The performance of a water jet propulsion system is related to the inlet duct,rotor,stator,and nozzle.Generally,the flow inlet design must fit the bottom line of the hull,and the design of the inlet duct is often limi...The performance of a water jet propulsion system is related to the inlet duct,rotor,stator,and nozzle.Generally,the flow inlet design must fit the bottom line of the hull,and the design of the inlet duct is often limited by stern space.The entire section,from the rotor to the nozzle through the stator,must be designed based on system integration in that the individual performance of these three components will influence each other.Particularly,the section from the rotor to the nozzle significantly impacts the performance of a water jet propulsion system.This study focused on nozzle design and established referable analysis results to facilitate subsequent integrated studies on the design parameters regarding nozzle contour.Most existing studies concentrate on discussions on rotor design and the tip leakage flow of rotors or have replaced the existing complex computational domain with a simple flow field.However,research has yet to implement an integrated,optimal design of the section from the rotor to the nozzle.Given the above,our program conducted preliminary research on this system integration design issue,discussed the optimal nozzle for this section in-depth,and proposed design suggestions based on the findings.This program used an existing model as the design case.This study referred to the actual trial data as the design conditions for the proposed model.Unlike prior references’simple flow field form,this study added a jet ski geometry and free surface to the computational domain.After the linear hull shape was considered,the inflow in the inlet duct would be closer to the actual condition.Based on the numerical calculation result,this study recommends that the optimal nozzle outlet area should be 37%of the inlet area and that the nozzle contour should be linear.Furthermore,for the pump head,static pressure had a more significant impact than dynamic pressure.展开更多
Flight vehicle conceptual design appears to be a promising area for application of the Genetic Algorithm （GA） as an approach to help to automate part of the design process. This computational research effort strives...Flight vehicle conceptual design appears to be a promising area for application of the Genetic Algorithm （GA） as an approach to help to automate part of the design process. This computational research effort strives to develop a propulsion system design strategy for liquid rocket to optimize take-off mass, satisfying the mission range under the constraint of axial overload. The method by which this process is accomplished by using GA as optimizer is outlined in this paper. Convergence of GA is improved by introducing initial population based on Design of Experiments Technique.展开更多
The hydrodynamic performance of a hybrid CRP pod propulsion system was studied by RANS method with SST k ？？ turbulence model and sliding mesh. The effect of axial spacing on the hydrodynamic performance of the hybri...The hydrodynamic performance of a hybrid CRP pod propulsion system was studied by RANS method with SST k ？？ turbulence model and sliding mesh. The effect of axial spacing on the hydrodynamic performance of the hybrid CRP pod propulsion system was investigated numerically and experimentally. It shows that RANS with the sliding mesh method and SST k -ω turbulence model predicts accurately the hydrodynamic performance of the hybrid CRP pod propulsion system. The axial spacing has little influence on the hydrodynamic performance of the forward propeller, but great influence on that of the pod unit. Thrust coefficient of the pod unit declines with the increase of the axial spacing, but the trend becomes weaker, and the decreasing amplitude at the lower advance coefficient is larger than that at the higher advance coefficient. The thrust coefficient and open water efficiency of the hybrid CRP pod propulsion system decrease with the increase of the axial spacing, while the torque coefficient keeps almost constant. On this basis, the design principle of axial spacing of the hybrid CRP pod propulsion system was proposed.展开更多
A marine propulsion system is a very complicated system composed of many mechanical components.As a result,the vibration signal of a gearbox in the system is strongly coupled with the vibration signatures of other com...A marine propulsion system is a very complicated system composed of many mechanical components.As a result,the vibration signal of a gearbox in the system is strongly coupled with the vibration signatures of other components including a diesel engine and main shaft.It is therefore imperative to assess the coupling effect on diagnostic reliability in the process of gear fault diagnosis.For this reason,a fault detection and diagnosis method based on bispectrum analysis and artificial neural networks (ANNs) was proposed for the gearbox with consideration given to the impact of the other components in marine propulsion systems.To monitor the gear conditions,the bispectrum analysis was first employed to detect gear faults.The amplitude-frequency plots containing gear characteristic signals were then attained based on the bispectrum technique,which could be regarded as an index actualizing forepart gear faults diagnosis.Both the back propagation neural network (BPNN) and the radial-basis function neural network (RBFNN) were applied to identify the states of the gearbox.The numeric and experimental test results show the bispectral patterns of varying gear fault severities are different so that distinct fault features of the vibrant signal of a marine gearbox can be extracted effectively using the bispectrum,and the ANN classification method has achieved high detection accuracy.Hence,the proposed diagnostic techniques have the capability of diagnosing marine gear faults in the earlier phases,and thus have application importance.展开更多
