Prelaunch rolling of maritime rockets threatens the reliability of launch in rough sea conditions.In order to suppress the prelaunch rolling,this study introduces advanced smart prediction designed especially for mari...Prelaunch rolling of maritime rockets threatens the reliability of launch in rough sea conditions.In order to suppress the prelaunch rolling,this study introduces advanced smart prediction designed especially for maritime rockets.The suggested approach introduces a hybrid model that combines random forest(RF)and Adaptive boosting(Ada Boost)methods to describe the coupling mechanism of factors affecting rocket rolling and to suppress the rolling.This combination improves forecast accuracy.Thereafter,the dimensionality reduced response surfaces are used to visually present the coupling between rocket rolling and influencing factors,which reveals the prelaunch rolling mechanism.When angle between the launch device and the ship's bow is within 80°-100°,the dynamic friction coefficient between adapters and guideways is 0.4,and the dynamic friction coefficient between the rocket and launchpad is within 0-0.15 or0.5-0.7,the prelaunch rolling of rocket during one motion cycle of the ship is less than 0.065°,originally 0.27°,reduced by 75.93%,effectively suppressing the prelaunch rolling.This study improves the prelaunch stability of maritime rockets in rough sea conditions and establishes a mapping relationship between the factors affecting rocket rolling and the structure of the sea launch system,guiding the optimization of future sea launch systems.展开更多
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
The active control theory and methods of initial disturbances for rockets and missiles are investigated. The rocket or missile/launcher is simplified as a flexible beam excited by a moving varying velocity rigid body ...The active control theory and methods of initial disturbances for rockets and missiles are investigated. The rocket or missile/launcher is simplified as a flexible beam excited by a moving varying velocity rigid body which has two points in contact with the beam. The control force is applied at the supporting point on the beam. Active control strategies based on optimal control theory are proposed and computer simulation is carried out. Simulation results are consistent with the theoretical results, and show that the active control strategies proposed can accomplish the purpose to control the initial disturbances actively. The results show that active control of initial disturbances for rockets and missiles is feasible for application.展开更多
In the range of the rockets/launcher system itself, the dynamic equations for rocket and directional tube during semi-constraint period have been constructed by using Newton-Ether method. Considering the interaction o...In the range of the rockets/launcher system itself, the dynamic equations for rocket and directional tube during semi-constraint period have been constructed by using Newton-Ether method. Considering the interaction of rockets and directional tubes when clearances exist, the method of estimating initial disturbances for the rocket by using vibration data of the directional tube has been given. The estimated results have been compared with the simulation results computed by the dynamic simulating software ADAMS. Results computed by the two methods are basically consistent and the computing errors do not increase with the variation of the clearance. The validity of the proposed method has been proved.展开更多
5 October 2013, Houston--The Houston Rockets and ZTE USA, the fastest-growing smartphone provider in the United States, announced that ZTE will be the official smartphone of the Houston Rockets for the 2013-14 NBA sea...5 October 2013, Houston--The Houston Rockets and ZTE USA, the fastest-growing smartphone provider in the United States, announced that ZTE will be the official smartphone of the Houston Rockets for the 2013-14 NBA season. This is the first partnership of its kind for ZTE globally and the first big consumer marketing push in the United States since the company entered the country 15 years ago.展开更多
A LM-2D/Yuanzheng 3 launch vehicle successfully launched 6 Yunhai 2 satellites and one test microsatellite named'Chongqing'into their preset orbits,concluding China’s final orbital launch of2018.The launch to...A LM-2D/Yuanzheng 3 launch vehicle successfully launched 6 Yunhai 2 satellites and one test microsatellite named'Chongqing'into their preset orbits,concluding China’s final orbital launch of2018.The launch took place at 16:00 Beijing time on December 29,2018 from the Jiuquan Satellite Launch Center.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
