thrust runner design
thrust runner design
(OP)
The results of sectional-3D FEA on a Thrust Runner show that the Runner "bows" under the thrust load. The axial displacement of the periphery of the Runner is ~60 µm. The thickness of fluid-film between the Thrust Runner and Tilting Pads is estimated to be ~10 µm.
Radial interference of 5 mils/inch diameter is modeled between the Shaft and the Runner. The applied loads are: (i) Interference, (ii) Centrifugal, and (iii) Axial Thrust (mapped from 1 Tilting Pad on to the Runner Surface).
I am concerned that the excessive deformation on the periphery of the Runner will cause the lubricant film to be unsustainable, and drastically reduce the load-carrying capacity.
My question is, how much displacement is allowable on the Runner?





RE: thrust runner design
RE: thrust runner design
Mike Halloran
Pembroke Pines, FL, USA
RE: thrust runner design
Some EP additives and viscosity modifiers have a pronounced effect on the displacement of an oil film.
RE: thrust runner design
Mike,
We use pressure mapping obtained from one of the bearing analysis codes to generate the FEA pressure loads on the face of the pad. So, there is no "fluid-film model".
Are you suggesting that it may be possible to perform the entire fluid-structure interaction simulation in some kind of a software package?
Can you send me more information on such a simulation?
RE: thrust runner design
<<<
I'm suggesting that it _should_ be possible, given any of today's "multiphysics" solvers, and enough computer. to analyze the flow through a bearing with flexible pads.
I'm not suggesting it will be easy or straightforward.
Mike Halloran
Pembroke Pines, FL, USA
RE: thrust runner design
What would be the largest permissible axial deflection at the OD of Thrust Runner? The working surface on the Thrust Runner is ~15" OD x 6.5" ID.
RE: thrust runner design
Can you increase the thickness of the thrust runner or change materials to decrease the deflection?
RE: thrust runner design
Can you add stiffeners or ribs behind (on the back side) of the thrust runner to prevent movement?
Seems like you got a more of "structural" strength (bending-related) problem due to high loads trying to go through the metal runner, rather than a lubricant-caused problem between the runner and the fixed surface.
RE: thrust runner design
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(2B)+(2B)' ?
RE: thrust runner design
This program was used to correct some bearing problems in our HNO3 plant compressor which allowed us to operate a higher RPM from a safe 10,000 RPM to a safe 12,500 rpm, a previously unsteady operating point. 25,000 hp likes steady state operation.
http://www.rsr.com/index.html
RE: thrust runner design
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(2B)+(2B)' ?
RE: thrust runner design
Mike Halloran
Pembroke Pines, FL, USA
RE: thrust runner design
GSB, can you provide any information on the dimensions of the thrust runner, axial load, shaft rpm, etc. that would give me and others a better idea of what you are up against. I mean a 60µm deflection isn't all that big if your thrust runner is 120 inches in diameter.
Regards,
Tom Moritz
US Bureau of Reclamation
Tom Moritz
Mechanical Engineer
US Bureau of Reclamation
RE: thrust runner design
We've been talking 5 mils per inch
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(2B)+(2B)' ?
RE: thrust runner design
Tom Moritz
Mechanical Engineer
US Bureau of Reclamation