大间隙阶梯式磁流体旋转密封失效机理及耐压性能研究

The stepped magnetic fluid sealing technology is one of effective methods to improve anti-pressure capabilities of an universal magnetic fluid seal with large gap. However, on the occasions of high speed and heavy load, the performance and reliability of the stepped magnetic fluid seal decrease dramatically because of the influence of centrifugal force, eccentricity and so on. Therefore, in order to improve anti-pressure performance of stepped magnetic fluid seal with large gap, Considering the influences of centrifugal force, eccentricity and so on and starting from the equation of magnetic fluid motion, the function for the magnetic fluid film thickness will be constructed and the anti-pressure formula of the stepped magnetic fluid rotary will be derived. The failure mechanism of stepped magnetic fluid rotating seal with large gap will be revealed. The stepped magnetic fluid sealing structure is preliminary designed according to the stepped magnetic fluid sealing theory and the effects of key parameters such as centrifugal force, eccentricity, step height and amount of magnetic poles on the anti-pressure performance of stepped magnetic fluid seal will be investigated. The change regulation of the stepped magnetic fluid sealing performance will be revealed and its theoretical values will be verified by the experimental method. According to the above study, the theoretical support is provided for designing the stepped magnetic fluid sealing structure with high sealing performance and high sealing reliability and the application scope of the magnetic fluid sealing technology is broadened.

阶梯式磁流体密封技术是提高大间隙普通磁流体密封耐压性能的有效方法之一。但在高速及重载等场合中，阶梯式磁流体密封由于受到离心力和偏心等因素的影响，其密封性能和密封可靠性显著降低。因此,为了进一步提高大间隙阶梯式磁流体旋转密封耐压性能，本项目考虑离心力和偏心率等因素的影响,从磁流体运动方程出发，构建大间隙阶梯式磁流体旋转密封间隙内磁流体液膜厚度关系式，推导出阶梯式磁流体旋转密封耐压公式，揭示大间隙阶梯式磁流体旋转密封失效机理。根据阶梯式磁流体密封耐压公式设计出一种阶梯式磁流体旋转密封结构，研究离心力、偏心率、阶梯高度、磁极参数和磁极数量等关键参数对该阶梯式磁流体旋转密封性能的影响，揭示阶梯式磁流体旋转密封耐压性能的变化规律，验证阶梯式磁流体旋转密封耐压公式的正确性。通过以上研究为研制出高密封性能及高密封可靠性的阶梯式磁流体旋转密封结构提供理论依据，并拓宽磁流体密封技术应用范围。

本课题针对大间隙工况下普通磁流体密封耐压性能低的难题，提出了阶梯式磁流体密封的方法，对阶梯式磁流体密封机理与性能进行了研究。搭建了密封机理微型试验台，研究了阶梯式磁流体密封的压力传递过程，揭示了阶梯式磁流体密封的耐压及失效机理。构建了阶梯式磁流体密封耐压公式，根据阶梯式磁流体密封耐压理论设计了阶梯式磁流体密封结构，采用实验的方法验证了阶梯式磁流体密封理论的正确性。采用磁场有限元法研究了不同径向极齿数量、轴向极齿数量、径向密封间隙高度、轴向密封间隙宽度和转轴偏心率时发散型和聚合型阶梯式磁流体密封的轴向与径向密封间隙内的磁场分布，并根据发散型和聚合型阶梯式磁流体密封耐压理论计算出不同参数下发散型和聚合型阶梯式磁流体密封耐压理论值。搭建了阶梯式磁流体密封实验台，实验研究了磁流体注入量、极齿数量、密封间隙和转轴偏心率等关键参数对发散型和聚合型阶梯式磁流体密封耐压能力的影响，揭示了发散型和聚合型阶梯式磁流体密封理论耐压能力的影响规律。研究结果表明当磁流体注入量未达到饱和值时，阶梯式磁流体密封耐压能力随着磁流体注入量的增加而增加。发散型阶梯式磁流体密封耐压能力随着径向齿数的增加先增大后减小，随着轴向齿数的增加而增大，随着径向间隙的增大先增大后减小，随着轴向间隙的增大先增大后趋于稳定。聚合型阶梯式磁流体密封耐压能力随着径向齿数的增加保持不变，随着轴向齿数的增大而增大，随着径向密封间隙高度的增大先减小后趋于稳定，随着轴向密封间隙宽度的增大先减小后增大。发散型和聚合型阶梯式磁流体密封耐压能力随着转轴偏心率的增大而减小，并且转轴偏心时发散型和聚合型阶梯式磁流体密封耐压的理论值和实验值的变化趋势基本一致。. 在项目执行期间共发表SCI论文10篇，其中2区SCI论文2篇，授权发明专利10项，培养硕士研究生4名，获广西科技进步一等奖和机械工业科学技术一等奖各1项，研究成果达到了申请时的预期。