Sea-based rocket launches encounter significant challenges stemming from dynamic marine environmental interactions.During the hot launch phase,characterized by low-velocity ascent,the departure of the rocket from the ...Sea-based rocket launches encounter significant challenges stemming from dynamic marine environmental interactions.During the hot launch phase,characterized by low-velocity ascent,the departure of the rocket from the oscillatory platform exhibits heightened sensitivity to external disturbances.In the development stage,assessing the launch dynamics and the clearance between the rocket and framed launcher are crucial for improving the reliability of sea-based rocket launches in rough sea conditions.This study presents a high-fidelity dynamic model of maritime hot launch system,demonstrating 3.21%prediction error through rigorous validation against experimental datasets from comprehensive modal analyses and the full-scale rocket flight test.To mitigate collision risks,we develop a computational method employing spatial vector analysis for dynamic measurement of rocket-launcher clearance during departure.Systematic investigations reveal that in rough sea conditions,optimal departure dynamics are achieved at θ_(thrust)=270°nozzle azimuth configuration,reducing failure probability compared to conventional orientations.The developed assessment framework not only resolves critical safety challenges in current sea launch systems but also establishes foundational principles for optimizing adapter axial configuration patterns in future designs.展开更多
Taking a C1x motor with a backward-facing step which can generate a typical corner vortex as a reference,a numerical methodology using large eddy simulation was established in this study.Based on this methodology,the ...Taking a C1x motor with a backward-facing step which can generate a typical corner vortex as a reference,a numerical methodology using large eddy simulation was established in this study.Based on this methodology,the position of the backward-facing step of the motor was computed and analyzed to determine a basic configuration.Two key geometrical parameters,the head cavity angle and submerged nozzle cavity height,were subsequently introduced.Their effects on the corner vortex motion and their interactions with the acoustic pressure downstream of the backward-facing step were analyzed.The phenomena of vortex acoustic coupling and characteristics of pressure oscillations were further explored.The results show that the maximum error between the simulations and experimental data on the dominant frequency of pressure oscillations is 5.23%,which indicates that the numerical methodology built in this study is highly accurate.When the step is located at less than 5/8 of the total length of the combustion chamber,vortex acoustic coupling occurs,which can increase the pressure oscillations in the motor.Both the vorticity and the scale of vortices in the downstream step increase when the head cavity angle is greater than 24°,which increases the amplitude of the pressure oscillation by maximum 63.0%.The submerged nozzle cavity mainly affects the vortices in the cavity itself rather than those in the downstream step.When the height of the cavity increases from 10 to 20 mm,the pressure oscillation amplitude under the main frequency increases by 39.1%.As this height continues to increase,the amplitude of pressure oscillations increases but the primary frequency decreases.展开更多
As the performance of the box-type multiple launch rocket system(BMLRS)improves,its mechanical structures,particularly the plane clearance design between the slider on the rocket and the guide inside the launch canist...As the performance of the box-type multiple launch rocket system(BMLRS)improves,its mechanical structures,particularly the plane clearance design between the slider on the rocket and the guide inside the launch canister,have grown increasingly complex.However,deficiencies still exist in the current launch modeling theory for BMLRS.In this study,a multi-rigid-flexible-body launch dynamics model coupling the launch platform and rocket was established using the multibody system transfer matrix method and the Newton-Euler formulation.Furthermore,considering the bending of the launch canister,a detection algorithm for slider-guide plane clearance contact was proposed.To quantify the contact force and friction effect between the slider and guide,the contact force model and modified Coulomb model were introduced.Both the modal and launch tests were conducted.Additionally,the modal convergence was verified.By comparing the modal experiments and simulation results,the maximum relative error of the eigenfrequency is 3.29%.thereby verifying the accuracy of the developed BMLRS dynamics model.Furthermore,the launch test validated the proposed plane clearance contact model.Moreover,the study investigated the influence of various model parameters on the dynamic characteristics of BMLRS,including launch canister bending stiffness,slider and guide material,slider-guide clearance,slider length and layout.This analysis of influencing factors provides a foundation for future optimization in BMLRS design.展开更多
