介质温度对密封润滑膜颗粒沉积特性及性能影响

Effect of medium temperature on particle deposition characteristics and performance of sealing lubrication film

在考虑水的饱和蒸汽压力与温度的关系、黏温效应以及牛顿流体内摩擦效应基础上,建立了涉及润滑膜温度的上游泵送机械密封微间隙气液固多相流动计算模型,采用Fluent中Mixture模型和DPM模型进行了数值模拟,研究了介质温度对密封润滑膜固体颗粒运动、沉积分布、沉积率及密封性能的影响规律.研究表明:介质温度升高,外槽根高压区压力减小,吸入颗粒数量增多且进入槽区的颗粒更易向外槽根和坝区运动,进入膜区的颗粒多数在较大离心力和压力梯度力的作用下从外径侧逃逸,颗粒沉积区域向外槽根收缩,沉积率降低,转速较低时颗粒易在外槽根附近槽区沉积且介质温度越低,沉积区域越向内槽根拓展,转速较高时则易在外槽根及坝区沉积;润滑膜开启力和摩擦扭矩随介质温度升高而减小,摩擦扭矩随转速升高而增大且对介质温度更敏感,泄漏量随介质温度的升高而向正泄漏方向移动.

On the basis of considering the relationship between the saturated vapor pressure and temperature of water,the viscous temperature effect and the internal friction effect of Newtonian fluid,a calculation model of gas-liquid-solid multiphase flow in micro-gap of upstream pumping mechanical seals involving lubrication film temperature was established.The effects law of medium temperature on the movement,deposition distribution,deposition rate and sealing performance of solid particles in the sealing lubrication film was studied by using Mixture model and DPM model in Fluent.The results show that when the temperature of the medium increases,the pressure in the high-pressure zone of the outer groove root decreases,and the number of inhaled particles increases.The particles entering the groove area are easier to move outwards to the groove root and dam area.Most of the particles entering the membrane area escape from the outer diameter side under the action of larger centrifugal force and pressure gradient force,and the particle deposition area shrinks to the outer groove root,and the deposition rate decreases.When the rotation speed is low,the particles tend to deposit in the groove area near the outer root and the lower the medium temperature.The more the deposition area extends to the inner groove root and when the rotating speed is high,which is easy to deposit in the outer groove root and dam area.The opening force and friction torque of the lubrication film decrease with the increase of the medium temperature.The friction torque increases with the increase of the rotating speed and is more sensitive to the medium temperature,and the leakage amount moves to the direction of positive leakage with the increase of the medium temperature.