Rong Yi,chief designer of the Long March-2F rocket that has launched China’s all manned space flight missions,talks about China’s progress in manned carrier rocket development and launch vehicle technology.AT 10:44 ...Rong Yi,chief designer of the Long March-2F rocket that has launched China’s all manned space flight missions,talks about China’s progress in manned carrier rocket development and launch vehicle technology.AT 10:44 am on June 5,the gaze of TV audiences globally riveted on the Long March-2F Y14 carrier rocket launch at northwest China’s Jiuquan Satellite Launch Center.About 577 seconds later,the Shenzhou-14 crewed spaceship separated from the rocket and entered its designated orbit.展开更多
We present Dark Matter candidates from non SUSY processes, in a way emphasizing how a Dark Matter (DM) candidate of roughly 100 - 400 GeV could be formed. As has been said about the Photon rocket and Axions rockets, t...We present Dark Matter candidates from non SUSY processes, in a way emphasizing how a Dark Matter (DM) candidate of roughly 100 - 400 GeV could be formed. As has been said about the Photon rocket and Axions rockets, the presence of a magnetic field supposedly would switch DM particle candidates to photons, in such a way as to in the end configure a photon rocket style device from DM in a thrust chamber. The presence of Dark Matter (DM) would in itself merely indicate that the emerging photon thrust would be comparatively greater than it would be for more conventional photon rockets. This amplifies and improves upon a so called axion rocket ram jet for interstellar travel. We assume that much the same sort of methodology for a would-be axion ramjet could be employed for DM, with perhaps greater thrust/power conversion efficiencies.展开更多
Gravity-1 solid-propellant carrier rocket utilizes a three-vertical testing and launch mode, and adopts a sea-based launch method. As the demand for satellite launches continues to grow, the scarcity of launch site re...Gravity-1 solid-propellant carrier rocket utilizes a three-vertical testing and launch mode, and adopts a sea-based launch method. As the demand for satellite launches continues to grow, the scarcity of launch site resources,and the consideration of cost savings, the need for rapid testing and launch of carrier rockets has become increasingly strong. The capability of rapid testing and launch has even become one important aspect of evaluating a rocket. This paper focuses on the characteristics of the Gravity-1 solid-propellant strap-on medium-sized carrier rocket and designs and implements a highly reliable, convenient, and intelligent low-cost rapid testing and launch solution. The main aspects include the design of a highly reliable dual-redundant ground architecture and the application of ground-based shelf products.展开更多
The hybrid propulsion performed with paraffin waxes exhibits most attractive capabilities compared to solid or liquid engines,e.g.,throttleability and re-ignition,alongside higher regression rates compared to the conv...The hybrid propulsion performed with paraffin waxes exhibits most attractive capabilities compared to solid or liquid engines,e.g.,throttleability and re-ignition,alongside higher regression rates compared to the conventional hydroxyl terminated polybutadiene(HTPB)hybrid fuel.This is because the paraffin wax forms a thin and hydro-dynamically unstable liquid layer,and then enhances the regression rate with the entrainment of droplets from the liquid-gas interface.Nevertheless,some critical open points on the manufacturing of the paraffin fuel grains still persist,because the paraffin wax exhibits high shrinkage during the solidification phase,leading to the formation of cavities,cracks and internal rips,which may be detrimental to the mechanical properties and the structural integrity of the fuel grain.In this context,this paper deals with a wide calorimetric,thermo-mechanical and physical characterization of the paraffin wax selected to manufacture the hybrid rocket engines(HRE)fuel grain,in order to gain a thorough knowledge of the material necessary to avoid the formation of critical defects.Several manufacturing methods were investigated,and it was found that only laboratory scale processes,based on the use of a heated circular mould-piston apparatus,are able to avoid the formation of critical defects,with the application of both high temperature and pressure.展开更多
For technological reasons many high-performance solid rocket motors are made from segmented propellant grains with non-uniform port geometry. In this paper parametric studies have been carried out to examine the geome...For technological reasons many high-performance solid rocket motors are made from segmented propellant grains with non-uniform port geometry. In this paper parametric studies have been carried out to examine the geometric dependence of transient flow features in solid rockets with non-uniform ports. Numerical computations have been carried out in an inert simulator of solid propellant rocket motor with the aid of a standard k-ω turbulence model. It was seen that the damping of the temperature fluctuation is faster in solid rocket with convergent port than with divergent port geometry. We inferred that the damping of the flow fluctuations using the port geometry is a meaningful objective for the suppression and control of the instability and/or pressure/thrust oscillations during the starting transient of solid rockets.展开更多
