Thrust-vectoring capability has become a critical feature for propulsion systems as space missions move from static to dynamic.Thrust-vectoring is a well-developed area of rocket engine science.For electric propulsion...Thrust-vectoring capability has become a critical feature for propulsion systems as space missions move from static to dynamic.Thrust-vectoring is a well-developed area of rocket engine science.For electric propulsion,however,it is an evolving field that has taken a new leap forward in recent years.A review and analysis of thrust-vectoring schemes for electric propulsion systems have been conducted.The scope of this review includes thrust-vectoring schemes that can be implemented for electrostatic,electromagnetic,and beam-driven thrusters.A classification of electric propulsion schemes that provide thrust-vectoring capability is developed.More attention is given to schemes implemented in laboratory prototypes and flight models.The final part is devoted to a discussion on the suitability of different electric propulsion systems with thrust-vectoring capability for modern space mission operations.The thrust-vectoring capability of electric propulsion is necessary for inner and outer space satellites,which are at a disadvantage with conventional unidirectional propulsion systems due to their limited maneuverability.展开更多
Solid propellants are essential energy sources for rockets and other aerospace vehicles,and improvements in their performance have significant implications for the aerospace industry.The application of additive manufa...Solid propellants are essential energy sources for rockets and other aerospace vehicles,and improvements in their performance have significant implications for the aerospace industry.The application of additive manufacturing(AM)in the production of solid propellants promises a substantial leap in the design and fabrication of solid propellant grains.This review summarizes recent research on AM techniques for solid propellant manufacturing,evaluates current applications,and explores development trends.This review highlights that AM technology for solid propellants offers unparalleled advantages in terms of propellant design flexibility and functional gradient loading compared with traditional processes.This study presents a new perspective for the future manufacturing of intelligent and controllable solid propulsion systems.展开更多
The Propellant Feed System(PFS)is a crucial component of Electric Propulsion System(EPS)which is widely used in satellites for its high reliability and specific impulse.The Switching and Proportional Hybrid-controlled...The Propellant Feed System(PFS)is a crucial component of Electric Propulsion System(EPS)which is widely used in satellites for its high reliability and specific impulse.The Switching and Proportional Hybrid-controlled Xenon Feed System(SPHXFS)is a novel type of PFS with high flow regulation precision.This study develops a system-level simulation model with 75 components for the SPHXFS.The accuracy of the model is validated through the comparison with test data,showing an error of less than 3%during the startup phase and less than 0.1%after stabilization.The study analyzes the startup process and finds that the two-stage pressure reduction system avoids two-phase flow interference downstream,achieving a regulation accuracy of±0.1%.A long-term operation simulation of the system is conducted,revealing that pressure fluctuations occur upstream at 4767 s due to Bang-Bang control.However,with proportional control adjustments,these fluctuations do not affect the flow supply.Further research examines the impact of synchronous and asynchronous control modes of the Bang-Bang Valve(TPBBV)under the tank pressures of 6-10 MPa on the system's dynamic characteristics.It is found that the asynchronous control scheme results in a flow supply settling time that is 7.2-10s longer than the synchronous control scheme,with an overshoot increase of 4.1%-4.9%.These insights provide valuable reference and guidance for system optimization design and the formulation of operational strategies.展开更多
Space ion electric propulsion has been widely used in the north-south position maintenance and orbit transfer missions for high-orbit satellites.However,unexpected electric breakdown by ion electric propulsion systems...Space ion electric propulsion has been widely used in the north-south position maintenance and orbit transfer missions for high-orbit satellites.However,unexpected electric breakdown by ion electric propulsion systems is still a challenging problem that needs to be solved,as it affects reliability.Based on the analysis of in-orbit and ground test data of ion thrusters from simulation and experimental results,the main influencing factors of induced electric breakdown are clarified and the mechanisms of induced electric breakdown are analyzed.It is found that the main factors inducing breakdown are the voltage and electric field strength between the grids.In addition,by monitoring the waveform of plasma discharge,the temporal characteristics of breakdown can be defined as three stages of“breakdown-spark-loop response”.Thus,three kinds of engineering suppression methods for breakdown of static vacuum with periodic short-term heating,electrode surface polishing and sealing insulation with plasma,add energy suppression circuit are carried out,and the experimental results show that the electric breakdown frequency can be reduced by about 30%.展开更多
Distributed Electric Propulsion(DEP)aircraft use multiple electric motors to drive the propulsors,which gives potential benefits to aerodynamic-propulsion interaction.To investigate and quantify the aerodynamic-propul...Distributed Electric Propulsion(DEP)aircraft use multiple electric motors to drive the propulsors,which gives potential benefits to aerodynamic-propulsion interaction.To investigate and quantify the aerodynamic-propulsion interaction effect of the wing section,we built a DEP demonstrator with 24"high-lift"Electric Ducted Fans(EDFs)distributed along the wing’s trailing edge.This paper explores and compares the aero-propulsion coupling characteristics under various upstream speed,throttle,and EDF mounting surface deflection angles using a series of wind tunnel tests.We compare various lift-augmentation power conditions to the clean configuration without propulsion unit under the experiment condition of 15-25 m/s freestream flow and angles of attack from-4°to 16°.The comparison of computational results to the experimental results verifies the effectiveness of the computational fluid dynamic analysis method and the modeling method for the DEP configuration.The results show that the EDFs can produce significant lift increment and drag reduction simultaneously,which is accordant with the potential benefit of Boundary Layer Ingestion(BLI)at low airspeed.展开更多
