Abstract
The drive to maintain the environmental sustainability and save the global energy consumption is urgent, making every powertrain system component a candidate to enhance efficiency. In this work, the combined effects of the slip boundary and textured surface in hydrodynamic journal bearing as one of the critical components in industrial powertrain and engine systems are assessed using a multiphase computational fluid dynamic analysis that allows for phase change in a cavitation process and arbitrary textured geometry. The texture studied consists of regularly spaced rectangular dimples through two-dimensional (infinitely long) journal bearing. The modified Navier–slip model is employed to describe the slip boundary condition. A systematic comparison is made for various textured configurations varying the texture depth and the length of the texturing zone with respect to the performance of a smooth (untextured) bearing for several eccentricity ratios. The effectiveness of the texture with or without slip at enhancing the load support over a corresponding smooth bearing is investigated with the parameters. The detrimental or beneficial effect of surface texturing as well as the slip promotion is explained in terms of the mechanisms of pressure generation for several eccentricity ratios. The results of the present work indicate that journal bearing textured by a proper texturing zone and dimple depth are characterized by substantial load support levels. However, in the range of high eccentricity ratios, the promotion of texturing and slip can significantly degrade the performance of the load support.
Highlights
Tribological characteristics have a highly important effect on the resource and energy efficiency of both the manufacture and operation of powertrain components
It is necessary to validate the CFD solution set up, the multiphase cavitation was employed for the turbulent kinetic energy as well as for the turbulent dissipation rate and the model implemented in this simulation, and the author’s code for the slip model for analyzing the volume fraction equation
There is potential to employ the textured surface in order to determine the length of the texturing zone and texture depth that will be optimal for a specific operation
Summary
Tribological characteristics have a highly important effect on the resource and energy efficiency of both the manufacture and operation of powertrain components. Components pointing out a high potential for efficiency enhancement include piston rings, cylinder liners, and journal bearing. With growing demand for increased environmental awareness and decreased energy consumption, surface texturing is well-known as an effective approach for enhancing tribological bearing performance quantified in terms of the friction coefficient and the load support in the frame of both experimental and theoretical studies. Lubricants 2019, 7, 97 publications have shown that surface texturing has a considerable effect on tribological properties. Starting from the pioneering study of Hamilton et al [1], the positive influences of surface texturing have been highlighted in lubricated contact. By introducing the texture pattern on the whole of the bearing shell circumference, substantial friction reduction
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