转轴转速对磁流体液体动密封耐压能力影响的实验研究

Effect of Rotation Speed on Failure-Pressure of Liquid Sealed with Magnetic Fluid

在磁流体液体动密封过程中,转轴的旋转引起磁流体与被密封液体的相对运动,在液-液界面处产生剪切力,使界面出现不稳定现象,易导致磁流体密封耐压能力下降。为进一步研究转轴转速对磁流体液体动密封耐压能力的影响,本文从理论上推导出液-液界面处磁流体所受的剪切力与转轴转速间的关系式,并设计出用于密封液体的磁流体密封结构,搭建了磁流体动密封实验台,实验研究磁流体密封液体的耐压值与转轴转速间的关系。实验表明,随着转轴转速的升高,磁流体密封液体耐压能力下降。转轴从静止到转轴转速为1500 r/min时,耐压值比较稳定,下降较小;转轴转速从1500到3000 r/min时,耐压值明显下降。

We experimentally addressed the instability at the interface of the sealed liquid and magnetic fluid,originated from the shearing force induced by their relative motion. The influence of the rotation speed of the shaft on the interfacial shearing force and failure pressure of the sealed liquid was mathematically modeled,theoretically analyzed and experimentally investigated with the lab-built test rig. The calculated results show that the interfacial shearing force is proportional to the rotation speed. As shown by the test results of the self-designed magnetic fluid seal structure,the rotation speed significantly affected the failure pressure of the sealed liquid. For example,as the rotation speed increased,the failure pressure of the sealed liquid decreased at varying rates. At a rotation speed below 1500 r / min,the fairly stable failure-pressure slowly decreased; whereas at a rotation speed in 1500 to 3000 r /min range,the rather unstable failure pressure markedly decreased.