The role of lubricant feeding conditions on the performance improvement and friction reduction of journal bearings

Most conventional hydrodynamic journal bearing performance tools can not suitably assess the effect of lubricant feeding conditions on bearing performance, even though these conditions are known to affect important performance parameters such as eccentricity and powerloss. A thermohydrodynamic analysis suitable to deal with realistic feeding conditions has been proposed. Special attention was given to the treatment of phenomena taking place within grooves and their vicinity,as well as to the ruptured film region. The effec to flubricant feeding pressure and temperature, groove length ratio,width ratio and number (single/twin) on bearing performance has been analyzed for a broad range of conditions.It was found that a careful tuning of the feeding conditions may indeed improve bearing performance.FCT - POCTI/EME/39202/200

Analysis of transient PIG motion in natural gas pipeline

In this study, the dynamic analysis of Pipeline Inspection Gauge (PIG) flow control in natural gas and liquid pipeline is considered. The basic equations are differential forms of the mass and linear momentum for compressible liquid and gas flows. The fluid flow equations and a linear momentum equation of the PIG are solved simultaneously using an appropriate numerical method. Solution of these nonlinear equations results in a set of diagrams for the variations of the fluid pressure, mass flow rate of the gas and the PIG velocity through the pipeline. Comparing the results of mathematical model for the PIG with the established experimental data in a segment of Ahwaz gas pipeline shows a good agreement between the measurements and computations

Thermohydrodynamic behaviors of finite journal bearings with cavitation

This paper presents thermohydrodynamic solutions for a finite-width journal bearing with single axial groove on the crown by considering turbulent effects in lubricant film. Appropriate governing equations and boundary conditions are used for the fluid flow and heat transfer process occurring in finite full journal bearings. A general computer program is developed to numerically solve the set of governing equations. Results are provided for THD characteristics of journal bearing in terms of Reynolds number, clearance ratio and eccentricity ratio. Good agreement with published experimental results was achieved. The results indicate that the bearing temperature field and pressure field are considerably influenced by the journal bearing parameters

An experimental study of the influence of loading direction on the thermohydrodynamic behaviour of twin axial groove journal bearing

Abstract: An experimental assessment of the influence of angle between the groove axis and the load line on the thermohydrodynamic behaviour of twin groove hydrodynamic journal bearings has been undertaken. At nine different loading direction angles, the oil-bush interface temperature profiles, oil outlet temperature, maximum bush temperature, total flow rate, and oil flow rate through each groove were measured for variable applied load and oil supply pressure while the feeding temperature was kept constant (40 C). To the authors' knowledge, this is the first study of the influence of loading direction on the performance of journal bearing with two axial grooves in which the flow rate were measured in each groove for different working conditions under laminar regime. It was found that the variation of loading direction has a strong effect on the bearing performance. Under some running conditions, negative lubricant flow rate (hot oil reflux) at one groove was detected. This seldom-reported phenomenon was found to affect the bearing performance dramatically. Increasing supply pressure yielded a temperature decrease, especially for high loads, and sometimes prevented the occurrence of hot oil reflux

An experimental study of the influence of loading direction on the thermohydrodynamic behavior of twin axial grooves journal bearings

An experimental assessment of the influence of angle between the groove axis and the load line on the thermohydrodynamic behaviour of twin groove hydrodynamic journal bearings has been undertaken. At nine different loading direction angles, the oil–bush interface temperature profiles, oil outlet temperature, maximum bush temperature, total flow rate, and oil flow rate through each groove were measured for variable applied load and oil supply pressure while the feeding temperature was kept constant (40°C). To the authors’ knowledge, this is the first study of the influence of loading direction on the performance of journal bearing with two axial grooves in which the flow rate were measured in each groove for different working conditions under laminar regime. It was found that the variation of loading direction has a strong effect on the bearing performance. Under some running conditions, negative lubricant flow rate (hot oil reflux) at one groove was detected. This seldom-reported phenomenon was found to affect the bearing performance dramatically. Increasing supply pressure yielded a temperature decrease, especially for high loads, and sometimes prevented the occurrence of hot oil reflux