Limits...
A Thermal Equilibrium Analysis of Line Contact Hydrodynamic Lubrication Considering the Influences of Reynolds Number, Load and Temperature.

Yu X, Sun Z, Huang R, Zhang Y, Huang Y - PLoS ONE (2015)

Bottom Line: These variations have caused some inconsistencies in the conclusions of different researchers regarding the relative contributions of these thermal effects.The results indicate that the contribution of each thermal effect sharply varies with the Reynolds number and temperature.Convective effect could be dominant under certain conditions.

View Article: PubMed Central - PubMed

Affiliation: Department of Energy Engineering, Zhejiang University, Hangzhou, 310027, China.

ABSTRACT
Thermal effects such as conduction, convection and viscous dissipation are important to lubrication performance, and they vary with the friction conditions. These variations have caused some inconsistencies in the conclusions of different researchers regarding the relative contributions of these thermal effects. To reveal the relationship between the contributions of the thermal effects and the friction conditions, a steady-state THD analysis model was presented. The results indicate that the contribution of each thermal effect sharply varies with the Reynolds number and temperature. Convective effect could be dominant under certain conditions. Additionally, the accuracy of some simplified methods of thermo-hydrodynamic analysis is further discussed.

No MeSH data available.


The variations of δ0 with different load force F.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4526673&req=5

pone.0134806.g011: The variations of δ0 with different load force F.

Mentions: Fig 10 shows the calculated results of Qb, Qf, Qconv and Qvis for various values of applied load F. The results show that the values of Qb and Qf increase, and their proportions of the thermal effects change slightly with increasing applied load F. For low linear speed U (4.71 m/s), Qvis does not vary obviously with increasing F, but at high linear speed, Qvis increases far more obviously with applied load F. These results can be explained through the calculated variation of oil film thickness, which is shown in Fig 11 and is consistent with the previous studies [29]. The minimum oil film thickness δ0 decreases when the applied load F increases regardless of the cylindrical surface speed U, but the degree of variation of δ0 under high speed conditions is much larger than under low speed conditions. This behavior of δ0 leads to two consequences: 1) a higher temperature gradient near the metal surfaces and 2) a higher shear rate in the oil film, which causes Qb, Qf and Qvis to all increase. However, regarding the proportions, Qvis changes more than the others, so the proportions of Qb and Qf decrease slightly. The value and proportion of Qconv both increase, but not obviously, with the applied load F.


A Thermal Equilibrium Analysis of Line Contact Hydrodynamic Lubrication Considering the Influences of Reynolds Number, Load and Temperature.

Yu X, Sun Z, Huang R, Zhang Y, Huang Y - PLoS ONE (2015)

The variations of δ0 with different load force F.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4526673&req=5

pone.0134806.g011: The variations of δ0 with different load force F.
Mentions: Fig 10 shows the calculated results of Qb, Qf, Qconv and Qvis for various values of applied load F. The results show that the values of Qb and Qf increase, and their proportions of the thermal effects change slightly with increasing applied load F. For low linear speed U (4.71 m/s), Qvis does not vary obviously with increasing F, but at high linear speed, Qvis increases far more obviously with applied load F. These results can be explained through the calculated variation of oil film thickness, which is shown in Fig 11 and is consistent with the previous studies [29]. The minimum oil film thickness δ0 decreases when the applied load F increases regardless of the cylindrical surface speed U, but the degree of variation of δ0 under high speed conditions is much larger than under low speed conditions. This behavior of δ0 leads to two consequences: 1) a higher temperature gradient near the metal surfaces and 2) a higher shear rate in the oil film, which causes Qb, Qf and Qvis to all increase. However, regarding the proportions, Qvis changes more than the others, so the proportions of Qb and Qf decrease slightly. The value and proportion of Qconv both increase, but not obviously, with the applied load F.

Bottom Line: These variations have caused some inconsistencies in the conclusions of different researchers regarding the relative contributions of these thermal effects.The results indicate that the contribution of each thermal effect sharply varies with the Reynolds number and temperature.Convective effect could be dominant under certain conditions.

View Article: PubMed Central - PubMed

Affiliation: Department of Energy Engineering, Zhejiang University, Hangzhou, 310027, China.

ABSTRACT
Thermal effects such as conduction, convection and viscous dissipation are important to lubrication performance, and they vary with the friction conditions. These variations have caused some inconsistencies in the conclusions of different researchers regarding the relative contributions of these thermal effects. To reveal the relationship between the contributions of the thermal effects and the friction conditions, a steady-state THD analysis model was presented. The results indicate that the contribution of each thermal effect sharply varies with the Reynolds number and temperature. Convective effect could be dominant under certain conditions. Additionally, the accuracy of some simplified methods of thermo-hydrodynamic analysis is further discussed.

No MeSH data available.