核主泵用双锥度端面流体静压机械密封热弹流效应研究

针对核主泵用双锥度端面流体静压型机械密封热弹流效应研究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,提出了收敛型双锥面流体静压型机械密封,并建立了热-流-固耦合数学模型;通过采用有限差分法求解端面温度和端面流体膜压的控制方程组,采用有限元法求解密封环的热、弹变形,对密封进行了流、固、热耦合分析,研究了热弹变形对密封性能的影响,并对单锥面和双锥面2种流体静压型机械密封的密封性能、温度分布进行了对比研究.结果表明:双锥面密封与单锥面密封相比,不仅稳定性更好,而且端面温度分布更均匀,可靠性更高,但是泄漏率略有上升;在泄漏入口处即高压侧,外锥面锥度的大小对开启力影响较大,而在泄漏出口处即低压侧,内锥面锥度的大小对泄漏率影响较大;内锥面宽度比取0.05左右时能获得较大的刚漏比.

Thermo-Elasto-Hydrostatic Effect Analysis of a Double Tapered Hydrostatic Mechanical Seal in Reactor Coolant Pumps

The surface thermo-elastic deformations of a hydrostatic mechanical seal in reactor coolant pumps play an important role on sealing performance when they operate at high pressures and high speeds. A thermo-elasto-hydrostatic coupling model is established for such a seal with a double tapered face forming a convergent gap by considering the variations of dynamic viscosity of sealed fluid with fluid pressure and temperature, heat transfer between lubrication film and seal rings and the deformation of end faces. The governing equations for fluid film pressure and temperature are numerically solved by using finite difference method, and the thermal-mechanical deformations are simulated by using finite element method. The thermal-fluid-solid coupled analyses are carried out. The effects of thermo-elastic deformation on sealing are studied. A comparison of sealing performance between the two types of such seals with one or double tapered surface are analyzed. The results show that a double tapered hydrostatic mechanical seal has higher stability than that of a one tapered hydrostatic mechanical seal. The outlet cone has greater influence on leakage rate than that of the inlet cone, but it has less effect on the opening force than that of the inlet cone. The film stiffness to leakage ratio becomes larger when the inlet cone face width ratio equals to 0.05. The surface temperature distribution of a double tapered face seal ias more uniform than that of a one tapered face seal.