Theoretical And Experimental Research On Key Issues Of Magnetic Fluid Seal For Electro-optical Pod

Electro-optical pod is a kind of advanced equipment equipped with precision photoelectric instruments.In order to make the pod have better environmental adaptability,dry gas is used to fill it.It is necessary to seal the shaft system of electro-optical pod dynamically.The dynamic seal method used in electro-optical pod in our country has the defects of insufficient air tightness,high friction torque and low reliability.In this thesis,the dynamic seal of electro-optical pod shaft system is improved by using magnetic fluid seal.The application of magnetic fluid seal in electro-optical pod needs to solve the following two key technical issues,one is the torque control of magnetic fluid seal,the other is the evaporation of magnetic fluid.Aiming at the above key issues,this thesis carries out the following research:(1)The magnetic fluid seal structure of thin-walled pole piece is designed for the first time,the magnetic circuit of the structure is analyzed,and the influence of the thickness of the thin wall on the pressure-resistance capacity is expounded.(2)Based on the designed seal structure,the integrated thin-walled pole piece magnetic fluid seal device for the electro-optical pod is designed for the first time.(3)The maximum theoretical pressure-resistance capacity of the designed magnetic fluid seal device is calculated by numerical method.(4)Based on the designed magnetic fluid seal device,MF1,MF2 and MF3 magnetic fluids are used to carry out the magnetic fluid seal pressure-resistance experiments.The influence of injection volume of magnetic fluid and temperature on the magnetic fluid pressure-resistance capacity and the self-repair ability of magnetic fluid seal are researched.The experimental results show that: the injection volume of different types of magnetic fluids are the same when they reach their maximum theoretical pressureresistance capacity;the effect of temperature on the pressure-resistance capacity of magnetic fluid is independent of the volume of magnetic fluid injected;the pressureresistance capacity of the magnetic fluid seal device decreases with the increase of breaking times.(5)The evaporation model of magnetic fluid is established.Based on this,the formula of evaporation rate of magnetic fluid in test tube is deduced.(6)The evaporation rate of magnetic fluid is predicted theoretically according to the established evaporation model of magnetic fluid.The evaporation experiment of magnetic fluid is carried out with kerosene-based magnetic fluid,to research the effect of the environmental temperature,volume fraction of magnetic particles,the distance between the fluid surface and the mouth of the test tube and the presence of magnetic field on the evaporation rate of magnetic fluid,and the experimental results are compared with theoretical predictions.Results show that: the evaporation rate of magnetic fluid decreases with the evaporation process;the evaporation rate of the magnetic fluid is less than that of the base fluid;the evaporation rate of magnetic fluid increases with the decrease of the volume fraction of magnetic particles.There are 53 figures,7 tables,77 references in this thesis.