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In the present work, a magnetic-hydrodynamic hybrid thrust bearing is investigated. The force of the bearing comes from the hydrodynamic film and magnetic field. This paper studies a model of the bearing force and develops an experimental rig to investigate the thrust bearing. Predictions from the model are compared with measured data from the experimental rig. 相似文献
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提出一种求解表面织构动压轴承油膜力的解析模型。基于Sommerfeld油膜边界,通过分离变量的方法,求解表面织构动压滑动轴承二阶偏微分Reynolds方程,得到表面织构动压滑动轴承油膜压力解析式。以圆形凹坑轴承为例,在油膜区域通过积分求得织构轴承的油膜力,分析织构参数对油膜压力的影响,研究发现,表面织构位于收敛区域(升压区)的轴承,其润滑与承载性能优于表面织构位于发散区域(降压区)的轴承、全织构轴承以及光滑轴承。对比了提出的解析模型与FDM和CFD模型在不同长径比和偏心率下的计算结果,结果表明,提出的解析模型能准确地描述表面织构动压滑动轴承的油膜力,且计算结果同FDM和CFD模型计算结果基本一致,验证了该模型的正确性。 相似文献
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A model is developed to describe dynamic friction effects in lubricated surfaces. The model covers the hydrodynamic, mixed and boundary lubrication regions. The dynamic friction model can predict the friction force for time-varying velocity, and is useful in precise motion control. The model presented is for a short journal bearing, but can be extended to other geometries of sliding surfaces, such as point and line contacts or rolling element bearings. The friction is related to a time variable fluid film thickness, resulting from journal vibrations relative to the sleeve. The proposed model agrees qualitatively with experimental results for lubricated line contact. Both show similar hysteresis-type friction curves under oscillating velocity. 相似文献
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螺旋桨重力会导致船舶推进轴系发生挠曲,造成艉轴承边缘润滑状态恶劣。采用一种磁水复合支撑形式的艉轴承,通过引入永磁体磁力作用,改善桨重因素对艉轴承边缘润滑状态的不利影响;构建永磁体三维磁力特性分析方法,探究不同永磁体材料磁性质和布置形式对磁力承载性能的影响规律;基于艉轴承弹性流体动压润滑分析方法,获取永磁体形性特征对润滑特性的影响规律。结果表明:磁承载力受永磁体材料剩磁的影响明显,材料剩磁越大,永磁体承载力越大,轴承润滑状态相对越好;沿周向增加磁块数目或增加永磁块轴向长度可以增大永磁体的承载力,但永磁体承载效率可能下降,设计时需综合考虑;磁体的布置形式也对磁力承载性能和润滑性能影响显著,在永磁体体积相同的情况下,更为合理的布置形式可使永磁体承载力与艉轴承最小水膜厚度明显增大。 相似文献
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This work is concerned with theoretical study of hydrodynamic journal bearings lubricated with ferrofluids exhibiting non-Newtonian behavior. Based on the momentum and continuity equations for ferrofluid under an applied magnetic field, a modified Reynolds equation has been obtained. Assuming linear behavior for the magnetic material of the ferrofluid, the magnetic force was calculated. The Reynolds equation has been derived to be able to apply to any magnetic field distribution model. Using different magnetic field models, the equation has been solved numerically by the finite-difference technique with appropriate iterative technique and pressure distributions have been obtained. The boundary shape of the load-carrying active regions (positive-pressure regions) and cavitation regions (zero-pressure regions) could be then determined. The solution renders the bearing performance characteristics, namely: load-carrying capacity, attitude angle of the journal center, frictional force at the journal surface, friction coefficient and bearing side leakage. The results indicated that the flow-behavior index has a large effect on the bearing performance. When the bearing operates at high eccentricity ratios, the increase of flow-behavior index gives higher load capacity, lower attitude angle, higher frictional force, lower friction coefficient and higher side leakage. At low eccentricity ratios where the magnetic effects are significant, the effect of the flow-behavior index depends mainly on the magnetic field distribution model used. 相似文献
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On the vibration of rotor-bearing system with squeeze film damper in an energy storage flywheel 总被引:1,自引:0,他引:1
The permanent magnetic bearing and the small-sized hydrodynamic spiral groove bearing are utilized as supports for the rotor of the energy storage flywheel system. The hydrodynamic bearing and the squeeze film damper do not need the oil cycle to remove the heat caused by friction because the friction loss is small. The linear dynamics model with four degrees of freedom is built to describe the vibration of the flywheel rotor-bearing system. The squeeze film dampers show good behavior in suppressing the vibration and improving the stability of the rotor-bearing system. The analytical solution of the dynamic characteristic coefficients of the squeeze film is achieved from Reynolds equation after some simplifications are taken. The numerical computation shows that the moment unbalance excites larger vibration of the rotor than the force unbalance. The upper damper plays an important role in helping the rotor pass its critical speed. The damping coefficient of the squeeze film dampers should be selected carefully. The flywheel arrived at the speed of 39,000 rpm and stored the energy of 308 Wh in the experiment. The calculated unbalance response is compared to the test response of the rotor storing quantities of kinetic energy. The comparison indicates that the dynamics model of the rotor-bearing-damper system is appropriate. 相似文献
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The hydrodynamic performance of a journal bearing under starved lubrication conditions is studied theoretically and experimentally. When lubricant is supplied to a journal bearing from an oil groove at an insufficient oil flow rate, the hydrodynamic oil film cannot cover the full width of the bearing at the inlet of the convergent bearing clearance, and the covered width increases gradually with the decrease in film thickness in the circumferential direction. This phenomenon affects the static and dynamic performance of the journal bearing. The oil film boundary in the bearing clearance is calculated numerically for a constant load and a constant speed under the assumption of laminar, iso-viscous lubrication. Measurements are in good agreement with predictions. Some more calculations of journal centre loci are given. 相似文献
