基于分布式超声测量的滑动轴承润滑膜特性的在线检测及实验研究

The lubricant film's thickness and distribution information of sliding bearing are the important parameters in theory research of fluid lubrication and condition monitoring of rotor-bearing system. Because of the confined space, tiny scale and fast change of lubricant film, it restricts the implementation and development of the distributed measurement of the lubricant film's thickness. In this project, a ultrasonic measurement method of lubricant film's thickness would be studied based on the principle of equivalent stiffness, which would be used for the measurement of lubricant film's thickness of the mixed lubrication state, and it could widely expand the adaptive range of the measurement. Through deploying the ultrasonic transducer by distribution, it could achieve a ultrasonic measurement method of lubricant film's thickness, and this method could be used for lubricant film's thickness measurement of sliding bearing and lubricant condition monitoring in real work condition as well as solving the technology bottleneck that the lubrication condition monitoring is difficult to apply in engineering. The technique to be developed would be tested by experiments in the typical bearing apparatus,through which the complete lubricant film distribution could be obtained in the different situations such that varying experimental parameters, inclined journal and the mixed lubrication state. The research achievement could be a significant meaning for theory research of sliding bearing and working condition monitoring.

滑动轴承润滑膜厚度及其分布信息是流体润滑理论研究与转子-轴承系统运行状态监测的重要参数，而润滑膜所在空间的密闭性、尺度的微小性以及变化快速等特点制约了膜厚分布检测的实施与发展。本项目研究基于等效刚度原理的超声膜厚检测方法，使之能够用于混合润滑状态的膜厚检测，大大拓展了超声膜厚检测的适应范围；通过分布式布设超声波换能器，实现分布式超声膜厚测量，并能够用于真实工况下滑动轴承膜厚检测和润滑状态监测，解决润滑状态监测难以工程应用的技术瓶颈。在典型轴承实验台上进行实验验证，通过对实验参数的改变，模拟轴颈偏斜及混合润滑状态，获得完整的润滑膜分布信息。研究成果对滑动轴承的理论研究以及运行状态监测都具有重要意义。

滑动轴承润滑膜厚度及其分布信息是流体润滑理论研究与转子-轴承系统运行状态监测的重要参数，而润滑膜所在空间的密闭性、尺度的微小性以及变化快速等特点制约了膜厚分布检测的实施与发展。本项目针对滑动轴承润滑膜厚超声检测中的一系列关键问题进行了系统的研究，主要研究内容有：.研究了现有膜厚超声检测三种方法的统一模型并对现有膜厚超声检测方法进行了改进。建立超声波在中间层上的连续性模型，根据超声波在中间层上下界面的声压和速度连续性条件，研究了润滑膜厚超声检测三种方法间的内在关系，将传统属于时域分析的超声波飞行时间法转化到频域求解，并将其与共振法统一融合为拓展共振法，使膜厚超声检测的三种方法统一为频域方法，避免了在膜厚尺度变化较大时需要在时域与频域内相互切换。.研究了混合润滑状态下润滑膜厚超声检测方法。针对混合润滑状态下存在粗糙峰接触而影响测量精度的问题，建立了超声波在流固耦合界面的反射模型，通过载荷比例系数法获得各工况下润滑膜刚度占界面总刚度的比例，从界面总刚度中提取润滑膜刚度用于膜厚测量，提高混合润滑状态下膜厚测量的精度.研究了具有衬层结构的推力轴承膜厚超声检测方法。针对薄衬层结构推力轴承由于多层反射导致信号重叠失真问题，提出采用高斯回波和噪声重构原始信号，发展了一种融合最大期望值方法、支撑匹配追踪算法以及遗传算法的重叠回波快速自适应分离算法，通过该分离算法获得超声波在润滑膜层上的反射信号并进而获得润滑膜厚值，实现了具有薄衬层结构的推力轴承膜厚的超声检测，将传统三层结构模型的膜厚超声检测方法拓展应用到四层及多层结构模型的膜厚超声检测中。.研究了可倾瓦推力轴承膜厚分布检测的实验方法。基于润滑膜厚分布获取对测点个数的要求和传感器安装空间的限制，研究采用超声波压电元件作为超声波传感器，在可倾瓦推力轴承的瓦背上分布式嵌入多个超声波压电元件。利用多测点的膜厚实测值通过插值拟合获得轴瓦的膜厚分布及轴瓦姿态。