A dynamic marine propeller simulation system was developed, which is utilized for meeting the experimental requirement of theory research and engineering design of marine electric propulsion system. By applying an act...A dynamic marine propeller simulation system was developed, which is utilized for meeting the experimental requirement of theory research and engineering design of marine electric propulsion system. By applying an actual ship parameter and its accurate propeller J＇ -KT＇ and J＇ - Kp＇ curve data, functional experiments based on the simulation system were carried out. The experiment results showed that the system can correctly emulate the propeller characteristics, produce the dynamic and steady performances of the propeller under different navigation modes, and present actual load torque for electric propulsion motor.展开更多
With the development of aviation electrification,higher demands for electrical machines are put forward in aircraft electric propulsion systems.The aircraft electric propulsion requirements and propulsion motor featur...With the development of aviation electrification,higher demands for electrical machines are put forward in aircraft electric propulsion systems.The aircraft electric propulsion requirements and propulsion motor features are analyzed in this paper.Comparing with conventional PM machines,ironless stator axial flux permanent magnet(AFPM)machine topologies with Litz wire windings allow designs with higher compactness,lightness and efficiency,which are suitable for high-frequency and high-power density applications.Based on the motor requirements and constraints of aircraft electric propulsion systems,this paper investigates a high-power 1 MW multi-stack ironless stator AFPM machine,which is composed of four 250kW modular motors by stacking in axial.The design guidelines and special attentions are presented,in term of electromagnetic,thermal,and mechanical performance for the high-frequency coils and Halbach-array PM rotor.Finally,an ironless stator AFPM motor is manufactured,tested and evaluated with the consideration of cost and processing cycle.The results show that the output power is up to 53.8kW with 95%efficiency at 9000r/min at this stage.The proposed ironless stator AFPM machine with oil immersed forced cooling proves to be a favorable candidate for application in electric aircraft as propulsion motors.展开更多
The optimization of the Earth-moon trajectory using solar electric propulsion is presented. A feasible method is proposed to optimize the transfer trajectory starting from a low Earth circular orbit （500 km altitude...The optimization of the Earth-moon trajectory using solar electric propulsion is presented. A feasible method is proposed to optimize the transfer trajectory starting from a low Earth circular orbit （500 km altitude） to a low lunar circular orbit （200 km altitude）. Due to the use of low-thrust solar electric propulsion, the entire transfer trajectory consists of hundreds or even thousands of orbital revolutions around the Earth and the moon. The Earth-orbit ascending （from low Earth orbit to high Earth orbit） and lunar descending （from high lunar orbit to low lunar orbit） trajectories in the presence of J2 perturbations and shadowing effect are computed by an analytic orbital averaging technique. A direct/indirect method is used to optimize the control steering for the trans-lunar trajectory segment, a segment from a high Earth orbit to a high lunar orbit, with a fixed thrust-coast-thrust engine sequence. For the trans-lunar trajectory segment, the equations of motion are expressed in the inertial coordinates about the Earth and the moon using a set of nonsingular equinoctial elements inclusive of the gravitational forces of the sun, the Earth, and the moon. By way of the analytic orbital averaging technique and the direct/indirect method, the Earth-moon transfer problem is converted to a parameter optimization problem, and the entire transfer trajectory is formulated and optimized in the form of a single nonlinear optimization problem with a small number of variables and constraints. Finally, an example of an Earth-moon transfer trajectory using solar electric propulsion is demonstrated.展开更多
To enhance the controllability of stratosphere airship,a vectored electric propulsion system is used.By using the Lagrangian method,a kinetic model of the vectored electric propulsion system is established and validat...To enhance the controllability of stratosphere airship,a vectored electric propulsion system is used.By using the Lagrangian method,a kinetic model of the vectored electric propulsion system is established and validated through ground tests.The fake gyroscopic torque is first proposed,which the vector mechanism should overcome besides the inertial torque and the gravitational torque.The fake gyroscopic torque is caused by the difference between inertial moments about two principal inertial axes of the propeller in the rotating plane,appears only when the propeller is rotating and is proportional with the rotation speed.It is a sinusoidal pulse,with a frequency that is twice of the rotation speed.Considering the fake gyroscope torque pulse and aerodynamic efficiency,three blade propeller is recommended for the vectored propulsion system used for stratosphere airship.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
Electric propulsion is used for all electric propulsion satellites to perform the orbit transfer,attitude control and station-keeping tasks. Generally electric propulsion subsystem contains 4 thrusters. But if one thr...Electric propulsion is used for all electric propulsion satellites to perform the orbit transfer,attitude control and station-keeping tasks. Generally electric propulsion subsystem contains 4 thrusters. But if one thruster fails in the beginning of satellite lifetime,other thrusters will undertake all the firing tasks. The firing time will be 2 to 3 times of thrusters without failure. Thus it may go beyond the allow ed lifetime of thruster. This paper puts forward two thruster redundancy configuration solutions with 6 thrusters to solve this problem. Two layout configurations and their corresponding station-keeping strategies are simulated and compared. The results show that the maximum firing time of both layout configurations can meet the lifetime limitation. This solution is a good reference for all electric propulsion satellites design.展开更多
