The viscoelastic properties of multigrade oils and their effect on journal-bearing characteristics

Numerical study of flows of complex fluids between eccentric cylinders using transformation functions

“…The velocity parameter (dimensionless factor) is v * = !r 0 . Consistent comparisons of azimuthal velocities v  between our results and data from the literature [7], for a Newtonian and a purely viscous uid obeying a Carreau equation, are shown in Figure 5(a) and 5(b), respectively. Figure 6 shows normalized velocity proÿles v  versus r * for the three viscoelastic uids investigated in the present work: Maxwell, Oldroyd-B and K-BKZ at a Weissenberg number We = 2:0 for = 0:1 and two angular sections ( = = 0 and  = = ).…”

“…In the Newtonian case, the initial estimates of the separation angle  1 between the sub-domains 1 and 2 and of the kinematic function to be deÿned at the reference sections were given by the lubrication theory [7]. The size of the computational sub-domains is expected to change during the iterations in relation to the moving positions of the separating angle between the two domains.…”

“…The growing interest in considering materials with non-Newtonian properties in lubrication [6,7,10] has led to generate various numerical techniques being formulated for investigating such ows with complex constitutive equations, where experimental, mathematical and computational techniques are concerned.…”

Non-Newtonian effects on lubricant thin film flows

“…This problem has been tackled since the mid-1950s with the appearance of the so-called multigrade oils [1, pp. 111-114], [2,Chapter 1], [3,Chapter 3], [4,Chapter 6], and has recently taken on added significance with the transition to lubricants of yet lower viscosity for improved energy efficiency [5,6]. Any factor influencing load capacity and wear in journal bearings is clearly of renewed importance; consequently, there are good practical reasons to reopen the general question of viscoelastic effects on lubrication.…”

Gas-Expanded Lubricants for Increased Energy Efficiency and Control in Rotating Machinery

“…Samantaray et al [90] investigated the effect of two-phase (liquid-solid) lubricants on bearing stability and found that these fluids have the potential to provide stabilizing, spring-like forces in journal bearings to control whirl orbit size. A number of studies have also been published evaluating the effects of non-Newtonian, viscoelastic lubricants on bearing stability [91,92], load capacity [93], and minimum film thickness [94].…”