Investigation On Static Performance Of Hydrodynamics Bearing

Hydrodynamic journal bearing is widely used in steam turbine, gas turbine, gearbox andother power transmission systems, it presents many characteristics such as high load capacity,low power dissipation, impact resistance, high anti-shaking, high-precision. Controlling thejournal bearing bush temperature within a range is a requirement for ensuring the journalbearing’s load capacity and location precision. As demand of higher speed and load capacityof journal bearing, the temperature rise of bush has become the focus of many scholars. Thisdissertation takes hydrodynamic journal bearing as research subject, the method of combiningexperiment and theoretical computation is applied, and Computational fluid dynamics (CFD)method has been used. The static characteristics and other factors affect static characteristicshave been studied deeply, this dissertation could provide the theory base for journal bearingoptimization design.The main content of the dissertation are flowed:(1) The hydrodynamic journal bearing static characteristics, lubrication method, andjournal bearing structural style have been reviewed. The transport equations for journalbearing flow field are given, cavitation effect and the temperature-viscosity effect of oil areconsidered, SIMPLE algorithm was applied to solve the governing equations. The gridindependency investigation has been carried out and the numerical results have beencompared with other scholars’ work, the model predictions agree well with test results.(2) The bush temperature rise, oil film load capacity, friction moments, oil flow rateshave been calculated in this dissertation. Firstly, the heat transfer mechanism of journalbearing has been discussed, the results show that when calculating the flow field of thejournal bearing, the energy equation and viscosity-temperature effect could not be ignored.The effects of oil supply pressure, supply temperature, cavitation pressure have beenanalyzed.(3) The circumferential groove and micro transverse groove’s effects on journal bearingperformance have been simulated. For circumferential groove, the groove angle (location),groove width and groove depth in both load and unload zone have been considered. Thepressure distribution and other parameters have been given and discussed. When the circumferential groove is within a millimeter, the circumferential groove in unload zone couldenhance the cooling capacity.(4) In order to learn the mechanism of circumferential groove effects on journal baring staticperformance, the secondary flow in journal bearing flow field has been discussed. Theconcentric-cylinders Taylor flow and lid-driven flow have been simulated as a basic research,after that, the Taylor vortex in journal bearing flow field and the backflow vortex caused byshearing action in groove has been analyzed. The influential mechanism of circumferentialgroove is embodied in mass flow rate of the oil, a backflow vortex is generated incircumferential groove, which results in if the groove is in load zone, the oil mass flow rate isdecreased, if the groove is in unload zone, the flow rate is increased. When thecircumferential groove is microndimension, it affects very slightly. When there are microtransverse grooves in either load zone or unload zone, the friction coefficient of the journalbearing is increased.(5) An experimental study has been carried out by designing a new journal bearing whoseratio of height to radius is0.375, the experiment is done in friction and wear testing machineM2000-A. The maximum bush temperature and journal bearing friction torque have beenmeasured, the experiment results have been compared with CFD.