CFD analysis of hydrodynamic journal bearing with Bingham plastic lubricant considering roughness

Figures & data

Figure 1. Schematic of uniform sand-grain roughness model (Adams et al., 2012; ANSYS, 2019).

Table 1. Surface roughness level (JIS, 2013)

Ra (μm)	Ks (m)	Level
0	0	Ideal
0.4	2.345 x 10^−6	Fine
1.6	9.381 x 10^−6	Medium
12.5	7.329 x 10^−5	Rough

Figure 2. Scheme of journal bearing with surface roughness, (a) top view, (b) front view.

Table 2. Journal bearing parameter

Parameter	Symbol	Value	Unit
Bearing
Journal diameter	$D_j$	49.53	mm
Bushing diameter	Db	50	mm
Bushing length	$L_b$(Z)	50	mm
Radial clearance	$\mathit{C}$	0.235	mm
Attitude angle	φ	30	deg
Eccentricity ratio	ε	0.4, 0.6, 0.71, 0.8	-
Roughed surface length	LRz	50	mm
Roughed surface width	θRx	180	o
Roughness level	Ra	0, 0.4, 1.6, 12.5	µm
Rotating speed	ω	120	rpm
Lubricant
Lubricant density	$\mathit{\rho }$	960	kg/m^3
Lubricant viscosity	$\mathit{\mu }$	0.2	Pa.s
Vapor density	${\rho }_v$	0.02556	kg/m^3
Vapor viscosity	${\mu }_v$	1.256 x 10^−5	Pa.s

Figure 3. Results of the independence mesh study.

Figure 4. Representation in three dimensions of the meshed journal bearing.

Figure 5. Boundary condition of journal bearing.

Figure 6. Comparison between the result of the present investigation and the references (Gertzos et al., 2008; Wada et al., 1974).

Figure 7. Effect of surface roughness level on (a) load-carrying capacity, (b) friction force, and (c) average acoustic power level.

Figure 8. Distribution of hydrodynamic pressure of the bearing varying surface roughness levels.

Figure 9. Comparison of pressure contour of the bearing for several roughness levels: (a) R_a = 0 μm (Smooth), (b) R_a = 0.4 μm (Fine), (c) R_a = 1.6 μm (Medium), R_a = 12.5 μm (Rough).

Figure 10. Distribution of hydrodynamic pressure and vapor volume fraction varying surface roughness levels.

Figure 11. Effect of eccentricity ratio on (a) load-carrying capacity, (b) friction force, and (c) average acoustic power level of the roughed journal bearing.

Figure 12. Distribution of acoustic power level of roughed journal bearing varying eccentricity ratios.

Adams, T., Grant, C., & Watson, H. (2012). A simple algorithm to relate measured surface roughness to equivalent sand-grain roughness. International Journal of Mechanical Engineering and Mechatronics (IJMEM), 1, 66–71. https://doi.org/10.11159/IJMEM.2012.008

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