This study investigates the potential of metal additives in acrylonitrile butadiene styrene(ABS)polymer fuel to enhance hybrid rocket motor(HRM)performance through computational analysis,Chemical Equilibrium with Appl...This study investigates the potential of metal additives in acrylonitrile butadiene styrene(ABS)polymer fuel to enhance hybrid rocket motor(HRM)performance through computational analysis,Chemical Equilibrium with Applications(CEA),software.ABS was selected as the base fuel due to its thermoplastic nature,which allows for the creation of complex fuel geometries through 3D printing,offering significant flexibility in fuel design.Hybrid rockets,which combine a solid fuel with a liquid oxidiser,offer advantages in terms of operational simplicity and safety.However,conventional polymer fuels often exhibit low regression rates and suboptimal combustion efficiencies.In this research,we evaluated a range of metal additives-aluminium(Al),boron(B),nickel(Ni),copper(Cu),and iron(Fe)-at chamber pressures ranging from 1 to 30 bar and oxidiser-to-fuel(O/F)ratios between 1.1 and 12,resulting in 1800 unique test conditions.The main performance parameters used to assess each formulation were characteristic velocity(C^(*))and adiabatic flame temperature.The results revealed that each test produced a different optimum O/F ratio,with most ratios falling between 4 and 6.The highest performance was achieved at a chamber pressure of 30 bar across all formulations.Among the additives,Al and B demonstrated significant potential for improved combustion performance with increasing metal loadings.In contrast,Fe,Cu,and Ni reached optimal performance at a minimum loading of 1%.Future work includes investigating B-Al metal composites as additives into the ABS base polymer fuel,and doing experimental validation tests where the metallised ABS polymer fuel is 3D printed.展开更多
How to effectively evaluate the firing precision of weapon equipment at low cost is one of the core contents of improving the test level of weapon system.A new method to evaluate the firing precision of the MLRS consi...How to effectively evaluate the firing precision of weapon equipment at low cost is one of the core contents of improving the test level of weapon system.A new method to evaluate the firing precision of the MLRS considering the credibility of simulation system based on Bayesian theory is proposed in this paper.First of all,a comprehensive index system for the credibility of the simulation system of the firing precision of the MLRS is constructed combined with the group analytic hierarchy process.A modified method for determining the comprehensive weight of the index is established to improve the rationality of the index weight coefficients.The Bayesian posterior estimation formula of firing precision considering prior information is derived in the form of mixed prior distribution,and the rationality of prior information used in estimation model is discussed quantitatively.With the simulation tests,the different evaluation methods are compared to validate the effectiveness of the proposed method.Finally,the experimental results show that the effectiveness of estimation method for firing precision is improved by more than 25%.展开更多
The introduction of nano-sized energetic ingredients first occurred in Russia about 60 years ago and arose great expectations in the rocket propulsion community, thanks to the higher energy densities and faster energy...The introduction of nano-sized energetic ingredients first occurred in Russia about 60 years ago and arose great expectations in the rocket propulsion community, thanks to the higher energy densities and faster energy release rates exhibited with respect to conventional ingredients. But, despite intense worldwide research programs, still today mostly laboratory level applications are reported and often for scientific purposes only. A number of practical reasons prevent the applications at industrial level: inert native coating of the energetic particles, nonuniform dispersion, aging, excessive viscosity of the slurry propellant, possible limitations in mechanical properties, more demanding safety issues, cost, and so on.This paper describes the main features in terms of performance of solid rocket propellants loaded with nanometals and intends to emphasize the unique properties or operating conditions made possible by the addition of the nano-sized energetic ingredients. Steady and unsteady combustion regimes are examined.展开更多
A joint international effort to improve solid propellant performance within the framework of a FP7European Project was described.Several metallized solid rocket propellants,of the broad family AP/HTPB/Metal in the rat...A joint international effort to improve solid propellant performance within the framework of a FP7European Project was described.Several metallized solid rocket propellants,of the broad family AP/HTPB/Metal in the ratio 68/14/18,were experimentally analyzed seeking to optimize the delivered specific impulse by identifying the most suitable high-energy fuel.Keeping the same nominal composition,different metallic fuels(including micrometric and nanometric Al,AlH3,and a variety of dual metal compositions)were characterized,tested,and contrasted to a conventional micrometric aluminum(30μm average grain size)certified for space flights.In order to overcome the intrinsic performance limitations of the matrix AP/HTPB,a new matrix consisting of ADN/GAP satisfying also the need for environmentally benign propellant formulation was considered as well.A comparative analysis between the two solid propellant systems in terms of ideal thermochemistry and experimental combustion properties reveals advantages and disadvantages of both.Overall,it is judged worthwhile to develop ADN/GAP propellants,with or without metallic fuels,to enhance the current status of solid rocket propulsion.Controlling morphology and mechanical properties of ADN/GAP compositions and understanding their flame structure and aggregation/agglomeration properties are the main issues still challenging industrial users.展开更多