Atmosphere-Breathing Electric Propulsion(ABEP)can compensate for lost momentum of spacecraft operating in Very Low Earth Orbit(VLEO)which has been widely concerned due to its excellent commercial potential.It is a key...Atmosphere-Breathing Electric Propulsion(ABEP)can compensate for lost momentum of spacecraft operating in Very Low Earth Orbit(VLEO)which has been widely concerned due to its excellent commercial potential.It is a key technology to improve the capture efficiency of intakes,which collect and compress the atmosphere for ABEP.In this paper,the mechanism of the capture section affecting capture efficiency is investigated by Test Particle Monte Carlo(TPMC)simulations with 3D intake models.The inner surface smoothness and average collision number are determined to be key factors affecting capture efficiency,and a negative effect growth model is accordingly established.When the inner surface smoothness is less than 0.2,the highest capture efficiency and its corresponding average collision number interval are independent of the capture section’s geometry and its mesh size.When the inner surface smoothness is higher than 0.2,the capture efficiency will decrease by installing any capture section.Based on the present results,the manufacturing process and material selection are suggested to be prioritized during the intake geometry design in engineering projects.Then,the highest capture efficiency can be achieved by adjusting the length and mesh size of the capture section.展开更多
Plasma discharge stability is an important problem in atmosphere-breathing electric propulsion system when maintaining long-term missions at ultra-low earth orbit.This paper designed an inductively coupled plasma sour...Plasma discharge stability is an important problem in atmosphere-breathing electric propulsion system when maintaining long-term missions at ultra-low earth orbit.This paper designed an inductively coupled plasma source to imitate the ionization section.The effect of inflow rate and Radio Frequency(RF)power on the plasma discharge mode transition is experimentally studied.A discharge mode detection method is proposed,which determines the discharge mode by identifying the morphology of the plasma core.By using the method,the discharge mode transition is quantified and a control model based on the parameter sensitivity is constructed.To verify the method,the spectra are measured and the electron temperature spatial distribution is calculated.And the method has been proven effective.The results show that the inductively coupled discharge contains capacitive components affected by the mass flow rate and the radio frequency power.The plasma characteristics can be maintained stably by controlling the radio frequency power when the mass flow rate randomly changes in a certain range.It is demonstrated that the application of detection method effectively identifies the discharge mode,which is a promising active control method for the plasma discharge mode.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
Aiming to maximize the aerodynamic performance of the Distributed Electric Propulsion(DEP)aircraft,a hybrid design framework which focuses on the aerodynamic performance of the propeller/wing integration has been deve...Aiming to maximize the aerodynamic performance of the Distributed Electric Propulsion(DEP)aircraft,a hybrid design framework which focuses on the aerodynamic performance of the propeller/wing integration has been developed and validated numerically.Variable-fidelity modelling for propeller aerodynamics has been used to achieve computational efficiency with reasonable accuracy.By optimizing the aerodynamic loading distributions on the tractor propeller disk,the induced slipstream is redistributed into a form that is beneficial for the wing downstream,based on which the propeller blade geometry is generated through a rapid inversed design procedure.As compared with the Minimum Induced Loss(MIL)propeller at a specified thrust level,significant improvements of both the lift-to-drag ratio of the wing and the propeller/wing integrated aerodynamic efficiency is achieved,which shows great promise to deliver aerodynamic benefits for the wing within the propeller slipstream without any additional devices.展开更多
The fuel-optimal transfer trajectories using solar electric propulsion are designed considering the power constraints and solar array performance degradation.Three different performance degradation models including li...The fuel-optimal transfer trajectories using solar electric propulsion are designed considering the power constraints and solar array performance degradation.Three different performance degradation models including linear,positive and negative exponential degradations are used in the analysis of three typical rendezvous missions including Apophis,Venus and Ceres,respectively.The optimal control problem is formulated using the calculus of variations and Pontryagin’s maximum principle,which leads to a bang-bang control that is solved by indirect method combined with a homotopic technique.In demonstrating the effects of the power constraints and solar array performance degradation on the power budget and fuel consumption,the time histories of the power profile and the fuel consumptions are compared for the three missions.This study indicates that it is necessary to consider the power constraints and solar array performance degradation for the SEP-based low-thrust trajectory design,espacially for long-duration outbound flights.展开更多
To maximize the power density of the electric propulsion motor in aerospace application,this paper proposes a novel Dynamic Neighborhood Genetic Learning Particle Swarm Optimization(DNGL-PSO)for the motor design,which...To maximize the power density of the electric propulsion motor in aerospace application,this paper proposes a novel Dynamic Neighborhood Genetic Learning Particle Swarm Optimization(DNGL-PSO)for the motor design,which can deal with the insufficient population diversity and non-global optimal solution issues.The DNGL-PSO framework is composed of the dynamic neighborhood module and the particle update module.To improve the population diversity,the dynamic neighborhood strategy is first proposed,which combines the local neighborhood exemplar generation mechanism and the shuffling mechanism.The local neighborhood exemplar generation mechanism enlarges the search range of the algorithm in the solution space,thus obtaining highquality exemplars.Meanwhile,when the global optimal solution cannot update its fitness value,the shuffling mechanism module is triggered to dynamically change the local neighborhood members.The roulette wheel selection operator is introduced into the shuffling mechanism to ensure that particles with larger fitness value are selected with a higher probability and remain in the local neighborhood.Then,the global learning based particle update approach is proposed,which can achieve a good balance between the expansion of the search range in the early stage and the acceleration of local convergence in the later stage.Finally,the optimization design of the electric propulsion motor is conducted to verify the effectiveness of the proposed DNGL-PSO.The simulation results show that the proposed DNGL-PSO has excellent adaptability,optimization efficiency and global optimization capability,while the optimized electric propulsion motor has a high power density of 5.207 kW/kg with the efficiency of 96.12%.展开更多
