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How does one estimate the fluid loss based on plane bearing fit?

CalG

Diamond
Joined
Dec 30, 2008
Location
Vt USA
Consider a 1 inch shaft, plane bearing fit with .0015 clearance (no visible shake) two inches length No labyrinths or any such like.

100psi 10wt mineral oil at 100c ...

It's hard to even put it into qualitative terms. Is it pressure drop or volume loss?

eta

Oh! Shaft speeds between 1000 and 4000 rpm....
 
I can visualize the problem but I don't have the math. Some constraints would also have to be given or at least calculate answers for different conditions.

There should be formulas for the fluid friction through the clearance which would then let you calculate flow from the pressure. You have the case with a shaft centered and also with it displaced.

I'm interested in hearing from someone more competent than I to show the way.
 
Very Interesting! Where is oil being introduced? What is surface finish on both components? Why 100PSI? Where is the 100PSI being measured? Where is the temperature measured? Is the 0.0015 inch total diametrical clearance? Is this a circulating system? What is the radial load?
And while you are taking questions.

Why is Irma coming through here?
Way to many undefined conditions. Which member is rotating? IS the assembly vertical or hoz.? None of the studies, test and engineering data, that I have read, studied will not give you the answer you seek. If,IF you were paying me to determine the answer, I would have to duplicate your device in full size and capabilities and determine the oil flow in gpm@psi graph. Starting whenever the free component centered it self and continuing until max speed you specified was obtained or the rotating member lost its stability. I would ask for possibility of using a different oils. I interested in why you specify 100psig as the required operating pressure. Viscosity chartericis of some oil solutions change as temperature and pressure changes. If it is possible to eliminate the pressure requirement and let position of the rotating component govern, all would be better. Excuse me if I have misunderstood your question.
 
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http://allaboutmetallurgy.com/wp/wp...-Component-Design-by-Juvinall-and-Marshek.pdf

chapter 13 should give you a good start. i have a hard copy from 1983 and it doesn't say what version it is, its pretty similar to whats in the edition i "discovered" via google.. just now..

I might have an enter book on the subject somewhere, if i find it i'll let you know.

A wonderful reference.

The illumination of Ocvirks Short Bearing Approximation with the formula for side flow (R/c)^2 un/P is most helpful

But what really was most beneficial is the worked example that reveals a side flow of about 80% of total flow ;-)

Of course, the example is not a perfect match to my application, but I can deal with that. ;-) Thanks!
 
I went back and read the question. volume loss The pressure drop will at the orifice.

muckalee

What orifice are you thinking of?

It is the pressure drop across the bearing that I am most interested in, for the fluid pressure is required to perform other functions in addition to lubrication of the bearing described.
 
We will have to look at the schematic to determine the smallest passage. This is the resistance to flow that is allowing the 100PSIG to develop. What is supplying the flow? Positive displacement pump? Centrifugal pump? Accumulator? Is this a single rotatory system? Where is the pressure being measured? Is a relief valve in the system?
The clearance between the shaft and mating member may be the orifice. Calculate this clearance and use it as the orifice size. Not as a sharp edge orifice. If the oil is being introduced near the center of length, two orifices exist.
 








 
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