The instable combustion or oscillation combustion which occurs in three high capacity solid rocket motors using high energy composite propellant with finocyl grain is studied. The reasons of the acoustic combustion in...The instable combustion or oscillation combustion which occurs in three high capacity solid rocket motors using high energy composite propellant with finocyl grain is studied. The reasons of the acoustic combustion instability are also discussed. Three engineering methods that can eliminate combustion instability are proposed and discussed. The study shows that the combustion instability mainly depends on the propellant grain shape and nozzle structure. Some measures to reduce the acoustic energy and mass generation rate of combustion gas can be adopted. The test results indicate that the modified rocket motors can significantly eliminate the instable combustion and improve the motor internal ballistic performance.展开更多
The results of a system analysis of the efficiency of nitrous oxide(N_2O) as a propellant component for small space vehicles(SSV) were presented. A criterion for mass efficiency of the SSV propulsion system(PS) is det...The results of a system analysis of the efficiency of nitrous oxide(N_2O) as a propellant component for small space vehicles(SSV) were presented. A criterion for mass efficiency of the SSV propulsion system(PS) is determined. The current global state-of-the-art of SSV PSs is shown. The application field of nitrous oxide in SSV PSs is calculated and mass efficiency of N_2O application is quantitatively determined. An overview of physical and chemical as well as operational properties of nitrous oxide as a promising, non-toxic component of rocket propellant is provided. Main physical and chemical constants of gaseous and liquid nitrous oxide; chemical properties of N_2O, thermal stability of N_2O, catalytic decomposition of N_2O, a mechanism of decomposition of N_2O, catalysts for decomposition of N_2O, ballast additives to N_2O, application of nitrous oxide, nitrous oxide as a rocket propellant, production of nitrous oxide, toxicity of nitrous oxide, fire hazard of N_2O, requirements to equipment when handling N_2O; storage and transportation of N_2O are considered. It is demonstrated that nitrous oxide is a chemical compound meeting the requirements to rocket propellants, including those related to the environmental friendliness of propellants. With 75 references.展开更多
In view of that existing opening technologies of front cover for rocket launch canister have disadvantages such as causing damage on the ground equipment,not being reused and easily broken.A novel reusable non-separat...In view of that existing opening technologies of front cover for rocket launch canister have disadvantages such as causing damage on the ground equipment,not being reused and easily broken.A novel reusable non-separation spring-driven opening scheme is proposed to achieve rapid and reliable opening of the front cover.The mathematical model of the opening process of the front cover is established by the rigid body dynamics theory.To establish a response surface model to optimize the opening scheme,three main influencing factors of the opening process are obtained through the designed experiments,including the pre-compression,the stiffness of the thrust spring,and the thrust spring force arm length.In addition,the prescribed kinematic law was taken as constraint,and the smaller thrust spring preliminary pressure and angular velocity was taken as optimization expectations.The results show that the opening scheme meets the design requirements on opening process well.It also shows that the optimized scheme can reduce the kinetic energy of the front cover,and the impact on the canister effectively,achieving a reliable and rapid opening of the front cover.展开更多
This paper studies the four-engine liquid rocket flow field during the launching phase.Using threedimensional compressible Navier-Stokes equations and two-equation realizable k-epsilon turbulence model,an impact model...This paper studies the four-engine liquid rocket flow field during the launching phase.Using threedimensional compressible Navier-Stokes equations and two-equation realizable k-epsilon turbulence model,an impact model is established and flow fields of plume impinging on the two different shapes of flame deflectors,including wedge-shaped flame deflector and cone-shaped flame deflector,are calculated.The finite-rate chemical kinetics is used to track chemical reactions.The simulation results show that afterburning mainly occurs in the mixed layer.And the region of peak pressure occurs directly under the rocket nozzle,which is the result of the direct impact of exhaust plume.Compared with the wedgeshaped flame deflector,the cone-shaped flame deflector has great performance on guiding exhaust gas.The wedge-shaped and cone-shaped flame deflectors guide the supersonic exhaust plume away from the impingement point with two directions and circumferential direction,respectively.The maximum pressure and temperature on the wedge-shaped flame deflector surface are 37.2%and 9.9%higher than those for the cone-shaped flame deflector.The results provide engineering guidance and theoretical significance for design in flame deflector of the launch platforms.展开更多