Distributed electric propulsion(DEP)uses multiple propellers driven by motors distributed along the leading edge of the wing to produce beneficial aerodynamic interactions.However,the wing will be in the sliding flow ...Distributed electric propulsion(DEP)uses multiple propellers driven by motors distributed along the leading edge of the wing to produce beneficial aerodynamic interactions.However,the wing will be in the sliding flow of the propeller and the lift and drag characteristics of the wing will change accordingly.The performance of the propeller will also be affected by the wing in its rear.In this paper,combined with wind tunnel tests,the low Reynolds aerodynamic properties of multiple DEP structures are numerically simulated by solving the Reynolds averaged Navier-Stokes(RANS)equation of multiple reference frames(MRF)or slip grid technology.The results demonstrate that the lift and drag of DEP increase in all cases,with the magnitude depending on the angle of attack(AOA)and the relative positions of propellers and wing.When the AOA is less than 16°(stall AOA),the change of lift is not affected by it.By contrast,when the AOA is greater than 16°the L/D(lift-to-drag ratio)of the DEP system increases significantly.This is because the propeller slipstream delays laminar flow separation and increases the stall AOA.At the same time,the inflow and the downwash effect,which is generated on both sides of the rotating shaft,result in the actual AOA of the wing being greater than the free flow AOA with a fluctuation distribution of the lift coefficient along the span.Also,for the propeller in the DEP,the blocking effect of the wing and the vortex of the trailing edge of the wing result in a significant increase in thrust.展开更多
Purpose-Thruster point assembly mechanism(TPAM)of the electric propulsion system allows to adjust the thrust vector,sothat the thrust vectorisdirectedtothesatellitecenterof gravity(COG)during the satellite on-orbit wo...Purpose-Thruster point assembly mechanism(TPAM)of the electric propulsion system allows to adjust the thrust vector,sothat the thrust vectorisdirectedtothesatellitecenterof gravity(COG)during the satellite on-orbit working period.In this way the impact of disturbance torque caused by deviation of the thrust vector from the satellite COG during thruster ignition can be decreased.Therefore,the control accuracy of satellite is influenced directly by the control accuracy of TPAM.On the other hand,the on-orbit application of TPAM is restricted to the on-orbit computer resource.Therefore,the purpose of this paper is to design a control strategy for TPAM,and the strategy should not only be able to control the TPAM precisely but also be easily implemented by the on-board computer.Design/methodology/approach-First,the structure and work principle of TPAM are discussed,and the mathematical model based on D-H coordinate system is built for it.Then the fitting methods are utilized to design the control strategy of TPAM.Absolute position fitting-based control strategy and relative position fitting-based control strategy are designed,and the least squares algorithm is introduced for parameter selection.Findings-Simulations and tests are provided for the TPAM.Compared with the state-of-the-art PD controller,the proposed control strategy shows smaller overshoot and more simple realization.The experiment results are matched with the simulation results and both the experiment and simulation results show the validity of the proposed control strategies.Practical implications-The designed control strategies can be used for the TPAM of some satellite’s electric propulsion system.Originality/value-The mathematical model of the TPAM based on D-H coordinate system is given.The absolute position fitting-based control strategy and relative position fitting-based control strategy are proposed.Compared with existing methods,the two control strategies have more simple structure and smaller amount of computations.Furthermore,the relative position fitting-based control strategy achieves high precision with simple structure.展开更多
Combined power plant is widely used in large or medium surface vessel for its predominant performance. It is important to research on using combined power plant as electrical propulsion prime mover for developing the ...Combined power plant is widely used in large or medium surface vessel for its predominant performance. It is important to research on using combined power plant as electrical propulsion prime mover for developing the electric propulsion warship.This paper, designs a multi-module experiment-rig and introduces its composition, working principle and disposition scheme,and carried out the dynamic characteristic experiment of the GTD350 gas turbine.展开更多
The common propellants used for electric thrusters, such as xenon and krypton, are rare, expensive,and difficult to acquire. Solid iodine attracts much attention with the advantages of low cost,extensive availability,...The common propellants used for electric thrusters, such as xenon and krypton, are rare, expensive,and difficult to acquire. Solid iodine attracts much attention with the advantages of low cost,extensive availability, low vapor pressure, and ionization potential. The performance of a lowpower iodine-fed Hall thruster matched with a xenon-fed cathode is investigated across a broad range of operation conditions. Regulation of the iodine vapor's mass flow rates is stably achieved by using a temperature control method of the iodine reservoir. The thrust measurements are finished utilizing a thrust target during the tests. Results show that thrust and anode-specific impulse increase approximately linearly with the increasing iodine mass flow rate.At the nominal power of 200 W class, iodine mass flow rates are 0.62 and 0.93 mg/s, thrusts are7.19 and 7.58 m N, anode specific impulses are 1184 and 826 s, anode efficiencies are 20.8%and 14.5%, and thrust to power ratios are 35.9 and 37.9 m N/k W under the conditions of 250 V,0.8 A and 200 V, 1.0 A, respectively. The operating characteristics of iodine-fed Hall thruster are analyzed in different states. Further work on the measurements of plasma characteristics and experimental optimization will be carried out.展开更多
