激光加工的多孔端面机械密封的性能数值分析

建立激光加工多孔端面机械密封的分析模型,采用有限差分法求解雷诺方程,得到不同操作条件和微孔结构参数 下密封端面间的流体压力分布,进而可以计算端面间的密封开启力和液膜刚度。通过分析端面结构参数对密封开启力 和液膜刚度的影响规律,可得到端面结构的优化参数。分析结果表明,微孔密封面可产生明显的动压效应。     

激光加工多孔端面非接触机械密封的性能研究

建立了激光加工多孔端面机械密封的计算模型,采用有限差分法求解雷诺方程,获得在不同操作工况和表面微孔结构参数下密封面的无量纲压力分布,进而得到了产生最大端面压力时的优化结构参数,且与Etsion等研究的试验结果较为一致。分析结果表明密封面上的微孔可产生明显的动压效应。     

激光加工多孔端面机械密封的理论研究

通过建立矩形截面轮廓激光加工多孔端面机械密封的理论分析模型,采用有限元方法求解雷诺方程,研究了不同微孔结构参数及工况参数对密封端面平均压力的影响规律,以能够产生最大端面平均压力为优化目标,指出微孔深径比最优值应不小于0．1,面积密度最优值大约为0．2。该研究方法与结果对多孔端机械密封的设计和使用具有重要意义。     

部分端面微孔机械密封端面间液膜压力分布的理论研究

建立了研究部分端面微孔机械密封端面间液膜压力分布规律的理论模型,应用有限差分法求解了端面液膜压力的Reynolds控制方程,获得了端面液膜压力分布规律,并与端面全区域开微孔机械密封的情况进行了对比.研究了微孔密度Sp和微孔深径比ε对端面液膜压力的影响规律.结果表明:部分端面微孔机械密封的端面间液膜压力比端面全微孔的小;端面间液膜沿半径方向的最大压力降发生在孔区域结束处;端面液膜压力值最大值所对应的微孔密度Sp≈0.2,深径比ε≈0.02.     

激光加工多孔端面机械密封的摩擦性能分析

分析了工况参数和结构参数对激光加工多孔端面机械密封摩擦性能的影响。建立了激光加工多孔端面机械密封的计算模型和边界条件,采用有限差分法求解液膜控制方程,获得在不同操作工况和表面微孔结构参数下的密封开启力。理论推导得到了激光加工多孔端面机械密封的摩擦扭矩表达式,并对其进行了分析。结果表明,密封端面间的摩擦扭矩随着密封环转速的增加而增大;微孔深度和微孔密度有最佳参数,使密封端面间的摩擦扭矩最小,且与试验结果吻合。     

激光加工多孔端面机械密封的摩擦特性试验研究

对激光加工的多孔端面机械密封进行了摩擦性能试验研究，并与一般机械密封进行比较，结果表明，其端面温升，摩擦扭矩和摩擦系数远低于后者的相应值。说明该密封结构产生的动压效应使密封面间处于良好的摩擦状态。     

激光加工多孔端面机械密封静压分析

建立了在部分密封端面上加工微孔的激光加工多孔端面机械密封理论分析模型,用有限元法求解雷诺方程,获得了不同微孔结构参数下端面的无量纲膜压分布,以获得最大端面静压为目标,提出了微孔结构参数的最优值,指出开孔区长度比最优值约为0.6,面积密度最优值大约为0.5.研究表明在部分密封端面上加工微孔可有效增大端面静压.     

激光加工多孔端面机械密封变形的数值分析

针对离心泵用激光加工多孔端面机械密封,通过采用有限元法求解雷诺方程获得密封端面流体膜压分布,计算了不同约束、不同结构动、静密封环的力变形以及端面泄漏量、液膜刚度和刚漏比等密封性能参数,分析了变形对密封性能的影响。结果表明:端面变形对密封性能影响很大,将导致泄漏量增大,刚漏比减小;密封环的约束对变形起着重要作用,选择合适的约束可以减小密封面转角,提高液膜刚度,增强密封工作稳定性。     

微孔参数对激光加工多孔端面机械密封性能的影响

通过建立激光加工多孔端面机械密封的理论分析模型,应用有限元方法在给定工况下研究了不同微孔截面型线的微孔深径比ε和面积密度Sp对端面开启力、液膜刚度、摩擦扭矩及泄漏量等密封性能参数的影响规律。结果表明:当微孔深径比ε小于或等于0.2时,激光开孔端面密封的开启力、液膜刚度和摩擦力矩随其的增大急剧下降,但当微孔深径比ε大于0.2时,密封性能受其的影响很小;当面积密度Sp为0.4~0.6时,密封可获得最大的开启力或液膜刚度。     

上游泵送机械密封环端面激光加工工艺参数

上游泵送机械密封是一种具有环保概念、长寿命、低能耗的高新密封技术,其应用前景将十分广阔.采用Nd:YAG灯泵浦系列脉冲激光进行了上游机械密封端面开槽加工试验,研究了激光加工工艺参数对开槽加工质量的影响.试验研究结果表明,激光电流是影响激光开槽质量的重要因素,对于硬质合金材料,激光电流为14.6A,开槽质量较高,槽深为5.5μm.这为上游泵送机械密封的理论与应用研究奠定一定试验基础.     

