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Toroidal Vortex Flow Conditions for vortex flow: Taylor Number:

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Presentation on theme: "Toroidal Vortex Flow Conditions for vortex flow: Taylor Number:"— Presentation transcript:

1 Toroidal Vortex Flow Conditions for vortex flow: Taylor Number:
Reynolds Number: Figure Toroidal vortex flow in a journal bearing.

2 Mass Flow Figure Mass flow through rectangular-section control volume. (a) x-y plane; (b) y-z plane; (c) x-y plane. [From Hamrock and Dowson (1981).]

3 Reynolds Equation

4 Reynolds Equation Terms
Figure Density wedge. Figure Stretch mechanism.

5 Reynolds Equation Terms
Figure Physical wedge mechanism. Figure Normal squeeze mechanism.

6 Reynolds Equation Terms
Figure Translation squeeze mechanism. Figure Local expansion mechanism.

7 Possible Motion in Bearings
Figure Normal squeeze and sliding velocities.

8 Possible Motion in Bearings
Figure Normal squeeze and sliding velocities.

9 Parallel-Surface Slider Bearing
Figure Velocity profiles in a parallel-surface slider bearing.

10 Flow in Inclined Slider
Figure Flow within a fixed-incline slider bearing (a) Couette flow; (b) Poiseuille flow; (c) resulting velocity profile.

11 Thrust Bearing Figure Force components and oil film geometry in a hydrodynamically lubricated thrust sector. Figure Thrust bearing geometry.

12 Parallel-Surface Bearing
Figure Parallel-surface slider bearing.

13 Fixed-Incline Slider Bearing
Figure Fixed-incline slider bearing. Figure Pressure distributions of fixed-incline slider bearing.

14 Fixed-Incline Bearing Results
Figure Effect of film thickness ratio on normal load-carrying capacity. Figure Effect of film thickness ratio on force components.

15 Fixed-Incline Bearing Results
Figure Effect of film thickness ratio on friction coefficient parameter. Figure Effect of film thickness ratio on dimensionless volume flow rate.

16 Fixed-Incline Bearing Results
Figure Effect of film thickness ratio on dimensionless adiabatic temperature rise. Figure Effect of film thickness ratio on dimensionless center of pressure.

17 Streamlines in Fixed-Incline Slider Bearing
Figure Streamlines in fixed-incline bearing at four film thickness ratios Ho. (a) Ho =2; (b) Ho =1 (critical value).

18 Streamlines in Fixed-Incline Slider Bearing (cont.)
Figure Concluded. (c) Ho = 0.5; (d) Ho = 0.25.

19 Parallel-Step Bearing
Figure Parallel-step slider bearing.

20 Parallel-Step Pad Slider Bearing
Figure Finite parallel-step-pad slider bearing.

21 Parallel-Step-Pad Bearing Results

22 Parallel-Step-Pad Bearing Results

23 Parallel-Step-Pad Bearing Results
Figure Shrouded-step slider bearings. (a) Semicircular step; (b) truncated triangular step.

24 Fixed-Incline-Pad Slider Bearing
Figure Side view of fixed-incline-pad bearing. [From Raimondi and Boyd (1955).] Figure Configurations of multiple fixed-incline-pad thrust bearing. [From Raimondi and Boyd (1955).]

25 Film Thickness for Given Surface Finish

26 Fixed-Incline Slider Results
Figure Chart for determining minimum film thickness corresponding to maximum load or minimum power loss for various pad proportions - fixed-incline-pad bearings. [From Raimondi and Boyd (1955).]

27 Fixed-Incline Slider Results
Figure Chart for determining minimum film thickness for fixed-incline-pad thrust bearings. [From Raimondi and Boyd (1955).]

28 Fixed-Incline Slider Results
Figure Chart for determining dimensionless temperature rise due to viscous shear heating of lubricant in fixed-incline-pad thrust bearings. [From Raimondi and Boyd (1955)]

29 Fixed-Incline Slider Results
Figure Chart for determining performance parameters of fixed-incline-pad thrust bearings. (a) Friction coefficient; (b) power loss. [From Raimondi and Boyd (1955)].