The Ultrasonic Electric Propulsion(UEP)system is a cutting-edge propulsion technology that is mostly used on platforms for small satellites(less than 10 kg).The characteristics of droplet partial emissions(DPEs)in the...The Ultrasonic Electric Propulsion(UEP)system is a cutting-edge propulsion technology that is mostly used on platforms for small satellites(less than 10 kg).The characteristics of droplet partial emissions(DPEs)in the UEP system are investigated using a high-speed imaging technique(an ultra-high speed camera(NAC HX-6)and a long-distance microscope)in this work.The experiments demonstrate that there are a few partial emission modes,including left-side emission,double-side emission,and right-side emission,that are present in the droplet emission process of the UEP system.These modes are primarily caused by the partial formation of capillary standing waves(CSWs)on the emission surface of the ultrasonic nozzle.The emission rate for single-and double-sided emissions varies at different times,indicating that there are different CSWs engaged in droplet emission due to variations in the liquid film thickness and charge state of the liquid cones.Additionally,as the droplets emit continuously,a raised area on the emission surface appears,with several droplets emitting there as a result of charge accumulation.Additionally,photos of the CSWs with emitting droplets are obtained,which highlights the CSWs'distinctive wave morphology.展开更多
The bipolar ionic liquid thruster employs ionic liquid as a propellant to discharge positively and negatively charged high-energy particles under an alternating current(AC)power source,effectively suppressing electroc...The bipolar ionic liquid thruster employs ionic liquid as a propellant to discharge positively and negatively charged high-energy particles under an alternating current(AC)power source,effectively suppressing electrochemical reaction and ensuring charge neutrality.Determining an optimal AC supply power source frequency is critical for sustained stable thruster operation.This study focuses on the emission characteristics of the ionic liquid thruster under varied AC conditions.The AC power supply was set within the frequency range of 0.5-64 Hz,with eight specific frequency conditions selected for experimentation.The experimental results indicate that the thruster operates steadily within a voltage range of±1470 to±1920 V,with corresponding positive polarity current ranging from 0.41 to 4.91μA and negative polarity current ranging from−0.49 to−4.10μA.During voltage polarity switching,an emission delay occurs,manifested as a prominent peak signal caused by circuit capacitance characteristics and a minor peak signal resulting from liquid droplets.Extended emission test was conducted at 16 Hz,demonstrating approximately 1 h and 50 min of consistent emission before intermittent discharge.These findings underscore the favorable impact of AC conditions within the 8-16 Hz range on the self-neutralization capability of the ionic liquid thruster.展开更多
Environmental issues associated with the aviation industry are getting more attention as air traffic increases.Stringent standards are imposed for fuel consumption and pollution emissions for next-generation aircraft....Environmental issues associated with the aviation industry are getting more attention as air traffic increases.Stringent standards are imposed for fuel consumption and pollution emissions for next-generation aircraft.Superconducting electrical propulsion aircraft(SEPA)have been seen as an efficient way to achieve this goal.High-temperature superconducting(HTS)devices are extensively used in the power system to supply enormous energy.Power is distributed to the different loads via a DC distribution network.However,it will generate an inrush current over ten times higher than the rated current in short-circuit state,which is very harmful to the system.Therefore,it is essential to adopt an appropriate protection scheme.This paper discusses one protection scheme that combines DC vacuum circuit breakers(DC VCB)and resistive superconducting current limiters(RSFCL)for superconducting aircraft applications.Considering problems of cost and loss,the auxiliary capacitor is pre-charged by system voltage,and mechanical elements extinguish the arc.Furthermore,combined with RSFCL,the interrupting environment is fully improved.RSFCL limits fault current,and then the VCB breaks this limited current based on creating an artificial current zero(ACZ).The prospective rated power is 8MW,rated voltage and current are 4 kV and 1 kA,respectively.In this paper,we discuss and simulate switching devices that protect SEPA.The interrupting performance of the circuit breaker is analysed in the DC short-circuit fault that occurs on the transmission line.Finally,the residual energy consumption of different situations is calculated.A comparison is made between using RSFCL with metal oxide varistor(MOV)and just using MOV.The scheme with RSFCL shows a significant advantage in energy consumption.展开更多
The brushless DC motor can be used in the marine electric propulsion system for its excellent control characteristics and large thrust. In order to estimate the operating performances of the brushless DC motor for the...The brushless DC motor can be used in the marine electric propulsion system for its excellent control characteristics and large thrust. In order to estimate the operating performances of the brushless DC motor for the high-power shipping during the design stage, the steady-state analysis is as important as the dynamic analysis generally. A mathematical model of the brushless DC propulsion motor is established according to the state-space method for the dynamic and steady-state performance analysis. The state-space mathematical model is a set of linear differential equations, so the steady-state currents of the armature windings can be gained directly by the symmetrical boundary conditions and the eigenvalues of the system matrix. The steady-state simulation results are compared with the dynamic ones to validate the correctness of this eigenvector method.展开更多
基金supported by the Fund of Shanghai Committee of Science and Technology(Grant No.11170501700)the International Cooperation and Exchange Projects of the Ministry of Science and Technology(Grant No.2012DFG71850)
文摘A dynamic marine propeller simulation system was developed, which is utilized for meeting the experimental requirement of theory research and engineering design of marine electric propulsion system. By applying an actual ship parameter and its accurate propeller J＇ -KT＇ and J＇ - Kp＇ curve data, functional experiments based on the simulation system were carried out. The experiment results showed that the system can correctly emulate the propeller characteristics, produce the dynamic and steady performances of the propeller under different navigation modes, and present actual load torque for electric propulsion motor.
