Oil whirl Help!!!

[mcatltu]

Hi,

I have a question about cascade plot. Cascade plot is usually for an imbalance rotors. Why is there a peak at 1x at low frequency?

Also is it possible to have 1x without imbalance?

 

[electricpete]

Why is there a peak at 1x at low frequency

There is always some 1x although it should go toward zero as speed goes toward zero IF the cause is unbalance (leads to your next equestionn). Is the reading slow-roll compensated?

Also is it possible to have 1x without imbalance?

Yes, for example: bowed shaft or misalignment.


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[mcatltu]

Thanks electricpete.

I am running a FEM simulations using COMSOL (FEMLAB). A thing is that even though I do not put an unbalance, when I look at the trasient journal motion, I get a periodic circle, not an equilibrium point. I thought I only get a periodic circle when I have an unbalance.

 

[spciesla]

What does this have to do with "Oil Whirl"?