双向旋转式T型槽干气密封稳定性研究

发布时间：2019-01-01 09:57

【摘要】：工业装备的日益高参数化，给其旋转轴密封提出苛刻的要求：结构简洁、寿命长、性能稳定、适应性强。干气密封因其具有泄漏量少、磨损小、能耗低、寿命长、操作简单可靠且不易受油污染等特点，逐渐成为转动设备中轴密封的主流。根据旋转方向，干气密封可分为单向旋转式和双向旋转式，槽型结构的非对称性，使得单向旋转式非接触式机械密封只能在正转时工作，而在反向运转时不能。在干气密封中，，具有对称槽型、在正反向旋转时均能建立起隔离动静环硬性固相接触动压的双向旋转式T型槽干气密封，引起了人们愈来愈多的关注。本文针对T型槽干气密封的稳定性进行了较为深入的研究，其主要内容和结果如下：选择T型槽干气密封启动、运行及停车三个阶段对其稳定性进行研究，按照干气密封理论推导、仿真计算及实验研究三者结合验证这一技术路线，对影响T型槽干气密封的稳定性参数及如何提高T型槽干气密封的稳定性进行研究和讨论。鉴于启动及停车阶段的干摩擦运转对稳定性影响最大，也是造成干气密封早期失效的主因。产生失效的主因是密封副较长时间运行在转速未达到密封副分离要求的开启转速下，对此阶段开启转速的研究有助于密封副在最短时间内达到计算开启转速，以减少干摩擦对稳定性的影响。避免干气密封早期失效后，其稳定性主要体现于正常运转阶段，需对此阶段稳定性进行深入分析。采用故障树分析法对干气密封系统进行了分析，得出影响干气密封稳定性运行的主要因素。并依据仿真分析得出T型槽各参数对密封性能的影响权重，定义出影响干气密封稳定运行的稳定性参数：开启力、开启转速、气膜刚度、端面温度、摩擦功耗、端面扭矩及泄漏量。相关的理论计算、仿真模拟及实验研究都围绕稳定性参数进行。在仿真实验中，依据较大气膜开启力及气膜刚度有利于干气密封稳定性的提高，对双向旋转式T型槽进行了槽型优化分析。通过Mesh-free法对Reynolds进行了无量纲化处理，对T型槽干气密封流体动、静压的产生、压力分布、承载能力进行了分析计算。得到了流场压力分布的规律特征，并得出了动静压在密封端面的三维分布视图，再此基础上，参考分布规律及最大开启力，进一步运用Fluent软件对不同参数T型槽进行了大量的仿真优化计算，并将优化后所得槽型与原槽形在端面开启力、气膜刚度及泄漏量上作了对比分析，获得了开启力及气膜刚度有较大提升的新型槽型—OTG。基于PH线性法，将非线性偏微分方程转化为线性偏微分方程，近似求得了T型槽槽内气体动压分布的解析解，得出了稳定性参数表达式，并从结构上提出了防止和减轻此阶段的摩擦磨损设计方案。同时考虑轴向微扰及角向摆动时的影响，建立了此时的气膜刚度表达式，绘制了干气密封稳定运行特性曲线，提出了干气密封的运行稳定性判据。在实验参数测定方面，对T型槽干气密封实验中主轴转速、扭矩、端面温度、端面压力等参数进行了测量。一方面与仿真模拟得出的规律进行对比，验证仿真模拟数据的正确性；另一方面通过实验测得的扭矩、端面温度等参数确定开启转速，同时通过外部干扰研究密封稳定性能，得出稳定性参数区间。本文的研究结果可以进一步提高双向旋转式机械密封系统的稳定性，为进一步深入开展T型槽干气密封的研究及应用提供了基础和参考，也为干气密封的设计和工业应用提供了必要的理论依据。
[Abstract]:The industrial equipment is becoming more and more parameters, and it is required to seal the rotating shaft seal: the structure is simple, the service life is long, the performance is stable, and the adaptability is strong. The dry-air seal has the characteristics of little leakage, small abrasion, low energy consumption, long service life, simple and reliable operation, and is not easy to be polluted by oil and the like, and gradually becomes the main flow of the shaft seal of the rotating equipment. According to the direction of rotation, the dry-air seal can be divided into one-way rotary type and two-way rotary type, and the non-symmetry of the groove-type structure makes the one-way rotary non-contact type mechanical seal can only work at the time of forward rotation, and can not be used in the reverse operation. in that dry-air seal, a two-way rotary type T-shaped groove dry-air seal with a symmetrical groove type and an isolating and static ring hard-solid joint touch pressure can be established in the forward and reverse rotation, so that more and more attention has been paid to. In this paper, the stability of the T-shaped groove dry-air seal is studied. The main contents and results are as follows: The stability of T-type tank dry-gas seal start-up, operation and shutdown is studied, and it is based on dry-gas seal theory. In this paper, the stability parameters of the T-type tank dry-air seal and the stability of the dry-air seal of the T-type tank are studied and discussed in the light of the combination of the pilot, the simulation calculation and the experimental study. In view of the fact that the dry friction running at the start and stop stages has the greatest influence on the stability, it is also the early failure of the dry-air seal. The main cause of the failure is that the main reason that the failure is caused is that the seal pair is operated for a long time, and at the opening rotation speed which does not reach the requirement of the seal auxiliary separation, the research on the opening speed of the stage helps the seal pair to reach the calculated opening rotation speed in the shortest time, so as to reduce the stability of the dry friction pair. The stability of the dry-gas seal is mainly reflected in the