接触式机械密封热力耦合模型与端面变形控制

发布时间：2018-05-01 16:18

本文选题：机械密封 + 热力耦合　；参考：《浙江工业大学》2016年硕士论文

【摘要】：潜水器等深海作业设备用机械密封端面热力变形随水深的不同而不同,且存在复杂的热力耦合作用。过大的端面变形会影响密封性能及其使用寿命,甚至会危害到操乘人员的生命安全。对接触式机械密封进行热力耦合变形分析,能有效地对密封端面变形进行预测和评估,有助于研究机械密封端面变形控制的方法以及促进深海机械密封的发展与应用。本文以深海作业装备用机械密封为研究对象,综合考虑密封环热力变形、润滑液膜压力分布和粘温特性等之间的耦合关系,通过建立接触式机械密封的稳态和瞬态轴对称模型,研究稳态密封性能和瞬态密封性能演化规律,为机械密封环的变形控制提供了方法。主要工作和结果如下:考虑密封端面的热、力变形和液膜温度、厚度等之间的耦合关系,建立了机械密封稳态热力耦合模型,分析了密封端面的变形规律,研究了密封压力和转速对端面热力变形和密封性能的影响;通过建立机械密封启动瞬态工况下的热力耦合模型,研究了等压启动和变压启动两种工况条件下密封环端面变形和密封间隙的变化规律,分析了各性能参数的演化规律;在稳态热力耦合模型的基础上考虑端面磨损的影响,建立机械密封端面磨损的数学模型,研究了端面磨合过程中密封间隙和动环端面形状的演变规律,分析了密封端面热力变形、液膜厚度和泄漏率等的变化规律;基于密封端面热力耦合变形,研究了密封环结构尺寸对端面变形的影响规律,重点探究了“尾部支撑”轴向长度和动环端面力变形之间的关系,提出了通过控制动环力变形改变其锥度进而实现动静环端面相对零变形的方法。结果表明,在稳态工况下,密封端面热、力变形沿径向呈近似线性分布,并非呈完全线性分布;力变形引起动环端面形成发散锥形,热变形形成收敛锥形,综合效果为形成收敛状锥形间隙;启动瞬态工况下,随时间的增加,端面间隙由发散型转变为收敛型;在端面磨合过程中,密封间隙逐渐由收敛型转变为平行型,且磨损后动环的几何形貌由静环热力变形后的形貌所决定;通过设计合理的动环结构尺寸控制端面力变形,可获得稳态工况下近似平行状的密封间隙。论文模型和相关结论可用于指导机械密封的失效分析和密封环的结构设计。
[Abstract]:The thermal deformation of mechanical seal end surface for deep-sea operation equipment such as submersible varies with the depth of water, and there are complex thermodynamic coupling effects. Excessive end face deformation will affect the sealing performance and service life, and even endanger the safety of crew. The thermo-mechanical coupling deformation analysis of contact mechanical seal can effectively predict and evaluate the end face deformation of mechanical seal. It is helpful to study the control method of mechanical seal end face and to promote the development and application of deep-sea mechanical seal. In this paper, the mechanical seal used in deep-sea operation equipment is taken as the research object, and the coupling relations between the thermal deformation of seal ring, the pressure distribution of lubricating liquid film and the characteristics of viscosity and temperature are considered synthetically, and the steady and transient axisymmetric models of contact mechanical seal are established. The evolution law of steady seal performance and transient seal performance is studied, which provides a method for deformation control of mechanical seal ring. The main work and results are as follows: considering the coupling relations between heat, force deformation and liquid film temperature and thickness of the seal end face, a mechanical seal steady state thermodynamic coupling model is established, and the deformation law of the seal end face is analyzed. The effects of seal pressure and rotational speed on the thermal deformation and sealing performance of the end face are studied. The variation law of the end face deformation and seal clearance of the seal ring under the condition of constant pressure start-up and variable pressure start are studied, and the evolution law of each performance parameter is analyzed, and the effect of end surface wear is considered on the basis of the steady state thermodynamic coupling model. The mathematical model of the end face wear of mechanical seal is established. The evolution law of the seal clearance and the shape of the moving ring end face during the running-in process of the end face is studied, and the variation law of the thermal deformation, the thickness of liquid film and the leakage rate of the seal end face are analyzed. Based on the thermo-mechanical coupling deformation of the seal end face, the influence of the structure size of the seal ring on the end face deformation is studied, and the relationship between the axial length of the "tail support" and the force deformation of the moving ring end face is studied. A method is proposed to realize the relative zero deformation of the end surface of the dynamic ring by changing the taper of the dynamic ring by controlling the force deformation of the moving ring. The results show that under the steady state condition, the thermal and force deformation of the seal face is approximately linear distribution along the radial direction, but not completely linear distribution, and the end surface of the dynamic ring formed divergent cones due to the force deformation, and the thermal deformation formed a convergent cone. The synthetic effect is to form a convergent cone clearance; under start-up transient conditions, the end gap changes from divergent to convergent with the increase of time; during the end face running-in, the seal clearance gradually changes from convergent to parallel. The geometric morphology of the motion ring after wear is determined by the shape of the static ring after thermal deformation, and the close parallel seal clearance can be obtained by designing the reasonable structure size of the moving ring to control the deformation of the end face force. The model and related conclusions can be used to guide the failure analysis of mechanical seals and the structural design of sealing rings.
【学位授予单位】：浙江工业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：P754

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