A new marine propulsion system is proposed . A small liquid sodium cooled reactor acts as prime mover; alkali-metal thermal-to-electric conversion ( AMTEC) cells are employed to convert the heat energy to electricity;...A new marine propulsion system is proposed . A small liquid sodium cooled reactor acts as prime mover; alkali-metal thermal-to-electric conversion ( AMTEC) cells are employed to convert the heat energy to electricity; superconducting magneto-hydrodynamic thruster combined with spray-water thruster works as pr opulsion. The configuration and characteristics of this system are described. Such a nuclear-powered propulsion system is not only free of noise, but also has high reliability and efficiency. It would be a preferable propulsion system for ships in the future.展开更多
Fault diagnosis of liquid rocket propulsion systems （LRPSs） is a very important issue in space launch activities particularly when manned space missions are accompanied, since the safety and reliability can be signi...Fault diagnosis of liquid rocket propulsion systems （LRPSs） is a very important issue in space launch activities particularly when manned space missions are accompanied, since the safety and reliability can be significantly enhanced by exploiting an efficient fault diagnosis system. Currently, inverse problem-based diagnosis has attracted a great deal of research attention in fault diagnosis domain. This methodology provides a new strategy to model-based fault diagnosis for monitoring the health of propulsion systems. To solve the inverse problems arising from the fault diagnosis of LRPSs, GAs have been adopted in recent years as the first and effective choice of available numerical optimization tools. However, the GA has many control parameters to be chosen in advance and there still lack sound theoretical tools to analyze the effects of these parameters on diagnostic performance analytically. In this paper a comparative study of the influence of GA parameters on diagnostic results is conducted by performing a series of numerical experiments. The objective of this study is to investigate the contribution of individual algorithm parameter to final diagnostic result and provide reasonable estimates for choosing GA parameters in the inverse problem-based fault diagnosis of LRPSs. Some constructive remarks are made in conclusion and will be helpful for the implementation of GA to the fault diagnosis practice of LRPSs in the future.展开更多
To lower the difficulty of fault protection,a doubly-fed induction machine based shipboard propulsion system(DFIM-SPS)that is partially power decoupled is presented.In such an intrinsically safe SPS architecture,a syn...To lower the difficulty of fault protection,a doubly-fed induction machine based shipboard propulsion system(DFIM-SPS)that is partially power decoupled is presented.In such an intrinsically safe SPS architecture,a synchronous generator(SG)is employed for power generation,and the accuracy of the parameters of power generation unit(PGU)plays an important role in SPS stable operation.In this paper,the PGU parameter deviations are studied to evaluate the effects on system performance.The models of salient-pole SG,type DC1A excitation system(EXS)and DFIM are illustrated first.Besides,the corresponding control scheme is explained.For the 16 important parameters of PGU,up to 40%of parameter deviations are applied to implement parameter sensitivity analysis.Then,simulation studies are carried out to evaluate the parameter deviation effects on system performance in detail.By defining three parameter deviation effect indicators(PDEIs),the effects on the PGU output variables,which are the terminal voltage and output active power,are studied.Moreover,the increasing rates of PDEIs with different degrees of parameter deviations for the key parameters are analyzed.Furthermore,the overall system performance is investigated for the two most influential PGU parameters.This paper provides some vital clues on SG and EXS parameter identification for DFIM-SPS.展开更多
