Calculating or measuring heat generation in a thrust bearing assembly

[thrusterpump]

I have a vertical shaft, 2 thrust bearing configurationin a stationary housing where the bearing cones are spinning at a constant speed with a known axial thrust load. I would like to hear some of your ideas on how to determine the heat generation with a given grease lube or how to use available information to determine the heat generation. Any advice is appreciated.

 

[reidh]

I'm partial to measuring the temperature and calculating the heat load. Thermocouples distributed around the object of interest is a cheap and simple way to measure temperature, which can then be used to calculate heat load.

Reidh

 

[electricpete]

what's a bearing cone? Is that the rollers in a wheel style bearing?

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[thrusterpump]

Reidh,

The information i have available is just as you mentioned. I have various thermocouples recording temperatures on the housing, bearing races etc. Can you refer me to some information on calculating the heat load. Thanks!

 

[reidh]

The equations you need are:

h=k/delta X
Qdot=h*A*delta T

You can look up the thermal conductivity (k value) of all the materials that are physically between the source of heat and your thermocouples, including grease lube, metal etc.

Then calculate your h value by dividing your k value by the distance that the heat would have to travel through each medium. For example, if you are measuring the temperature on the outer race, you would use the k value of the race metal and the thickness of the race as delta X.

Sum all of your h values by using (1/h1+1/h2+1/h3...)^-1

Your A is the cross sectional area that the heat travels through, such as the surface area of the outer race.

Delta T is your measured temperature - ambient temperature.

Hopefully somebody else can verify these equations, I am currently on travel overseas and don't have my usual textbooks handy to check these formulas. This is all from memory, which is not getting any better with age...

Reidh

 

[handleman]

Do you want to know the heat generation, or are you really interested in the bearing temperature? If you can find the frictional resistance torque of the bearing and you know the shaft speed you can calculate the work done per unit time. Pretty much all of that work is heat generation.

 

[MarkUMSU]

I just went though a similar exercise last week and found the SKF Frictional Moment/Power Loss calcs to be quite detailed and helpful.

http://www.skf.com/skf/productcatalogue/calculationsFilter?lang=en&newlink=&prodid=&action=Calc5

 

[MarkUMSU]

I just went through a similar exercise last week and found the SKF Frictional Moment/Power Loss calcs to be quite detailed and helpful.

http://www.skf.com/skf/productcatalogue/calculationsFilter?lang=en&newlink=&prodid=&action=Calc5