This paper develops a modular modeling and efficient formulation of launch dynamics with marching fire(LDMF)using a mixed formulation of the transfer matrix method for multibody systems(MSTMM)and Newton-Euler formulat...This paper develops a modular modeling and efficient formulation of launch dynamics with marching fire(LDMF)using a mixed formulation of the transfer matrix method for multibody systems(MSTMM)and Newton-Euler formulation.Taking a ground-borne multiple launch rocket systems(MLRS),the focus is on the launching subsystem comprising the rocket,flexible tube,and tube tail.The launching subsystem is treated as a coupled rigid-flexible multibody system,where the rocket and tube tail are treated as rigid bodies while the flexible tube as a beam with large motion.Firstly,the tube and tube tail can be elegantly handled by the MSTMM,a computationally efficient order-N formulation.Then,the equation of motion of the in-bore rocket with relative kinematics w.r.t.the tube using the Newton-Euler method is derived.Finally,the rocket,tube,and tube tail dynamics are coupled,yielding the equation of motion of the launching subsystem that can be regarded as a building block and further integrated with other subsystems.The deduced dynamics equation of the launching subsystem is not limited to ground-borne MLRS but also fits for tanks,self-propelled artilleries,and other air-borne and naval-borne weapons undergoing large motion.Numerical simulation results of LDMF are given and partially verified by the experiment.展开更多
In this paper,a novel launch dynamics measurement system based on the photoelectric sensor pair is built.The actual muzzle time(i.e.a time duration that originates from the initial movement to the rocket’s departure ...In this paper,a novel launch dynamics measurement system based on the photoelectric sensor pair is built.The actual muzzle time(i.e.a time duration that originates from the initial movement to the rocket’s departure from the muzzle)and the muzzle velocity are measured.Compared with the classical methods,the actual muzzle time is obtained by eliminating the ignition delay.The comparative analysis method is proposed with numerical simulations established by the transfer matrix method for multibody systems.The experiment results indicate that the proposed measurement system can effectively measure the actual muzzle time and reduce the error of classical methods,which match well with the simulation results showing the launch dynamics model is reliable and helpful for further analysis and design of the MLRS.展开更多
A 500 N model engine filled with LO2/GCH4 was designed and manufactured.A series of ignition attempts were performed in it by both head spark plug and body spark plug.Results show that the engine can be ignited but th...A 500 N model engine filled with LO2/GCH4 was designed and manufactured.A series of ignition attempts were performed in it by both head spark plug and body spark plug.Results show that the engine can be ignited but the combustion cannot be sustained when head spark plug applied as the plug tip was set in the gaseous low-velocity zone with thin spray.This is mainly because flame from this zone cannot supply enough ignition energy for the whole chamber.However,reliable ignition and stable combustion can be achieved by body spark plug.As the O/F ratio increases from 2.61 to 3.49,chamber pressure increases from 0.474 to 0.925 MPa and combustion efficiency increases from 57.8%to 95.1%.This is determined by the injector configuration,which cannot produce the sufficiently breakup of the liquid oxygen on the low flow rate case.展开更多
The Al and La elements are added to the Sn9Zn alloy to obtain the fusible alloy for the mitigation devices of solid propellant rocket motors. Differential scanning calorimetry(DSC), metallographic analysis,scanning el...The Al and La elements are added to the Sn9Zn alloy to obtain the fusible alloy for the mitigation devices of solid propellant rocket motors. Differential scanning calorimetry(DSC), metallographic analysis,scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS), tensile testing and fracture analysis were used to study the effect of Al and La elements on the microstructure, melting characteristics, and mechanical properties of the Sn9Zn alloy. Whether the fusible diaphragm can effectively relieve pressure was investigated by the hydrostatic pressure at high-temperature test. Experimental results show that the melting point of the Sn9Zn-0.8Al0·2La and Sn9Zn-3Al0·2La fusible alloys can meet the predetermined working temperature of ventilation. The mechanical properties of those are more than 35% higher than that of the Sn9Zn alloy at-50°C-70°C, and the mechanical strength is reduced by 80% at 175°C. It is proven by the hydrostatic pressure at high-temperature test that the fusible diaphragm can relieve pressure effectively and can be used for the design of the mitigation devices of solid propellant rocket motors.展开更多
