Fluid Film Lubrication

Explain the phenomenon of squeeze film lubrication. Also state the practical application of squeeze film action. 4

Derive Reynolds's equation for 3-D hydrodynamic lubrication. Also state the assumptions made in this derivation. 10

Explain: 6

1. Full Sommerfeld number and half sommerfeld conditions.
2. Reynold's condition

Draw a neat sketch of a Hydrodynamic Journal Bearing with the pressure distribution and derive the expression for eccentricity ratio and minimum oil film thickness ratio. 8

The Rayleigh step bearing of length 213 mm and width 860 mm is required to support 150 kN load. The sum of surface roughness on contacting surfaces of bearing is 5 microns. The minimum oil-film thickness required is 20 times the sum of surface roughness on contacting surfaces. The sliding velocity is 8 m/s. Using optimum conditions, calculate: 14

1. The location of step
2. The maximum oil-film thickness
3. The viscosity of lubricating oil
4. The maximum pressure
5. The ratio of maximum pressure to average pressure

Discuss behaviour and boundary conditions used in non-circular bearings. 7

Discuss the optimum design of hydrostatic step bearing. 7

Explain the working principle of hydrostatic thrust bearing. 7

Explain the function of Restrictor in Hydrostatic Lubrication System. What are the advantages and limitations of Hydrostatic Bearing? 7

State applications of gas bearings? Derive the governing equation of gas bearings. 7

Explain the following numerical methods for solution of fluid film bearing: 7

1. Orthogonality method
2. Finite difference method

Explain the following terms related to rolling contact bearings: 9

1. Bearing life
2. Series of ball bearing
3. Self aligning rolling contact bearing

Where will you use lubricating oil and grease as lubricant in rolling contact bearing? State giving relative advantages and disadvantages. 5

Write short note on the following: 14