基金This work was supported in part by National Natural Science Foundation for Excellent Young Scholar of China under Award 51622704,in part by Jiangsu provincial key research and development project under Award BE2017160。
文摘With the development of aviation electrification,higher demands for electrical machines are put forward in aircraft electric propulsion systems.The aircraft electric propulsion requirements and propulsion motor features are analyzed in this paper.Comparing with conventional PM machines,ironless stator axial flux permanent magnet(AFPM)machine topologies with Litz wire windings allow designs with higher compactness,lightness and efficiency,which are suitable for high-frequency and high-power density applications.Based on the motor requirements and constraints of aircraft electric propulsion systems,this paper investigates a high-power 1 MW multi-stack ironless stator AFPM machine,which is composed of four 250kW modular motors by stacking in axial.The design guidelines and special attentions are presented,in term of electromagnetic,thermal,and mechanical performance for the high-frequency coils and Halbach-array PM rotor.Finally,an ironless stator AFPM motor is manufactured,tested and evaluated with the consideration of cost and processing cycle.The results show that the output power is up to 53.8kW with 95%efficiency at 9000r/min at this stage.The proposed ironless stator AFPM machine with oil immersed forced cooling proves to be a favorable candidate for application in electric aircraft as propulsion motors.
基金National Natural Science Foundation of China (10603005)
文摘The optimization of the Earth-moon trajectory using solar electric propulsion is presented. A feasible method is proposed to optimize the transfer trajectory starting from a low Earth circular orbit （500 km altitude） to a low lunar circular orbit （200 km altitude）. Due to the use of low-thrust solar electric propulsion, the entire transfer trajectory consists of hundreds or even thousands of orbital revolutions around the Earth and the moon. The Earth-orbit ascending （from low Earth orbit to high Earth orbit） and lunar descending （from high lunar orbit to low lunar orbit） trajectories in the presence of J2 perturbations and shadowing effect are computed by an analytic orbital averaging technique. A direct/indirect method is used to optimize the control steering for the trans-lunar trajectory segment, a segment from a high Earth orbit to a high lunar orbit, with a fixed thrust-coast-thrust engine sequence. For the trans-lunar trajectory segment, the equations of motion are expressed in the inertial coordinates about the Earth and the moon using a set of nonsingular equinoctial elements inclusive of the gravitational forces of the sun, the Earth, and the moon. By way of the analytic orbital averaging technique and the direct/indirect method, the Earth-moon transfer problem is converted to a parameter optimization problem, and the entire transfer trajectory is formulated and optimized in the form of a single nonlinear optimization problem with a small number of variables and constraints. Finally, an example of an Earth-moon transfer trajectory using solar electric propulsion is demonstrated.
文摘To enhance the controllability of stratosphere airship,a vectored electric propulsion system is used.By using the Lagrangian method,a kinetic model of the vectored electric propulsion system is established and validated through ground tests.The fake gyroscopic torque is first proposed,which the vector mechanism should overcome besides the inertial torque and the gravitational torque.The fake gyroscopic torque is caused by the difference between inertial moments about two principal inertial axes of the propeller in the rotating plane,appears only when the propeller is rotating and is proportional with the rotation speed.It is a sinusoidal pulse,with a frequency that is twice of the rotation speed.Considering the fake gyroscope torque pulse and aerodynamic efficiency,three blade propeller is recommended for the vectored propulsion system used for stratosphere airship.
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.
文摘Electric propulsion is used for all electric propulsion satellites to perform the orbit transfer,attitude control and station-keeping tasks. Generally electric propulsion subsystem contains 4 thrusters. But if one thruster fails in the beginning of satellite lifetime,other thrusters will undertake all the firing tasks. The firing time will be 2 to 3 times of thrusters without failure. Thus it may go beyond the allow ed lifetime of thruster. This paper puts forward two thruster redundancy configuration solutions with 6 thrusters to solve this problem. Two layout configurations and their corresponding station-keeping strategies are simulated and compared. The results show that the maximum firing time of both layout configurations can meet the lifetime limitation. This solution is a good reference for all electric propulsion satellites design.
