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Hello Vibration Analysts,

we are a gas Turbine Nuveo Pignone 5002D was under Major Inspection, after start up we get high temperature in first journal bearing (DE axial compressor bearing), the below data are FFT 0-1000 Hz taken from radial plan X,Y with axial proximator 1652A.

can someone have a good explanation for that, for me it seems that we Oil whirl instability phenomena (frequency between .4 - .48 XRPM), but I didn't understand the Orbit shapes,

Regards

Attachments

Images (5)
  • orb 1615X
  • RGCC ZI1652A
  • VI1615X ORB
  • RGCC VE1615X
  • RGCAVI1615Y
Tags: journal, Orbit, FFT, Turbine, temperature, Major Inspection

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Am a bit confused....you say X and Y radial plan(e) but axial proximiter? Can you confirm we are talking radial measurements or axial "thrust" measurements

On initial glance, this data appears to show your orbit shaft highly preloaded in 0-180 deg direction. Not sure how you set up your probes so I am assuming the horizontal direction.  Since you state it was only an inspection, I would assume no work was done to it?  yes/no?

I would check carefully how you replaced the bearing after inspection.   Did you check alignment?

Regards

Jim P

RM
@Registered Member posted:

Am a bit confused....you say X and Y radial plan(e) but axial proximiter? Can you confirm we are talking radial measurements or axial "thrust" measurements

Absolutely, the journal bearing controlled by X,Y probes (radially) with position of 45 deg(X at 45 deg and Y at 135 deg), in addition also there is a displacement probe in the horizontal direction (thrust). the installed probes as following ;

in radial plan we have VI1615X AND VI1615Y

in thrust direction we have ZI1652A and ZI 1652B

On initial glance, this data appears to show your orbit shaft highly preloaded in 0-180 deg direction. Not sure how you set up your probes so I am assuming the horizontal direction.  Since you state it was only an inspection, I would assume no work was done to it?  yes/no? yes no work was done yet,



I would check carefully how you replaced the bearing after inspection.   Did you check alignment? absolutely, alignment check was done.

Regards

Jim P

hello Mr Jim

thank you , in above my answer for your question.

attached is the alignment report.

Regrads

Attachments

Images (1)
  • RGC-C Vibration  Brg01 01-09-202
RM

I dont have extensive field experience with gas turbines (others on this forum do), but it seems to me that the orbit displays you provided shows a very high preload in the horizontal direction  <--- assuming the 0 deg reference is the top/vertical direction.

Do you have orbits and vibration data from before recent inspection for comparison?

Orbit shapes will change with speed (and perhaps load) due to the accompanying dynamic stiffness changes. It would be nice to plot these various displays for proper interpretation.

Regards

Jim P

RM
Last edited by Registered Member

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