The combined effect of couple stresses, variable viscosity and velocity-slip on the lubrication of finite journal bearings

Dass, Tyrone D.; Gunakala, Sreedhara Rao; Comissiong, Donna M. G.

doi:10.1016/j.asej.2020.01.002

Cited by 17 publications

(9 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The reason was that the decreasing vertical height at the end plane of bearing was much less than the journal radius when the misalignment angle was small. Friction coefficient and leakage flow rate were closely related to the distribution of film within the whole area of clearance (as shown in equations (12)(13)(14)), a minor change of film thickness supported a small impact on these parameters. Different from couple stress, misalignment angle cannot change fluids properties under thin-film condition and the lubricants still obeyed Newtonian fluids.…”

Section: Effects Of Axial Motion On Lubrication Performances Of Diffe...mentioning

confidence: 86%

“…When the axial velocity was low, bearing leakage flow rate with a high value of couple stress parameter was large, but its increasing amplitude was opposite to the magnitude of couple stress parameter. The reason was that leakage flow rate was composed of the difference between the flow generated by the axial velocity (FAV) and the flow generated by hydrodynamic effect (FHE) according to equation (14). FAV increased rapidly with the increasing axial velocity, and FHE came to a great value because of the improvement of film thickness (caused by the couple stress effect) and the lifting amplitude was positively correlated with the couple stress parameter.…”

Section: Effects Of Axial Motion On Lubrication Performances Of Diffe...mentioning

confidence: 99%

“…Punit et al 13 presented theoretical research of the journal taking into account couple stress effects and elastic deformation, the load capacity, dynamic coefficient and stability parameters versus different couple stress parameters and elasticity parameters were discussed. The combined effects of couple stress, viscosity-variation and velocity-slip on the finite journal was examined by Dass et al, 14 who observed that couple stress was regarded as an added force, and the slip parameter improved the carrying capacity. Based on different slipping positions, three cases of lubricant operating conditions have been considered.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Effects of axial motion and couple stress on lubrication performances of ship stern shaft

Zheng

Zhu

Fan

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part J:

View full text Add to dashboard Cite

Increasingly prominent marine oil pollution problems highlight the importance of environmentally friendly lubricants in a ship. According to the actual navigation environment, the couple stress effect of environmentally friendly lubricants and axial motion of stern shaft is considered to establish a new hydrodynamic lubrication model, and finite difference method and Simpson integral method have been utilized to solve film pressure and bearing carrying capacity, respectively. Various performance characteristics were obtained for a range of couple stress parameters, misalignment angles and rotation speeds. The results show that axial motion and couple stress have opposite effects on film distribution, the minimum film thickness decreases with the increasing of axial velocity while the maximum film pressure significant reduce as couple stress parameter grows. The axial position corresponding to the maximum pressure is reduced from 0.51 to 0.49 m as axial velocity enhances from 0 to 0.8 m/s while couple stress parameter is 0, but nearly remains the place while couple stress is considered. Meanwhile, couple stress lubricants effectively restrain friction of journal caused by hydrodynamic effect, and the decreasing amplitude is nearly independent of axial velocity.

show abstract

Section: Effects Of Axial Motion On Lubrication Performances Of Diffe...mentioning

confidence: 86%

Section: Effects Of Axial Motion On Lubrication Performances Of Diffe...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effects of axial motion and couple stress on lubrication performances of ship stern shaft

Zheng

Zhu

Fan

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part J:

View full text Add to dashboard Cite

show abstract

“…It was also shown that the bearing stability increases as the elastic coefficient increases. Dass et al [21] examined the associated effects of viscosity, velocity slip and the couple stress fluid on the performance of journal bearing. The obtained results indicated that including the effect of slip improves the load carrying capacity and decreases the friction coefficient significantly.…”

Section: Introductionmentioning

confidence: 99%

Effect of micro protrusions on the performance of elliptical journal bearings operating with couple stress lubricant

Abass¹,

Mahdi²

2021

Diagnostyka

View full text Add to dashboard Cite

Elliptical bearing is characterized by low induced temperature and high stability at higher speed in comparison with the cylindrical journal bearing. The performance of such bearings can be affected by the type of oil used and its surface properties. The main goal of this work is to study the surface micro protrusion effect on the steady state operation of elliptical journal bearing lubricated with couple stress lubricant. The modified Reynolds' equation to take into account the effects of couple stress lubricant and micro protrusions of the bearing surfaces is solved using finite difference method. The governing equations were solved using a prepared FORTRAN computer program. Pressure distribution, load carrying capacity and coefficient of friction have been studied for a bearing in laminar flow regime. The mathematical model was validated by comparing pressure results for the elliptical bearing of the present work with that obtained by Hussain et al.(1996). The obtained results demonstrate that the lubricant pressure and the load carried by the bearing decrease for the bearing with higher ellipticity factor while the load carried by the bearing increases for the bearing with higher protrusions or when using a couple stress fluid with higher couple stress variable.

show abstract

“…Their results show that the stability of the bearing increases as the value of the elastic coefficient and couple stress parameter increase. Later, Dass et al 19 analyzed the combined effect of couple stresses, variable viscosity, and velocity-slip on the lubrication of finite journal bearings. They utilized the Stokes microcontinuum theorem, the Barus formula, and an artificial slip surface to improve the lubrication performance of journal bearings.…”

Section: Introductionmentioning

confidence: 99%

Dynamic stability analysis of noncircular two-lobe journal bearings with couple stress lubricant regime

Mehrjardi¹

2020

Proceedings of the Institution of Mechanical Engineers, Part J:

View full text Add to dashboard Cite

In this research, the steady state and dynamic performances of two-lobe noncircular journal bearings with couple stress lubricant are presented. The lubricating oil, containing additives and contaminants, is modeled as the couple stress fluid. The modified Reynolds equation is obtained using the couple stress lubrication theory and is then solved by finite element method as an efficient numerical technique. The steady-state characteristics of bearings, including the load carrying capacity and attitude angle, are determined for various values of the couple stress parameter. The results show that applying the couple stress fluid improves the efficiency of two-lobe bearings in terms of an increased load carrying capacity and reduced attitude angle. Also, the stability performance of the investigated bearings is studied using rotor motion equations based on linear and nonlinear dynamic methods. The results indicate that any increase in the lubricant couple stress parameter enhances the bearing ability to damp the rotor perturbations. In other words, by varying the lubricant from Newtonian oil to the couple stress type and upgrading its properties, the curves of the critical mass parameter and whirl frequency ratio have an increasing and decreasing trend, respectively. Based on the fourth-order Runge–Kutta method results, the dynamic trajectory of the rotor center in the bearing space changes with increasing the couple stress parameter from diverging disturbances and limits the cycle perturbations around the bearing center to converging oscillations to the static equilibrium point. Moreover, the effect of changing lubricant properties on the two-lobe bearing’s performance is more pronounced at higher values of the couple stress parameter, especially with an increase in the noncircularity of bearings’ geometry.

show abstract

The combined effect of couple stresses, variable viscosity and velocity-slip on the lubrication of finite journal bearings

Cited by 17 publications

References 29 publications

Effects of axial motion and couple stress on lubrication performances of ship stern shaft

Effects of axial motion and couple stress on lubrication performances of ship stern shaft

Effect of micro protrusions on the performance of elliptical journal bearings operating with couple stress lubricant

Dynamic stability analysis of noncircular two-lobe journal bearings with couple stress lubricant regime

Contact Info

Product

Resources

About