Maneuverability is one of the most important sailing performances of vessels. In this article, a motion control model with three degrees of freedom(DoFs) for twin-waterjet propulsion vessel is proposed. The model is d...Maneuverability is one of the most important sailing performances of vessels. In this article, a motion control model with three degrees of freedom(DoFs) for twin-waterjet propulsion vessel is proposed. The model is developed on the basis of maneuvering model group(MMG) maneuverability equations. A simulation environment is constructed on the Matlab Simulink platform. Standard turning tests and zig-zag tests are simulated by solving the motion control model, and the corresponding maneuverability parameters are calculated. Simulation results demonstrate that the maneuverability parameters are in accordance with the vessel maneuverability standard.The approach may be applied to the rapid prediction of vessel maneuverability.展开更多
The waterjet propulsion is widely applied in the marine vessels over 30 knots,and the intake duct is considered as an essential component that strongly relates to the propulsion performance.This paper sheds light on t...The waterjet propulsion is widely applied in the marine vessels over 30 knots,and the intake duct is considered as an essential component that strongly relates to the propulsion performance.This paper sheds light on the flow features inside an intake duct under mooring conditions by using the particle image velocimetry(PIV)technique with three-dimensional(3D)numerical simulations.The hydraulic loss gradually increase as the flow-rate increases.According to analyses via the Bernoulli equation,the hydraulic loss is composed of the frictional head loss(h_(f)~V^(1.75))and the local head loss(h_(j)~V^(2.0)).A recirculation region is observed near the duct lower wall with a high-velocity flow near the upper wall,and subsequently a shear flow presents in the horizontal straight pipe with an obvious velocity gradient.Three-dimensional simulations demonstrate that the vortex pair is very strong in the recirculation region and then it gradually decreases as the fluid flows downstream.With the flow-rate increasing,the non-uniformity at the duct outlet firstly increases to a peak and then slightly decreases,while the perpendicularity at the duct outlet dramatically decreases to a minimum and then increases.This work not only reveals some physics of the waterjet propulsion under mooring conditions,but also promotes its efficient operation.展开更多
In order to optimize the laser ablation performance of a micro-thruster with 1U dimensions,which employs a micro semiconductor laser,the impacts of pulse width and glycidyl azide polymer(GAP)thickness on thrust perfor...In order to optimize the laser ablation performance of a micro-thruster with 1U dimensions,which employs a micro semiconductor laser,the impacts of pulse width and glycidyl azide polymer(GAP)thickness on thrust performance were researched.The results showed that with a GAP thickness of 200μm,the single-pulse impulse(I)increased gradually with the increase in the laser pulse width from 50 to 800μs,while the specific impulse(I_(sp)),impulse coupling coefficient(Cm)and ablation efficiency(η)all reached optimal values with a 200μs pulse width.It is worth noting that the optimal pulse width is identical to the ignition delay time.Both Cmandηpeaked with a pulse width of 200μs,reaching 242.22μN W^(-1)and 35.4%,respectively.With the increase in GAP thickness,I and Cmincreased gradually.GAP of different thicknesses corresponded to different optimal laser pulse widths.Under a certain laser pulse width,the optimal GAP thickness should be the most vertical thickness of the ablation pit,and the various propulsion performance parameters at this time were also optimal.With the current laser parameters,the optimal GAP thickness was approximately 150μm,I_(sp)was approximately 322.22 s,andηwas approximately 34.94%.展开更多
High power Hall electric propulsion technology is a very competitive electric propulsion technology for future large space missions such as large GEO satellites,manned space programs,deep space explorations,cargo ship...High power Hall electric propulsion technology is a very competitive electric propulsion technology for future large space missions such as large GEO satellites,manned space programs,deep space explorations,cargo ships,space tugs.Based on the experience of more than 20 years in research and development of Hall electric propulsion,the Shanghai Institute of Space Propulsion(SISP)has developed 3 high power Hall thrusters,i.e.,the 10 k W class HET-500,20 k W class HET-1000,and 50 k W class HET-3000.This paper presents the development status of the high power(≥10 k W)Hall electric propulsion at SISP,including tests of 3 high power Hall thrusters in the power range from 10 k W to 50 k W,the qualification of a single string of a 10 k W Hall electric propulsion system,and the study of a cluster of two 1.35 k W HET-80 Hall thrusters to understand the technical issues related to multi-thruster high power electric propulsion systems.展开更多
Water-jet propulsion is a widely applied ship propulsion technology.Its steering control system has an important impact on manoeuvre performance.In this paper,transfer function model is firstly established on the basi...Water-jet propulsion is a widely applied ship propulsion technology.Its steering control system has an important impact on manoeuvre performance.In this paper,transfer function model is firstly established on the basis of mechanism analysis of water-jet steering system.Then,by considering the variability of model parameters and input constraints in practical operation,a model predictive controller is designed for steering system control.Subsequently,model based disturbance observer is employed in an attempt to reject environmental disturbances.The performance of the proposed model predictive control (MPC) scheme for a particular steering system is compared with that of conventional proportional integral derivative (PID) control strategy.Simulation results demonstrate that the proposed model predictive controller outperforms conventional PID controller,particularly in robustness,response delay and tracking accuracy.展开更多
A computational model of laser ablated polymer was established. Set the ablation criterion based on threshold energy. Put forward the polymer ablation criterion in the numerical model. It established the energy distri...A computational model of laser ablated polymer was established. Set the ablation criterion based on threshold energy. Put forward the polymer ablation criterion in the numerical model. It established the energy distribution equation to describe the laser ablation process. When the ablation products ejected, the target gained recoil impulse from ejection process. Get the ejection energy and the recoil momentum of target based on momentum conservation law. The numerical analysis model can reflect the propulsion capability of different polymer propellant, revealed the law of propulsion parameters in laser ablation process.展开更多
Based on the requirements of manned spaceships,this paper introduces the characteristics of the propulsion system from the perspectives of design scheme,basic composition,safety and reliability measures,and also intro...Based on the requirements of manned spaceships,this paper introduces the characteristics of the propulsion system from the perspectives of design scheme,basic composition,safety and reliability measures,and also introduces the ground test verification and on-orbit flight characteristics of the Shenzhou 13 propulsion system.According to the flight results,it was seen that the performance of the Shenzhou 13 propulsion system fully met the engineering requirements for the manned space mission.展开更多
