Numerical Study of the Pressure Pattern in a Two-Dimensional Hybrid Journal Bearing Recess, Laminar, and Turbulent Flow Results

Abstract

The present work is a parametric study of the pressure pattern in a two-dimensional recess of a hybrid journal bearing (HJB). It is known that theoretical models of HJB are largely dependent on the recess pressure pattern especially for severe working conditions (high rotation speeds, shallow pockets, etc.). The difficulty is that the recess flow is dominated by the interaction of viscous and inertia forces and cannot be analyzed using a thin film model. The present analysis is based on the numerical resolution of the two-dimensional Navier-Stokes equations where only one recess is modeled (with the film lands and the supply region), the fluid being regarded as incompressible and isothermal. Both the laminar and the turbulent flow regimes are considered. The study is governed by two parameters, one related to the HJB operating conditions and the other related to the recess geometric characteristics. The first parameter is the ratio of the runner versus the supply Reynolds number, Rer/Res∈{0,1/4,1/2,1,4,8}. The supply Reynolds number is fixed at 100 for the laminar regime and at 5000 for the turbulent one. The second parameter is the ratio of the recess depth versus the film thickness. Six values of this ratio are considered, ranging from 4 (shallow recess) to 152 (deep recess). Detailed pressure patterns on the runner wall are presented in a systematic manner giving a clear insight of the flow effects intervening in the recess and of their mutual interaction. Some effects are explained by analyzing the recirculation zones inside the recess. It is also shown that for certain parameters turbulent flows have qualitatively similar effects as laminar ones but they can also have specific trends. In order to sustain this remark, the pressure variation at the recess downstream end is analyzed in the paper. Finally, the present results and specially the turbulent ones are intended to contribute to the understanding of viscous and inertia effects interactions in a recess flow and to represent a database in view of HJB theoretical modeling.

Performance Analysis of High-Speed Deep/Shallow Recessed Hybrid Bearing

“…Compared to the conventional deep recess bearing, they put forward the design criterion of shallow recess depth about the hybrid bearing. Helene et al [13] presented the theoretical analysis of the pressure pattern in a two-dimensional recess of a hybrid journal bearing. They introduced the ratio of the recess depth versus the film thickness.…”

An investigation into the thermal mixing in journal bearings

“…The computational challenge is high for any one attempting to simulate the multiscale of lubricant flow in the groove and film together. Nevertheless, this had been pursued [16,17]. Braun and Dzodzo [16] performed three-dimensional computational analysis of flow in circular pockets of the hydrostatic journal bearing.…”

“…This attested to the complexity of the flow. Helene et al [17] presented a numerical study on the interaction of pressure and shear effects. The parametric study considered two parameters, namely the ratio of the sliding surface Reynolds number to the supply Reynolds number and the ratio of the cavity depth to the film thickness.…”

Translating circular thrust bearings

“…The numerical simulations show that for Re > 1600 and deep pockets, the Rayleigh step effect is often present and the current predictions for tilting moment would be questionable. Helene, Arghir & Frene (2003) also examined laminar flow in a two-dimensional journal bearing, but extended the analysis to include turbulent flows using a classical k-ε model of turbulence. In the laminar regime, they obtain qualitative agreement with the results of Braun & Dzodzo (1995).…”