| Existing swing of solid rocket motor nozzle separation at the O-ring seal under high temperature and high pressure gas conditions exist aging,high temperature resistant ability is poor,swinging the friction torque of engineering problems,therefore,this paper proposes a new magnetic medium sealing method for high temperature and high pressure gas conditions,namely magnetic powder sealing,it differs from that of magnetic fluid seal and magnetic sealing grease,At high temperature is not easy to volatilize,magnetic powder filling rate is higher,the pressure resistance is far stronger than the above two sealing methods.In order to explore the performance and influencing factors of magnetic powder in reciprocating sealing,the sealing performance of magnetic powder reciprocating seal were studied by theoretical analysis,numerical simulation and experiment.In view of the above research contents,the research work completed in this thesis is as follows:(1)The research background,significance and sealing principle of magnetic powder reciprocating seal are introduced.The research work and progress of traditional reciprocating seal and magnetic medium reciprocating seal at home and abroad are summarized.(2)Based on the response characteristics of magnetic particles to magnetic fields,magnetic field force on the magnetic particles in magnetic field and magnetic field gradient force were analyzed,the shear stress of the chain structure formed by magnetic particles was deduced,besides,the magnetic powder in the seal gap is magnetized to form solid like material under the action of magnetic field,which has the property of porous medium,the theory of porous medium is introduced to improve the sealing theory of magnetic powder.(3)The simplified model of shaft seal for the face seal model,to explore the mechanism of the magnetic powder,clear laws of magnetic powder seal leakage and pressure transmission,different seal fluid exists leakage rate,according to the experimental phenomenon and law,analyzed the factors that affect magnetic powder static sealing performance,and according to the analysis,the design idea of the sealing structure is provided.(4)For the purpose of magnetic powder reciprocating sealing experiment,the design of the magnetic powder reciprocating sealing device,combined with ANSYS finite element analysis software,the magnetic field analysis is carried out on the main mechanism that constitutes the magnetic circuit,respectively analyzing the trunnion,seal clearance,tooth width and tooth groove width and depth for the effects of the magnetic induction intensity and magnetic field gradient in seal gap,and determined the related structural parameters according to the results of the magnetic field analysis.(5)Fluent software is used to analyze the flow field of the fluid in the sealed structure,the introduction of porous medium model,comparison analysis model is established,the internal flow field analysis of sealing medium in sealing structure,the influence of void fraction,in addition,the effects of the porosity of the sealing medium,the sealing clearance of the sealing structure and the tooth width on the flow field in the sealing structure are analyzed,it is found that the change of porosity has the greatest effect on fluid velocity.(6)A reciprocating seal test platform was built for magnetic powder reciprocating seal experiments.Gas and water were sealed with seals respectively,research in static sealing tooth width and the effect of sealing pressure to seal,dynamic seal to explore in the reciprocating shaft speed and reciprocating motion parameters including reciprocating stroke for sealing,experimental phenomenon observation and result analysis were carried out,then the verification experiment was carried out to improve the sealing performance by reducing the friction force between the magnetic powder and the reciprocating shaft.The experiment showed that the friction force was an important factor causing the increase of the leakage of dynamic seal.Graph 68,table 13,67 references. |
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