Multi-phase Flows and Phase Change

Chapter 11

Abstract

Flow and Heat Transfer in Jet

The real flow field inside a jet cooling ball bearing is an air-oil two-phase flow since the air entrainment in the lubricant is ineluctable. The flow heat transfer characteristics are thought to have significant impacts in cooling effect forecast and temperature control. To this end, the fluid flow and heat transfer characteristics of the air-oil two-phase flow inside a jet cooling rolling bearing have been investigated by simulation and experiment herein. A multiphase VOF numerical method for the flow field calculation has been proposed. The temperature distributions of the bearing system have been measured, and the flow pattern under different operation speeds has also been captured. The parameter effects on the jet cooling rolling bearing flow field and temperature distribution have been revealed accordingly. The research findings can be used for the structural optimization and the precise

Keywords: ball bearings, jet cooling, two-phase flow, VOF, flow pattern,

Rolling bearings are the most widely used bearings in the vehicle transmission industry due to their advantages of less friction coefficient for rotatory movements [1]. With the future trends of vehicle transmission development shifting toward lighter and more compact designs with greater power density, the main shaft bearings are subjected to more severe demands of simultaneous shrinking size and excessive loading [2, 3]. These requirements enforce higher thermal load on the bearings. The rolling bearings under stress overload and poor heat dissipation conditions are prone to wear out easily due to metal-to-metal contact, which corrode

Hence, lubrication of bearings plays a significant role in fatigue life assurance by reducing friction and wear, which ensure the safe and reliable operation of bearings. The choice of lubrication mode of rolling bearing mainly depends on load, working speed, and temperature. Grease and splash lubrication are capable enough for lowspeed rolling bearings [4], while oil-jet lubrication could better meet the requirements under heavy load, high-speed, and high-temperature conditions [5]. Fluid jet heat transfer enhances the heat transfer rates in comparison with conventional methods. In an oil-jet cooling rolling bearing, a portion of the oil is utilized to lubricate the ball bearing and form lubricant film in ball raceway

Cooling Rolling Bearing

Wei Wu, Jibin Hu and Shihua Yuan

lubrication design of the rolling bearing.

temperature distribution

1. Introduction

surface of bearings.

215