基金the auspices of National Key R&D Program of China(No.2020YFC2201100)the National Natural Science Foundation of China(No.52077169)+1 种基金the State Key Laboratory of Electrical Insulation and Power Equipment,China(No.EIPE22116)HPC Platform,Xi’an Jiaotong University,China。
文摘Atmosphere-Breathing Electric Propulsion(ABEP)can compensate for lost momentum of spacecraft operating in Very Low Earth Orbit(VLEO)which has been widely concerned due to its excellent commercial potential.It is a key technology to improve the capture efficiency of intakes,which collect and compress the atmosphere for ABEP.In this paper,the mechanism of the capture section affecting capture efficiency is investigated by Test Particle Monte Carlo(TPMC)simulations with 3D intake models.The inner surface smoothness and average collision number are determined to be key factors affecting capture efficiency,and a negative effect growth model is accordingly established.When the inner surface smoothness is less than 0.2,the highest capture efficiency and its corresponding average collision number interval are independent of the capture section’s geometry and its mesh size.When the inner surface smoothness is higher than 0.2,the capture efficiency will decrease by installing any capture section.Based on the present results,the manufacturing process and material selection are suggested to be prioritized during the intake geometry design in engineering projects.Then,the highest capture efficiency can be achieved by adjusting the length and mesh size of the capture section.
基金This study was funded by the National Natural Science Foundation of China(No.T2221002)the Hunan Provincial Natural Science Foundation,China(No.2024JJ5405).
文摘Plasma discharge stability is an important problem in atmosphere-breathing electric propulsion system when maintaining long-term missions at ultra-low earth orbit.This paper designed an inductively coupled plasma source to imitate the ionization section.The effect of inflow rate and Radio Frequency(RF)power on the plasma discharge mode transition is experimentally studied.A discharge mode detection method is proposed,which determines the discharge mode by identifying the morphology of the plasma core.By using the method,the discharge mode transition is quantified and a control model based on the parameter sensitivity is constructed.To verify the method,the spectra are measured and the electron temperature spatial distribution is calculated.And the method has been proven effective.The results show that the inductively coupled discharge contains capacitive components affected by the mass flow rate and the radio frequency power.The plasma characteristics can be maintained stably by controlling the radio frequency power when the mass flow rate randomly changes in a certain range.It is demonstrated that the application of detection method effectively identifies the discharge mode,which is a promising active control method for the plasma discharge mode.
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supported by the Key Research and Development Program of Shaanxi Province of China(No.2018ZDCXL-GY-03-04)。
文摘Aiming to maximize the aerodynamic performance of the Distributed Electric Propulsion(DEP)aircraft,a hybrid design framework which focuses on the aerodynamic performance of the propeller/wing integration has been developed and validated numerically.Variable-fidelity modelling for propeller aerodynamics has been used to achieve computational efficiency with reasonable accuracy.By optimizing the aerodynamic loading distributions on the tractor propeller disk,the induced slipstream is redistributed into a form that is beneficial for the wing downstream,based on which the propeller blade geometry is generated through a rapid inversed design procedure.As compared with the Minimum Induced Loss(MIL)propeller at a specified thrust level,significant improvements of both the lift-to-drag ratio of the wing and the propeller/wing integrated aerodynamic efficiency is achieved,which shows great promise to deliver aerodynamic benefits for the wing within the propeller slipstream without any additional devices.
基金supported by National Basic Research Program of China (Grant No. 2012CB720000)the Fund of Science and Technology on Aerospace Flight Dynamic Laboratory (Grant No. 2012AFDL006)
文摘The fuel-optimal transfer trajectories using solar electric propulsion are designed considering the power constraints and solar array performance degradation.Three different performance degradation models including linear,positive and negative exponential degradations are used in the analysis of three typical rendezvous missions including Apophis,Venus and Ceres,respectively.The optimal control problem is formulated using the calculus of variations and Pontryagin’s maximum principle,which leads to a bang-bang control that is solved by indirect method combined with a homotopic technique.In demonstrating the effects of the power constraints and solar array performance degradation on the power budget and fuel consumption,the time histories of the power profile and the fuel consumptions are compared for the three missions.This study indicates that it is necessary to consider the power constraints and solar array performance degradation for the SEP-based low-thrust trajectory design,espacially for long-duration outbound flights.
基金supported by the National Natural Science Foundation of China(No.:52177028)Aeronautical Science Foundation of China(No.201907051002)+1 种基金the Fundamental Research Funds for the Central Universities,China(No.YWF21BJJ522)the Major Program of the National Natural Science Foundation of China(No.51890882).
文摘To maximize the power density of the electric propulsion motor in aerospace application,this paper proposes a novel Dynamic Neighborhood Genetic Learning Particle Swarm Optimization(DNGL-PSO)for the motor design,which can deal with the insufficient population diversity and non-global optimal solution issues.The DNGL-PSO framework is composed of the dynamic neighborhood module and the particle update module.To improve the population diversity,the dynamic neighborhood strategy is first proposed,which combines the local neighborhood exemplar generation mechanism and the shuffling mechanism.The local neighborhood exemplar generation mechanism enlarges the search range of the algorithm in the solution space,thus obtaining highquality exemplars.Meanwhile,when the global optimal solution cannot update its fitness value,the shuffling mechanism module is triggered to dynamically change the local neighborhood members.The roulette wheel selection operator is introduced into the shuffling mechanism to ensure that particles with larger fitness value are selected with a higher probability and remain in the local neighborhood.Then,the global learning based particle update approach is proposed,which can achieve a good balance between the expansion of the search range in the early stage and the acceleration of local convergence in the later stage.Finally,the optimization design of the electric propulsion motor is conducted to verify the effectiveness of the proposed DNGL-PSO.The simulation results show that the proposed DNGL-PSO has excellent adaptability,optimization efficiency and global optimization capability,while the optimized electric propulsion motor has a high power density of 5.207 kW/kg with the efficiency of 96.12%.