The main purpose of the present work is to study the possibilities of reducing calculation time while maintaining the validity in the numerical simulation of the combustion product flow in SPRM chamber.Three ways of d...The main purpose of the present work is to study the possibilities of reducing calculation time while maintaining the validity in the numerical simulation of the combustion product flow in SPRM chamber.Three ways of decreasing the calculation time-the use of numerical methods of high accuracy order,the reduction in spatial dimension of the problem,and the use of physical features of the processes in SPRM chamber while constructing a calculation model-were considered.Presented calculation data show that the use of these approaches makes it possible to reduce the time for solving the problems of SPRM simulation significantly(up to 100times).Also conclusions about the applicability of the mentioned above approaches in SPRM design were made.展开更多
基金the experimental technology support provided by the China Academy of Launch Vehicle Technology
文摘Sea-based rocket launches encounter significant challenges stemming from dynamic marine environmental interactions.During the hot launch phase,characterized by low-velocity ascent,the departure of the rocket from the oscillatory platform exhibits heightened sensitivity to external disturbances.In the development stage,assessing the launch dynamics and the clearance between the rocket and framed launcher are crucial for improving the reliability of sea-based rocket launches in rough sea conditions.This study presents a high-fidelity dynamic model of maritime hot launch system,demonstrating 3.21%prediction error through rigorous validation against experimental datasets from comprehensive modal analyses and the full-scale rocket flight test.To mitigate collision risks,we develop a computational method employing spatial vector analysis for dynamic measurement of rocket-launcher clearance during departure.Systematic investigations reveal that in rough sea conditions,optimal departure dynamics are achieved at θ_(thrust)=270°nozzle azimuth configuration,reducing failure probability compared to conventional orientations.The developed assessment framework not only resolves critical safety challenges in current sea launch systems but also establishes foundational principles for optimizing adapter axial configuration patterns in future designs.
基金Sponsored by the Natural Science Foundation of Shaanxi Province (Grant No. S2025-JC-YB-0532)the Practice and Innovation Funds for Graduate Students of Northwestern Polytechnical University (PF2024044)
文摘Taking a C1x motor with a backward-facing step which can generate a typical corner vortex as a reference,a numerical methodology using large eddy simulation was established in this study.Based on this methodology,the position of the backward-facing step of the motor was computed and analyzed to determine a basic configuration.Two key geometrical parameters,the head cavity angle and submerged nozzle cavity height,were subsequently introduced.Their effects on the corner vortex motion and their interactions with the acoustic pressure downstream of the backward-facing step were analyzed.The phenomena of vortex acoustic coupling and characteristics of pressure oscillations were further explored.The results show that the maximum error between the simulations and experimental data on the dominant frequency of pressure oscillations is 5.23%,which indicates that the numerical methodology built in this study is highly accurate.When the step is located at less than 5/8 of the total length of the combustion chamber,vortex acoustic coupling occurs,which can increase the pressure oscillations in the motor.Both the vorticity and the scale of vortices in the downstream step increase when the head cavity angle is greater than 24°,which increases the amplitude of the pressure oscillation by maximum 63.0%.The submerged nozzle cavity mainly affects the vortices in the cavity itself rather than those in the downstream step.When the height of the cavity increases from 10 to 20 mm,the pressure oscillation amplitude under the main frequency increases by 39.1%.As this height continues to increase,the amplitude of pressure oscillations increases but the primary frequency decreases.
基金supported by National Natural Science Foundation of China(Grant No.92266201).
文摘As the performance of the box-type multiple launch rocket system(BMLRS)improves,its mechanical structures,particularly the plane clearance design between the slider on the rocket and the guide inside the launch canister,have grown increasingly complex.However,deficiencies still exist in the current launch modeling theory for BMLRS.In this study,a multi-rigid-flexible-body launch dynamics model coupling the launch platform and rocket was established using the multibody system transfer matrix method and the Newton-Euler formulation.Furthermore,considering the bending of the launch canister,a detection algorithm for slider-guide plane clearance contact was proposed.To quantify the contact force and friction effect between the slider and guide,the contact force model and modified Coulomb model were introduced.Both the modal and launch tests were conducted.Additionally,the modal convergence was verified.By comparing the modal experiments and simulation results,the maximum relative error of the eigenfrequency is 3.29%.thereby verifying the accuracy of the developed BMLRS dynamics model.Furthermore,the launch test validated the proposed plane clearance contact model.Moreover,the study investigated the influence of various model parameters on the dynamic characteristics of BMLRS,including launch canister bending stiffness,slider and guide material,slider-guide clearance,slider length and layout.This analysis of influencing factors provides a foundation for future optimization in BMLRS design.
