| Magnetic fluid is a new type of functional material that appeared in modern times,and sealing is one of its most successful applications.Compared with traditional seals such as mechanical seals and labyrinth seals,magnetic liquids are widely used in various industries because of their long life and no leakage.With the development of magnetic liquid sealing technology,magnetic liquid has been maturely applied in sealing gas.However,when magnetic liquid is sealed,due to the instability of the sealing interface of the magnetic liquid and the unknown sealing failure mechanism,the magnetic liquid has never been able to achieve a breakthrough in sealing liquid.In order to solve the problem of magnetic liquid sealing liquid medium,this paper discusses the instability of the magnetic liquid interface from a theoretical perspective.Through the establishment of an experimental platform,the influence of factors such as the rotating speed of the shaft,the injection volume of the magnetic liquid,and the pressure on the interface instability are verified.On this basis,a spacer is added to reduce the erosion of the sealed liquid to the magnetic liquid;a new sealing structure for sealing the liquid medium is proposed.The structure proposed in this paper can monitor the sealing performance of the magnetic liquid in real time,can give early warning before leakage,do a good job of prevention,and can automatically fill the sealing gap according to the set early warning safety amount to reduce the adverse effects caused by leakage,can effectively improve the sealing life of magnetic liquid.Aiming at the above goals,this thesis completes the following research:(1)In theory,the mechanism of the influence of the relative velocity difference between the magnetic liquid and the sealed liquid,whether the applied magnetic field and the direction of the applied magnetic field,and the pressure difference between the two sides of the magnetic liquid on the instability of the magnetic liquid sealing interface is discussed.And the finite element simulation of the magnetic field of the sealing structure was carried out by ANSYS software,and the influence of the above factors on the stability of the magnetic liquid sealing interface was simulated by CFD simulation.(2)Comparing different types of magnetic liquids,according to the physical and chemical characteristics of the sealed liquid medium,determine the magnetic liquid-based carrier liquid and surfactant used in the experiment,and select the oil-based magnetic liquid as the sealing material used in this paper.(3)Build an experimental platform that can visually observe the state of the sealing interface of the magnetic liquid.Through the experimental platform built,the relative speed difference of the magnetic liquid and the sealed liquid,the magnetic field,the pressure,the injection amount of the magnetic liquid and other factors on the sealing life and the interface state change process and based on the existing sealing structure,a new experimental structure to increase the spacer was proposed to reduce the erosion effect of the sealed liquid on the magnetic liquid.Through multiple comparison experiments,it was found that the newly proposed additional spacer can effectively improve the Liquid seal life.(4)According to the research on the instability of the magnetic liquid interface,with the help of the existing equipment in the laboratory,a new type of magnetic liquid sealing liquid structure is proposed.The new sealing structure can realize real-time monitoring of the sealing performance and can automatically supplement the sealing gap Magnetic liquid.The theory and application feasibility of the new structure have been verified through finite element analysis and experiments.The new seal structure significantly improves the magnetic liquid seal life.Compared with the common magnetic liquid sealing liquid structure,the sealing life of the new magnetic liquid sealing structure is increased by more than 3 times. |
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