基金This work is supported by the National Natural Science Foundation of China(No.51505087)the Fujian Provincial Industrial Robot Basic Components Technology Research and Development Center(No.2014H2004),China.
文摘Distributed electric propulsion(DEP)uses multiple propellers driven by motors distributed along the leading edge of the wing to produce beneficial aerodynamic interactions.However,the wing will be in the sliding flow of the propeller and the lift and drag characteristics of the wing will change accordingly.The performance of the propeller will also be affected by the wing in its rear.In this paper,combined with wind tunnel tests,the low Reynolds aerodynamic properties of multiple DEP structures are numerically simulated by solving the Reynolds averaged Navier-Stokes(RANS)equation of multiple reference frames(MRF)or slip grid technology.The results demonstrate that the lift and drag of DEP increase in all cases,with the magnitude depending on the angle of attack(AOA)and the relative positions of propellers and wing.When the AOA is less than 16°(stall AOA),the change of lift is not affected by it.By contrast,when the AOA is greater than 16°the L/D(lift-to-drag ratio)of the DEP system increases significantly.This is because the propeller slipstream delays laminar flow separation and increases the stall AOA.At the same time,the inflow and the downwash effect,which is generated on both sides of the rotating shaft,result in the actual AOA of the wing being greater than the free flow AOA with a fluctuation distribution of the lift coefficient along the span.Also,for the propeller in the DEP,the blocking effect of the wing and the vortex of the trailing edge of the wing result in a significant increase in thrust.
文摘Purpose-Thruster point assembly mechanism(TPAM)of the electric propulsion system allows to adjust the thrust vector,sothat the thrust vectorisdirectedtothesatellitecenterof gravity(COG)during the satellite on-orbit working period.In this way the impact of disturbance torque caused by deviation of the thrust vector from the satellite COG during thruster ignition can be decreased.Therefore,the control accuracy of satellite is influenced directly by the control accuracy of TPAM.On the other hand,the on-orbit application of TPAM is restricted to the on-orbit computer resource.Therefore,the purpose of this paper is to design a control strategy for TPAM,and the strategy should not only be able to control the TPAM precisely but also be easily implemented by the on-board computer.Design/methodology/approach-First,the structure and work principle of TPAM are discussed,and the mathematical model based on D-H coordinate system is built for it.Then the fitting methods are utilized to design the control strategy of TPAM.Absolute position fitting-based control strategy and relative position fitting-based control strategy are designed,and the least squares algorithm is introduced for parameter selection.Findings-Simulations and tests are provided for the TPAM.Compared with the state-of-the-art PD controller,the proposed control strategy shows smaller overshoot and more simple realization.The experiment results are matched with the simulation results and both the experiment and simulation results show the validity of the proposed control strategies.Practical implications-The designed control strategies can be used for the TPAM of some satellite’s electric propulsion system.Originality/value-The mathematical model of the TPAM based on D-H coordinate system is given.The absolute position fitting-based control strategy and relative position fitting-based control strategy are proposed.Compared with existing methods,the two control strategies have more simple structure and smaller amount of computations.Furthermore,the relative position fitting-based control strategy achieves high precision with simple structure.
文摘Combined power plant is widely used in large or medium surface vessel for its predominant performance. It is important to research on using combined power plant as electrical propulsion prime mover for developing the electric propulsion warship.This paper, designs a multi-module experiment-rig and introduces its composition, working principle and disposition scheme,and carried out the dynamic characteristic experiment of the GTD350 gas turbine.
基金supported by Joint Fund for Equipment Preresearch and Aerospace Science and Technology (No. 6141B061203)。
文摘The common propellants used for electric thrusters, such as xenon and krypton, are rare, expensive,and difficult to acquire. Solid iodine attracts much attention with the advantages of low cost,extensive availability, low vapor pressure, and ionization potential. The performance of a lowpower iodine-fed Hall thruster matched with a xenon-fed cathode is investigated across a broad range of operation conditions. Regulation of the iodine vapor's mass flow rates is stably achieved by using a temperature control method of the iodine reservoir. The thrust measurements are finished utilizing a thrust target during the tests. Results show that thrust and anode-specific impulse increase approximately linearly with the increasing iodine mass flow rate.At the nominal power of 200 W class, iodine mass flow rates are 0.62 and 0.93 mg/s, thrusts are7.19 and 7.58 m N, anode specific impulses are 1184 and 826 s, anode efficiencies are 20.8%and 14.5%, and thrust to power ratios are 35.9 and 37.9 m N/k W under the conditions of 250 V,0.8 A and 200 V, 1.0 A, respectively. The operating characteristics of iodine-fed Hall thruster are analyzed in different states. Further work on the measurements of plasma characteristics and experimental optimization will be carried out.