As the development tends towards high-speed, large-scale and high-power, power of the ship main engine becomes larger and larger. This make the engine design and cabin arrangement become more and more difficult. Ship ...As the development tends towards high-speed, large-scale and high-power, power of the ship main engine becomes larger and larger. This make the engine design and cabin arrangement become more and more difficult. Ship maneuverability becomes bad. A new ship propulsion system, integrated hydraulic propulsion （IHP）, is put forward to meet the development of modem ship. Principle of IHP system is discussed. Working condition matching characteristic of IHP ship is studied based on its matching characteristic charts. According to their propulsion principle, dynamic mathematic models of IHP ship and direct propulsion （DP） ship are developed. These two models are verified by test sailing and test stand data. Based on the software Matlab/Simulink, comparison research between IHP ship and DP ship is conducted. The results show that cabin arrangement of IHP ship is very flexible, working condition matching characteristic of IHP ship is good, the ratio of power to weight of IHP ship is larger than DP ship, and maneuverability is excellent. IHP system is suitable for engineering ship, superpower ship and warship, etc.展开更多
Modern satellite propulsion systems are generally designed to fulfill multiphase-missions.Traditional reliability modelling methods have problems of inadequate depict capacity considering complex systems such as satel...Modern satellite propulsion systems are generally designed to fulfill multiphase-missions.Traditional reliability modelling methods have problems of inadequate depict capacity considering complex systems such as satellite propulsion system.An extended object-oriented Petri net(EOOPN)method was proposed to facilitate the reliability modelling of satellite propulsion system in the paper.The proposed method was specified for modelling of phased mission system,and it could be implemented by generating combination of Petri net(PN)principles and object-oriented(OO)programming.The effectiveness of the proposed method was demonstrated through the reliability modelling of a satellite propulsion system with EOOPN.The major advantage of the proposed method is that the dimension of net model can be reduced significantly,and phased mission system at system,phase,or component levels can be respectively depicted.Furthermore,the state-space explosion problem is solved by the proposed EOOPN model efficiently.展开更多
The paper presents a technical solution which provides energy saving at full speed, as well as duplication of screw propeller and main propulsion system incase it＇s out of order. The description of the corresponding ...The paper presents a technical solution which provides energy saving at full speed, as well as duplication of screw propeller and main propulsion system incase it＇s out of order. The description of the corresponding device, designed for transport refrigerator ship, is shown as well as its location on board. Value of energy saving from the use of contra propeller is estimated. The results of the assessment required power to move the ship at low speed by the action of the contra propeller operating in the reactive mode are demonstrated. It is shown, that the ship equipped with the proposed device will get the additional class notation related to the redundancy or duplication of the propulsion system of Russian Maritime Register of Shipping.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
Developed by the Academy of Aerospace Liquid Propulsion Technology (AALPT), the propulsion system for the new-generation light-lift liquid launch vehicle passed its first ground test firing on November 27, 2012 at the...Developed by the Academy of Aerospace Liquid Propulsion Technology (AALPT), the propulsion system for the new-generation light-lift liquid launch vehicle passed its first ground test firing on November 27, 2012 at the Beijing Institute of Aerospace Testing Technology. The event signifies that this is the only domestic static test-firing facility for rocket propulsion systems that can meet the development requirements for new-generation launch vehicles,展开更多
Thrust bearing is a key component of the propulsion system of a ship. It transfers the propulsive forces from the propeller to the ship＇s hull, allowing the propeller to push the ship ahead. The performance of a thru...Thrust bearing is a key component of the propulsion system of a ship. It transfers the propulsive forces from the propeller to the ship＇s hull, allowing the propeller to push the ship ahead. The performance of a thrust bearing pad is critical. When the thrust bearing becomes damaged, it can cause the ship to lose power and can also affect its operational safety. For this paper, the distribution of the pressure field of a thrust pad was calculated with numerical method, applying Reynolds equation. Thrust bearing properties for loads were analyzed, given variations in outlet thickness of the pad and variations between the load and the slope of the pad. It was noticed that the distribution of pressure was uneven. As a result, increases of both the outlet thickness and the slope coefficient of the pad were able to improve load beating capability.展开更多
