热弹变形对核主泵用流体静压型机械密封性能的影响

Effects Analysis of Thermo-elastic Deformation on the Performance of Hydrostatic Mechanical Seals in Reactor Coolant Pumps

针对核主泵用流体静压型机械密封在高压和高速条件下,其密封性能易受端面热弹变形影响的特点,通过建立收敛台阶端面流体静压型机械密封的稳态传热模型,并考虑流体粘度随压力、温度的变化,建立端面流体膜压力和密封环温度的控制方程,采用有限差分法求解各控制方程,采用有限元法求解密封环热、弹变形,对密封进行流、固、热耦合分析,研究热弹变形对密封性能的影响;同时改变操作参数,研究端面温度、热弹变形、端面流体膜平衡间隙等随之产生的变化规律。结果表明,端面的弹性变形大于热变形;热弹变形的综合影响使端面由外径向内径形成收敛间隙,导致开启力、泄漏率和液膜刚度增加;动环角速度越高,流体温升越大,端面热变形越明显,泄漏率越大;流体注入温度越低,温粘效应越显著;流体注入压力越高,热弹变形量越大,密封端面平衡间隙亦越大。

The thermo-elastic deformation of a hydrostatic mechanical seal used in reactor coolant pumps plays an important role in sealing performance because of the operations at high-pressure,high-speed and in a wide temperature range.A steady heat transfer model is established for such a hydrostatic face seal with convergence gap.Considering the variation of dynamic viscosity along with that of fluid pressure and temperature,the governing equations of fluid film pressure and seal ring temperature are set up and solved by using finite difference method.The thermo-elastic deformation is solved by using finite element method.The thermal-fluid-solid coupled analyses are carried out.The effects of thermo-elastic deformation on sealing performance are studied.The variations of face temperature,thermal-elastic deformation,and fluid film thickness with operating conditions are presented.It is found that the amount of elastic deformation is greater than that of thermal deformation under the considered conditions.A convergence gap between two sealing faces from the outer radius to inner radius is formed by thermo-elastic deformation,which results in the increases of opening force,leakage rate and liquid film stiffness.The higher the angular speed of rotating ring is,the greater the fluid temperature rise,the more obvious the face thermal deformation,and the greater the leakage rate will be.A lower temperature of the inlet fluid will lead to a greater effect of temperature on viscosity.A higher pressure of the inlet fluid will result in the increases of thermo-elastic deformation and the balancing film thickness.