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磁流体润滑滑动轴承的研制和性能研究 总被引:7,自引:0,他引:7
研制了磁流体润滑滑动轴承 ,建立了磁流体滑动轴承试验装置。对磁流体滑动轴承和传统滑动轴承进行了对比试验研究。通过大量试验的测试结果分析比较 ,发现磁流体滑动轴承能形成良好的全油膜润滑 ,产生的摩擦力比传统滑动轴承要小得多 ,因此推断出磁流体滑动轴承的承载能力和抗磨损能力大于同等条件下的传统滑动轴承。 相似文献
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The paper is an attempt to include the effect of journal motion and the oil film forces on the determination of dynamic gear tooth loading in a hydrodynamic bearing-rotor-gear pair system. A mathematical model has been developed which relates dynamic loads on the teeth of an involute spur gear pair to the instantaneous state of the pinion journal centre in the oil film space and various bearing parameters. The direction of instantaneous line of action is determined from kinematic considerations. effects of both the full-film (360 degrees) and the cavitated π-film models of the journal bearing are used to arrive at the aforementioned relationships. Dynamic loads on gear teeth as well as on bearing film have been calculated when the journal traces certain specified paths in the clearance space. Some of the results emphasize the importance of coupling gear analysis with bearing analysis. 相似文献
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Xiaoping Pang Jin Chen Sinan H. Hussain 《Journal of Mechanical Science and Technology》2012,26(10):3149-3158
This paper deals with multi-objective shape optimization related to the geometrical design of a hydrodynamic journal bearing. The aim proposed here is to show that optimum shape design with better performance could surpass the limitations of existing bearing profiles. Attempting to remove the difficulty of selecting the weighting factor in multi-objective journal bearing optimization problems, a modified non-dominant sort in genetic algorithm was used as an optimization tool with a penalty to those solutions that violate constraints. Three kinds of optimized shapes were manufactured and taken as experimental objects. Experimental apparatus was described and some experimental data was presented. The comparison was made for the optimized bearings between numeric values and experimental data. The results show that the new method for shape optimization of hydrodynamic journal bearings based on the general film thickness equation is feasible. 相似文献
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The measurement of the thickness of an oil film in a lubricated component is essential information for performance monitoring and control. In this work, a new method for oil film thickness measurement, based on the reflection of ultrasound, is evaluated for use in fluid film journal bearing applications. An ultrasonic wave will be partially reflected when it strikes a thin layer between two solid media. The proportion of the wave reflected depends on the thickness of the layer and its acoustic properties. A simple quasi-static spring model shows how the reflection depends on the stiffness of the layer alone. This method has been first evaluated using flat plates separated by a film of oil, and then used in the measurement of oil films in a hydrodynamic journal bearing. A transducer is mounted on the outside of the journal and a pulse propagated through the shell. The pulse is reflected back at the oil film and received by the same transducer. The amplitude of the reflected wave is processed in the frequency domain. The spring model is then used to determine the oil film stiffness that can be readily converted to film thickness. Whilst the reflected amplitude of the wave is dependent on the frequency component, the measured film thickness is not; this indicates that the quasi-static assumption holds. Measurements of the lubricant film generated in a simple journal bearing have been taken over a range of loads and speeds. The results are compared with predictions from classical hydrodynamic lubrication theory. The technique has also been used to measure oil film thickness during transient loading events. The response time is rapid and film thickness variation due to step changes in load and oil feed pressure can be clearly observed. 相似文献
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The well-known solutions for the pressure distribution in the lubricating film of a hydrodynamic journal bearing, satisfying the Reynolds boundary conditions, show a sudden change in the pressure gradient at the position of maximum film thickness, which is possible only if the lubricant is added precisely at this position. Since the pressure develops smoothly because of hydrodynamic action, a correction in the Reynolds boundary conditions is proposed and a new solution for the pressure distribution is obtained. The steady state characteristics of a hydrodynamic journal bearing using the new boundary conditions are compared with the well-known characteristics using the Reynolds boundary conditions. 相似文献
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针对曲轴主轴承润滑性能的影响因素研究,建立考虑轴颈直径、轴承宽径比和轴承间隙3种轴承结构参数的曲轴主轴承热弹性流体动力润滑模型,分析不同轴承结构参数下的主轴承最大油膜压力、最小油膜厚度、最高轴承温度和最大摩擦功率损失。计算结果表明:轴承结构参数对主轴承润滑性能有很大影响;当轴颈直径和轴承宽径比变大时,主轴承最大油膜压力会出现减小的情况,最小油膜厚度变大、最高轴承温度升高和摩擦功率损失增加;内燃机主轴承的轴承间隙会随着轴颈直径和轴承宽径比的不同而有不同影响,且轴承间隙对主轴承最高温度和最大摩擦功率损失的影响较为显著。 相似文献