Shaft Centerline Movement of Overhung Rotor

What will be the normal shaft centreline movement for Overhung Rotor supported by tilting pad bearings? Particularly with reference to a light overhung rotor, like Power Turbine Shaft in twin-shaft gas turbine driving heavier centrifugal compressor rotor.

I have attached shaft centreline movements for 2 different set of machines. In one case, power turbine is driving LP and HP rotors.

In another case, Power turbine is driving only 1 HP Rotor. 

 

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Shaft Centerline Movement of Overhung Rotors
Original Post

If gravity is the main force, one expects journals in tilt pads to move up.  I see different probe orientations, check that things are wired in accordance with the indicated probe orientations.

On GTs thermal growth can complicate the shaft plots, but the ones going aT 45 degrees looks suspicious for thermal growth of the mounting.  Check the wiring compared to the configured probe orientations.

The issue is that 3 identical trains have almost identical SCL and the other 7 identical trains also have identical behavior. All trains are Solar Titan 130. How likely is it that they have all been wired incorrectly.

Also this is an overhung rotor. So journal at Bearing No. 4 will move up and move down at bearing no.5. Concerning thing is the side load and movement.

Unless the loading is up on bearing 5, it should move up if  there is a net downward loading (static loading).

The wiring configuration of your setup could be consistently inconsistent with the actual field wiring.  Have you checked how it is configured compared to the actual physical orientation?

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