maximum frequency suggestion
maximum frequency suggestion
(OP)
User's group
I m working on a centrifugal fan wheel and I'm studing the natural
frequency of the rotor. This rotor has a shaft with two bearing at the
ends. All the pieces are steel made. The first shape is at 19Hz.
What is your opinion about the maximum velocity to avoid resonance
problem?
Thank you
Filippo Garuti
Italy
I m working on a centrifugal fan wheel and I'm studing the natural
frequency of the rotor. This rotor has a shaft with two bearing at the
ends. All the pieces are steel made. The first shape is at 19Hz.
What is your opinion about the maximum velocity to avoid resonance
problem?
Thank you
Filippo Garuti
Italy





RE: maximum frequency suggestion
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Eng-tips forums: The best place on the web for engineering discussions.
RE: maximum frequency suggestion
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: maximum frequency suggestion
The blades on the two sides are not alligned.
Filippo Garuti
RE: maximum frequency suggestion
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: maximum frequency suggestion
Also donot forget the second, third… natural frequency.
RE: maximum frequency suggestion
Actually, for a rocking mode acting on a rotating wheel, the gyroscopic theory predicts that the original mode (static) will split into two speed dependent branches. I have seen this effect on satellite reaction wheels as from wheel speed of 300 rpm but obviously this depends on the geometry of your system.
Best regards,
Franck
RE: maximum frequency suggestion
Thanks for your input. You are right. For positive whirl, the natural frequency increases with the rotational speed. For negative whirl, the natural frequency decreases with the rotational speed. But in most cases, only positive whirl is considered in rotor dynamics.