A surface pyrolysis and gas-phase combustion of the Ammonium Perchlorate(AP)/Hydroxy Terminated Polybutadiene(HTPB)composite propellant reaction kinetic mechanism with five-step chemical reaction is adopted.The effect...A surface pyrolysis and gas-phase combustion of the Ammonium Perchlorate(AP)/Hydroxy Terminated Polybutadiene(HTPB)composite propellant reaction kinetic mechanism with five-step chemical reaction is adopted.The effects of helium injection on the burning rate and combustion of AP/HTPB propellant are analyzed in details,and the characteristics of motor performance are obtained.The numerical simulation results demonstrate that helium injection enhances the combustion chamber pressure,thereby increasing the burning rate of propellant.However,the primary combustion reaction of the AP/HTPB propellant takes place within a thin layer on the burning surface,so the low-temperature helium has minimal impact on the gasphase combustion.Ultimately,the helium not only elevates the nozzle exit velocity,resulting in specific impulse gain,but also reduces the exhaust plume temperature.With an increase of helium mass flow rate,the area of the velocity increase zone at the nozzle exit continuously decreases,but the average velocity in the motor exit continuously increases.Overall,when the helium flow rate is 2.5 kg/s,the specific impulse can reach 10.5%.Reducing the helium injection hole diameter enhances mixing of helium and combustion gas and expands the velocity increase zone,thereby maximizing the exit velocity gain in average velocity at the nozzle exit.When the injection hole diameter is reduced from 100 mm to 20 mm,the specific impulse gain increases from 3.1%to 10.6%.Furthermore,increasing helium injection temperature greatly boosts the velocity of the mixed gas with the same helium mass fraction ultimately improving specific impulse.展开更多
Hypervelocity rocket sled systems are critical for testing advanced military technologies,yet track damage at speeds exceeding Mach 5 remains a significant challenge for system reliability and performance.In this stud...Hypervelocity rocket sled systems are critical for testing advanced military technologies,yet track damage at speeds exceeding Mach 5 remains a significant challenge for system reliability and performance.In this study,we investigated the hypervelocity impact response and protection for highstrength U71 Mn or bainitic steel used in rocket sled tracks.Flyer plate impact experiments using a two-stage light-gas gun were conducted to study the hypervelocity collision response,followed by the microstructural characterization via optical microscope,scanning electron microscopy equipped with electron backscatter diffraction to reveal underlying damage mechanisms.Then,the calibrated thermalmechanical coupled finite element simulations using the Johnson-Cook constitutive model and MieGrüneisen equation of state were carried out.Results indicated that bainitic steel exhibits superior impact resistance with predominantly smooth scratch-dominated damage due to its higher ductility.In contrast,U71 Mn suffered significant material spallation and crack propagation arising from brittle fracture mechanisms.Zinc-rich epoxy primer coatings effectively mitigated stress concentration and temperature rise in the substrate at impacting velocities below 2.4 km/s,so as to suppress the microstructural damage such as adiabatic shear bands and dynamic recrystallization.However,coating protection diminished at ultra-high-speed impacts due to the coating failure.Dimensional analysis established quantitative relationships of the gouge damage size to projectile mass,impact velocity,and material yield strength.This study provides in-depth insights into damage mechanisms in hypervelocity rail systems,demonstrating that bainitic steel combined with protective coatings can significantly enhance impact resistance and system reliability,offering valuable guidance for the design and optimization of hypervelocity testing platforms.展开更多