As we enter the age of electrochemical propulsion,there is an increasing tendency to discuss the viability or otherwise of different electrochemical propulsion systems in zero-sum terms.These discussions are often gro...As we enter the age of electrochemical propulsion,there is an increasing tendency to discuss the viability or otherwise of different electrochemical propulsion systems in zero-sum terms.These discussions are often grounded in a specific use case;however,given the need to electrify the wider transport sector it is evident that we must consider systems in a holistic fashion.When designed adequately,the hybridisation of power sources within automotive applications has been demonstrated to positively impact fuel cell efficiency,durability,and cost,while having potential benefits for the safety of vehicles.In this paper,the impact of the fuel cell to battery hybridisation degree is explored through the key design parameter of system mass.Different fuel cell electric hybrid vehicle(FCHEV)scenarios of various hydridisation degrees,including light-duty vehicles(LDVs),Class 8 heavy goods vehicles(HGVs),and buses are modelled to enable the appropriate sizing of the proton exchange membrane(PEMFC)stack and lithium-ion battery(LiB)pack and additional balance of plant.The operating conditions of the modelled PEMFC stack and battery pack are then varied under a range of relevant drive cycles to identify the relative performance of the systems.By extending the model further and incorporating a feedback loop,we are able to remove the need to include estimated vehicle masses a priori enabling improving the speed and accuracy of the model as an analysis tool for vehicle mass and performance estimation.展开更多
To accurately predict the three-dimensional flow characteristics of the flow field inside a waterjet propulsion pump,data assimilation(DA)method based on unsteady ensemble Kalman filter(EnKF)is used for the reconstruc...To accurately predict the three-dimensional flow characteristics of the flow field inside a waterjet propulsion pump,data assimilation(DA)method based on unsteady ensemble Kalman filter(EnKF)is used for the reconstruction of the flow field of a pump at different flow rates Q/Q_(opt)=0.85,1,1.15,where Q_(opt)is optimal flow rate at the design point.As a compensation to the spatial limitation of planar particle image velocimetry(PIV)measurements,dynamic delayed detached-eddy simulation(DDES)results validated by the PIV data is used to provide the observational data at the optimized probe locations.In DA procedure,the shear stress transport(SST)model constants are optimized by the EnKF approach.The model constants are subsequently rescaled and fitted to form a variation with the flow rate,which is extended to the prediction of the flow field with other flow rates in the vicinity of the design condition.The results show that the SST model with recalibrated constants has improved the prediction of the internal flow field in the waterjet propulsion pump,especially the separation flow in the diffuser section.The modified model constants mainly reduce the eddy viscosity and significantly improve the fluctuation characteristics in the flow field.This study provides a reference for the fast and accurate prediction of the flow field information in the waterjet propulsion pump.展开更多
This work analyzes a novel MEMS-based architecture of submillimeter size thruster for the propulsion of small spacecrafts,addressing its preliminary characterization of performance.The architecture of microthruster co...This work analyzes a novel MEMS-based architecture of submillimeter size thruster for the propulsion of small spacecrafts,addressing its preliminary characterization of performance.The architecture of microthruster comprises a setup of miniaturized channels surrounding the solid-propellant reservoir filled up with a high-energetic polymer.These channels guide the hot gases from the combustion region towards the nozzle entrance located at the opposite side of the thruster.Numerical simulations of the transient response of the combustion gases and wafer heating in thruster firings have been conducted with FLUENT under a multiphysics modelling that fully couples the gas and solid parts involved.The approach includes the gas-wafer and gas-polymer thermal exchange,burnback of the polymer with a simplified non-reacting gas pyrolysis model at its front,and a slip-model inside the nozzle portion to incorporate the effect of gas-surface and rarefaction onto the gas expansion.Besides,accurate characterization of thruster operation requires the inclusion of the receding front of the polymer and heat transfer in the moving gas-solid interfaces.The study stresses the improvement attained in thermal management by the inclusion of lateral micro-channels in the device.In particular,the temperature maps reveal the significant dependence of the thermal loss on the instantaneous surface of the reservoir wall exposed to the heat flux of hot gases.Specifically,the simulations stress the benefit of implementing such a pattern of micro-channels connecting the exit of the combustion reservoir with the nozzle.The results prove that hot gases flowing along the micro-channels exert a sealing action upon the heat flux at the reservoir wall and partly mitigate the overall thermal loss at the inner-wall vicinity during the burnback.The analysis shows that propellant decomposition rate is accelerated due to surface preheating and it suggests that a delay of the flame extinction into the reservoir is possible.The simulated operation of the thruster concept shows encouraging performance.展开更多
In this paper,micropropulsion systems are analyzed in conjunction with the various mission requirements of China’s deep space exploration.As a great challenge facing the world,deep space exploration can be enabled on...In this paper,micropropulsion systems are analyzed in conjunction with the various mission requirements of China’s deep space exploration.As a great challenge facing the world,deep space exploration can be enabled only in a few countries with a success rate of around 50%.With the advancement of spacecraft and scientific instruments,it is now feasible to build small and low-cost spacecraft for a variety of deep space missions.As spacecraft become smaller,there is a need for proper micropropulsion systems.Examples of propulsion system selections for deep space exploration are discussed with a focus on products developed by Beijing Institute of Control Engineering(BICE).The requirements for propulsion systems are different in lunar/interplanetary exploration and gravitational wave detection.Chemical propulsion is selected for fast orbit transfer and electric propulsion for increasing scientific payloads.Cold gas propulsion and microelectric propulsion are good choices for space-based gravitational wave detection due to the capability of variable thrust output at the micro-Newton level.The paper also introduces the sub-1-U micropropulsion modules developed by BICE with satisfactory performance in flight tests,which are promising propulsion systems for small deep space platforms.A small probe with an electric sail propulsion system has been proposed for the future solar system boundary exploration of China.The electric sail serves as not only a propellant-free thruster but also a detector probing the properties of the space medium.展开更多