30 Fixed-Incline Slider Results
Figure 9.9 Concluded. (c) Lubricant flow; (d) lubricant side flow.

31 Pivoted-Pad Slider Bearing
Figure Side view of pivoted-pad thrust bearing. [From Raimondi and Boyd (1955).] Figure Configuration of multiple pivoted-pad thrust bearing. [From Raimondi and Boyd (1955).]

32 Pivoted-Pad Slider Results
Figure Chart for determining pivot location corresponding to maximum load or minimum power loss for various pad proportions - pivoted-pad bearings. [From Raimondi and Boyd (1955).]

33 Pivoted-Pad Slider Results
Figure Chart for determining dimensionless temperature rise due to viscous shear heating of lubricant for pivoted-pad thrust bearing. [From Raimondi and Boyd (1955).] Figure Chart for determining outlet film thickness for pivoted-pad thrust bearings. [From Raimondi and Boyd (1955).]

34 Pivoted-Pad Slider Results
Figure Chart for determining performance parameters for pivoted-pad thrust bearings. (a) Dimensionless load; (b) friction coefficient. [From Raimondi and Boyd (1955).]

35 Pivoted-Pad Slider Results
Figure Concluded. (c) Lubricant flow; (d) lubricant side flow; (e) power loss.

36 Journal Bearing Figure 10.2 Unwrapped film shape in a journal bearing.
Figure Hydrodynamic journal bearing geometry.

37 Sommerfeld Angle

38 Full Sommerfeld Solution
Sommerfeld substitution: Pressure distribution: Maximum pressure: Figure Pressure distribution for full Sommerfeld solution.

39 Forces for Sommerfeld Solution
Figure Coordinate system and force components in a journal bearing. Figure Vector forces acting on a journal.

40 Reynolds Boundary Condition
Figure Pressure profile for a journal bearing using Reynolds boundary condition. Figure Location of shaft center for full and half Sommerfeld journal bearing solutions.

41 Hydrodynamic Journal Bearings
Sommerfeld number: Diameter-to-width ratio: Figure Pressure distribution around a journal bearing.

42 Film Thickness and Eccentricity
Figure Effect of bearing number on minimum film thickness for four diameter-to-width ratios. [From Raimondi and Boyd (1958)].

43 Attitude Angle Figure Effect of bearing number on attitude angle for four diameter-to-width ratios. [From Raimondi and Boyd (1958).]

44 Friction Coefficient Figure Effect of bearing number on friction coefficient for four diameter-to-width ratios. [From Raimondi and Boyd (1958).]

45 Fluid Flow Figure Effect of bearing number on dimensionless flow rate for four diameter-to-width ratios. [From Raimondi and Boyd (1958).] Figure Effect of bearing number on volume side flow ratio for four diameter-to-width ratios. [From Raimondi and Boyd (1958).]

46 Maximum Pressure & Location
Figure Effect of bearing number on dimensionless maximum film pressure for four diameter-to-width ratios. [From Raimondi and Boyd (1958).] Figure Effect of bearing number on location of terminating and maximum pressures for four diameter-to-width ratios. [From Raimondi and Boyd (1958).]

47 Effect of Radial Clearance
Figure Effect of radial clearance on some performance parameters for a particular case.

48 Fixed-Incline Pad Journal Bearings

49 Effect of Preload Figure Effect of preload factor mp on two-lobe bearings. (a) Largest shaft that fits in bearing. (b) mp =0; largest shaft, ra; bearing clearance cb = c. (c) mp =1.0; largest shaft, rb; bearing clearance cb =0. [From Allaire and Flack (1980).]

50 Hydrodynamic Squeeze Film Bearings
Figure Journal bearing with normal squeeze film action. Rotational velocities are all zero. Figure Parallel-surface squeeze film bearing.

51 Parallel Circular Plate
Load support: Time of approach: Figure Parallel circular plate approaching a plane surface.

52 Rigid Cylinder Load support: Time of approach:
Figure Rigid cylinder approaching a plane surface.


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