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February 19th, 2019, 02:16 AM   #1
Joined: Feb 2018
From: England

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Speed of rotation.

Hi All,

How can I find of the speed of rotation without rpm or any speed?

A bearing on a flywheel has a diameter of 28.0mm and axial length 18.0mm with a radial clearance of 14.4 micro m. The kinematic viscosity of the lubricating oil is 2.09 x 10^-5 m^2 S^-1 and the density is 835kg m^-3.
If the power loss of the bearing is 1.34KW, how is it possible to calculate the rotation?

I am unable to calculate the angular velocity and rotation rate without ω?
ω = 2 πn/60

I have also tried using Petrov's equation
Power loss - 2 πR³lw²/Cr.

Any guidance would be appreciated.

Last edited by skipjack; February 19th, 2019 at 05:17 PM.
NAC54321 is offline  
February 19th, 2019, 05:41 AM   #2
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I think Petroff's equation is the one to use here. Can you rearrange it to make the angular velocity the subject?
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February 19th, 2019, 12:20 PM   #3
Joined: Feb 2018
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Hi Benit13,

I was thinking the same but doubting myself its the wrong approach.
I will try rearranging the equation, not an easy one is it.

Many thanks.
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