Besides safety and low-cost,the start/shutdown/restarting and throttling ability are the other two significant advantages of hy-brid rocket motors(HRMs) compared with liquid and solid ones.In this study,a two-stage va...Besides safety and low-cost,the start/shutdown/restarting and throttling ability are the other two significant advantages of hy-brid rocket motors(HRMs) compared with liquid and solid ones.In this study,a two-stage variable thrust and non-toxic 98%HP/HTPB hybrid rocket motor(VTHRM) is designed and applied in a sounding rocket,and the design parameters of the motor are analyzed and optimized.A computational program is developed to design the motor system structure,to predict the interior ballistics and the ballistic trajectory.A star grain and a wheel grain are compared.The design of experiment(DOE),variance analysis and the main effect analysis are employed to investigate the influence of the main design parameters on mo-tor performance.The multidiscipline feasible(MDF) approach is applied to establish the optimization procedure after analyz-ing the system design structure matrix.A modified differential evolution algorithm is employed to maximize the load mass.The results indicate that the wheel grain could obtain a larger load mass and a lower length to diameter ratio,and that throttling markedly meliorates the motor and rocket performance.The conclusions drawn from the analysis and optimization could pro-vide instructive guide and theoretical basis for engineering designs.展开更多
An optimal feedback guidance law with disturbance rejection objective is proposed for endoatmospheric powered descent.This guidance law with an affine form is derived by solving a novel problem called Endoatmospheric ...An optimal feedback guidance law with disturbance rejection objective is proposed for endoatmospheric powered descent.This guidance law with an affine form is derived by solving a novel problem called Endoatmospheric Powered Descent Guidance with Disturbance Rejection(Endo-PDG-DR).The key idea of formulating the Endo-PDG-DR problem is dividing disturbances into two parts,modeled and unmodeled disturbances:the modeled disturbance is proactively exploited by augmenting it as a new state of a dynamics model;the unmodeled disturbance is reactively attenuated in terms of its effect on the guidance performance by adjoining a parameterized time-varying quadratic performance index in the proposed optimal guidance problem.A Pseudospectral Differential Dynamic Programming(PDDP)method is developed to solve the Endo-PDG-DR problem,and correspondingly a robust neighboring optimal state feedback law is obtained,which has two synergistic functionalities.One is adaptive optimal steering to accommodate the modeled disturbance,and the other is disturbance attenuation to compensate for the state perturbation effect induced by the unmodeled disturbance.Using the derived feedback guidance law,a disturbance rejection level is quantified,and is correspondingly optimized by designing a quadratic weighting parameter tuning law.The numerical computations of interest are performed within a pseudospectral setting,ensuring polynomial analytical solution,high computational efficiency,and reliable convergence.展开更多
Long March 12 Makes Debut Flight from New Commercial Spaceport China successfully launched a new carrier rocket into space from the Hainan commercial spacecraft launch site in the southern island province of Hainan on...Long March 12 Makes Debut Flight from New Commercial Spaceport China successfully launched a new carrier rocket into space from the Hainan commercial spacecraft launch site in the southern island province of Hainan on November 30,2024.The Long March-12 carrier rocket sent two experimental satellites into their planned orbits.The launch mission was a complete success,according to Hainan provincial authorities.The mission was the maiden flight of the Long March-12 carrier rocket,and the first launch mission undertaken by the Hainan commercial spacecraft launch site.展开更多
1 If astronauts want to stay on the Moon for more than a few days,they must find local resources,and water is one of the most crucial ones.Scientists believe there's water on the Moon,but they're unsure of whe...1 If astronauts want to stay on the Moon for more than a few days,they must find local resources,and water is one of the most crucial ones.Scientists believe there's water on the Moon,but they're unsure of where it lies.2 Two probes are on their way to the Moon to solve this mystery.They will be launched on the same SpaceX Falcon 9 rocket from Cape Canaveral.If everything goes as planned,the first probe to reach the Moon will be Athena.Timothy Crain,the chief technology officer of Intuitive Machines,says it will take about 3 to 4 days,depending on the launch time.They'll orbit the Moon for 2 to 3 days to wait for the Sun to reach the landing site,because the lander's solar panels need sunlight to generate power.It only takes about 15 minutes to land softly after the engine is started.展开更多