In the mid seventies a new propulsor for aircraft was designed and investigated - the so-called PROPFAN. With regard to the total pressure increase, it ranges between a conventional propeller and a turbofan with very ...In the mid seventies a new propulsor for aircraft was designed and investigated - the so-called PROPFAN. With regard to the total pressure increase, it ranges between a conventional propeller and a turbofan with very high bypass ratio. This new propulsion system promised a reduction in fuel consumption of 15 to 25% compared to engines at that time.A lot of propfans (Hamilton Standard, USA) with different numbers of blades and blade shapes have been designed and tested in wind tunnels in order to find an optimum in efficiency, Fig.1. Parallel to this development GE, USA, made a design of a counter rotating unducted propfan, the so-called UDF, Fig.2. A prototype engine was manufactured and investigated on an in-flight test bed mounted at the MD82 and the B727. Since that time there has not been any further development of propfans (except AN 70 with NK 90-engine, Ukraine, which is more or less a propeller design) due to relatively low fuel prices and technical obstacles. Only technical programs in different countries are still going on in order to prepare a data base for designing counter rotating fans in terms of aeroacoustics, aerodynamics and aeroelasticities. In DLR, Germany, a lot of experimental and numerical work has been undertaken to understand the physical behaviour of the unsteady flow in a counter rotating fan.展开更多
Open-end winding motors are used extensively in ship electric propulsion systems,in which medium-voltage high-power inverters are a critical component.To increase the system voltage and power density,a dual five-level...Open-end winding motors are used extensively in ship electric propulsion systems,in which medium-voltage high-power inverters are a critical component.To increase the system voltage and power density,a dual five-level active neutral-point clamped(ANPC)inverter is proposed herein to drive medium-voltage open-end winding motors for ship electric propulsion.Each phase of this inverter comprises two five-level ANPC bridges and all the phases are powered by a common direct-current link.A hybrid modulation method is proposed to control this inverter.The series-connected switches in all the five-level ANPC bridges are operated at the fundamental frequency,and the other switches are controlled with a phase-shifted pulse-width modulation(PWM),which can achieve a natural balance between the neutral-point voltage and flying capacitor voltages in a carrier period.A closed-loop capacitor voltage balancing method based on adjusting the duty ratios of the PWM signals is proposed.The neutral-point voltage and flying capacitor voltages can be controlled independently and balanced without affecting the output phase voltage.Simulation and experimental results are presented to demonstrate the validity of this method.展开更多
Currently,iodine-compatible cathodes for iodine propulsion systems that can provide ampere-level electron currents with a reasonable power consumption are lacking.In this study,a conventional LaB_(6)hollow cathode mad...Currently,iodine-compatible cathodes for iodine propulsion systems that can provide ampere-level electron currents with a reasonable power consumption are lacking.In this study,a conventional LaB_(6)hollow cathode made with iodine-resistant materials was designed and tested in an iodine-compatible vacuum facility.The ignition characteristics,the V-I(Volt-Ampere characteristic)curve,and long steady-state discharge sequence of the iodine hollow cathode were analyzed and compared with those using a krypton propellant.After the experiment,the composition of the cathode emitter was studied by scanning electron microscope and energy-dispersive X-ray spectroscopy(EDS).The results show that ignition takes>10 s to reach a steady state,and the discharge voltage of the iodine was 25-95 V higher than that of krypton.According to the EDS results,this was mainly caused by emitter contamination with iron from the stainless-steel components of the cathode and oxygen from the iodine feed system.The iodine hollow cathode achieved a cumulative 12.5 h stable discharge,with the longest single discharge of 5 h and a 3%change in the inner diameter of the emitter.展开更多
Hall thrusters with large height-radius ratio,owing to their unique advantages in compactness,lightweight,and high performance,have progressively emerged as a preferred choice for diverse space propulsion applications...Hall thrusters with large height-radius ratio,owing to their unique advantages in compactness,lightweight,and high performance,have progressively emerged as a preferred choice for diverse space propulsion applications in the future.However,the amplification of the annular effect in structures with a large height-radius ratio poses a practical problem of plume over-focusing,which seriously restricts the further improvement of Hall thruster performance and the extension of its life.In this study,the formation mechanism of over-focused plume is deeply investigated,and it is ascertained that an intensified radial electric field directed towards the inner wall within the channel serves as a key contributing factor.This phenomenon is fundamentally attributed to structural characteristics of large height-radius ratio that induce pronounced inward inclination of field lines within strong magnetic field zone.Based on this,the design concept of focused magnetic field is proposed,wherein straight magnetic field lines are established within the strong magnetic field zone to generate a quasi-axial accelerating electric field.Simultaneously,the symmetrical magnetic field inside the channel ensures ionization concentration near the channel center,thereby achieving optimal matching between the ionization zone and accelerating field.Experimental results demonstrate that employing a focused magnetic field significantly reduces the divergence half-angle of the plume and yields an excellently barrel-shaped focusing plume morphology in HEP-1350PM.Consequently,the total efficiency of the thruster surpasses 60%,while erosion belt on the inner wall is shortened by nearly 50%.These advancements effectively enhance thruster performance and prolong its operational lifespan.This study can not only resolve practical problems associated with plume over-focusing,but also provide a fundamental guiding principle for magnetic field design of Hall thrusters.展开更多
基金performed at large-scale research facility"Beam-M"of Bauman Moscow State Technical University following the government task by the Ministry of Science and Higher Education of the Russian Federation(No.FSFN-2024-0007).
