论文总字数：22139字

摘 要

流体动压润滑指的是利用流体的动压特性，使流体在润滑端面间形成稳定均匀的液膜起到润滑与密封的作用。但传统的流体动压润滑在面对变化的工况时难以做出及时响应。磁流体凭借其可以在磁场作用下控制粘度的特性在润滑与密度等方面得到了广泛的应用。利用磁流体的这一特性，在工况参数改变时利用磁场改变磁流体的粘度便可以实现磁流体动压润滑机械密封的可控。

本文以磁流体作为密封端面的润滑介质，设计了磁流体动压润滑性能试验装置，通过改变工况参数，研究了磁流体的动压润滑特性，得到了转轴转速、介质压力、磁场强度对液膜厚度、摩擦扭矩和泵送量等参数的影响规律，提出了在变化的工况下控制动压润滑机械密封的方法。

研究表明：转轴转速和介质压力越大，摩擦扭矩和泵送量越大，膜厚越小。当密封介质压力高于0.3 MPa时，磁流体粘度过大，动压效应受阻，润滑失效。磁场强度越大，摩擦扭矩越大，泵送量和膜厚越小。磁场强度对磁流体的动压润滑性能的影响相较于转轴转速和被密封介质压力更大，因此为了密封的稳定与可靠，可以通过调节磁场强度来改变磁流体膜的压力以适应工况的变化，使磁流体膜始终保持动压平衡。

关键词：磁流体 动压润滑 机械密封

Design of the Magnetic Fluid Hydrodynamic Lubrication Performance Test Device

Abstract

Hydrodynamic lubrication refers to the use of the dynamic pressure characteristics of the fluid to form a stable and uniform liquid film between the lubricating end faces to play a role in lubrication and sealing. However, traditional hydrodynamic lubrication is difficult to make timely response in the face of changing conditions. Magnetic fluid has been widely used in lubrication and density because of its ability to control viscosity under the action of magnetic field. By using this characteristic of magnetic fluid, when the working condition parameter changes, the viscosity of the magnetic fluid can be changed by using magnetic field to realize the control of the hydrodynamic lubrication mechanical seal.

In this paper, the magnetic fluid is used as the lubricating medium of the seal face, and a test device for the hydrodynamic lubrication performance of the magnetic fluid is designed. By changing the working condition parameters, the hydrodynamic lubrication characteristics of the magnetic fluid are studied. The effects of the rotating speed of the shaft, the pressure of the medium, and the intensity of the magnetic field on the parameters such as the thickness of the liquid film, the friction torque and the pumping capacity are received. The method of controlling the hydrodynamic lubrication mechanical seal under the variable working conditions is proposed.

The results show that with the increase of the rotating speed and the medium pressure, the friction torque and the pumping capacity increase, and the film thickness decrease; the larger the magnetic field strength is, the larger the friction torque is, the smaller the pumping capacity and the film thickness are. When the pressure of sealing medium is higher than 0.3MPa, the viscosity of magnetic fluid is too large, the dynamic pressure effect is blocked, and the lubrication fails. The influence of magnetic field strength on the hydrodynamic lubrication performance of magnetic fluid is greater than that of rotating speed and sealing medium pressure. Therefore, in order to make the seal more stabilize and reliable , the pressure of magnetic fluid film can be changed by adjusting the magnetic field strength to adapt to the changes of working conditions, so that the dynamic pressure balance of magnetic fluid film is always maintained.

Key Words: magnetic fluid; hydro-dynamical lubrication; mechanical seal

目 录

摘 要 I

ABSTRACT II

第一章 绪论 1

1.1 课题研究背景与意义 1

1.2 磁流体的性质与应用 2

1.2.1 磁流体的组成与性质 2

1.2.2 磁流体的应用 2

1.3 磁流体润滑发展历史与国内外研究现状 4

1.4 课题研究内容 5

第二章 磁流体动压润滑性能试验装置的设计 7

2.1 磁流体动压润滑性能试验装置 7

2.1.1 磁流体动压润滑性能试验装置的基本结构 7

2.1.2 磁流体动压润滑性能试验装置的基本原理 8

2.2 机械系统设计 8

2.2.1 传动方式拟定 8

2.2.2 电机选型 9

2.2.3 带轮的设计 10

2.2.4 转轴结构设计与强度校核 11

2.2.5 轴承定位方案及定位元件设计 15

2.2.6 机械密封设计 16

2.2.7 附属机构设计 19

2.3 计算机数据采集系统 20

2.4 经济评价 21

2.4.1 总投资估算 21

2.4.2 维护费用 22

第三章 磁流体动压润滑性能试验方案 23

3.1 磁流体动压润滑性能的试验测试 23

3.1.1 试验方案设计 23

3.1.2 试验流程 23

第四章 试验结果与分析 25

4.1 磁流体动压润滑性能的试验测试结果 25

4.1.1 试验条件 25

4.1.2 实验内容 25

4.2 实验结果分析 31

第五章 结论与展望 33

5.1 结论 33

5.2 展望 33

参考文献 35

致谢 39

第一章 绪论

1.1 课题研究背景与意义

化工生产中时常会出现密封泄露的问题，这不仅影响了生产质量与效率，还具有一定的危险性^[1]。机械密封是最常见的密封形式之一，但普通的机械密封在被密封介质压力变化或转速的突变时，不具备实时调节和应变的能力，常常会导致密封失效^[2]。利用流体的动压特性可以使得密封端面间充满一层均匀的流体膜以达到分离端面并密封的效果^[3]。流体动压润滑机械密封凭借其不易泄漏、润滑性能好、使用期限长、安全稳定等特点在高温、高压、高速或超低温、真空等极端工况下得到了较好的应用^[4]。当采用磁流体作为流体动压润滑机械密封的端面润滑介质时，不但可以改善摩擦端面的润滑状况，还可以通过改变外部磁场以改变薄膜的动压特性达到实时调控的作用^[5]，从而使装置起到更稳定的润滑和密封作用，也能在一定程度上减少和规避密封泄露的发生。

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