Aluminum-water(Al-H_(2)O)propellants represent an innovative class of solid propellants characterized by low cost and minimal signal signature.However,conventional formulations are hindered by significant aluminum(Al)...Aluminum-water(Al-H_(2)O)propellants represent an innovative class of solid propellants characterized by low cost and minimal signal signature.However,conventional formulations are hindered by significant aluminum(Al)agglomeration,leading to reduced combustion efficiency and substantial residues.This study introduces a method for modifying Al powder with Polyvinylidene Fluoride(PVDF)to enhance the performance of Al-H_(2)O propellants by mitigating agglomeration during combustion.Experimental methodologies,including thermogravimetric analysis under ambient-pressure nitrogen atmosphere and laser ignition tests,were employed to investigate the influence of varying PVDF content on the combustion characteristics of the propellants.Furthermore,the effect of PVDF on motor performance was systematically evaluated through laboratoryscale Solid Rocket Motor(SRM)tests.The results demonstrate that the addition of 7.5%PVDF significantly enhances the burning rate from 1.12 mm/s to 3.78 mm/s and reduces the mean particle size of condensed combustion products from 699μm to 527μm.Combustion efficiency rises from88.57%to 94.51%,while injection efficiency improves significantly from 30.45%to 70.45%.SRM tests further demonstrate an increase in combustion chamber pressure from 0.17 MPa to 0.58 MPa.A dynamic agglomeration model explains these improvements,attributing reduced agglomeration to enhanced aerodynamic forces and a thinner melting layer,while increased gas yield improves injection performance.This study highlights PVDF's potential in advancing Al-H_(2)O propellants by improving combustion and injection efficiency.展开更多
文摘Prelaunch rolling of maritime rockets threatens the reliability of launch in rough sea conditions.In order to suppress the prelaunch rolling,this study introduces advanced smart prediction designed especially for maritime rockets.The suggested approach introduces a hybrid model that combines random forest(RF)and Adaptive boosting(Ada Boost)methods to describe the coupling mechanism of factors affecting rocket rolling and to suppress the rolling.This combination improves forecast accuracy.Thereafter,the dimensionality reduced response surfaces are used to visually present the coupling between rocket rolling and influencing factors,which reveals the prelaunch rolling mechanism.When angle between the launch device and the ship's bow is within 80°-100°,the dynamic friction coefficient between adapters and guideways is 0.4,and the dynamic friction coefficient between the rocket and launchpad is within 0-0.15 or0.5-0.7,the prelaunch rolling of rocket during one motion cycle of the ship is less than 0.065°,originally 0.27°,reduced by 75.93%,effectively suppressing the prelaunch rolling.This study improves the prelaunch stability of maritime rockets in rough sea conditions and establishes a mapping relationship between the factors affecting rocket rolling and the structure of the sea launch system,guiding the optimization of future sea launch systems.
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.
文摘The active control theory and methods of initial disturbances for rockets and missiles are investigated. The rocket or missile/launcher is simplified as a flexible beam excited by a moving varying velocity rigid body which has two points in contact with the beam. The control force is applied at the supporting point on the beam. Active control strategies based on optimal control theory are proposed and computer simulation is carried out. Simulation results are consistent with the theoretical results, and show that the active control strategies proposed can accomplish the purpose to control the initial disturbances actively. The results show that active control of initial disturbances for rockets and missiles is feasible for application.
文摘In the range of the rockets/launcher system itself, the dynamic equations for rocket and directional tube during semi-constraint period have been constructed by using Newton-Ether method. Considering the interaction of rockets and directional tubes when clearances exist, the method of estimating initial disturbances for the rocket by using vibration data of the directional tube has been given. The estimated results have been compared with the simulation results computed by the dynamic simulating software ADAMS. Results computed by the two methods are basically consistent and the computing errors do not increase with the variation of the clearance. The validity of the proposed method has been proved.
文摘5 October 2013, Houston--The Houston Rockets and ZTE USA, the fastest-growing smartphone provider in the United States, announced that ZTE will be the official smartphone of the Houston Rockets for the 2013-14 NBA season. This is the first partnership of its kind for ZTE globally and the first big consumer marketing push in the United States since the company entered the country 15 years ago.
文摘A LM-2D/Yuanzheng 3 launch vehicle successfully launched 6 Yunhai 2 satellites and one test microsatellite named'Chongqing'into their preset orbits,concluding China’s final orbital launch of2018.The launch took place at 16:00 Beijing time on December 29,2018 from the Jiuquan Satellite Launch Center.