The fundamental performance analysis of an advanced concept ramjet propulsion system using antimatter is presented. Antimatter is generated by ultra-intense laser pulses incident on a gold target. The scientific found...The fundamental performance analysis of an advanced concept ramjet propulsion system using antimatter is presented. Antimatter is generated by ultra-intense laser pulses incident on a gold target. The scientific foundation for the generation of antimatter by an ultra-intense laser was established in the early 1970’s and later demonstrated at Lawrence Livermore National Laboratory from 2008 to 2009. Antimatter on the scale of 2 × 1010 positrons were generated through a ~1 ps pulse from the Lawrence Livermore National Laboratory Titan laser that has an intensity of ~1020 W/cm2. The predominant mechanism is the Bethe-Heitler process, which involves high-energy bremsstrahlung photons as a result of electron-nuclei interaction. Propulsion involving lasers through chemical rather than non-chemical interaction has been previously advocated by Phipps. The major utilities of the ultra-intense laser derived antimatter ramjet are the capability to generate antimatter without a complex storage system and the ability to decouple the antimatter ramjet propulsion system from the energy source. For instance the ultra-intense laser and energy source could be terrestrial, while the ramjet could be mounted to a UAV as a propulsion system. With the extrapolation of current technologies, a sufficient number of pulses by ultra-intense lasers are eventually anticipated for the generation of antimatter to heat the propulsive flow of a ramjet. Fundamental performance analysis is provided based on an ideal ramjet derivation that is modified to address the proposed antimatter ramjet architecture.展开更多
Antimatter has been generated in large quantities by the Lawrence Livermore National Laboratory Titan laser. The Titan laser is an ultra-intense laser system on the order of approximately 1020W/cm2 with pulse duration...Antimatter has been generated in large quantities by the Lawrence Livermore National Laboratory Titan laser. The Titan laser is an ultra-intense laser system on the order of approximately 1020W/cm2 with pulse durations of roughly 1ps. With the Titan laser incident on a high atomic number target, such as gold, antimatter on the scale of 2 × 1010 positrons are generated. Roughly 90% of the generated positrons are ejected anisotropic and aft to the respective target. The mechanisms for the laser-derived positron antimatter generation involve electron interaction with the nuclei based on bremsstrahlung photons that yield electron-positron pairs as a consequence of the Bethe-Heitler process, which predominates the Trident process. Given the constraints of the current and near future technology space, a pulsed space propulsion configuration is advocated for antimatter derived space propulsion, similar in concept to pulsed radioisotope propulsion. Antimatter is generated through an ultra-intense laser on the scale of a Titan laser incident on a gold target and annihilated in a closed chamber, representative of a combustion chamber. Upon reaching a temperature threshold, the closed chamber opens, producing a pulse of thrust. The implication of the pulsed space propulsion antimatter architecture is that the energy source for the antimatter propulsion system can be decoupled from the actual spacecraft. In contrast to conventional chemical propulsion systems, which require storage of its respective propulsive chemical potential energy, the proposed antimatter propulsion architecture may have the energy source at a disparate location from the spacecraft. The ultra-intense laser could convey its laser energy over a distance to the actual spacecraft equipped with the positron antimatter pulsed space propulsion system. Hydrogen is considered as the propulsive fluid, in light of its low molecular weight. Fundamental analysis is applied to preliminarily define the performance of the positron antimatter derived pulsed space propulsion system. The fundamental performance analysis of the antimatter pulsed space propulsion system successfully reveals the architecture is viable for further evaluation.展开更多
Photofission enables a unique capability for the domain of non-chemical space propulsion. An ultra-intense laser enables the capacity to induce nuclear fission through the development of bre- msstrahlung photons. A fu...Photofission enables a unique capability for the domain of non-chemical space propulsion. An ultra-intense laser enables the capacity to induce nuclear fission through the development of bre- msstrahlung photons. A fundamental architecture and performance analysis of a photofission pulsed space propulsion system through the operation of an ultra-intense laser is presented. A historical perspective of previous conceptual nuclear fission propulsion systems is addressed. These applications use neutron derived nuclear fission;however, there is inherent complexity that has precluded further development. The background of photofission is detailed. The conceptual architecture of photofission pulsed space propulsion and fundamental performance parameters are established. The implications are the energy source and ultra-intense laser can be situated far remote from the propulsion system. Advances in supporting laser technologies are anticipated to increase the potential for photofission pulsed space propulsion. The fundamental performance analysis of the photofission pulsed space propulsion system indicates the architecture is feasible for further evaluation.展开更多
