螺旋槽式液体机械密封的动力学性能分析

Analysis of Dynamic Performance of Spiral Seals for Liquid

采用有限元法求解螺旋槽式液体机械密封的雷诺方程,得到了机械密封中的二维压力分布,并在此基础上建立了机械密封的动特性参数的表达方式和计算方法.结合对某典型的人字形螺旋槽式液体机械密封的动特性参数的计算与分析,给出了结构参数和运行参数对螺旋槽式液体机械密封动力学性能的影响,在密封间隙大于10μm时可忽略流体动力学的影响.分析了液体机械密封的动力学稳定性,在一定工况下机械密封的力刚度和力矩刚度系数会成为负值而造成密封系统失稳.在机械密封设计中引入了密封动力学设计的概念.

The finite element method is adopted to solve the Reynolds equation of spiral seals, and two dimensional pressure distribution of mechanical seals is presented. The seal dynamic properties, such as stiffness coefficients, damping coefficients, torque stiffness coefficients and torque damping coefficients, are analyzed. The dynamic properties of the herringbone spiral seal are calculated, and the influences of the rotating speed and clearance on the dynamic properties of the seal are studied. The calculation results show that if the clearance of the mechanical seal is large enough (>10 μm) the dynamic influences of the seal liquid can be neglected, and the damping coefficients and torque damping coefficients hardly change with the variation of rotating speed, but change greatly with the seal clearance. At high rotating speed the stiffness coefficients and torque stiffness coefficients increase at first and then decrease with the increasing of seal clearance; if the rotating speed is low, the stiffness coefficients and torque stiffness coefficients decrease with increasing of seal clearance, and within some regions the stiffness coefficients and torque stiffness coefficients may even be negative, which leads the mechanical seal system to instability.