Influence of thermal pressure and temperature profile approximations in thermohydrodynamic analysis of surface-textured noncircular journal bearing

The present study aims to study the thermohydrodynamic performance of noncircular journal bearings lubricated with multigrade oil. Experimental investigations are carried out on phosphorous bronze hydrodynamic journal bearing with a surface textured at different loading conditions with multigrade oil (MAK 2T oil) as lubricant at different constant rotational speeds (i.e., 1000–4000 rpm) for studying the dynamic characteristics. The journal-bearing's thermodynamic behavior is analyzed by simplifying modified Reynolds and energy equations to obtain surface-textured bearing performance characteristics, such as load-carrying capacity, mass flow rate, and power loss. The noncircular bearings suggest several design parameters, such as a tilt angle for designers. By considering thermal effects for MAK 2T oil lubricant, the requirements of a specific application can be fulfilled.     

Study on lubrication performance of hydrostatic clearance oil film considering multi-factor coupling

The lubricating performance of the clearance oil film determines the machining accuracy of the hydrostatic thrust bearing and the stability of the oil film. From the perspective of working parameters and cavity structure, based on tribological principles and lubrication theory, the clearance oil film temperature rise equation, pressure equation, and viscosity-temperature equation are deduced, and the relationship between load-rotating speed-oil film thickness for different cavity shapes is matched. Through the combination of simulation and experiment, the multi-factor coupling influences on the lubricating performance of the clearance oil film are studied. The study found that the degree of influence on the clearance oil film temperature is in order: rotational speed, hydraulic oil viscosity, load, and cavity depth, and the degree of influence on the clearance oil film pressure is in order: load, hydraulic oil viscosity, rotational speed, and cavity depth. This work provides a theoretical basis for the research and optimization of the lubrication performance of hydrostatic thrust bearings, and provides a research direction for the machining accuracy and running stability of high-speed and heavy-duty CNC equipment.     

不同开槽方式的椭圆瓦轴承润滑性能对比研究

为解决某电厂开槽椭圆瓦轴承在运行过程中存在温度过高的问题,考虑紊流、质量守恒边界等效应建立了轴承的热流体动力学润滑分析模型,采用有限元法求解了轴承性能,对比得出了四种不同开槽方式的椭圆瓦轴承对润滑性能(膜厚、膜压、膜温、功耗和流量等)的影响规律。结果表明:相对于上下瓦均不开槽(光滑表面)轴承,下瓦开中心槽导致油膜承载面积减小,油膜厚度大幅降低,油膜压力和油膜温度均显著升高;上瓦开槽对轴承性能影响较小,整体上降低了摩擦功耗,但略微增加油膜温度。     

增压中冷柴油机主轴承润滑特性研究

基于弹性流体动力润滑理论,建立了4缸柴油机主轴承润滑仿真模型,研究了不同转速下内燃机轴瓦与轴承座的弹性变形、轴瓦与轴颈粗糙度对主轴承润滑特性的影响。研究结果表明:5个主轴承膜厚比均大于1,其中第5主轴承峰值油膜压力与其他4个主轴承相比明显偏大,而且存在偏磨现象,润滑相对恶劣;优化后第5主轴承峰值油膜压力平均降低了20%,最小油膜厚度平均增加了25%,摩擦功耗平均降低了43%。     

滑动轴承非线性动态油膜压力分布特性的研究

针对有限长径向滑动轴承非线性动态油膜压力的分析与计算,定量阐明了非稳定润滑油膜的动态压力特性,进一步研究了轴承中转子自转速度、涡动速度及转子偏心速度等参数对非线性油膜压力分布变化规律的影响。图8参6。     

低速船用柴油机主轴承弹流润滑性能分析

以某低速二冲程船用柴油机为研究对象，结合弹性流体动力学、多体动力学以及有限元方法，建立了包含机架-机座-主轴承盖-曲轴的整机动力学润滑耦合分析模型，对低速船舶柴油机主轴承的润滑性能进行研究。研究结果表明:第7主轴承(靠近飞轮端)润滑性能最为恶劣，总压峰值达到87.95 MPa，高出其他主轴承19.7%至413.7%不等；在整个推进工况主轴承油膜厚度均满足最小膜厚要求；不同工况轴承液动润滑和混合润滑的时间占比也不尽相同，液动润滑占比从100%负荷的20.7%提高到25%负荷的99.3%；轴承结构对主轴承的润滑磨损性能有较大影响，径向间隙的设计须综合考虑油膜承载与摩擦功耗。     