The main aim of this research is to get a better knowledge and understanding of the micro-scale oscillatory networks behavior in the solid propellants reactionary zones. Fundamental understanding of the micro-and nano...The main aim of this research is to get a better knowledge and understanding of the micro-scale oscillatory networks behavior in the solid propellants reactionary zones. Fundamental understanding of the micro-and nano-scale combustion mechanisms is essential to the development and further improvement of the next-generation technologies for extreme control of the solid propellant thrust. Both experiments and theory confirm that the micro-and nano-scale oscillatory networks excitation in the solid propellants reactionary zones is a rather universal phenomenon. In accordance with our concept,the micro-and nano-scale structures form both the fractal and self-organized wave patterns in the solid propellants reactionary zones. Control by the shape, the sizes and spacial orientation of the wave patterns allows manipulate by the energy exchange and release in the reactionary zones. A novel strategy for enhanced extreme thrust control in solid propulsion systems are based on manipulation by selforganization of the micro-and nano-scale oscillatory networks and self-organized patterns formation in the reactionary zones with use of the system of acoustic waves and electro-magnetic fields, generated by special kind of ring-shaped electric discharges along with resonance laser radiation. Application of special kind of the ring-shaped electric discharges demands the minimum expenses of energy and opens prospects for almost inertia-free control by combustion processes. Nano-sized additives will enhance self-organizing and self-synchronization of the micro-and nano-scale oscillatory networks on the nanometer scale. Suggested novel strategy opens the door for completely new ways for enhanced extreme thrust control of the solid propulsion systems.展开更多
The aim of this project is to design and analyze the propulsion system for a tugboat for optimum performance. In so doing, certain approved procedures were followed;these procedures included getting the desired tugboa...The aim of this project is to design and analyze the propulsion system for a tugboat for optimum performance. In so doing, certain approved procedures were followed;these procedures included getting the desired tugboat dimension, using ITTC methods, Gertlers charts, Bp charts etc. to estimate the bare hull resistance of the tugboat, estimating the effective power that must be employed to overcome this tug resistance. Numerical software code was developed to determine the various performance indicators of the propulsion system. The effective power was used as a basis for selecting the main engine and designing of a suitable propeller capable of propelling the tugboat for the various sea state were evaluated. Propeller cavitation was also put into consideration during this design. Hence in matching the engine to the propeller a series of calculations were done across a speed range of 300 - 500 rpm in other to effectively ascertain the engine-propeller matching point. The result shows that the point of engine-propeller matching is at 335 rpm and 2550 KW respectively. This provides a guide for the selection of a main engine with an acceptable sea service margins. All designs were done in accordance to classification organization and regulations.展开更多
The inverter-fed induction motor drive system may become unstable at low frequencies and light load, and phase current and speed of the induction motor may oscillate periodically, which will threaten safety and reliab...The inverter-fed induction motor drive system may become unstable at low frequencies and light load, and phase current and speed of the induction motor may oscillate periodically, which will threaten safety and reliability of the system. This paper chooses nine-phase induction motor simulated propulsion system as the research object, small disturbance model of three-phase induction motor is built, and average equivalent model of the converter is built by introducing switch function. On the basis above, small disturbance mathematic model of the whole system is obtained. As for the limitation of parameters adjustment method of restrain low-frequency oscillation, the restrain method combining current close-loop with dead-time compensation is put forward. Finally, the proposed restrain method is verified respectively on the built simulation and experimental analogue platform. And the simulation and experimental results indicate that the proposed method can not only satisfy the requirement of low-frequency oscillation restraining, but also be expanded widely, and the stability of the system can get improved greatly.展开更多
The 200mm class ion propulsion system(LIPS-200)developed by CAST subsidiary Lanzhou Institute of Vacuum Physics(LIP)has passed its 6000-hour accumulative ground test recently with 3000 times on-off switching throughou...The 200mm class ion propulsion system(LIPS-200)developed by CAST subsidiary Lanzhou Institute of Vacuum Physics(LIP)has passed its 6000-hour accumulative ground test recently with 3000 times on-off switching throughout the test.It is capable of ensuring reliable in-orbit operation of a satellite for 15 years.China’s indigenous state-of-the-art electric propulsion system is ready to apply on spacecraft meeting the requirement for the展开更多
基金the financial support from the National Science and Technology Council,Taiwan(Grant No.MOST 111-2221-E-019-035-).
