Abstract
In itself, there is a very thin boundary layer physically adsorbed to the bearing surface. When the bearing clearance is far larger than the thickness of this layer, the boundary layer effect in the bearing is negligible, and conventional hydrodynamic lubrication theory just addresses on this topic. However, with the worsening of the operating condition, the bearing clearance can be largely reduced and comparable to the thickness of the adsorbed boundary layer. For this case, the effect of the adsorbed boundary layer must be considered. The present paper presents the multiscale analysis for the performance of the hydrodynamic journal bearing in a wide range of bearing clearance considering the effect of the physically adsorbed boundary layer. The calculation results indicate for how low bearing clearances the adsorbed boundary layer effect should be incorporated. When the minimum bearing clearance is on the same scale with the thickness of the adsorbed boundary layer, the hydrodynamic pressure in the bearing is locally largely increased by the effect of the adsorbed boundary layer, and the load-carrying capacity of the bearing is correspondingly largely increased. This is particularly significant for a strong fluid-bearing surface interaction. The study shows the great contribution of the physically adsorbed boundary layer to the performance of the hydrodynamic journal bearing in the condition of low surface clearances, and indicates the necessity of the multiscale analysis for this bearing.
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Abbreviations
- a 0, a 1, a 2 :
-
constants
- c :
-
bearing clearance, R-r
- C q :
-
ρ effbf /ρ
- C y :
-
η effbf /η
- D :
-
fluid molecule diameter
- e :
-
eccentricity of the bearing
- h :
-
continuum fluid film thickness
- h bf :
-
thicknesses of the adsorbed boundary layer
- h cr,bf :
-
critical thickness
- H bf :
-
hbf/hcr,bf
- K :
-
hbf/c
- m 0, m 1, m 2, m 3 :
-
constants
- N :
-
numbers of the discretized points
- p :
-
hydrodynamic pressure
- P :
-
dimensionless hydrodynamic pressure
- P conv :
-
hydrodynamic pressure calculated from the conventional hydrodynamic theory
- q 0 :
-
Δj+1/Δj
- q m :
-
mass flow rate per unit contact length through the bearing
- Q m :
-
dimensionless mass flow rate per unit contact length through the bearing
- r :
-
radius of the shaft
- R :
-
radius of the sleeve
- u :
-
shaft circumferential speed
- w :
-
load per unit contact length carried by the bearing
- W :
-
dimensionless load per unit contact length carried by the bearing
- x, y :
-
coordinates
- β :
-
angel, Equation (20)
- γ :
-
exponent
- ε :
-
eccentricity ratio, e/c
- ε 0 :
-
parameter, Equation (28)
- λ bf :
-
hbf/h
- ϕ :
-
angular coordinate
- ϕ 0 :
-
angular coordinate of the location where the maximum pressure occurs in the bearing
- ϕ e :
-
angular coordinate of the exit of the bearing
- Δϕ :
-
envelope angles of the two neighboring discretized points
- Δx :
-
separation between the neighboring fluid molecules in the circumferential direction in the adsorbed layer
- Δj :
-
separation between the (j+1)th and jth fluid molecules across the layer thickness
- Δn−2 :
-
separation between the neighboring fluid molecules across the layer thickness just on the adsorbed layer-fluid interface
- θ 0,conv :
-
sommerfeld transformation angle, π-β
- ρ :
-
fluid bulk density
- ρ effbf : effective density of the adsorbed layer η :
-
fluid bulk viscosity
- η eff bf :
-
effective viscosity of the adsorbed boundary layer
- η linc, j−1 :
-
local viscosity between the jth and (j−1)th fluid molecules across the adsorbed layer thickness
- conv :
-
calculated from the conventional hydrodynamic theory
- i :
-
on the ith discretized point
References
Aktas, O. and Aluru, N. R. (2002). A combined continuum/DSMC technique for multiscale analysis of microfluidic filters. J. Computational Physics 178, 2, 342–372.
Allmaier, H., Sander, D. E., Priebsch, H. H., Witt, M., Füllenbach, T. and Skiadas, A. (2016). Non-Newtonian and running-in wear effects in journal bearings operating under mixed lubrication. Proc. Institution of Mechanical Engineers, Part J: J. Engineering Tribology 230, 2, 135–142.