文摘Thrust-vectoring capability has become a critical feature for propulsion systems as space missions move from static to dynamic.Thrust-vectoring is a well-developed area of rocket engine science.For electric propulsion,however,it is an evolving field that has taken a new leap forward in recent years.A review and analysis of thrust-vectoring schemes for electric propulsion systems have been conducted.The scope of this review includes thrust-vectoring schemes that can be implemented for electrostatic,electromagnetic,and beam-driven thrusters.A classification of electric propulsion schemes that provide thrust-vectoring capability is developed.More attention is given to schemes implemented in laboratory prototypes and flight models.The final part is devoted to a discussion on the suitability of different electric propulsion systems with thrust-vectoring capability for modern space mission operations.The thrust-vectoring capability of electric propulsion is necessary for inner and outer space satellites,which are at a disadvantage with conventional unidirectional propulsion systems due to their limited maneuverability.
基金supported by National Key Research and Development Program of China(Grant.No.2022YFB4603102)Insight Action(Grant.No.AA5F41D0).
文摘Solid propellants are essential energy sources for rockets and other aerospace vehicles,and improvements in their performance have significant implications for the aerospace industry.The application of additive manufacturing(AM)in the production of solid propellants promises a substantial leap in the design and fabrication of solid propellant grains.This review summarizes recent research on AM techniques for solid propellant manufacturing,evaluates current applications,and explores development trends.This review highlights that AM technology for solid propellants offers unparalleled advantages in terms of propellant design flexibility and functional gradient loading compared with traditional processes.This study presents a new perspective for the future manufacturing of intelligent and controllable solid propulsion systems.
基金supported by the Fundamental Research Funds for the Central Universities,China(No.JKF-2025009442288)the Excellent Youth Team Cultivation Project for Central Universities of the Ministry of Education,China(No.YWF-22/23/24-JT-106)。
文摘The Propellant Feed System(PFS)is a crucial component of Electric Propulsion System(EPS)which is widely used in satellites for its high reliability and specific impulse.The Switching and Proportional Hybrid-controlled Xenon Feed System(SPHXFS)is a novel type of PFS with high flow regulation precision.This study develops a system-level simulation model with 75 components for the SPHXFS.The accuracy of the model is validated through the comparison with test data,showing an error of less than 3%during the startup phase and less than 0.1%after stabilization.The study analyzes the startup process and finds that the two-stage pressure reduction system avoids two-phase flow interference downstream,achieving a regulation accuracy of±0.1%.A long-term operation simulation of the system is conducted,revealing that pressure fluctuations occur upstream at 4767 s due to Bang-Bang control.However,with proportional control adjustments,these fluctuations do not affect the flow supply.Further research examines the impact of synchronous and asynchronous control modes of the Bang-Bang Valve(TPBBV)under the tank pressures of 6-10 MPa on the system's dynamic characteristics.It is found that the asynchronous control scheme results in a flow supply settling time that is 7.2-10s longer than the synchronous control scheme,with an overshoot increase of 4.1%-4.9%.These insights provide valuable reference and guidance for system optimization design and the formulation of operational strategies.
文摘Space ion electric propulsion has been widely used in the north-south position maintenance and orbit transfer missions for high-orbit satellites.However,unexpected electric breakdown by ion electric propulsion systems is still a challenging problem that needs to be solved,as it affects reliability.Based on the analysis of in-orbit and ground test data of ion thrusters from simulation and experimental results,the main influencing factors of induced electric breakdown are clarified and the mechanisms of induced electric breakdown are analyzed.It is found that the main factors inducing breakdown are the voltage and electric field strength between the grids.In addition,by monitoring the waveform of plasma discharge,the temporal characteristics of breakdown can be defined as three stages of“breakdown-spark-loop response”.Thus,three kinds of engineering suppression methods for breakdown of static vacuum with periodic short-term heating,electrode surface polishing and sealing insulation with plasma,add energy suppression circuit are carried out,and the experimental results show that the electric breakdown frequency can be reduced by about 30%.
基金supported by the National Natural Science Foundation of China(No.51877178)。
文摘Distributed Electric Propulsion(DEP)aircraft use multiple electric motors to drive the propulsors,which gives potential benefits to aerodynamic-propulsion interaction.To investigate and quantify the aerodynamic-propulsion interaction effect of the wing section,we built a DEP demonstrator with 24"high-lift"Electric Ducted Fans(EDFs)distributed along the wing’s trailing edge.This paper explores and compares the aero-propulsion coupling characteristics under various upstream speed,throttle,and EDF mounting surface deflection angles using a series of wind tunnel tests.We compare various lift-augmentation power conditions to the clean configuration without propulsion unit under the experiment condition of 15-25 m/s freestream flow and angles of attack from-4°to 16°.The comparison of computational results to the experimental results verifies the effectiveness of the computational fluid dynamic analysis method and the modeling method for the DEP configuration.The results show that the EDFs can produce significant lift increment and drag reduction simultaneously,which is accordant with the potential benefit of Boundary Layer Ingestion(BLI)at low airspeed.
