磁性液体是一种由包裹了表面活性剂的纳米磁性颗粒弥散分布在基载液中所形成的胶体溶液，具有流动性，且能受磁场控制。磁性液体密封是磁性液体最为成熟的应用之一，具有“零”泄漏、可靠性高、磨损小等诸多优点，并广泛应用于军工、航空航天等领域的气体密封或真空密封场合。然而由于磁性液体密封结构的特殊性，密封间隙内磁性液体在失效过程中的分布状态难以观察，导致磁性液体密封不同介质的失效机理尚不明晰，从而限制了磁性液体密封的发展。本文以制备的机油基磁性液体和添加稠化剂改性的磁性液体为材料，设计了几种可视装置，随后通过对这些可视装置的理论及实验研究揭示了磁性液体密封失效机理，并指导磁性液体旋转密封的设计与实验，最后针对磁性液体密封液体介质时寿命短的问题提出了两种优化方案，并进行了实验验证。为了解决磁性液体在失效过程中分布状态难以观察的难题，设计了一种磁性液体静密封可视装置，利用该装置磁场与密封间隙相互独立的特点，开展了磁性液体静密封实验，分析了磁场、密封间隙、磁性液体长度对耐压能力的影响规律，建立了耐压能力的理论模型，并进行了修正。利用图像识别算法建立了一种磁性液体界面捕捉方法，基于磁性液体静密封可视装置开展了磁性液体密封不同介质的密封可视化研究，实时捕捉了磁性液体在失效过程中的位置参数，并定量分析了磁性液体在失效过程中的运动规律与变形规律，进而揭示了在静密封条件下磁性液体密封不同介质的机理。为了探究液液界面速度对磁性液体界面稳定性的影响，验证磁性液体改性的效果，设计了一种磁性液体液面冲刷可视装置，探究在不同水流冲刷速度下，磁性液体界面形态的变化规律，并将磁性液体与改性磁性液体的实验效果进行比较，发现添加聚异丁烯增大粘度能有效提高磁性液体抗水流冲刷的能力。根据两种密封可视装置的研究结果开展了磁性液体旋转密封的耐压实验和自恢复特性实验，结果表明补充磁性液体能有效恢复磁性液体密封的耐压能力。此外开展了磁性液体密封水的寿命实验并提出了采用改性磁性液体增加磁性液体粘度和磁性液体自生成两种优化方案，并通过实验验证了两种优化方案均能有效提高磁性液体密封液体介质的寿命，为磁性液体密封液体介质的工程应用提供了指导。

Magnetic fluid is a colloidal solution formed by the dispersion of nano-magnetic particles coated with surfactant in a base carrier. It has fluidity and can be controlled by magnetic field. Magnetic fluid seal is one of the most mature applications of magnetic fluid. It has many advantages such as "zero" leakage, high reliability and low wear, and is widely used in gas sealing or vacuum sealing occasions in military, aerospace and other fields. However, due to the particularity of the magnetic fluid sealing structure, the distribution state of the magnetic fluid in the sealing gap during the failure process is difficult to observe, resulting in the unclear failure mechanism of the magnetic fluid sealing different media, thus limiting the development of the magnetic fluid seal.In this paper, starting from the nature of magnetic fluid seal, several kinds of visual devices were designed based on the oil-based magnetic fluid and the magnetic fluid modified by polyisobutylene. The mechanism of magnetic fluid seal was introduced, and the design and experiment of magnetic fluid rotary seal were guided. Finally, two optimization schemes were proposed to enhance the life of magnetic fluid sealing liquid medium, and the experimental verification was carried out.In order to solve the problem that the distribution state of the magnetic fluid is difficult to observe during the failure process, a magnetic fluid static sealing visual device was designed. Using the feature that the magnetic field and the sealing gap of the device are independent of each other, the magnetic fluid static sealing experiment was carried out. the influence of magnetic field, sealing gap and length of magnetic fluid on the pressure resistance was analyzed, and a theoretical model of pressure resistance was established and modified.An image recognition algorithm was used to establish a magnetic fluid interface capture method, and a magnetic fluid static sealing visual device was used to carry out the sealing visualization research of magnetic fluid sealing different media. The position parameters of the magnetic fluid during the failure process were captured in real time and quantitatively analyzed The motion law and deformation law of the magnetic fluid in the process of failure were revealed, and the mechanism of the magnetic fluid sealing different media under static sealing conditions was revealed.In order to explore the influence of liquid-liquid interface speed on the stability of magnetic fluid interface and to verify the effect of modified magnetic fluid, a visual device was designed to explore the change of magnetic fluid interface morphology under different flushing velocities of water. At the same time, by comparing the experimental results of the magnetic fluid and the modified magnetic fluid, it is found that adding polyisobutylene to increase the viscosity can effectively improve the ability of the magnetic fluid to bear water flushing.According to the research results of the sealing visualization devices, the pressure resistance experiment and the self-recovery characteristic experiment of the magnetic fluid rotary seal were carried out. The results show that the sealing capacity of the magnetic fluid can be effectively recovered by supplementing the magnetic fluid. In addition, the life experiment of magnetic fluid sealing water was carried out, and two optimization schemes of using modified magnetic fluid and self-generation of magnetic fluid were proposed, and it was verified by experiments that both optimization schemes can effectively improve the lifte of the magnetic fluid seal. It provides guidance for the engineering application of the magnetic fluid sealed liquid medium.