A new type of impulsive microthruster and its measurement system were designed for the aim of testing the performance of a basic prototype of solid propellant impulsive microthruster. Two sets of tests were conducted....A new type of impulsive microthruster and its measurement system were designed for the aim of testing the performance of a basic prototype of solid propellant impulsive microthruster. Two sets of tests were conducted. The tests show that the ignitor and the main charge of the microthruster match well, the dynamic and static capability of the test and measurement meets the test requirement and the result is creditable. The measured technical characteristics of the microthruster are that the ignition delay time is shorter than 0 3?ms, the total impulse is over 3?N·s, the operational time is shorter than 16?ms and the mass ratio of the thruster is 0 216.展开更多
An approach based on equivalent mechanics theory and computational fluid dynamics （CFD） technology is proposed to estimate dynamical influence of propellant sloshing on the spacecraft. A mechanical model is estab- l...An approach based on equivalent mechanics theory and computational fluid dynamics （CFD） technology is proposed to estimate dynamical influence of propellant sloshing on the spacecraft. A mechanical model is estab- lished by using CFD technique and packed as a ＂sloshing＂ block used in spacecraft guidance navigation and control （GNC） simulation loop. The block takes motion characteristics of the spacecraft as inputs and outputs of pertur- bative force and torques induced by propellant sloshing, thus it is more convenient for analyzing coupling effect between propellant sloshing dynamic and spacecraft GNC than using CFD packages. An example demonstrates the accuracy and the superiority of the approach. Then, the deducing process is applied to practical cases, and simulation results validate that the proposed approach is efficient for identifying the problems induced by sloshing and evaluating effectiveness of several typical designs of sloshing suppression.展开更多
The starting characteristics of thermodynamic undersea vehicle systems are determined by the geometry, size and combustion area of solid propellants, which directly effect liquid propellant pipeline design. It is nece...The starting characteristics of thermodynamic undersea vehicle systems are determined by the geometry, size and combustion area of solid propellants, which directly effect liquid propellant pipeline design. It is necessary to establish accurate burning models for solid propellants. Based on combustion models using powder rings and two different solid ignition grains, namely star-shaped ignition grains and stuffed ignition grains, a mathematic model of the ignition process of the propulsion system was built. With the help of Matlab, a series of calculations were made to determine the effects of different grains on ignition characteristics. The results show that stuffed ignition grain is best suited to be the ignition grain of a thermodynamic undersea vehicle system.展开更多
To study the gas dynamic and heat transfer phenomena inside a single isolated longitudinal solid propellant surface crack,two3-D geometric models with different crack shapes were constructed.Concerning the influence o...To study the gas dynamic and heat transfer phenomena inside a single isolated longitudinal solid propellant surface crack,two3-D geometric models with different crack shapes were constructed.Concerning the influence of propagation of jet from the igniter on the flame spreading phenomena in the crack,flow region around the opening of the crack was also included in the above geometric models.A theoretical framework was then adopted to model the conjugate heat transfer in the combustion channel and the crack cavity.Numerical simulation results indicate that the ignition shock wave can spread into the crack cavity.Extremely high overpressure and pressurization rate were observed along the crack front.It is possible that the crack may propagate before the flame front reaches it.An ignited region located at the crack front near to the channel surface in downstream direction was generated long before the flame front reached the crack opening in both models.展开更多
A study of flow rate limitation in an open wedge channel is reported in this paper. Under microgravity condition, the flow is controlled by the convection and the viscosity in the channel as well as the curvature of t...A study of flow rate limitation in an open wedge channel is reported in this paper. Under microgravity condition, the flow is controlled by the convection and the viscosity in the channel as well as the curvature of the liquid free surface. A maximum flow rate is achieved when the curvature cannot balance the pressure difference leading to a collapse of the free surface. A 1-dimensional theoretical model is used to predict the critical flow rate and calculate the shape of the free surface. Computa- tional Fluid Dynamics tool is also used to simulate the phenomenon. Results show that the 1-dimensional model overestimates the critical flow rate because extra pressure loss is not included in the governing equation. Good agreement is found in 3-dim- ensional simulation results. Parametric study with different wedge angles and channel lengths show that the critical flow rate increases with increasing the cross section area; and decreases with increasing the channel length. The work in this paper can help understand the surface collapsing without gravity and for the design in propellant management devices in satellite tanks.展开更多
文摘A new type of impulsive microthruster and its measurement system were designed for the aim of testing the performance of a basic prototype of solid propellant impulsive microthruster. Two sets of tests were conducted. The tests show that the ignitor and the main charge of the microthruster match well, the dynamic and static capability of the test and measurement meets the test requirement and the result is creditable. The measured technical characteristics of the microthruster are that the ignition delay time is shorter than 0 3?ms, the total impulse is over 3?N·s, the operational time is shorter than 16?ms and the mass ratio of the thruster is 0 216.