MLX系列减速机用扇形可倾瓦滑动推力轴承润滑性能分析

以MLX系列减速机用扇形可倾瓦滑动推力轴承为研究对象,建立基于计算流体动力学(CFD)的有限元仿真分析模型和基于数值分析方法的数值分析模型分析流体润滑性能,利用有限元分析模型研究分析了轴承中润滑油膜压力场和温度场的分布及其随轴承转速、润滑油粘度的变化情况。利用数值分析方法建立轴承油膜厚度模型,分析了轴承扇形瓦块倾角的变化对轴承润滑性能的影响。结果表明：随着轴承转速和润滑油粘度的增加,油膜最高压力和最高温度持续线性增大;扇形瓦块的周向、径向倾角对轴承油膜压力和厚度会造成影响,且径向倾角的影响更大。     

船用轴流压气机推力轴承特性计算及试验研究

为获得某新型推力轴承在某船用轴流压气机中的工作特性并进行试验验证,基于ARMD Bearings软件及自编程序对推力轴承特性进行了模拟计算,在全尺寸高速大推力滑动轴承试验台上进行了轴承特性试验研究,并在实机台架试验中对轴瓦温度进行了监测。计算分析了15种工作条件下油膜的压力、厚度、温度、刚度、阻尼及能量损失与推力和转速关系。轴承特性试验主要包括9种稳定工况下的性能试验,以及轴承超载、超速试验中每块轴瓦表面温度及油膜压力的测量。结果表明：模拟计算结果及试验测试得到的油膜温度、压力随推力及转速变化规律基本一致;轴瓦表面最大油膜压力位于支承块背部附近,与推力基本呈线性关系;转子转速越低、推力越大,则油膜厚度越小、油膜刚度及阻尼越大;转子转速越高、推力越大,则油膜温度越高、能量损失越大;在设计点轴承运行参数均有一定安全裕度,该推力轴承可以满足机组使用要求。     

单缸机主轴承轴心轨迹的测量

介绍了采用电涡流传感器组成轴心轨迹测试系统。该系统可测量内燃机主轴承的油膜厚度、油膜温度、曲轴转角、转速、轴心轨迹和最小油膜厚度。在S195柴油机上进行了多工况的实测，分析了负荷对油膜厚度和轴心轨迹的影响。为了提高测量精度，采取了一系列有效的措施，并对测量结果进行了误差分析。     

船用柴油机主轴承盖对轴承油膜润滑的影响研究

基于AVL Excite PU软件,采用弹性流体动力学耦合有限元法对某20V船用柴油机主轴承油膜进行了仿真分析。研究了不同材料、不同结构的主轴承盖对油膜润滑工作状态的影响。结果表明:同样结构的主轴承盖,采用铁材料比钢材料对轴承润滑更加有利;主轴承盖承压面两侧挖槽,在保证刚度的前提下,可以有效降低主轴承边缘压力峰值和平均热载峰值。     

12V240ZJ型柴油机继续强化后曲轴轴承模拟评价

对12V240ZJ型柴油机进一步强化后,主轴承和连杆大端轴承的可靠性进行了分析计算。采用Southwest Crank/Bearing轴承计算程序进行数值计算,然后用EXCEL表做图形分析,得出最小油膜厚度、最大油膜压力、空载负荷线变化角、轴心轨迹、油膜分布等参数和图形。由油膜分布图确定轴颈最佳油孔位置,并对其余参数进行了评价。分析了两种发火次序(即连续和间断)对轴承可靠性的影响。     

柴油机配气滚轮浮环轴承润滑特性优化研究

为研究配气机构滚轮浮环衬套动态载荷、运动与润滑特性的内在联系,以某高指标船用柴油机配气机构排气滚轮浮环轴承为对象,考虑动态载荷、弹性变形,建立了润滑仿真模型。研究了浮环衬套供油、间隙匹配、浮环衬套厚度等关键结构参数对滚轮浮环轴承动态润滑特性的影响规律。结果表明：浮环衬套周向油槽能增加供油流量,但对内圈油膜厚度、油膜压力不利;浮环衬套间隙匹配对内外圈油膜影响规律不同,但优化匹配方案能有效改善油膜厚度、油膜压力、平均热载等润滑特性;适当减薄浮环衬套厚度,也对润滑特性有益。     

增压内燃机主轴承载荷计算方法及其对轴心轨迹的影响

介绍了多缸增压内燃机主轴承载荷的简支梁和连续梁计算方法,分别用两种载荷计算了某4缸涡轮增压内燃机的轴心轨迹、最小油膜厚度和最大油膜压力。连续梁法计算出的主轴承载荷与简支梁法算出的结果相比,其最大值较大,最小值较小;两种方法计算出的轴心轨迹不同,最小油膜厚度和最大油膜压力也不同。连续梁法算出的最大油膜压力和最小油膜厚度比较接近于实际测量值。精确的润滑计算应采用连续梁轴承载荷计算方法。     

