Abstract:

Using the Eulerian multiphase flow model and the evaporative condensation model, a vapor-liquid-solid three-phase flow model of the dynamic pressure mechanical seal lubricating film involving high-temperature vaporization, solid particles, viscosity-temperature effects and Newtonian fluid internal friction effects was established, the variation law of the vapor-liquid-solid flow characteristics of the lubricating film with the working conditions, and the relationship between the vaporization of the lubricating film, the distribution of solid particles and the sealing performance were calculated and analyzed. The research showed that the vaporization of the lubricating film and the distribution of solid particles were mainly located in the groove and weir area, and there was a mutual restraint relationship between the vapor phase and the solid particle phase. Liquid phase vaporization and viscosity drop caused by high medium temperature weakened fluid dynamic pressure, which would cause the high pressure area of the outer groove root to be indistinct or even disappear. The degree of vaporization of the lubricating film decreased first and then increased slowly with the increase of the speed. There was a vaporization-inhibiting speed zone and moves to the high-speed direction with the increase of the medium temperature. The volume fraction of solid particles increased rapidly when approaching the vaporization inhibition speed region. When the medium pressure increased to a certain value, the phenomenon that the volume fraction of solid particles rapidly dropped to near zero occurs, and the higher the medium temperature, the smaller the medium pressure of the rapid drop. When the medium temperature was higher than 423K, the lubricating film opening force, leakage amount, and friction torque all changed from gentle to accelerated changes near the vaporization suppression speed.

Key words: high temperature mechanical seal, vapor-liquid-solid flow, vaporization, solid particles, sealing performance

摘要：

利用Eulerian多相流模型和蒸发冷凝模型，建立了涉及高温汽化、固体颗粒、黏温效应及牛顿流体内摩擦效应的动压型机械密封润滑膜汽液固三相流动模型，计算分析了润滑膜汽液固流动特性随工况的变化规律，以及润滑膜汽化、固体颗粒分布及密封性能的影响关系。研究表明：润滑膜汽化和固体颗粒分布均主要位于槽堰区，汽相和固体颗粒相之间存在相互制约关系；高介质温度导致的液相汽化和黏度下降使流体动压减弱，因而导致外槽根高压区不明显甚至消失。润滑膜汽化程度随转速增大呈先减小后缓慢增大变化规律，存在汽化抑制转速区且随介质温度的升高而向高速方向移动；固体颗粒体积分数在接近汽化抑制转速区时出现快速增大；介质压力增大至一定数值时出现固体颗粒体积分数迅速降至零附近的现象，且介质温度越高出现速降的介质压力越小；介质温度高于423K后，润滑膜开启力、泄漏量和摩擦扭矩均会在接近汽化抑制转速时出现由平缓变化到加速变化的过程。

关键词: 高温机械密封, 汽液固流动, 汽化, 固体颗粒, 密封性能