normal operation stage after the early failure of the dry-gas seal is avoided, and the stability of the stage is required to be deep In this paper, the dry-gas sealing system is analyzed by the fault tree analysis method, and the operation of the dry-gas sealing system is obtained. The influence weight of each parameter of the T-shaped groove on the sealing performance is obtained according to the simulation analysis, and the stability parameters affecting the stable operation of the dry-air seal are defined. The opening force, the opening speed, the air-film stiffness, the end-face temperature, the friction power consumption and the end-face torque are defined. Moment and amount of leakage. The relevant theoretical calculation, simulation and experimental study are all around the stability in that simulation experiment, the open force of the large air film and the stiffness of the air film are favorable to the improvement of the stability of the dry gas seal, and the two-way rotary T-shaped groove is The groove-type optimization analysis is carried out. The dimensionless treatment is carried out on Reynolds by the mesh-free method, and the production, pressure distribution and bearing capacity of the T-shaped groove dry-gas sealing fluid, the static pressure, the pressure distribution, the bearing capacity, The law of the pressure distribution of the flow field is obtained, and the three-dimensional distribution view of the dynamic and static pressure on the sealed end surface is obtained. On the basis of this, the distribution law and the maximum opening force are used to further use the Fluent software to carry out a large amount of the T-shaped grooves with different parameters. The simulation and optimization calculation is carried out, and compared with the original groove shape on the end face opening force, the air film stiffness and the leakage amount after the optimization, the opening force and the air film stiffness are greatly improved. Based on the PH linear method, the nonlinear partial differential equation is converted into a linear partial differential equation, and the analytical solution of the dynamic pressure distribution in the T-shaped groove is obtained. The expression of the stability parameter is obtained, and the prevention and mitigation of this stage are put forward from the structure. At the same time, considering the influence of axial micro-interference and angle-to-swing, this paper establishes the expression of the gas-film stiffness at this time, and draws the curve of the stable operating characteristic of the dry-gas seal, and puts forward the dry air-tightness. The operation stability criterion of the seal is the main shaft rotating speed, the torque, the end face temperature and the end in the T-shaped groove dry-air sealing experiment in the aspects of the measurement of the experimental parameters. The parameters such as surface pressure and so on are measured. On the one hand, compared with the law obtained by the simulation, the correctness of the simulation data is verified; on the other hand, the open rotating speed is determined by the parameters such as the measured torque and the end surface temperature, and the sealing stability is studied by external interference The results of this paper can further improve the stability of the two-way rotary mechanical seal system and provide the basis and reference for the further research and application of the dry-air seal of the T-groove, and also the design and work of the dry-air seal.
【学位授予单位】：南京林业大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TB42

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