深海环境机械密封端面波形的生成、传播与演变机制研究

Seal technology is one of key technologies which assure the reilable, safe and stable operation of submersible vehicles and operating equipments. Mechanical seal is one of the main seal type. Influenced by different sumbergence depth or ocean current, the end face waviness caused by "low pair" TEHD effect will prograte and evolve, which will lead to the mechanical seals' failure ahead of time. To solve such problem, the following research work will conduct in this project: (1) Based on fluid lubrication theory, low pair TEHD model for mechanical seals will be developed with combination of mixed-dimensional couple, boundary couple and static condensation method. The rapid computational technique based on FEM is seeking. The formulation and propagration mechanism of end face waviness and seal failure is disclosed. (2) End face wear discipline under sea water and the evolution history of waviness are investigated. Coevolution mechanism between wear and TEHD effect is clarified during diving or floating. The self-adaptation design concept on seal rings structure and prediction and control techniques on waviness is proposed. (3) Real-time dynamic measurement technique for end face friction state is investigated. The dynamic wear mechanism of seal face in deep-sea enviorment is disclosed effected by "low pair" TEHD effect. Interaction between face wear and TEHD effect is researched. Coevolution between surface waviness and surface wear is investigated. Through above studies, it is expected to solve performance degeneration of mechanical seals during operation, which is vital significant in enriching TEHD theory and in perfecting mechanical seals design theory.

密封技术是确保深海潜航器或作业装备可靠、安全、稳定运行的关键技术之一，机械密封是其中主要密封形式。受不同潜航深度和洋流变化影响，由"低副"热弹流效应引起的密封端面波形在面内传播和演变，易导致密封早期失效。为解决上述问题，项目开展如下研究工作：(1)基于流体润滑理论，建立机械密封低副热弹流数学模型，综合混合维度耦合、边界耦合和静力凝聚法，探索模型的有限元求解技术，揭示端面波形产生、传播和密封失效机理；(2)研究海水润滑条件下端面磨损规律及对波形的演变历程影响规律，阐明变潜深工况端面波形的传播和演变机制，提出波形预测、控制与协调优化技术及密封环结构自适应设计理念；(3)研究密封端面摩擦学状态的实时动态测量技术，揭示深海环境低副热弹流效应作用下端面动态磨损机理，实现端面波形与端面磨损的协同演化技术。该研究有望解决机械密封界面摩擦性能恶化问题，对于丰富热弹流理论及完善机械密封设计理论具有重要意义。

机械密封是深海潜航器或深海作业装备的关键基础部件。机械密封摩擦配对环在“低副”热弹流效应下引起密封端面的波度变形，并随潜航或作业深度的变化和洋流的冲击在密封端面上上产生动态演变，改变密封端面的润滑和磨损状态，影响密封性能和使用寿命。. 项目围绕深海装备用机械密封，考虑密封动静环、润滑液膜、密封腔内密封介质之间的流固热力耦合关系，提出了润滑液膜遵循质量守恒的有限元自适应空化算法；建立了机械密封拟三维热流体动力润滑理论模型，针对方程的对流扩散特性，探索了基于流线迎风的有限元求解流程；将密封环的热力变形耦合入上述理论模型，突破了机械密封多体多物理场多尺度的低副热弹流理论模型的数值仿真技术。基于上述理论模型和数值仿真方法，研究了稳定工况下热流体动力楔机械密封、微孔端面机械密封和普通接触式机械密封密封动静环端面的热力变形波形的形成机理及对密封性能的影响规律，分析了变潜深、变转速，装备主机启动、停机，密封环磨合、动态扰动等瞬变条件下机械密封密封环端面变形波形的传播和演变规律及对密封性能的影响规律；基于密封环的热力变形规律，以密封环端面变形波度的形成和控制为目标，开展了密封环宏观结构的优化设计研究，实现了密封环端面热力变形的抵消；完成了机械密封多功能多参数性能测试实验台架的设计与制造，进行了不同工况下机械密封性能试验研究。结果表明：(1) 端面开深“U”型槽机械密封的成膜机理可归因于深槽所导致的结构局部不连续性的周向力波度变形和径向温度梯度变形；(2) 接触式机械密封端面力热变形形式一般相反，通过合理的结构设计可对端面力热变形进行控制；(3) 机械密封端面存在的表面织构微孔可产生局部的微弹流效应，有助于提升密封的承载性能；(4) 液膜粘性剪切热在液膜承载力、密封环端面热变形方面产生至关重要的影响，尤其是在高参数工况，不能忽略热的影响。研究结果对于完善深海装备机械密封的结构设计具有重要的工程应用价值。