Study On Magnetic Fluid Seal Under Radial Fretting Condition Of Sodium Cooled Fast Reactor

The fourth generation of advanced nuclear energy systems is headed by a sodium cooled fast reactor that uses liquid sodium as its coolant,and the sealed media is radioactive sodium and argon due to the fact that the protection of the liquid sodium coolant is accomplished by inert gas,say,argon.At present,mechanical seal with complex structures and difficulties in assembly is used to seal the sodium cooled fast reactor,and zero leakage of sealed media is hard to achieve.Therefore,it is of great significance to apply magnetic fluid seal with simple structure,high reliability and zero leakage to the main shaft seal of sodium cooled fast reactor.The spindle will have a radial fretting during rotation process as a result of the use of rolling bearing at the upside of the spindle and sliding bearing at the downside.The application of magnetic fluid seals in sodium cooled fast reactor should avoid the leakage caused by the radial fretting.Focusing on this problem,this thesis completes following works:(1)The magnetic fluid sealing scheme was designed and modified gradually according to the working conditions.The combination of the magnetic fluid seal and the radial O-ring seal was used to overcome the sealing problem caused by the radial fretting of spindle.(2)The pressure resistance of the magnetic fluid seal was analyzed by ANSYS.Based on the analysis results of pressure resistance and working condition,the magnetic fluid seal structure was designed and a design scheme for extending the service life was proposed.(3)By ANSYS Workbench,a two-dimensional model was established to simulate the radial fretting behavior and service life of the O-ring.(4)Based on the simulation results,a friction and wear experiment was carried out,and the relationship between friction,displacement and vibration frequency was discussed.The friction measured in the experiment was substituted into the simulation through which the service life of the O-ring was obtained.(5)Experimental devices for magnetic fluid seal is designed,and the pressure resistance of static seal,dynamic seal,and vibration seal were verified,respectively.The experimental results show that the chosen scheme meets the pressure resistance requirements under actual working conditions,and the rationality of the designed structure is verified.