad, I dont think they would quiet
down. I just learn to live with the noise as long as the motors run.

G.T.
Fan designers have two principal ways of increasing output. Increase
horsepower or increase r.p.m. Increasing speed is a lot cheaper than
horsepower, ergo, NOISE.

Ivan Vegvary