基金the Open Project of the Key Laboratory of Science and Technology on Waterjet Propulsion(No.614222303051117)the Joint Fund of CSSC(No.6141B03020301)
文摘Maneuverability is one of the most important sailing performances of vessels. In this article, a motion control model with three degrees of freedom(DoFs) for twin-waterjet propulsion vessel is proposed. The model is developed on the basis of maneuvering model group(MMG) maneuverability equations. A simulation environment is constructed on the Matlab Simulink platform. Standard turning tests and zig-zag tests are simulated by solving the motion control model, and the corresponding maneuverability parameters are calculated. Simulation results demonstrate that the maneuverability parameters are in accordance with the vessel maneuverability standard.The approach may be applied to the rapid prediction of vessel maneuverability.
基金the National Natural Science Foundation of China(Grants 52006232 and 11772340)the Science and Technology on Water Jet Propulsion Laboratory(Grant 6142223190101).
文摘The waterjet propulsion is widely applied in the marine vessels over 30 knots,and the intake duct is considered as an essential component that strongly relates to the propulsion performance.This paper sheds light on the flow features inside an intake duct under mooring conditions by using the particle image velocimetry(PIV)technique with three-dimensional(3D)numerical simulations.The hydraulic loss gradually increase as the flow-rate increases.According to analyses via the Bernoulli equation,the hydraulic loss is composed of the frictional head loss(h_(f)~V^(1.75))and the local head loss(h_(j)~V^(2.0)).A recirculation region is observed near the duct lower wall with a high-velocity flow near the upper wall,and subsequently a shear flow presents in the horizontal straight pipe with an obvious velocity gradient.Three-dimensional simulations demonstrate that the vortex pair is very strong in the recirculation region and then it gradually decreases as the fluid flows downstream.With the flow-rate increasing,the non-uniformity at the duct outlet firstly increases to a peak and then slightly decreases,while the perpendicularity at the duct outlet dramatically decreases to a minimum and then increases.This work not only reveals some physics of the waterjet propulsion under mooring conditions,but also promotes its efficient operation.
基金supported by National Natural Science Foundation of China (Nos. 11502301, 11602304 and 62175260)
文摘In order to optimize the laser ablation performance of a micro-thruster with 1U dimensions,which employs a micro semiconductor laser,the impacts of pulse width and glycidyl azide polymer(GAP)thickness on thrust performance were researched.The results showed that with a GAP thickness of 200μm,the single-pulse impulse(I)increased gradually with the increase in the laser pulse width from 50 to 800μs,while the specific impulse(I_(sp)),impulse coupling coefficient(Cm)and ablation efficiency(η)all reached optimal values with a 200μs pulse width.It is worth noting that the optimal pulse width is identical to the ignition delay time.Both Cmandηpeaked with a pulse width of 200μs,reaching 242.22μN W^(-1)and 35.4%,respectively.With the increase in GAP thickness,I and Cmincreased gradually.GAP of different thicknesses corresponded to different optimal laser pulse widths.Under a certain laser pulse width,the optimal GAP thickness should be the most vertical thickness of the ablation pit,and the various propulsion performance parameters at this time were also optimal.With the current laser parameters,the optimal GAP thickness was approximately 150μm,I_(sp)was approximately 322.22 s,andηwas approximately 34.94%.
文摘High power Hall electric propulsion technology is a very competitive electric propulsion technology for future large space missions such as large GEO satellites,manned space programs,deep space explorations,cargo ships,space tugs.Based on the experience of more than 20 years in research and development of Hall electric propulsion,the Shanghai Institute of Space Propulsion(SISP)has developed 3 high power Hall thrusters,i.e.,the 10 k W class HET-500,20 k W class HET-1000,and 50 k W class HET-3000.This paper presents the development status of the high power(≥10 k W)Hall electric propulsion at SISP,including tests of 3 high power Hall thrusters in the power range from 10 k W to 50 k W,the qualification of a single string of a 10 k W Hall electric propulsion system,and the study of a cluster of two 1.35 k W HET-80 Hall thrusters to understand the technical issues related to multi-thruster high power electric propulsion systems.
基金the Open Project of the Key Laboratory of Science and Technology on Waterjet Propulsion(No.614222303051117)the Joint Fund of CSSC(No.6141B03020301)。
文摘Water-jet propulsion is a widely applied ship propulsion technology.Its steering control system has an important impact on manoeuvre performance.In this paper,transfer function model is firstly established on the basis of mechanism analysis of water-jet steering system.Then,by considering the variability of model parameters and input constraints in practical operation,a model predictive controller is designed for steering system control.Subsequently,model based disturbance observer is employed in an attempt to reject environmental disturbances.The performance of the proposed model predictive control (MPC) scheme for a particular steering system is compared with that of conventional proportional integral derivative (PID) control strategy.Simulation results demonstrate that the proposed model predictive controller outperforms conventional PID controller,particularly in robustness,response delay and tracking accuracy.
