Thermoelastic distortion in thin film hydrodynamic thrust bearings can lead to material failure if not controlled. The document proposes incorporating a cooling circuit near the heat source in thrust bearing pads to reduce oil film temperature. It describes solving the Reynolds, energy, heat conduction, and biharmonic equations to analyze pressure distribution, temperature distribution, heat transfer, and thermal/pressure deformations with and without the cooling circuit. Results show maximum temperatures decrease with increasing coolant flow velocity, indicating the cooling circuit is effective at controlling thermal effects and protecting the bearing pads.

1. THERMOELASTIC DISTORSION AND ITS CONTROL IN THIN
FILM HYDRODYNAMIC LUBRICATION THRUST BEARINGS
Presented by
Farooq Ahmad Najar
Under track Fluid Film Bearings
2015 STLE Annual Meeting & Exhibition,17-21 May 2015
Venue: Trinity 1, Omni Hotel Dallas, Texas USA
Time: 2030 hours
Dated: 21 May 2015
Session Chair: Michael Fillon

2. THERMOELASTIC DISTORSION AND ITS CONTROL IN THIN FILM
HYDRODYNAMIC LUBRICATION THRUST BEARINGS
 By
 Farooq Ahmad Najar
 Research Scholar
 Under the Supervision of
 Prof. G A Harmain

 Department of Mechanical Engineering
 National Institute of Technology
 Srinagar-190006, (J&K), India

3. Contents
 Outline
 Objectives of present work
 Motivation
 Methodology
 Numerical work & Solutions
 Reynolds Equation
 Energy Equation
 Heat Conduction Equation
 Biharmonic equation
 Results and Discussions
 Conclusion

4. Overview
 Conventional cooling of thrust bearings
 Thermo elastic deformation
 Piezoelastic deformation
 Material Failure of pads due to overheating.
 Innovative method of cooling pads.
 Increased Efficiency and availability of serviceability

5. Thrust bearing pads and their characteristic dimensions.

6. Deformations and damage of
Thrust Segments
Less due to Pressure & More due
to Temperature

7. Handmade Pad Set Model for Thrust Bearing Presenting
the new Cooling arrangement

8. Problem Description
 The present problem addresses the control of thermal effects
on a sector shaped pad extensively used in thrust bearings
which supports the heavy axial loads.
 Large hydro-generator thrust bearings are susceptible to
thermo-elastic deformation when oil film thickness is
subjected to high pressure and temperature which can even
lead to the bearing failure.
 The present study is an effort towards reducing the oil film
temperature by incorporating a suitable cooling
arrangement in the proximity of heat source.
 The cooling circuit, in this study, essentially follows a path of
hot spots observed by solving energy equation and
generalized conduction equation.
 The numerical scheme followed during investigation is finite
difference method (FDM).

9. Objectives
 To compute the pressure distribution in the oil film between pad
surface and runner by solving generalized Reynolds’s Equation
after introducing a cooling circuit.
 To compute the temperature distribution in the oil film by solving
Energy Equation with and without viscosity variation in
conventional pad and non conventional one.
 To compute the heat transfer between pad and water circuit by
solving 3D heat conduction equation.
 To study the pressure induced deformation and temperature
induced deformation of pad by solving 4th order bi-harmonic
equation.

10. Motivation
 Control of thermal effects.
 Temperature-viscosity variations lead to hot-spots ----
thin Babbitt lining gets damaged to a great extent.
 The conventional cooling --outside of thrust bearing
pads.
 An alternative way of cooling --Close proximity of
cooling arrangement to the actual location of heat
production.

11. Governing Equations
 Generalized Reynolds Equation
 Equation of Film Geometry
 Energy Equation
 Three Dimensional Heat Conduction Equation
 4th Order Bi-harmonic Equation.

12. Reynolds Equation
 where h is the film thickness, µ is the viscosity of oil
and ω is the angular speed of the runner.

13. Equation of Film Geometry
 where h is the film thickness, h0 is the minimum film
thickness, hs is the taper, θ and θt are the general
angular extent and total angular extent of the pad
respectively.

14. Energy Equation
where, ρ is the density of oil and cv is the
specific heat of the oil

15. Three dimensional heat conduction
equation
Kr, Kθ and Kz represent thermal conductivity of the pad in
radial, circumferential and (thickness) directions respectively,
and r,θ and z are the cylindrical coordinates.

16. Biharmonic Equation
 Where Load = Hydrodynamic Pressure or Thermal stress

17. The numerical strategy followed for
pressure distribution

18. Continued

19. Continued

20. Pressure Generation

21. Different possible cooling arrangements
in a thrust pad

22. Flow chart for computation

23. Continued

25. Temperature Profile

28. Maximum nodal Temperature (oC) Values along with the depth of
Pad.Pad Depth
In terms of Z’s
Flow Velocity(V=0.5m/s) Flow Velocity(V=1.0m/s) Flow Velocity(V=1.5m/s) Flow Velocity(V=2.0m/s)
Z=2 57.30 56.14 55.11 54.18
Z=3 52.05 50.48 49.05 47.70
Z=4 49.85 48.11 46.50 44.77
Z=5 48.93 47.11 45.43 43.09

30. THANK YOU