大轴径磁流体真空动密封装置的优化设计

Optimal design of large shaft diameter magnetic fluid vacuum dynamic sealing device

设计了一种大轴径两级真空磁流体密封装置,并在可变转速和径向间隙下测试其密封性能。利用ANSYS磁场有限元分析软件对不同极靴结构、径向间隙下的磁场强度进行数值计算,确定出具有最佳聚磁效果的极靴结构和密封间隙。基于计算结果设计了试验装置,采用饱和磁化强度分别为30.66 kA/m和41.75 kA/m的两种磁流体进行试验,转速可以在0~6000 r/min范围内调节,径向间隙取0.3 mm、0.5 mm和0.7 mm三种。结果表明,楔形极靴聚磁效果更好,可以大幅提高间隙内的磁感应强度;高饱和磁化强度的磁流体密封性能下降发生在低速区而低饱和磁化强度的磁流体密封性能下降发生在高速区;间隙对大轴径密封性能影响较大,尤其在高速工况下,0.7 mm间隙的密封结构密封时间仅为45 min左右。

A two-stage vacuum magnetic fluid sealing device with large shaft diameter was designed,and its sealing performance was tested under variable rotating speed and radial clearance.The magnetic field strength of different pole shoe structures under radial clearance was numerically calculated by using ANSYS magnetic field finite element analysis software,and the pole shoe structure and sealing clearance with the best magnetic accumulation effect were determined.Based on the calculation results,a test device was designed.Two kinds of magnetic fluid with saturation magnetization of 30.66 kA/m and 41.75 kA/m were used for the test.The rotating speed could be adjusted in the range of 0-6000 r/min,and the radial clearance was 0.3 mm,0.5 mm and 0.7 mm.The results show that the wedge-shaped pole shoe has a better magnetic accumulation effect and can greatly improve the magnetic induction intensity in the gap.The performance of MHD seals with high saturation magnetization decreases in the low speed region while the performance of MHD seals with low saturation magnetization decreases in the high speed region.The clearance has a great influence on the sealing performance of large shaft diameter.Especially at high speed,the sealing time of 0.7 mm clearance structure is only about 45 minutes.