文摘A computational model of laser ablated polymer was established. Set the ablation criterion based on threshold energy. Put forward the polymer ablation criterion in the numerical model. It established the energy distribution equation to describe the laser ablation process. When the ablation products ejected, the target gained recoil impulse from ejection process. Get the ejection energy and the recoil momentum of target based on momentum conservation law. The numerical analysis model can reflect the propulsion capability of different polymer propellant, revealed the law of propulsion parameters in laser ablation process.
文摘Based on the requirements of manned spaceships,this paper introduces the characteristics of the propulsion system from the perspectives of design scheme,basic composition,safety and reliability measures,and also introduces the ground test verification and on-orbit flight characteristics of the Shenzhou 13 propulsion system.According to the flight results,it was seen that the performance of the Shenzhou 13 propulsion system fully met the engineering requirements for the manned space mission.
文摘As we enter the age of electrochemical propulsion,there is an increasing tendency to discuss the viability or otherwise of different electrochemical propulsion systems in zero-sum terms.These discussions are often grounded in a specific use case;however,given the need to electrify the wider transport sector it is evident that we must consider systems in a holistic fashion.When designed adequately,the hybridisation of power sources within automotive applications has been demonstrated to positively impact fuel cell efficiency,durability,and cost,while having potential benefits for the safety of vehicles.In this paper,the impact of the fuel cell to battery hybridisation degree is explored through the key design parameter of system mass.Different fuel cell electric hybrid vehicle(FCHEV)scenarios of various hydridisation degrees,including light-duty vehicles(LDVs),Class 8 heavy goods vehicles(HGVs),and buses are modelled to enable the appropriate sizing of the proton exchange membrane(PEMFC)stack and lithium-ion battery(LiB)pack and additional balance of plant.The operating conditions of the modelled PEMFC stack and battery pack are then varied under a range of relevant drive cycles to identify the relative performance of the systems.By extending the model further and incorporating a feedback loop,we are able to remove the need to include estimated vehicle masses a priori enabling improving the speed and accuracy of the model as an analysis tool for vehicle mass and performance estimation.
基金supported by the National Natural Science Foundation of China(Grant Nos.12272231 and 12227803).
文摘To accurately predict the three-dimensional flow characteristics of the flow field inside a waterjet propulsion pump,data assimilation(DA)method based on unsteady ensemble Kalman filter(EnKF)is used for the reconstruction of the flow field of a pump at different flow rates Q/Q_(opt)=0.85,1,1.15,where Q_(opt)is optimal flow rate at the design point.As a compensation to the spatial limitation of planar particle image velocimetry(PIV)measurements,dynamic delayed detached-eddy simulation(DDES)results validated by the PIV data is used to provide the observational data at the optimized probe locations.In DA procedure,the shear stress transport(SST)model constants are optimized by the EnKF approach.The model constants are subsequently rescaled and fitted to form a variation with the flow rate,which is extended to the prediction of the flow field with other flow rates in the vicinity of the design condition.The results show that the SST model with recalibrated constants has improved the prediction of the internal flow field in the waterjet propulsion pump,especially the separation flow in the diffuser section.The modified model constants mainly reduce the eddy viscosity and significantly improve the fluctuation characteristics in the flow field.This study provides a reference for the fast and accurate prediction of the flow field information in the waterjet propulsion pump.
基金funded by the Spanish Ministry of Defence as part of the micropropulsion activities in the Small Satellites Programme
文摘This work analyzes a novel MEMS-based architecture of submillimeter size thruster for the propulsion of small spacecrafts,addressing its preliminary characterization of performance.The architecture of microthruster comprises a setup of miniaturized channels surrounding the solid-propellant reservoir filled up with a high-energetic polymer.These channels guide the hot gases from the combustion region towards the nozzle entrance located at the opposite side of the thruster.Numerical simulations of the transient response of the combustion gases and wafer heating in thruster firings have been conducted with FLUENT under a multiphysics modelling that fully couples the gas and solid parts involved.The approach includes the gas-wafer and gas-polymer thermal exchange,burnback of the polymer with a simplified non-reacting gas pyrolysis model at its front,and a slip-model inside the nozzle portion to incorporate the effect of gas-surface and rarefaction onto the gas expansion.Besides,accurate characterization of thruster operation requires the inclusion of the receding front of the polymer and heat transfer in the moving gas-solid interfaces.The study stresses the improvement attained in thermal management by the inclusion of lateral micro-channels in the device.In particular,the temperature maps reveal the significant dependence of the thermal loss on the instantaneous surface of the reservoir wall exposed to the heat flux of hot gases.Specifically,the simulations stress the benefit of implementing such a pattern of micro-channels connecting the exit of the combustion reservoir with the nozzle.The results prove that hot gases flowing along the micro-channels exert a sealing action upon the heat flux at the reservoir wall and partly mitigate the overall thermal loss at the inner-wall vicinity during the burnback.The analysis shows that propellant decomposition rate is accelerated due to surface preheating and it suggests that a delay of the flame extinction into the reservoir is possible.The simulated operation of the thruster concept shows encouraging performance.
基金supported by the National Key R&D Program of China(2020YFC2201100).
