A prototype of impulse thruster for radial thrust trajectory correction munitions is designed. It adopts semiconductor bridge (SCB) as ignition element,Ti/KClO4 (TK) as ignition charge and ammonium perchlorate/alumini...A prototype of impulse thruster for radial thrust trajectory correction munitions is designed. It adopts semiconductor bridge (SCB) as ignition element,Ti/KClO4 (TK) as ignition charge and ammonium perchlorate/aluminium (NA) or potassium picate/RDX (KR) as main charge. A thrust test device of impulse thruster is also designed. The output performance of the impulse thruster prototype is tested by the device. The tested results show that it can meet the safety requirements of 1A1W/5 min no-fire level and produce 0.2-0.6 N·s thrust impulse within 3ms of action time under certain test conditions; the corresponding ignition delay time is less than 0.5 ms.展开更多
In this study,new analytical solutions to the equations of motion of a propelled spacecraft are investigated using a shape-based approach.There is an assumption that the spacecraft travels a two-dimensional spiral tra...In this study,new analytical solutions to the equations of motion of a propelled spacecraft are investigated using a shape-based approach.There is an assumption that the spacecraft travels a two-dimensional spiral trajectory in which the orbital radius is proportional to an assigned power of the spacecraft angular coordinate.The exact solution to the equations of motion is obtained as a function of time in the case of a purely radial thrust,and the propulsive acceleration magnitude necessary for the spacecraft to track the prescribed spiral trajectory is found in a closed form.The analytical results are then specialized to the case of a generalized sail,that is,a propulsion system capable of providing an outward radial propulsive acceleration,the magnitude of which depends on a given power of the Sun-spacecraft distance.In particular,the conditions for an outward radial thrust and the required sail performance are quantified and thoroughly discussed.It is worth noting that these propulsion systems provide a purely radial thrust when their orientation is Sun-facing.This is an important advantage from an engineering point of view because,depending on the particular propulsion system,a Sun-facing attitude can be stable or obtainable in a passive way.A case study is finally presented,where the generalized sail is assumed to start the spiral trajectory from the Earth’s heliocentric orbit.The main outcome is that the required sail performance is in principle achievable on the basis of many results available in the literature.展开更多
The dynamics of a spacecraft propelled by a continuous radial thrust resembles that of a nonlinear oscillator.This is analyzed in this work with a novel method that combines the definition of a suitable homotopy with ...The dynamics of a spacecraft propelled by a continuous radial thrust resembles that of a nonlinear oscillator.This is analyzed in this work with a novel method that combines the definition of a suitable homotopy with a classical perturbation approach,in which the low thrust is assumed to be a perturbation of the nominal Keplerian motion.The homotopy perturbation method provides the analytical(approximate)solution of the dynamical equations in polar form to estimate the corresponding spacecraft propelled trajectory with a short computational time.The accuracy of the analytical results was tested in an orbital-targeting mission scenario.展开更多
In order to calculate the pressure distribution of radial grooved thrust bearing, analytical and numerical methods were applied respectively. Grooved region and land region were linked by u- sing the mass conservation...In order to calculate the pressure distribution of radial grooved thrust bearing, analytical and numerical methods were applied respectively. Grooved region and land region were linked by u- sing the mass conservations principle at the groove/land boundary in each method. The block-weight approach was implemented to deal with the non-coincidence of mesh and radial groove pattern in nu- merical method. It was observed that the numerical solutions had higher precision as mesh number exceed 70 x 70, and the relaxation iteration of differential scheme presented the fastest convergence speed when relaxation factor was close to 1.94.展开更多
Static and dynamic mechanical characteristics of a thrust magnetic bearing are studied owing to the inclination of the runner disk. The application refers to a thrust magnetic bearing for a turbo expander/compressor...Static and dynamic mechanical characteristics of a thrust magnetic bearing are studied owing to the inclination of the runner disk. The application refers to a thrust magnetic bearing for a turbo expander/compressor. The static tilt of the runner disk has remarkable influence on the mechanical characteristics of thrust magnetic bearing, it can change the static load distribution between two radial magnetic bearings and will exert violent coupling effect among a thrust magnetic bearing and two radial magnetic bearings. Such a finding can be used for the coupled electromechanical dynamics analysis of rotor system equipped with magnetic bearings.展开更多
基金the Ministerial Level Advanced Research Foundation (51305080302)
文摘A prototype of impulse thruster for radial thrust trajectory correction munitions is designed. It adopts semiconductor bridge (SCB) as ignition element,Ti/KClO4 (TK) as ignition charge and ammonium perchlorate/aluminium (NA) or potassium picate/RDX (KR) as main charge. A thrust test device of impulse thruster is also designed. The output performance of the impulse thruster prototype is tested by the device. The tested results show that it can meet the safety requirements of 1A1W/5 min no-fire level and produce 0.2-0.6 N·s thrust impulse within 3ms of action time under certain test conditions; the corresponding ignition delay time is less than 0.5 ms.
