Bearing support stiffness

[tgmcg]

I'm looking for info on the range of bearing support stiffnesses that might apply to 2000 HP, 6-stage, barrel-type centrifugal compressor running at 10,000 rpm. Not bearing stiffness, but the Kxx & Kyy stiffnesses of the bearing housings themselves.

I'm performing a rotordynamic analysis of this compressor. I don't have time or access right now to perform an impact test, so would like to approximate these stiffnesses with data from similar installations.

Many thanks!

Tom

 

[GregLocock]

In my experience driving point stiffnesses in excess of 50000 N/mm are rare, with 30000 being more typical. So maybe 100000 for a well designed robust bearing housing.

Cheers

Greg Locock

 

[vanstoja]

Bearing housing rather than bearing fluid film stiffness is a structural geometry-related problem that requires some definition of the actual geometry involved for solution or estimation. I would guess that the bearing housing of a compressor gas bearing is more or less a cylindrical shell structure whose ID, OD and end fixation conditions coupled with the bearing static loading can be solved for deflection with thick or thin shell deflection equations found in any good machine design or structural design book. The main problem is usually that of deciding what end conditions to use since the real geometry rarely gives the available combinations of idealized fixed, free, supported, hinged,etc conditions.