| Aeroengine has the reputation of "pearl on the crown of industry" and plays a very important role in the field of aviation industry.The sealing performance of main bearing chamber of aeroengine affects the safety and reliability of the engine.In graphite circumferential seal,due to the unique structure and material properties of the sealing ring,small deformation and wear of the sealing ring at work is inevitable,which may eventually lead to the weakening of the sealing performance.Therefore,the friction and wear characteristics and leakage characteristics of graphite circumferential seal are studied in this paper,and the influence of sealing pressure difference,temperature,speed and other conditions is discussed.Firstly,the friction and wear test of graphite circumferential sealing material was carried out.Analyze the wear process of graphite circumferential seal,select M210 graphite and40 CrNiMoA,one of the commonly used friction pair materials,and carry out standard friction and wear test on UMT Tribology friction and wear tester.Determine the parameters such as speed,temperature,load and time according to the working environment and test conditions.In the experiment,the friction coefficient,wear amount,wear rate and friction surface wear morphology of graphite material were measured and analyzed.The test results show that load,rotating speed and temperature all have effects on the friction and wear properties of graphite materials,among which the effect of load is the most significant.Secondly,the thermal-solid coupling friction and wear model of graphite circumferential seal is established,and the friction and wear properties are studied.The structural form and friction and wear form of the main seal in graphite circumferential seal were analyzed.The friction and wear model of graphite circumferential seal was established based on Archard wear theory and friction heat generation theory,and the numerical simulation calculation was carried out by using APDL programming language and ANSYS simulation software.The thermal power and temperature changes of the contact surface between the sealing ring and the runway were analyzed,the contact pressure and friction stress of the contact surface under different working conditions were analyzed,the wear law,wear depth and wear distribution law of the sealing ring were analyzed,and the maximum radial deformation of the sealing ring and the runway under different temperature,pressure difference and speed were summarized and analyzed.The friction and wear properties under key working conditions are obtained,which lays a foundation for in-depth optimization analysis.Finally,the fluid-solid-thermal multi-field coupling hybrid lubrication model of graphite circumferential seal is established,and the leakage characteristics of primary/secondary seal are studied.The structure field,temperature field and flow field of graphite circumferential seal were analyzed,and the mixed lubrication multi-field coupling model of graphite circumferential seal was deduced and established by semi-analytical solution method,including structure model,fluid bearing capacity model,slightly convex peak contact force model and temperature transfer model.The joint equations were established based on the multiple physical field boundaries and common parameters of graphite circumferential seal,and the equations were solved by MATLAB and COMSOL.After solving the fluid pressure and balance film thickness,the calculation method of friction force and leakage of graphite circumferential seal is established.The influence of key operating parameters such as roughness,temperature difference,pressure difference and speed on the friction,balance film thickness and leakage of the primary and secondary seal was studied by the mixed lubrication model,and the influence of key operating parameters on the leakage characteristics of the primary and secondary seal passages of graphite circumferential seal was analyzed.The results show that the leakage of the secondary seal channel accounts for30%-40% of the whole circumferential seal,which can’t be ignored in the analysis of the leakage characteristics of graphite circumferential seal. |
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