Prediction on Flow and Thermal Characteristics of Ultrathin Lubricant Film of Hydrodynamic Journal Bearing
Abstract
:1. Introduction
2. Numerical Method
2.1. Physical Model
2.2. Governing Equations
2.2.1. Reynolds Equation
2.2.2. Energy Equation
2.2.3. Viscosity-Temperature Equation
2.2.4. Cavitation
2.2.5. Sommerfeld Number
2.3. Boundary Conditions
2.3.1. No-Slip Boundary Conditions
2.3.2. Slip Boundary Conditions
2.4. Mesh Independence Verification
2.5. Validation of Model
3. Results and Discussion
3.1. Effects of Eccentricity Ratios
3.2. Effects of Length Diameter Ratios
3.3. Effects of Bearing Speeds
3.4. Effects of Clearance Ratios
4. Conclusions
- An increase in eccentricity ratio enlarges the differences between maximum and minimum peaks of thickness, flow rate and heat dissipation, severely strengthens the maximum peaks of pressure and temperature, and aggravates the degree of cavitation.
- A growth in length diameter ratio leads to the rise of the maximum peaks in pressure and temperature distributions, and promotes the degree of cavitation, meanwhile, intensify the differences between the maximum and minimum peaks of flow rate and heat dissipation.
- A rise in the bearing speed strongly increases the maximum peak of temperature, magnifies the distinctions between maximum and minimum peaks of flow rate, nevertheless, shrinks those of heat dissipation, and has slightly influence of cavitation.
- A lift in clearance ratios result in a sharply decline in maximum peak of temperature, exaggerating the differences between maximum and minimum peaks of heat dissipation, a mild decrease in the minimum flow rate, and slight effect on the maximum flow rate and cavitation.
- It is suggested that the optimization conditions for HJB can be a relative high eccentricity, medium length diameter ratio, relative high bearing speed, as well as medium clearance ratio, and in this research the combination could be ε = 0.6, L/D = 0.7, ω = 6 × 103 rpm and α = 0.003.
Author Contributions
Funding
Conflicts of Interest
Nomenclature
Symbols | Z | Dimensionless bearing length | |
C | Radial clearance, m | z | Axial direction |
C | Specific heat capacity, J·(kg·K)−1 | ||
D | Journal diameter, m | Greek | |
e | Eccentricity | α | Clearance ratio |
H | Dimensionless film thickness | ε | Eccentricity ratio |
h | Film thickness, m | μ | Dynamic viscosity, Pa·s−1 |
k | heat transfer coefficient, W·(m2·K)−1 | μ0 | Initial dynamic viscosity, Pa·s−1 |
L | Bearing length, m | θ | Angular coordinate, rad |
P | Dimensionless pressure | η* | Dimensionless viscosity |
p | Lubricant pressure, Pa | viscosity dissipation, W·m−3 | |
R | Journal radius, m | ρ | Lubricant density, kg·m−3 |
T | Lubricant temperature, K | ρ0 | Initial lubricant density, kg·m−3 |
U | Tangential velocity of bearing, m/s | ω | Bearing speed, rpm |
u | velocity component in x direction | ||
v | velocity component in y, z direction | Subscripts | |
W | Bearing load, N | b | bearing |
w | velocity component in z direction | c | cavitation |
x | Circumference direction | j | journal |
y | Radial direction | o | original |
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Parameter Name | Value |
---|---|
Bearing length (L), m | 6 × 10−2~1.2 × 10−1 |
Shaft radius (R), m | 6 × 10−2 |
Initial Radial clearance (C0), m | 1.2 × 10−2~2.4 × 10−2 |
Initial temperature (T0), K | 313 |
Initial dynamic viscosity of lubricant oil at 313 K (η0), Pa·s | 2.77 × 10−2 |
Initial density of lubricant at 313 K (ρ0), kg·m−3 | 860 |
Specific heat capacity of lubricant (C), J·(kg·K)−1 | 2000 |
Heat transfer coefficient of lubricant (h), W·(m2·K)−1 | 80 |
Eccentricity ratio (ε) | 0.3~0.7 |
Bearing speed (ω), rpm | 3 × 103~9 × 103 |
Bearing Length (L), m | Shaft Radius (R), m | Initial Radial Clearance (C0), m | Eccentricity Ratio (ε) | Bearing Speed (ω), rpm |
---|---|---|---|---|
0.1 × 10−1 | 0.6 × 10−1 | 0.18 × 10−3 | 0.6 | 6 × 103 |
Bearing Length (L), m | Shaft Radius (R), m | Initial Radial Clearance (C0), m | Lubricant Viscosity at 313 K (μ), Pa·s | Bearing Speed (ω), rpm |
---|---|---|---|---|
0.8 × 10−1 | 0.5 × 10−1 | 0.145 × 10−3 | 0.0277 | 6 × 103 |
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Jiang, Y.; Liang, B.; Huang, Z.; Chen, Z.; Xu, B. Prediction on Flow and Thermal Characteristics of Ultrathin Lubricant Film of Hydrodynamic Journal Bearing. Micromachines 2021, 12, 1208. https://doi.org/10.3390/mi12101208
Jiang Y, Liang B, Huang Z, Chen Z, Xu B. Prediction on Flow and Thermal Characteristics of Ultrathin Lubricant Film of Hydrodynamic Journal Bearing. Micromachines. 2021; 12(10):1208. https://doi.org/10.3390/mi12101208
Chicago/Turabian StyleJiang, Yulong, Bo Liang, Zhongwen Huang, Zhenqian Chen, and Bo Xu. 2021. "Prediction on Flow and Thermal Characteristics of Ultrathin Lubricant Film of Hydrodynamic Journal Bearing" Micromachines 12, no. 10: 1208. https://doi.org/10.3390/mi12101208
APA StyleJiang, Y., Liang, B., Huang, Z., Chen, Z., & Xu, B. (2021). Prediction on Flow and Thermal Characteristics of Ultrathin Lubricant Film of Hydrodynamic Journal Bearing. Micromachines, 12(10), 1208. https://doi.org/10.3390/mi12101208