文摘In this paper,micropropulsion systems are analyzed in conjunction with the various mission requirements of China’s deep space exploration.As a great challenge facing the world,deep space exploration can be enabled only in a few countries with a success rate of around 50%.With the advancement of spacecraft and scientific instruments,it is now feasible to build small and low-cost spacecraft for a variety of deep space missions.As spacecraft become smaller,there is a need for proper micropropulsion systems.Examples of propulsion system selections for deep space exploration are discussed with a focus on products developed by Beijing Institute of Control Engineering(BICE).The requirements for propulsion systems are different in lunar/interplanetary exploration and gravitational wave detection.Chemical propulsion is selected for fast orbit transfer and electric propulsion for increasing scientific payloads.Cold gas propulsion and microelectric propulsion are good choices for space-based gravitational wave detection due to the capability of variable thrust output at the micro-Newton level.The paper also introduces the sub-1-U micropropulsion modules developed by BICE with satisfactory performance in flight tests,which are promising propulsion systems for small deep space platforms.A small probe with an electric sail propulsion system has been proposed for the future solar system boundary exploration of China.The electric sail serves as not only a propellant-free thruster but also a detector probing the properties of the space medium.
文摘In the mid seventies a new propulsor for aircraft was designed and investigated - the so-called PROPFAN. With regard to the total pressure increase, it ranges between a conventional propeller and a turbofan with very high bypass ratio. This new propulsion system promised a reduction in fuel consumption of 15 to 25% compared to engines at that time.A lot of propfans (Hamilton Standard, USA) with different numbers of blades and blade shapes have been designed and tested in wind tunnels in order to find an optimum in efficiency, Fig.1. Parallel to this development GE, USA, made a design of a counter rotating unducted propfan, the so-called UDF, Fig.2. A prototype engine was manufactured and investigated on an in-flight test bed mounted at the MD82 and the B727. Since that time there has not been any further development of propfans (except AN 70 with NK 90-engine, Ukraine, which is more or less a propeller design) due to relatively low fuel prices and technical obstacles. Only technical programs in different countries are still going on in order to prepare a data base for designing counter rotating fans in terms of aeroacoustics, aerodynamics and aeroelasticities. In DLR, Germany, a lot of experimental and numerical work has been undertaken to understand the physical behaviour of the unsteady flow in a counter rotating fan.
文摘Open-end winding motors are used extensively in ship electric propulsion systems,in which medium-voltage high-power inverters are a critical component.To increase the system voltage and power density,a dual five-level active neutral-point clamped(ANPC)inverter is proposed herein to drive medium-voltage open-end winding motors for ship electric propulsion.Each phase of this inverter comprises two five-level ANPC bridges and all the phases are powered by a common direct-current link.A hybrid modulation method is proposed to control this inverter.The series-connected switches in all the five-level ANPC bridges are operated at the fundamental frequency,and the other switches are controlled with a phase-shifted pulse-width modulation(PWM),which can achieve a natural balance between the neutral-point voltage and flying capacitor voltages in a carrier period.A closed-loop capacitor voltage balancing method based on adjusting the duty ratios of the PWM signals is proposed.The neutral-point voltage and flying capacitor voltages can be controlled independently and balanced without affecting the output phase voltage.Simulation and experimental results are presented to demonstrate the validity of this method.
基金supported by the National Key R&D Program of China(No.2022YFE0204100)the Key Program of University-Enterprise Joint Project of National Natural Science Foundation of China(No.U22B20120).
文摘Currently,iodine-compatible cathodes for iodine propulsion systems that can provide ampere-level electron currents with a reasonable power consumption are lacking.In this study,a conventional LaB_(6)hollow cathode made with iodine-resistant materials was designed and tested in an iodine-compatible vacuum facility.The ignition characteristics,the V-I(Volt-Ampere characteristic)curve,and long steady-state discharge sequence of the iodine hollow cathode were analyzed and compared with those using a krypton propellant.After the experiment,the composition of the cathode emitter was studied by scanning electron microscope and energy-dispersive X-ray spectroscopy(EDS).The results show that ignition takes>10 s to reach a steady state,and the discharge voltage of the iodine was 25-95 V higher than that of krypton.According to the EDS results,this was mainly caused by emitter contamination with iron from the stainless-steel components of the cathode and oxygen from the iodine feed system.The iodine hollow cathode achieved a cumulative 12.5 h stable discharge,with the longest single discharge of 5 h and a 3%change in the inner diameter of the emitter.
基金financial support from the National Key R&D Program of China(No.2022YFE0204100)the National Natural Science Foundation of China(Nos.U23B20152 and 52402479)。
文摘Hall thrusters with large height-radius ratio,owing to their unique advantages in compactness,lightweight,and high performance,have progressively emerged as a preferred choice for diverse space propulsion applications in the future.However,the amplification of the annular effect in structures with a large height-radius ratio poses a practical problem of plume over-focusing,which seriously restricts the further improvement of Hall thruster performance and the extension of its life.In this study,the formation mechanism of over-focused plume is deeply investigated,and it is ascertained that an intensified radial electric field directed towards the inner wall within the channel serves as a key contributing factor.This phenomenon is fundamentally attributed to structural characteristics of large height-radius ratio that induce pronounced inward inclination of field lines within strong magnetic field zone.Based on this,the design concept of focused magnetic field is proposed,wherein straight magnetic field lines are established within the strong magnetic field zone to generate a quasi-axial accelerating electric field.Simultaneously,the symmetrical magnetic field inside the channel ensures ionization concentration near the channel center,thereby achieving optimal matching between the ionization zone and accelerating field.Experimental results demonstrate that employing a focused magnetic field significantly reduces the divergence half-angle of the plume and yields an excellently barrel-shaped focusing plume morphology in HEP-1350PM.Consequently,the total efficiency of the thruster surpasses 60%,while erosion belt on the inner wall is shortened by nearly 50%.These advancements effectively enhance thruster performance and prolong its operational lifespan.This study can not only resolve practical problems associated with plume over-focusing,but also provide a fundamental guiding principle for magnetic field design of Hall thrusters.