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Rong Yi,chief designer of the Long March-2F rocket that has launched China’s all manned space flight missions,talks about China’s progress in manned carrier rocket development and launch vehicle technology.AT 10:44 am on June 5,the gaze of TV audiences globally riveted on the Long March-2F Y14 carrier rocket launch at northwest China’s Jiuquan Satellite Launch Center.About 577 seconds later,the Shenzhou-14 crewed spaceship separated from the rocket and entered its designated orbit.
文摘We present Dark Matter candidates from non SUSY processes, in a way emphasizing how a Dark Matter (DM) candidate of roughly 100 - 400 GeV could be formed. As has been said about the Photon rocket and Axions rockets, the presence of a magnetic field supposedly would switch DM particle candidates to photons, in such a way as to in the end configure a photon rocket style device from DM in a thrust chamber. The presence of Dark Matter (DM) would in itself merely indicate that the emerging photon thrust would be comparatively greater than it would be for more conventional photon rockets. This amplifies and improves upon a so called axion rocket ram jet for interstellar travel. We assume that much the same sort of methodology for a would-be axion ramjet could be employed for DM, with perhaps greater thrust/power conversion efficiencies.
文摘Gravity-1 solid-propellant carrier rocket utilizes a three-vertical testing and launch mode, and adopts a sea-based launch method. As the demand for satellite launches continues to grow, the scarcity of launch site resources,and the consideration of cost savings, the need for rapid testing and launch of carrier rockets has become increasingly strong. The capability of rapid testing and launch has even become one important aspect of evaluating a rocket. This paper focuses on the characteristics of the Gravity-1 solid-propellant strap-on medium-sized carrier rocket and designs and implements a highly reliable, convenient, and intelligent low-cost rapid testing and launch solution. The main aspects include the design of a highly reliable dual-redundant ground architecture and the application of ground-based shelf products.
文摘The hybrid propulsion performed with paraffin waxes exhibits most attractive capabilities compared to solid or liquid engines,e.g.,throttleability and re-ignition,alongside higher regression rates compared to the conventional hydroxyl terminated polybutadiene(HTPB)hybrid fuel.This is because the paraffin wax forms a thin and hydro-dynamically unstable liquid layer,and then enhances the regression rate with the entrainment of droplets from the liquid-gas interface.Nevertheless,some critical open points on the manufacturing of the paraffin fuel grains still persist,because the paraffin wax exhibits high shrinkage during the solidification phase,leading to the formation of cavities,cracks and internal rips,which may be detrimental to the mechanical properties and the structural integrity of the fuel grain.In this context,this paper deals with a wide calorimetric,thermo-mechanical and physical characterization of the paraffin wax selected to manufacture the hybrid rocket engines(HRE)fuel grain,in order to gain a thorough knowledge of the material necessary to avoid the formation of critical defects.Several manufacturing methods were investigated,and it was found that only laboratory scale processes,based on the use of a heated circular mould-piston apparatus,are able to avoid the formation of critical defects,with the application of both high temperature and pressure.
文摘For technological reasons many high-performance solid rocket motors are made from segmented propellant grains with non-uniform port geometry. In this paper parametric studies have been carried out to examine the geometric dependence of transient flow features in solid rockets with non-uniform ports. Numerical computations have been carried out in an inert simulator of solid propellant rocket motor with the aid of a standard k-ω turbulence model. It was seen that the damping of the temperature fluctuation is faster in solid rocket with convergent port than with divergent port geometry. We inferred that the damping of the flow fluctuations using the port geometry is a meaningful objective for the suppression and control of the instability and/or pressure/thrust oscillations during the starting transient of solid rockets.