文摘This study investigates the potential of metal additives in acrylonitrile butadiene styrene(ABS)polymer fuel to enhance hybrid rocket motor(HRM)performance through computational analysis,Chemical Equilibrium with Applications(CEA),software.ABS was selected as the base fuel due to its thermoplastic nature,which allows for the creation of complex fuel geometries through 3D printing,offering significant flexibility in fuel design.Hybrid rockets,which combine a solid fuel with a liquid oxidiser,offer advantages in terms of operational simplicity and safety.However,conventional polymer fuels often exhibit low regression rates and suboptimal combustion efficiencies.In this research,we evaluated a range of metal additives-aluminium(Al),boron(B),nickel(Ni),copper(Cu),and iron(Fe)-at chamber pressures ranging from 1 to 30 bar and oxidiser-to-fuel(O/F)ratios between 1.1 and 12,resulting in 1800 unique test conditions.The main performance parameters used to assess each formulation were characteristic velocity(C^(*))and adiabatic flame temperature.The results revealed that each test produced a different optimum O/F ratio,with most ratios falling between 4 and 6.The highest performance was achieved at a chamber pressure of 30 bar across all formulations.Among the additives,Al and B demonstrated significant potential for improved combustion performance with increasing metal loadings.In contrast,Fe,Cu,and Ni reached optimal performance at a minimum loading of 1%.Future work includes investigating B-Al metal composites as additives into the ABS base polymer fuel,and doing experimental validation tests where the metallised ABS polymer fuel is 3D printed.
基金National Natural Science Foundation of China(Grant Nos.11972193 and 92266201)。
文摘How to effectively evaluate the firing precision of weapon equipment at low cost is one of the core contents of improving the test level of weapon system.A new method to evaluate the firing precision of the MLRS considering the credibility of simulation system based on Bayesian theory is proposed in this paper.First of all,a comprehensive index system for the credibility of the simulation system of the firing precision of the MLRS is constructed combined with the group analytic hierarchy process.A modified method for determining the comprehensive weight of the index is established to improve the rationality of the index weight coefficients.The Bayesian posterior estimation formula of firing precision considering prior information is derived in the form of mixed prior distribution,and the rationality of prior information used in estimation model is discussed quantitatively.With the simulation tests,the different evaluation methods are compared to validate the effectiveness of the proposed method.Finally,the experimental results show that the effectiveness of estimation method for firing precision is improved by more than 25%.
文摘The introduction of nano-sized energetic ingredients first occurred in Russia about 60 years ago and arose great expectations in the rocket propulsion community, thanks to the higher energy densities and faster energy release rates exhibited with respect to conventional ingredients. But, despite intense worldwide research programs, still today mostly laboratory level applications are reported and often for scientific purposes only. A number of practical reasons prevent the applications at industrial level: inert native coating of the energetic particles, nonuniform dispersion, aging, excessive viscosity of the slurry propellant, possible limitations in mechanical properties, more demanding safety issues, cost, and so on.This paper describes the main features in terms of performance of solid rocket propellants loaded with nanometals and intends to emphasize the unique properties or operating conditions made possible by the addition of the nano-sized energetic ingredients. Steady and unsteady combustion regimes are examined.
