Impact Phenomena in a Noncontacting Mechanical Face Seal
Impact Phenomena in a Noncontacting Mechanical Face Seal
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DOI：
10.1115/1.4033366
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发表时间：
2017-03
影响因子：
2.5
通讯作者：
P. Varney;I. Green
中科院分区：
文献类型：
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作者：
P. Varney;I. Green
非接触式机械端面密封通常被描述为不可预测的机器元件，从许多过早和意外故障的实例中获得了这个绰号。机器故障，如不对中或不平衡加剧密封振动，导致不希望和不可预见的密封面之间的接触。一个解释非接触式机械密封失效的高概率的假设是这种不希望的密封面接触。然而，支持这一假设的研究是启发式的和经验的，缺乏将接触纳入密封动力学的鲁棒模拟所提供的严密性。在这里，采用粗糙表面接触来模拟转子-定子摩擦的最新发展，以模拟设计在非接触状态下运行的柔性安装定子（FMS）机械面密封中的冲击现象。具体来说，弹塑性Jackson-Green粗糙表面接触模型使用真实的可测量的表面和材料参数来量化接触力。该方法还确保密封面间隙保持为正，从而允许计算流体膜力。密封运动方程进行了模拟，以表明几种接触操作模式，其中接触是通过波形、频谱和接触力计算来识别的。有趣的是，我们首次发现产生接触的某些参数会诱发非周期机械端面密封振动，这是一种有用的机械振动监测症状。此外，这项工作还首次从分析角度揭示了严重接触导致密封失效的机制，而以前人们只能通过直觉和/或经验来了解这一机制。讨论了密封面接触诊断的实用性，并提出了今后工作的方向。(DOI: 10.1115/1.4033366)
Noncontacting mechanical face seals are often described as unpredictable machine elements, gaining this moniker from numerous instances of premature and unexpected failure. Machine faults such as misalignment or imbalance exacerbate seal vibration, leading to undesirable and unforeseen contact between the seal faces. A hypothesis explaining the high probability of failure in noncontacting mechanical face seals is this undesired seal face contact. However, research supporting this hypothesis is heuristic and experiential and lacks the rigor provided by robust simulation incorporating contact into the seal dynamics. Here, recent developments in modeling rotor–stator rub using rough surface contact are employed to simulate impact phenomena in a flexibly mounted stator (FMS) mechanical face seal designed to operate in a noncontacting regime. Specifically, the elastoplastic Jackson–Green rough surface contact model is used to quantify the contact forces using real and measurable surface and material parameters. This method also ensures that the seal face clearance remains positive, thus allowing one to calculate fluid-film forces. The seal equations of motion are simulated to indicate several modes of contacting operation, where contact is identified using waveforms, frequency spectra, and contact force calculations. Interestingly, and for the first time, certain parameters generating contact are shown to induce aperiodic mechanical face seal vibration, which is a useful machine vibration monitoring symptom. Also for the first time, this work analytically shows a mechanism where severe contact precipitates seal failure, which was previously known only through intuition and/or experience. The utility of seal face contact diagnostics is discussed along with directions for future work. [DOI: 10.1115/1.4033366]