基金co-supported by the Fundamental Research Funds for Central Universities,China(No.3072024XX0206)the Natural Science Foundation of Heilongjiang Province,China(No.LH2024E069)。
文摘A surface pyrolysis and gas-phase combustion of the Ammonium Perchlorate(AP)/Hydroxy Terminated Polybutadiene(HTPB)composite propellant reaction kinetic mechanism with five-step chemical reaction is adopted.The effects of helium injection on the burning rate and combustion of AP/HTPB propellant are analyzed in details,and the characteristics of motor performance are obtained.The numerical simulation results demonstrate that helium injection enhances the combustion chamber pressure,thereby increasing the burning rate of propellant.However,the primary combustion reaction of the AP/HTPB propellant takes place within a thin layer on the burning surface,so the low-temperature helium has minimal impact on the gasphase combustion.Ultimately,the helium not only elevates the nozzle exit velocity,resulting in specific impulse gain,but also reduces the exhaust plume temperature.With an increase of helium mass flow rate,the area of the velocity increase zone at the nozzle exit continuously decreases,but the average velocity in the motor exit continuously increases.Overall,when the helium flow rate is 2.5 kg/s,the specific impulse can reach 10.5%.Reducing the helium injection hole diameter enhances mixing of helium and combustion gas and expands the velocity increase zone,thereby maximizing the exit velocity gain in average velocity at the nozzle exit.When the injection hole diameter is reduced from 100 mm to 20 mm,the specific impulse gain increases from 3.1%to 10.6%.Furthermore,increasing helium injection temperature greatly boosts the velocity of the mixed gas with the same helium mass fraction ultimately improving specific impulse.
基金financial support from the National Key Research and Development Program(Grant No.2024YFA1209801)the National Natural Science Foundation of China(Grant Nos.12302140,12325204)+4 种基金the China Postdoctoral Science Foundation(Grant No.2023M732794)the Fundamental Research Funds for the Central Universities of China(Grant No.sxzy012023213)the Scientific Research Program of Shaanxi Province(Grant No.2023JC-XJ-02)the Young Talent Support Program of Xi'an Science and Technology Association(Grant No.959202413069)Postdoctoral Fellowship Program(Grade B)of China Postdoctoral Science Foundation(Grant No.GZB20230575)。
文摘Hypervelocity rocket sled systems are critical for testing advanced military technologies,yet track damage at speeds exceeding Mach 5 remains a significant challenge for system reliability and performance.In this study,we investigated the hypervelocity impact response and protection for highstrength U71 Mn or bainitic steel used in rocket sled tracks.Flyer plate impact experiments using a two-stage light-gas gun were conducted to study the hypervelocity collision response,followed by the microstructural characterization via optical microscope,scanning electron microscopy equipped with electron backscatter diffraction to reveal underlying damage mechanisms.Then,the calibrated thermalmechanical coupled finite element simulations using the Johnson-Cook constitutive model and MieGrüneisen equation of state were carried out.Results indicated that bainitic steel exhibits superior impact resistance with predominantly smooth scratch-dominated damage due to its higher ductility.In contrast,U71 Mn suffered significant material spallation and crack propagation arising from brittle fracture mechanisms.Zinc-rich epoxy primer coatings effectively mitigated stress concentration and temperature rise in the substrate at impacting velocities below 2.4 km/s,so as to suppress the microstructural damage such as adiabatic shear bands and dynamic recrystallization.However,coating protection diminished at ultra-high-speed impacts due to the coating failure.Dimensional analysis established quantitative relationships of the gouge damage size to projectile mass,impact velocity,and material yield strength.This study provides in-depth insights into damage mechanisms in hypervelocity rail systems,demonstrating that bainitic steel combined with protective coatings can significantly enhance impact resistance and system reliability,offering valuable guidance for the design and optimization of hypervelocity testing platforms.
文摘Besides safety and low-cost,the start/shutdown/restarting and throttling ability are the other two significant advantages of hy-brid rocket motors(HRMs) compared with liquid and solid ones.In this study,a two-stage variable thrust and non-toxic 98%HP/HTPB hybrid rocket motor(VTHRM) is designed and applied in a sounding rocket,and the design parameters of the motor are analyzed and optimized.A computational program is developed to design the motor system structure,to predict the interior ballistics and the ballistic trajectory.A star grain and a wheel grain are compared.The design of experiment(DOE),variance analysis and the main effect analysis are employed to investigate the influence of the main design parameters on mo-tor performance.The multidiscipline feasible(MDF) approach is applied to establish the optimization procedure after analyz-ing the system design structure matrix.A modified differential evolution algorithm is employed to maximize the load mass.The results indicate that the wheel grain could obtain a larger load mass and a lower length to diameter ratio,and that throttling markedly meliorates the motor and rocket performance.The conclusions drawn from the analysis and optimization could pro-vide instructive guide and theoretical basis for engineering designs.