基金supported by the HISP project(High performance solid propellants for In-Space Propulsion)of the European Community′s Seventh Framework Programme(FP7/2007-2013), under Grant Agreement No.262099,coordinated by FOI
文摘A joint international effort to improve solid propellant performance within the framework of a FP7European Project was described.Several metallized solid rocket propellants,of the broad family AP/HTPB/Metal in the ratio 68/14/18,were experimentally analyzed seeking to optimize the delivered specific impulse by identifying the most suitable high-energy fuel.Keeping the same nominal composition,different metallic fuels(including micrometric and nanometric Al,AlH3,and a variety of dual metal compositions)were characterized,tested,and contrasted to a conventional micrometric aluminum(30μm average grain size)certified for space flights.In order to overcome the intrinsic performance limitations of the matrix AP/HTPB,a new matrix consisting of ADN/GAP satisfying also the need for environmentally benign propellant formulation was considered as well.A comparative analysis between the two solid propellant systems in terms of ideal thermochemistry and experimental combustion properties reveals advantages and disadvantages of both.Overall,it is judged worthwhile to develop ADN/GAP propellants,with or without metallic fuels,to enhance the current status of solid rocket propulsion.Controlling morphology and mechanical properties of ADN/GAP compositions and understanding their flame structure and aggregation/agglomeration properties are the main issues still challenging industrial users.
文摘The instable combustion or oscillation combustion which occurs in three high capacity solid rocket motors using high energy composite propellant with finocyl grain is studied. The reasons of the acoustic combustion instability are also discussed. Three engineering methods that can eliminate combustion instability are proposed and discussed. The study shows that the combustion instability mainly depends on the propellant grain shape and nozzle structure. Some measures to reduce the acoustic energy and mass generation rate of combustion gas can be adopted. The test results indicate that the modified rocket motors can significantly eliminate the instable combustion and improve the motor internal ballistic performance.
文摘The results of a system analysis of the efficiency of nitrous oxide(N_2O) as a propellant component for small space vehicles(SSV) were presented. A criterion for mass efficiency of the SSV propulsion system(PS) is determined. The current global state-of-the-art of SSV PSs is shown. The application field of nitrous oxide in SSV PSs is calculated and mass efficiency of N_2O application is quantitatively determined. An overview of physical and chemical as well as operational properties of nitrous oxide as a promising, non-toxic component of rocket propellant is provided. Main physical and chemical constants of gaseous and liquid nitrous oxide; chemical properties of N_2O, thermal stability of N_2O, catalytic decomposition of N_2O, a mechanism of decomposition of N_2O, catalysts for decomposition of N_2O, ballast additives to N_2O, application of nitrous oxide, nitrous oxide as a rocket propellant, production of nitrous oxide, toxicity of nitrous oxide, fire hazard of N_2O, requirements to equipment when handling N_2O; storage and transportation of N_2O are considered. It is demonstrated that nitrous oxide is a chemical compound meeting the requirements to rocket propellants, including those related to the environmental friendliness of propellants. With 75 references.
文摘In view of that existing opening technologies of front cover for rocket launch canister have disadvantages such as causing damage on the ground equipment,not being reused and easily broken.A novel reusable non-separation spring-driven opening scheme is proposed to achieve rapid and reliable opening of the front cover.The mathematical model of the opening process of the front cover is established by the rigid body dynamics theory.To establish a response surface model to optimize the opening scheme,three main influencing factors of the opening process are obtained through the designed experiments,including the pre-compression,the stiffness of the thrust spring,and the thrust spring force arm length.In addition,the prescribed kinematic law was taken as constraint,and the smaller thrust spring preliminary pressure and angular velocity was taken as optimization expectations.The results show that the opening scheme meets the design requirements on opening process well.It also shows that the optimized scheme can reduce the kinetic energy of the front cover,and the impact on the canister effectively,achieving a reliable and rapid opening of the front cover.
文摘This paper studies the four-engine liquid rocket flow field during the launching phase.Using threedimensional compressible Navier-Stokes equations and two-equation realizable k-epsilon turbulence model,an impact model is established and flow fields of plume impinging on the two different shapes of flame deflectors,including wedge-shaped flame deflector and cone-shaped flame deflector,are calculated.The finite-rate chemical kinetics is used to track chemical reactions.The simulation results show that afterburning mainly occurs in the mixed layer.And the region of peak pressure occurs directly under the rocket nozzle,which is the result of the direct impact of exhaust plume.Compared with the wedgeshaped flame deflector,the cone-shaped flame deflector has great performance on guiding exhaust gas.The wedge-shaped and cone-shaped flame deflectors guide the supersonic exhaust plume away from the impingement point with two directions and circumferential direction,respectively.The maximum pressure and temperature on the wedge-shaped flame deflector surface are 37.2%and 9.9%higher than those for the cone-shaped flame deflector.The results provide engineering guidance and theoretical significance for design in flame deflector of the launch platforms.