基于ADAMS—ENGINE的曲轴轴承润滑分析

针对主轴承,建立了含油膜润滑的曲柄连杆机构动力学模型,建立了曲轴主轴承的耦合模型,得到了曲轴轴心轨迹曲线,最小油膜厚度。同时分析了发动机转速、温度及轴承间隙对轴心轨迹和油膜最小厚度的影响。     

滑动轴承非线性动态油膜力及稳定性的研究

在对有限长滑动轴承非线性压力分布函数及油膜力分析的基础上,定义了4个轴承流固耦合作用特征系数,同时根据轴承流固耦合运动能量转化的载荷平衡方程,提出了油膜-转子系统中轴承运行失稳的判据方程,解释了油膜力的作用机理,根据实例给出了轴承失稳的动力学特征。图6参6     

润滑理论在曲轴轴承设计中的应用

本文论述了曲轴轴承的油膜压力分布、油膜承载力、油膜最小厚度、轴承的摩擦损失与粘性耗散损失、以及轴承副的磨损等方面的流体动力润滑理论与弹性流体动力润滑理论的分析方法,还讨论了轴承副磨损因素的确定方法。应用示例的分析结果表明,这些计算方法能更好地表征曲轴轴承的工作状况。     

柴油机滑动主轴承磨损的应变法监测

以 4 12 0 SG型柴油机为例 ,计算了在不同轴承间隙下轴承的负荷、主轴颈轴心轨迹和纵向油膜力。通过模拟试验实测了第 4档主轴承在不同轴承间隙状态下的纵向应变 ,对比了纵向应变与纵向油膜力 ,分析了纵向应变时域和频域特征 ,确定了应变信号与主轴承间隙之间的关系 ,从而证明了用应变法监测柴油机滑动主轴承磨损状态的可行性。     

Effect of Operating Condition and Structural Parameter in the Hydrostatic Thrust CO_2 Bearing

Hydrostatic thrust bearings are widely applied in rotating machinery field. Its comprehensive performance and safe operation is of great significance for ensuring equipment efficiency. In this paper, the numerical method is adopted to investigate the slit-restricted hydrostatic thrust CO_2 bearing with a small film thickness. The research is carried out from two aspects, which mainly consider the operating conditions and structural parameters. Firstly, the influence of different working fluid types including real air and CO_2(include subcritical and supercritical state) on the static characteristics of bearing is studied, and the results indicate that the bearing with CO_2 as working fluid has a better static performance. Secondly, the influence of rotor rotating speed is studied and the conclusion shows that the rotating speed has a significant effect on bearing static characteristics. Thirdly, the influence of different slit arrangement forms is investigated, and the consequence indicates that the circumferential slits show a better load capacity than that of radial slits, while the flow rate difference is small. Finally, the effect of film thickness on bearing static performance is investigated and the research shows that this factor affects static performance in a dramatical way. When the clearance tends to be smaller, the load capacity increases sharply, while the massflow rate of working fluid decreases.     

High-speed and heavy-load tribological properties of hydrostatic thrust bearing with double rectangular recess

The rotational speed and load are two main factors affecting the tribological properties of the hydrostatic thrust bearing, especially under high-speed and heavy-load conditions. The three-dimensional simulation models of oil film and bearing friction pairs are established. The oil film pressure field, oil film temperature field, bearing friction pairs deformation field, and oil film thickness field are obtained and discussed under high-speed and heavy-load working conditions. A test rig for studying high-speed and heavy-load tribological properties of hydrostatic thrust bearing with double rectangular recess is developed. The feasibility of the simulation method is validated by experiments. It is found that a reasonable matching relationship between rotational speed and load is obtained, and the burden is the main factor affecting oil film pressure. Still, the rotational speed has a significant impact on the oil film temperature. The influence of friction pairs deformation on tribological properties under high-speed and heavy-load working conditions is explored, the oil film thickness is obtained, and dry friction will appear if the working conditions are further enlarged. This work guides the application of hydrostatic thrust bearing under working conditions of high speed and heavy load.     

汽油机活塞销轴心轨迹计算及在故障诊断中的应用

采用汉氏法求解雷诺方程,计算出不稳定载荷下滑动轴承在不同偏心率和动力参数和条件下的油膜无量纲承载力,并根据实测的发动机气缸压力计算出活塞销所承受的负荷。然后根据实际负荷与油膜承载力的平衡关系,计算出动载荷下每一时刻的油膜厚度,从而确定活塞销轴心在连杆小头铜套中的运动轨迹。计算结果表明。连杆在整个运行周期中,绝大部分时间承受压缩载荷。且压缩载荷远比拉伸载荷大。此结果可用于发动机活塞连杆组的结构设计与故障诊断中,并能对一些实际故障现象进行合理的理论解释。