The migration of nitroglycerin(NG) has always been the critical issue that harmfully impacts the structural integrity and operational reliability of the solid rocket motor, which is mainly composed by Nitrate Ester Pl...The migration of nitroglycerin(NG) has always been the critical issue that harmfully impacts the structural integrity and operational reliability of the solid rocket motor, which is mainly composed by Nitrate Ester Plasticized Polyether(NEPE) propellant/Hydroxyl-terminated Polybutadiene(HTPB) liner/Ethylene Propylene Diene Monomer(EPDM) insulation bonding system. This paper proposes an innovative surface modification method attempting to modify the EPDM insulation layer coated with reduced graphene oxide(RGO), which exhibits ability to weaken the NG absorption by EPDM insulation layer,blocking the pathway of NG migration into EPDM insulation materials. The microstructure of RGO-coated layer was analyzed and the formation mechanism was investigated. The RGO-coated layer is well bonded to the HTPB liner, and its anti-migration performance to NG at different temperatures has been evaluated. Comparing with blank samples under the same storage conditions, the RGO-coated layers can reduce the diffusion coefficient of NG by up to 87.3% and increase the diffusion activation energy of NG by14.8 kJ,mol^(-1). This research provides a new strategy to effectively inhibit NG migration in NEPE propellant/HTPB liner/EPDM insulation bonding system.展开更多
The purpose of the present study is to establish a mixed lubrication model for the journal-thrust coupled microgroove bearings(also referred as coupled bearings)used for the ship shaftless rim-driven thrusters.During ...The purpose of the present study is to establish a mixed lubrication model for the journal-thrust coupled microgroove bearings(also referred as coupled bearings)used for the ship shaftless rim-driven thrusters.During the hydrodynamic modelling,the coupling hydrodynamic pressure between the journal bearing and the thrust bearing is considered.The mixed lubrication performances of the microgroove journal-thrust bearing with five different bottom shapes,including rectangle,semi-ellipse,right triangle,isosceles triangle and left triangle,are compared.Based on the numerical results,the optimal microgroove bottom shape of the journal bearing and tilting angle of the thrust pad are determined.Additionally,the comparative analysis shows that the coupled bearing with left triangle microgroove bottom shape exhibits the optimal mixed lubrication performance.The numerical result also indicates that the optimal inclination angle of the thrust bearing pad is 0.01°for the current simulation case.展开更多
In this paper,high cis-1,4 content hydroxyl-terminated polybutadiene(cis-HTPB)with different molecular weights was prepared through the oxidative cracking process using cis-butadiene rubber as raw material.Firstly,thi...In this paper,high cis-1,4 content hydroxyl-terminated polybutadiene(cis-HTPB)with different molecular weights was prepared through the oxidative cracking process using cis-butadiene rubber as raw material.Firstly,this article comprehensively compared the differences between cis-HTPB and conventional I-HTPB in terms of molecular weight distribution,functionality,viscosity,molecular polarity,and other physicochemical properties,which provided effective data support for its subsequent application.In addition,the reaction kinetics study showed that cis-HTPB with isocyanate curing agent has high reactivity,allowing it to be rapidly cured at low temperatures,and the cured elastomers had excellent mechanical properties,with tensile strength and elongation up to 1.89 MPa and 1100%,respectively.It was also found that cis-HTPB has extremely excellent low-temperature resistance,and the glass transition temperature(T_(g))of its cured elastomer is as low as-101℃.Based on the above studies,cis-HTPB is applied as a binder in composite solid propellants for the first time to investigate its practical performance,and the results indicated that cis-HTPB-based propellants have excellent process and mechanical properties.展开更多
基金National Natural Science Foundation of China(Grant No.22175059)to provide fund for conducting experiments.
文摘The migration of nitroglycerin(NG) has always been the critical issue that harmfully impacts the structural integrity and operational reliability of the solid rocket motor, which is mainly composed by Nitrate Ester Plasticized Polyether(NEPE) propellant/Hydroxyl-terminated Polybutadiene(HTPB) liner/Ethylene Propylene Diene Monomer(EPDM) insulation bonding system. This paper proposes an innovative surface modification method attempting to modify the EPDM insulation layer coated with reduced graphene oxide(RGO), which exhibits ability to weaken the NG absorption by EPDM insulation layer,blocking the pathway of NG migration into EPDM insulation materials. The microstructure of RGO-coated layer was analyzed and the formation mechanism was investigated. The RGO-coated layer is well bonded to the HTPB liner, and its anti-migration performance to NG at different temperatures has been evaluated. Comparing with blank samples under the same storage conditions, the RGO-coated layers can reduce the diffusion coefficient of NG by up to 87.3% and increase the diffusion activation energy of NG by14.8 kJ,mol^(-1). This research provides a new strategy to effectively inhibit NG migration in NEPE propellant/HTPB liner/EPDM insulation bonding system.
基金Project(51975064)supported by the National Natural Science Foundation of ChinaProject(cstc2018jcyj AX0442)supported by the General Projects of Basic Science and Frontier Technology Research of Chongqing,China+2 种基金Projects(2018M631059,2019T120805)supported by the Postdoctoral Science Foundation of ChinaProject(cstc2017zdcyzdzx X0001)supported by the Major Research and Development Program of ChinaProject supported by the Innovation Program on the Common and Key Technologise of Key Industries,China。
文摘The purpose of the present study is to establish a mixed lubrication model for the journal-thrust coupled microgroove bearings(also referred as coupled bearings)used for the ship shaftless rim-driven thrusters.During the hydrodynamic modelling,the coupling hydrodynamic pressure between the journal bearing and the thrust bearing is considered.The mixed lubrication performances of the microgroove journal-thrust bearing with five different bottom shapes,including rectangle,semi-ellipse,right triangle,isosceles triangle and left triangle,are compared.Based on the numerical results,the optimal microgroove bottom shape of the journal bearing and tilting angle of the thrust pad are determined.Additionally,the comparative analysis shows that the coupled bearing with left triangle microgroove bottom shape exhibits the optimal mixed lubrication performance.The numerical result also indicates that the optimal inclination angle of the thrust bearing pad is 0.01°for the current simulation case.
基金the support from the Open Research Fund Program of Science and Technology on Aerospace Chemical Power Laboratory(Grant No.STACPL120221B03)the National Natural Science Foundation of China(Grant No.22175059).
文摘In this paper,high cis-1,4 content hydroxyl-terminated polybutadiene(cis-HTPB)with different molecular weights was prepared through the oxidative cracking process using cis-butadiene rubber as raw material.Firstly,this article comprehensively compared the differences between cis-HTPB and conventional I-HTPB in terms of molecular weight distribution,functionality,viscosity,molecular polarity,and other physicochemical properties,which provided effective data support for its subsequent application.In addition,the reaction kinetics study showed that cis-HTPB with isocyanate curing agent has high reactivity,allowing it to be rapidly cured at low temperatures,and the cured elastomers had excellent mechanical properties,with tensile strength and elongation up to 1.89 MPa and 1100%,respectively.It was also found that cis-HTPB has extremely excellent low-temperature resistance,and the glass transition temperature(T_(g))of its cured elastomer is as low as-101℃.Based on the above studies,cis-HTPB is applied as a binder in composite solid propellants for the first time to investigate its practical performance,and the results indicated that cis-HTPB-based propellants have excellent process and mechanical properties.