基金The research is financially supported by the National Natural Science Foundation of China(No.11972193).
文摘This paper develops a modular modeling and efficient formulation of launch dynamics with marching fire(LDMF)using a mixed formulation of the transfer matrix method for multibody systems(MSTMM)and Newton-Euler formulation.Taking a ground-borne multiple launch rocket systems(MLRS),the focus is on the launching subsystem comprising the rocket,flexible tube,and tube tail.The launching subsystem is treated as a coupled rigid-flexible multibody system,where the rocket and tube tail are treated as rigid bodies while the flexible tube as a beam with large motion.Firstly,the tube and tube tail can be elegantly handled by the MSTMM,a computationally efficient order-N formulation.Then,the equation of motion of the in-bore rocket with relative kinematics w.r.t.the tube using the Newton-Euler method is derived.Finally,the rocket,tube,and tube tail dynamics are coupled,yielding the equation of motion of the launching subsystem that can be regarded as a building block and further integrated with other subsystems.The deduced dynamics equation of the launching subsystem is not limited to ground-borne MLRS but also fits for tanks,self-propelled artilleries,and other air-borne and naval-borne weapons undergoing large motion.Numerical simulation results of LDMF are given and partially verified by the experiment.
文摘In this paper,a novel launch dynamics measurement system based on the photoelectric sensor pair is built.The actual muzzle time(i.e.a time duration that originates from the initial movement to the rocket’s departure from the muzzle)and the muzzle velocity are measured.Compared with the classical methods,the actual muzzle time is obtained by eliminating the ignition delay.The comparative analysis method is proposed with numerical simulations established by the transfer matrix method for multibody systems.The experiment results indicate that the proposed measurement system can effectively measure the actual muzzle time and reduce the error of classical methods,which match well with the simulation results showing the launch dynamics model is reliable and helpful for further analysis and design of the MLRS.
基金Project(613239)supported by the National Basic Research Program of China
文摘A 500 N model engine filled with LO2/GCH4 was designed and manufactured.A series of ignition attempts were performed in it by both head spark plug and body spark plug.Results show that the engine can be ignited but the combustion cannot be sustained when head spark plug applied as the plug tip was set in the gaseous low-velocity zone with thin spray.This is mainly because flame from this zone cannot supply enough ignition energy for the whole chamber.However,reliable ignition and stable combustion can be achieved by body spark plug.As the O/F ratio increases from 2.61 to 3.49,chamber pressure increases from 0.474 to 0.925 MPa and combustion efficiency increases from 57.8%to 95.1%.This is determined by the injector configuration,which cannot produce the sufficiently breakup of the liquid oxygen on the low flow rate case.
基金the National Natural Science Foundation of China (Grant No. 11772058)。
文摘The Al and La elements are added to the Sn9Zn alloy to obtain the fusible alloy for the mitigation devices of solid propellant rocket motors. Differential scanning calorimetry(DSC), metallographic analysis,scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS), tensile testing and fracture analysis were used to study the effect of Al and La elements on the microstructure, melting characteristics, and mechanical properties of the Sn9Zn alloy. Whether the fusible diaphragm can effectively relieve pressure was investigated by the hydrostatic pressure at high-temperature test. Experimental results show that the melting point of the Sn9Zn-0.8Al0·2La and Sn9Zn-3Al0·2La fusible alloys can meet the predetermined working temperature of ventilation. The mechanical properties of those are more than 35% higher than that of the Sn9Zn alloy at-50°C-70°C, and the mechanical strength is reduced by 80% at 175°C. It is proven by the hydrostatic pressure at high-temperature test that the fusible diaphragm can relieve pressure effectively and can be used for the design of the mitigation devices of solid propellant rocket motors.
基金the sponsors of the conference for financial support
文摘The main purpose of the present work is to study the possibilities of reducing calculation time while maintaining the validity in the numerical simulation of the combustion product flow in SPRM chamber.Three ways of decreasing the calculation time-the use of numerical methods of high accuracy order,the reduction in spatial dimension of the problem,and the use of physical features of the processes in SPRM chamber while constructing a calculation model-were considered.Presented calculation data show that the use of these approaches makes it possible to reduce the time for solving the problems of SPRM simulation significantly(up to 100times).Also conclusions about the applicability of the mentioned above approaches in SPRM design were made.