Evaluation of mechanical face seals operating with hydrocarbon mixtures

Methods are introduced for calculating thermophysical properties of the common volatile media, such as hydrocarbon mixtures in a petrochemical plant. Using a suitable equation of state for simulating thermodynamic equilibrium of the media and taking parallel face seals as geometrical models, a computer program for predicting seal performance of various phase states mechanical face seals (MFS) operating with the mixtures is presented. Based on theoretical analysis and experimental results, a criterion named fluid film pressure coefficient K_m for identifying phase states and phase states stability of MFS is put forward. An appropriate model for determining mean face temperature is set up and compared to the test results. It is shown that the predicted results are in excellent agreement with the test results. It is proved that the methods and program may be useful in practice. It is concluded that performance of MFS can be predicted only if thermophysical properties of a sealed medium could be expressed in suitable expressions.     

端面微孔机械密封研究进展

端面微孔机械密封是一种新型机械密封技术,它是在普通机械密封的端面上加工出微米级的小坑孔,具有良好的润滑性能和密封性能,已在石油化工行业用泵上获得了成功应用。本文简要地介绍了端面微孔机械密封的典型结构及其工作原理、端面微孔机械密封产生发展概况、最新研究进展及其在化工泵上的应用情况。     

The mechinism of film generation in mechanical face seals

Examination of mechanical seals that have operated succesfully has shown that both faces develop a circumferential waviness. Numerical analysis of fluid film between two faces with circumferential waviness suggests that this can provide the necessary hydrodynamic pressure generation to maintain the faces in equilibrium, separated by a continuous fluid film. In order to give sensible leakage rates, the waviness amplitude is found to be an order of magnitude less than that measured on such faces removed from service after successful operation.     

Thermal performance of mechanical seals with textured side-wall

Experimental measurements and numerical simulations are presented to show the effectiveness of cooling of a mechanical seal's active surface by means of cylindrically shaped dimples engraved circumferentially on the outside diameter of the mating ring. The working fluid is propylene glycol solution (70% in water by volume) and the flush rate is 107 cm³/s. A commercially available CFD code (FLUENT) is employed to numerically confirm the experimental measurements, and the numerical and experimental results are in agreement. Results of this study demonstrate the heat augmentation effectiveness of surface texture techniques on the mechanical seals.     

流体回流式机械密封技术研究进展

现阶段机械密封的操作条件更加苛刻和多样化。在一些高参数的密封工况下,传统的接触式机械密封磨损严重、寿命较短,已迭不到密封的基本要求。发展流体润滑的非接触式机械密封是保证设备长时间连续正常运转的迫切要求。流体回流式机械密封对普通机械密封端面进行简单改型,其结构简单、应用前景广阔,特别适合高压、高温、大尺寸等高参数工况。对具有回流特性的圆弧槽机械密封、螺旋槽上游泵送机械密封和水平槽机械密封的研究发展情况进行了综述。指出了开展深入研究水平槽机械密封的必要性。     

Experimental and numerical evaluation of contact pressure in pneumatic seals

An experimental procedure is presented for measuring contact pressure between a pneumatic seal and its counterface. Measurements were performed using pressure-sensitive films, for which a suited calibration procedure was developed, also taking into account humidity influence. Having validated the experimental procedure on a lip seal rectilinear specimen, tests were carried out on commercial piston seals. Results were compared with those coming from numerical simulations performed using a finite-elements analysis.     

A study of sliding between rollers and races in a roller bearing with a numerical model for mechanical event simulations

A numerical model of a roller bearing is presented in this paper. These simulations provide us with the spatial and time distributions of stress and strain values, as well as all the nodal displacements at every time step. The model was developed with the finite element method (FEM) for mechanical event simulations (MES) with the commercial code Algor^TM. The model has been validated by verifying that the contact force distributions correspond to those predicted by the analytical model of Harris-Jones.As an application, a study of sliding between the rollers and the races has been carried out. For each roller, a rolling zone can be defined in which local sliding (computed between two consecutive time steps) is negligible. According to the simulations, we conclude that the rolling zone is practically the same for all the rollers in the same simulation; that this rolling zone is smaller than the corresponding load zone, and that rolling and load zones are angularly centered with respect to each other.     

螺旋槽气体润滑机械密封温度场有限元分析

应用有限元法计算了螺旋槽气体润滑机械密封的稳态温度场分布.计算了不同压力、转速及导热材料下密封环温度分布,并与实验值做以比较,并对计算结果进行分析.     

高压多级离心泵口环密封动力学性能研究

针对高压多级离心泵口环密封的动力学特性求解问题,提出添加出口压力恢复系数的"有限长"理论求解方法,完善了控制方程组的边界条件,并用"打靶法"对此新边界条件下的口环密封流体控制方程组进行了Matlab编程求解。同时,为使软件脱离Matlab运行环境而独立运行,采用动态链接库的方式将内核计算程序封装,并利用VB实现了界面的设计、数据传输与内核程序的调用。研究结果表明,该程序运行流畅,对口环密封动力学特性计算精度高。