How to calculate the jacking oil feed volume required to support the rotor with a minimum oil-film thickness when the jacking pressure is about 178 bar.

 

praveenkumar_k,

What has prompted this question? Was some mechanical work done on the unit which involved making adjustments to the jacking oil system?

What have you done to try to resolve the problem?

What IS the problem? Are you not getting enough lift? Too much lift?

To my knowledge, jacking oil flow-rate is not measured. Jacking oil pressure is measured, and on many turbines there are valves at each bearing which act like variable orifices which are used to achieve the desired lift, then locked into position (though many times the keys are left in the locks, only to be broken off...).

I'm certain that factory personnel have some method for determine approximate required flow-rates, but then they specify and install the variable orifices for the eventual changes required for actual (not theoretical) conditions, and wear and new bearing replacement and/or shaft work. But, I'm not aware of any field calculation procedure used to determine a required flow-rate (at least on GE-design heavy duty gas turbines and generators).

So, if new bearing(s) were installed, or the existing bearing(s) were moved/relocated for alignment purposes, or something like that, and now the desired lift is not being achieved (or is excessive, perhaps? we don't really know what the problem is that's prompting this question), then the first place I've seen mechanics (not controls people--mechanics) go is to try adjusting the variable orifices at the bearing(s) were the lift is not as desired or required.

I make my comments about GE heavy duty gas turbines built in the USA. (And here's another missing piece of information: What kind of equipment is experiencing some kind of issue--or is this just a generic question and hot related to a specific problem--we just don't know because we don't have enough information.) GE heavy duty gas turbines built outside of the USA can be VERY different beasts--in terms of auxiliaries and sensors and control schemes, including lift oil. And the twain shall never meet.

So, give us a little more information--to prevent us from having to make presumptions (because good engineers never make assumptions!)--and perhaps we can help. Perhaps. This is more of a controls-related forum, and this isn't really a controls issue (at least based on the (dearth of) information provided). Yes; often we cover mechanical equipment as it's affected or affects controls issues. But (without more information!) this doesn't really seem to be a controls issue (though I'm sure the Mechanical Department, which doesn't seem to be involved (from the information provided!) wants it to be a controls issue. Or, the Operations Department is trying to get some information to build a fire under the Mechanical Department to get the lift set properly so the unit can be started and run and revenue generated to make the Billing Department happy (if that's even really possible).