基金Innovation Foundation of Aerospace Science and Technology(CASC200902)~~
文摘An approach based on equivalent mechanics theory and computational fluid dynamics （CFD） technology is proposed to estimate dynamical influence of propellant sloshing on the spacecraft. A mechanical model is estab- lished by using CFD technique and packed as a ＂sloshing＂ block used in spacecraft guidance navigation and control （GNC） simulation loop. The block takes motion characteristics of the spacecraft as inputs and outputs of pertur- bative force and torques induced by propellant sloshing, thus it is more convenient for analyzing coupling effect between propellant sloshing dynamic and spacecraft GNC than using CFD packages. An example demonstrates the accuracy and the superiority of the approach. Then, the deducing process is applied to practical cases, and simulation results validate that the proposed approach is efficient for identifying the problems induced by sloshing and evaluating effectiveness of several typical designs of sloshing suppression.
文摘The starting characteristics of thermodynamic undersea vehicle systems are determined by the geometry, size and combustion area of solid propellants, which directly effect liquid propellant pipeline design. It is necessary to establish accurate burning models for solid propellants. Based on combustion models using powder rings and two different solid ignition grains, namely star-shaped ignition grains and stuffed ignition grains, a mathematic model of the ignition process of the propulsion system was built. With the help of Matlab, a series of calculations were made to determine the effects of different grains on ignition characteristics. The results show that stuffed ignition grain is best suited to be the ignition grain of a thermodynamic undersea vehicle system.
文摘To study the gas dynamic and heat transfer phenomena inside a single isolated longitudinal solid propellant surface crack,two3-D geometric models with different crack shapes were constructed.Concerning the influence of propagation of jet from the igniter on the flame spreading phenomena in the crack,flow region around the opening of the crack was also included in the above geometric models.A theoretical framework was then adopted to model the conjugate heat transfer in the combustion channel and the crack cavity.Numerical simulation results indicate that the ignition shock wave can spread into the crack cavity.Extremely high overpressure and pressurization rate were observed along the crack front.It is possible that the crack may propagate before the flame front reaches it.An ignited region located at the crack front near to the channel surface in downstream direction was generated long before the flame front reached the crack opening in both models.
文摘A study of flow rate limitation in an open wedge channel is reported in this paper. Under microgravity condition, the flow is controlled by the convection and the viscosity in the channel as well as the curvature of the liquid free surface. A maximum flow rate is achieved when the curvature cannot balance the pressure difference leading to a collapse of the free surface. A 1-dimensional theoretical model is used to predict the critical flow rate and calculate the shape of the free surface. Computa- tional Fluid Dynamics tool is also used to simulate the phenomenon. Results show that the 1-dimensional model overestimates the critical flow rate because extra pressure loss is not included in the governing equation. Good agreement is found in 3-dim- ensional simulation results. Parametric study with different wedge angles and channel lengths show that the critical flow rate increases with increasing the cross section area; and decreases with increasing the channel length. The work in this paper can help understand the surface collapsing without gravity and for the design in propellant management devices in satellite tanks.