Begelinger, A. and Gee de, A. W. J. (1974). Thin film lubrication of sliding point contacts of AISI 52100 steel. Wear 28, 1, 103–114.
Begelinger, A. and Gee de, A. W. J. (1976). On the mechanism of lubricant film failure in sliding concentrated steel contacts. ASME J. Lubrication Technology, 98, 575–579.
Begelinger, A. and Gee de, A. W. J. (1978). Wear in lubricated journal bearings. ASME J. Lubrication Technology, 100, 104–109.
Choi, J., Kim, S. S., Rhim, S. S. and Choi, J. H. (2012). Numerical modeling of journal bearing considering both elastohydrodynamic lubrication and multi-flexible-body dynamics. Int. J. Automotive Technology 13, 2, 255–261.
Gulwadi, S. D. and Shrimpling, G. (2003). Journal bearing analysis in engines using simulation techniques. SAE Trans., 406–431.
Jabbarzadeh, A., Atkinson, J. D. and Tanner, R. I. (1997). Rheological properties of thin liquid films by molecular dynamics simulations. J. Non-Newtonian Fluid Mechanics 69, 2–3, 169–193.
Lin, D. T. W. and Chen, C. K. (2004). A molecular dynamics simulation of TIP4P and Lennard-Jones water in nanochannel. Acta Mechanica 173, 1, 181–194.
Lin, W., Li, J. and Zhang, Y. (2022a). Comparison of the models for multiscale elastohydrodynamic lubrication in a line contact. J. Applied Fluid Mechanics 15, 2, 515–521.
Lin, W., Li, J. and Zhang, Y. (2022b). Mass transfer in the filtration membrane covering from macroscale, multiscale to nanoscale. Membrane and Water Treatment 13, 4, 167–172.
Liu, J., Chen, S., Nie, X. and Robbins, M. O. (2007). A continuum—atomistic simulation of heat transfer in micro-and nano-flows. J. Computational Physics 227, 1, 279–291.
Mishra, P. C. (2013). Mathematical modeling of stability in rough elliptic bore misaligned journal bearing considering thermal and non-Newtonian effects. Applied Mathematical Modelling 37, 8, 5896–5912.
Muzakkir, S. M., Hirani, H. and Thakre, G. D. (2013). Lubricant for heavily loaded slow-speed journal bearing. Tribology Trans. 56, 6, 1060–1068.
Pinkus, O. and Sternlicht, B. (1961). Theory of Hydrodynamic Lubrication. McGraw-Hill. New York, NY, USA.
Pradhan, S. K., Kumar, R. and Mishra, P. C. (2021). Material modeling and optimization of rough elliptic bore journal bearing. Materials Today: Proc., 44, 1021–1027.
Xie, F., Zhang, Y. and Chen, H. (2020). Analysis of hydrodynamic journal bearing with mixed hydrodynamic and boundary films. Australian J. Mechanical Engineering, DOI: https://doi.org/10.1080/14484846.2020.1790477
Yen, T. H., Soong, C. Y. and Tzeng, P. Y. (2007). Hybrid molecular dynamics-continuum simulation for nano/mesoscale channel flows. Microfluidics and Nanofuidics 3, 6, 665–675.
Zhang, Y. (2004). Modelling of molecularly thin film elastohydrodynamic lubrication. J. Balkan Tribological Association, 10, 394–421.
Zhang, Y. (2014). Lubrication analysis for a line contact covering from boundary lubrication to hydrodynamic lubrication: Part I-Micro contact results. J. Computational and Theoretical Nanoscience 11, 1, 62–70.
Zhang, Y. (2015). The flow factor approach model for the fluid flow in a nano channel. Int. J. Heat and Mass Transfer, 89, 733–742.
Zhang, Y. (2020). Modeling of flow in a very small surface separation. Applied Mathematical Modelling, 82, 573–586.
Zhang, Y. B. (2021). New explanation for the measured very low film thicknesses in lubricated concentrated contacts. J. Balkan Tribological Association 27, 3, 439–444.
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Gu, K., Shao, S. & Zhang, Y. Multiscale Analysis of Hydrodynamic Journal Bearing Considering the Effect of the Physically Adsorbed Boundary Layer. Int.J Automot. Technol. 24, 335–345 (2023). https://doi.org/10.1007/s12239-023-0028-3
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DOI: https://doi.org/10.1007/s12239-023-0028-3