基金supported by National Natural Science Foundation of China(No.12102099)the National Key R&D Program of China(No.2021YFC2202700)the Outstanding Academic Leader Project of Shanghai(Youth)(No.23XD1421700),respectively。
文摘The Ultrasonic Electric Propulsion(UEP)system is a cutting-edge propulsion technology that is mostly used on platforms for small satellites(less than 10 kg).The characteristics of droplet partial emissions(DPEs)in the UEP system are investigated using a high-speed imaging technique(an ultra-high speed camera(NAC HX-6)and a long-distance microscope)in this work.The experiments demonstrate that there are a few partial emission modes,including left-side emission,double-side emission,and right-side emission,that are present in the droplet emission process of the UEP system.These modes are primarily caused by the partial formation of capillary standing waves(CSWs)on the emission surface of the ultrasonic nozzle.The emission rate for single-and double-sided emissions varies at different times,indicating that there are different CSWs engaged in droplet emission due to variations in the liquid film thickness and charge state of the liquid cones.Additionally,as the droplets emit continuously,a raised area on the emission surface appears,with several droplets emitting there as a result of charge accumulation.Additionally,photos of the CSWs with emitting droplets are obtained,which highlights the CSWs'distinctive wave morphology.
基金co-supported by the National Key R&D Program of China(No.2020YFC2201001)the Shenzhen Science and Technology Program(No.20210623091808026).
文摘The bipolar ionic liquid thruster employs ionic liquid as a propellant to discharge positively and negatively charged high-energy particles under an alternating current(AC)power source,effectively suppressing electrochemical reaction and ensuring charge neutrality.Determining an optimal AC supply power source frequency is critical for sustained stable thruster operation.This study focuses on the emission characteristics of the ionic liquid thruster under varied AC conditions.The AC power supply was set within the frequency range of 0.5-64 Hz,with eight specific frequency conditions selected for experimentation.The experimental results indicate that the thruster operates steadily within a voltage range of±1470 to±1920 V,with corresponding positive polarity current ranging from 0.41 to 4.91μA and negative polarity current ranging from−0.49 to−4.10μA.During voltage polarity switching,an emission delay occurs,manifested as a prominent peak signal caused by circuit capacitance characteristics and a minor peak signal resulting from liquid droplets.Extended emission test was conducted at 16 Hz,demonstrating approximately 1 h and 50 min of consistent emission before intermittent discharge.These findings underscore the favorable impact of AC conditions within the 8-16 Hz range on the self-neutralization capability of the ionic liquid thruster.
基金supported by the 2022 Open funding of the State Key Laboratory of Electrical Insulation and Power Equipment(EIPE22211)the National Natural Science Foundation of China,“Research Fund for International Young Scientist(RFIS-1)”,Project:52150410419the 2021 Jiangsu“Shuang-Chuang Doctor(Mass Innovation and Entrepreneurship)Talent Program”,Fund:JSSCBS20211187.
文摘Environmental issues associated with the aviation industry are getting more attention as air traffic increases.Stringent standards are imposed for fuel consumption and pollution emissions for next-generation aircraft.Superconducting electrical propulsion aircraft(SEPA)have been seen as an efficient way to achieve this goal.High-temperature superconducting(HTS)devices are extensively used in the power system to supply enormous energy.Power is distributed to the different loads via a DC distribution network.However,it will generate an inrush current over ten times higher than the rated current in short-circuit state,which is very harmful to the system.Therefore,it is essential to adopt an appropriate protection scheme.This paper discusses one protection scheme that combines DC vacuum circuit breakers(DC VCB)and resistive superconducting current limiters(RSFCL)for superconducting aircraft applications.Considering problems of cost and loss,the auxiliary capacitor is pre-charged by system voltage,and mechanical elements extinguish the arc.Furthermore,combined with RSFCL,the interrupting environment is fully improved.RSFCL limits fault current,and then the VCB breaks this limited current based on creating an artificial current zero(ACZ).The prospective rated power is 8MW,rated voltage and current are 4 kV and 1 kA,respectively.In this paper,we discuss and simulate switching devices that protect SEPA.The interrupting performance of the circuit breaker is analysed in the DC short-circuit fault that occurs on the transmission line.Finally,the residual energy consumption of different situations is calculated.A comparison is made between using RSFCL with metal oxide varistor(MOV)and just using MOV.The scheme with RSFCL shows a significant advantage in energy consumption.
文摘The brushless DC motor can be used in the marine electric propulsion system for its excellent control characteristics and large thrust. In order to estimate the operating performances of the brushless DC motor for the high-power shipping during the design stage, the steady-state analysis is as important as the dynamic analysis generally. A mathematical model of the brushless DC propulsion motor is established according to the state-space method for the dynamic and steady-state performance analysis. The state-space mathematical model is a set of linear differential equations, so the steady-state currents of the armature windings can be gained directly by the symmetrical boundary conditions and the eigenvalues of the system matrix. The steady-state simulation results are compared with the dynamic ones to validate the correctness of this eigenvector method.