文摘In this study,new analytical solutions to the equations of motion of a propelled spacecraft are investigated using a shape-based approach.There is an assumption that the spacecraft travels a two-dimensional spiral trajectory in which the orbital radius is proportional to an assigned power of the spacecraft angular coordinate.The exact solution to the equations of motion is obtained as a function of time in the case of a purely radial thrust,and the propulsive acceleration magnitude necessary for the spacecraft to track the prescribed spiral trajectory is found in a closed form.The analytical results are then specialized to the case of a generalized sail,that is,a propulsion system capable of providing an outward radial propulsive acceleration,the magnitude of which depends on a given power of the Sun-spacecraft distance.In particular,the conditions for an outward radial thrust and the required sail performance are quantified and thoroughly discussed.It is worth noting that these propulsion systems provide a purely radial thrust when their orientation is Sun-facing.This is an important advantage from an engineering point of view because,depending on the particular propulsion system,a Sun-facing attitude can be stable or obtainable in a passive way.A case study is finally presented,where the generalized sail is assumed to start the spiral trajectory from the Earth’s heliocentric orbit.The main outcome is that the required sail performance is in principle achievable on the basis of many results available in the literature.
文摘The dynamics of a spacecraft propelled by a continuous radial thrust resembles that of a nonlinear oscillator.This is analyzed in this work with a novel method that combines the definition of a suitable homotopy with a classical perturbation approach,in which the low thrust is assumed to be a perturbation of the nominal Keplerian motion.The homotopy perturbation method provides the analytical(approximate)solution of the dynamical equations in polar form to estimate the corresponding spacecraft propelled trajectory with a short computational time.The accuracy of the analytical results was tested in an orbital-targeting mission scenario.
基金Supported by the Ministerial Level Foundation(2220060029)
文摘In order to calculate the pressure distribution of radial grooved thrust bearing, analytical and numerical methods were applied respectively. Grooved region and land region were linked by u- sing the mass conservations principle at the groove/land boundary in each method. The block-weight approach was implemented to deal with the non-coincidence of mesh and radial groove pattern in nu- merical method. It was observed that the numerical solutions had higher precision as mesh number exceed 70 x 70, and the relaxation iteration of differential scheme presented the fastest convergence speed when relaxation factor was close to 1.94.
文摘Static and dynamic mechanical characteristics of a thrust magnetic bearing are studied owing to the inclination of the runner disk. The application refers to a thrust magnetic bearing for a turbo expander/compressor. The static tilt of the runner disk has remarkable influence on the mechanical characteristics of thrust magnetic bearing, it can change the static load distribution between two radial magnetic bearings and will exert violent coupling effect among a thrust magnetic bearing and two radial magnetic bearings. Such a finding can be used for the coupled electromechanical dynamics analysis of rotor system equipped with magnetic bearings.
基金Supported by National Science and Technology Special Program(No.2011ZX04004-041)National Natural Science Foundation of China(No.90923023)Doctoral Program Foundation of Higher Education of China(No.20092302110055)