基金co-supported by the National Natural Science Foundation of China(No.62103014)。
文摘An optimal feedback guidance law with disturbance rejection objective is proposed for endoatmospheric powered descent.This guidance law with an affine form is derived by solving a novel problem called Endoatmospheric Powered Descent Guidance with Disturbance Rejection(Endo-PDG-DR).The key idea of formulating the Endo-PDG-DR problem is dividing disturbances into two parts,modeled and unmodeled disturbances:the modeled disturbance is proactively exploited by augmenting it as a new state of a dynamics model;the unmodeled disturbance is reactively attenuated in terms of its effect on the guidance performance by adjoining a parameterized time-varying quadratic performance index in the proposed optimal guidance problem.A Pseudospectral Differential Dynamic Programming(PDDP)method is developed to solve the Endo-PDG-DR problem,and correspondingly a robust neighboring optimal state feedback law is obtained,which has two synergistic functionalities.One is adaptive optimal steering to accommodate the modeled disturbance,and the other is disturbance attenuation to compensate for the state perturbation effect induced by the unmodeled disturbance.Using the derived feedback guidance law,a disturbance rejection level is quantified,and is correspondingly optimized by designing a quadratic weighting parameter tuning law.The numerical computations of interest are performed within a pseudospectral setting,ensuring polynomial analytical solution,high computational efficiency,and reliable convergence.
文摘Long March 12 Makes Debut Flight from New Commercial Spaceport China successfully launched a new carrier rocket into space from the Hainan commercial spacecraft launch site in the southern island province of Hainan on November 30,2024.The Long March-12 carrier rocket sent two experimental satellites into their planned orbits.The launch mission was a complete success,according to Hainan provincial authorities.The mission was the maiden flight of the Long March-12 carrier rocket,and the first launch mission undertaken by the Hainan commercial spacecraft launch site.
文摘1 If astronauts want to stay on the Moon for more than a few days,they must find local resources,and water is one of the most crucial ones.Scientists believe there's water on the Moon,but they're unsure of where it lies.2 Two probes are on their way to the Moon to solve this mystery.They will be launched on the same SpaceX Falcon 9 rocket from Cape Canaveral.If everything goes as planned,the first probe to reach the Moon will be Athena.Timothy Crain,the chief technology officer of Intuitive Machines,says it will take about 3 to 4 days,depending on the launch time.They'll orbit the Moon for 2 to 3 days to wait for the Sun to reach the landing site,because the lander's solar panels need sunlight to generate power.It only takes about 15 minutes to land softly after the engine is started.
基金supported by the National Natural Science Foundation of China(Nos.U2441284 and 22375164)the Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University,China(No.CX2024042)。
文摘Aluminum-water(Al-H_(2)O)propellants represent an innovative class of solid propellants characterized by low cost and minimal signal signature.However,conventional formulations are hindered by significant aluminum(Al)agglomeration,leading to reduced combustion efficiency and substantial residues.This study introduces a method for modifying Al powder with Polyvinylidene Fluoride(PVDF)to enhance the performance of Al-H_(2)O propellants by mitigating agglomeration during combustion.Experimental methodologies,including thermogravimetric analysis under ambient-pressure nitrogen atmosphere and laser ignition tests,were employed to investigate the influence of varying PVDF content on the combustion characteristics of the propellants.Furthermore,the effect of PVDF on motor performance was systematically evaluated through laboratoryscale Solid Rocket Motor(SRM)tests.The results demonstrate that the addition of 7.5%PVDF significantly enhances the burning rate from 1.12 mm/s to 3.78 mm/s and reduces the mean particle size of condensed combustion products from 699μm to 527μm.Combustion efficiency rises from88.57%to 94.51%,while injection efficiency improves significantly from 30.45%to 70.45%.SRM tests further demonstrate an increase in combustion chamber pressure from 0.17 MPa to 0.58 MPa.A dynamic agglomeration model explains these improvements,attributing reduced agglomeration to enhanced aerodynamic forces and a thinner melting layer,while increased gas yield improves injection performance.This study highlights PVDF's potential in advancing Al-H_(2)O propellants by improving combustion and injection efficiency.
