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Saturday, 25 August 2018

POWER ABSORBED IN VISCOUS FLOW

We were discussing the basic concept of kinetic energy correction factor and momentum correction factor, in the subject of fluid mechanics, in our recent posts. 

Now we will go ahead to find out the basic concept of power absorbed in viscous flow and we will also see here the required power to overcome the viscous resistance, in the subject of fluid mechanics, with the help of this post. 

Power absorbed in viscous flow

As we know that oil is used as lubricant for the lubrication of machine parts. Now let us consider the case of oil lubricated bearings as one example to understand this concept. Flow of oil in oil lubricated bearing will be a good example of viscous flow. 

Let us consider that we are using high viscosity grade oil as lubricant for the lubrication of bearings. High viscosity grade oil will offer higher resistance and hence more power will be lost. 

If we will use oil of lower viscosity grade as the lubricant for the lubrication of bearings, there will not be any possibility to secure the desired oil film thickness between rotating components and stationary metal surface. Therefore, there will be more wear and tear and service life of bearings (in this case) will be reduced. 

Therefore, it is very important to select the correct viscosity grade oil as the lubricant for bearings.
We will now find out the power required to overcome the viscous resistance in following conditions. 

  1. Viscous resistance of journal bearings
  2. Viscous resistance of foot-step bearings
  3. Viscous resistance of collar bearings

Now we will go ahead to start a new topic in the subject of fluid mechanics i.e. power requirement to overcome the viscous resistance of journal bearings

Do you have any suggestions? Please write in comment box. 

Reference: 

Fluid mechanics, By R. K. Bansal  
Image Courtesy: Google  

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