文摘The performance of a water jet propulsion system is related to the inlet duct,rotor,stator,and nozzle.Generally,the flow inlet design must fit the bottom line of the hull,and the design of the inlet duct is often limited by stern space.The entire section,from the rotor to the nozzle through the stator,must be designed based on system integration in that the individual performance of these three components will influence each other.Particularly,the section from the rotor to the nozzle significantly impacts the performance of a water jet propulsion system.This study focused on nozzle design and established referable analysis results to facilitate subsequent integrated studies on the design parameters regarding nozzle contour.Most existing studies concentrate on discussions on rotor design and the tip leakage flow of rotors or have replaced the existing complex computational domain with a simple flow field.However,research has yet to implement an integrated,optimal design of the section from the rotor to the nozzle.Given the above,our program conducted preliminary research on this system integration design issue,discussed the optimal nozzle for this section in-depth,and proposed design suggestions based on the findings.This program used an existing model as the design case.This study referred to the actual trial data as the design conditions for the proposed model.Unlike prior references’simple flow field form,this study added a jet ski geometry and free surface to the computational domain.After the linear hull shape was considered,the inflow in the inlet duct would be closer to the actual condition.Based on the numerical calculation result,this study recommends that the optimal nozzle outlet area should be 37%of the inlet area and that the nozzle contour should be linear.Furthermore,for the pump head,static pressure had a more significant impact than dynamic pressure.
文摘Flight vehicle conceptual design appears to be a promising area for application of the Genetic Algorithm （GA） as an approach to help to automate part of the design process. This computational research effort strives to develop a propulsion system design strategy for liquid rocket to optimize take-off mass, satisfying the mission range under the constraint of axial overload. The method by which this process is accomplished by using GA as optimizer is outlined in this paper. Convergence of GA is improved by introducing initial population based on Design of Experiments Technique.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.51479207 and 51179198)the High Technology Marine Scientific Research Project of the Ministry of Industry and Information Technology of China(Grant No.[2012]534)
文摘The hydrodynamic performance of a hybrid CRP pod propulsion system was studied by RANS method with SST k ？？ turbulence model and sliding mesh. The effect of axial spacing on the hydrodynamic performance of the hybrid CRP pod propulsion system was investigated numerically and experimentally. It shows that RANS with the sliding mesh method and SST k -ω turbulence model predicts accurately the hydrodynamic performance of the hybrid CRP pod propulsion system. The axial spacing has little influence on the hydrodynamic performance of the forward propeller, but great influence on that of the pod unit. Thrust coefficient of the pod unit declines with the increase of the axial spacing, but the trend becomes weaker, and the decreasing amplitude at the lower advance coefficient is larger than that at the higher advance coefficient. The thrust coefficient and open water efficiency of the hybrid CRP pod propulsion system decrease with the increase of the axial spacing, while the torque coefficient keeps almost constant. On this basis, the design principle of axial spacing of the hybrid CRP pod propulsion system was proposed.
基金Supported by the National Natural Sciences Foundation of China (No. 50975213 and No. 50705070)Doctoral Fund for the New Teachers of Ministry of Education of China (No. 20070497029)the Program of Introducing Talents of Discipline to Universities (No. B08031)
文摘A marine propulsion system is a very complicated system composed of many mechanical components.As a result,the vibration signal of a gearbox in the system is strongly coupled with the vibration signatures of other components including a diesel engine and main shaft.It is therefore imperative to assess the coupling effect on diagnostic reliability in the process of gear fault diagnosis.For this reason,a fault detection and diagnosis method based on bispectrum analysis and artificial neural networks (ANNs) was proposed for the gearbox with consideration given to the impact of the other components in marine propulsion systems.To monitor the gear conditions,the bispectrum analysis was first employed to detect gear faults.The amplitude-frequency plots containing gear characteristic signals were then attained based on the bispectrum technique,which could be regarded as an index actualizing forepart gear faults diagnosis.Both the back propagation neural network (BPNN) and the radial-basis function neural network (RBFNN) were applied to identify the states of the gearbox.The numeric and experimental test results show the bispectral patterns of varying gear fault severities are different so that distinct fault features of the vibrant signal of a marine gearbox can be extracted effectively using the bispectrum,and the ANN classification method has achieved high detection accuracy.Hence,the proposed diagnostic techniques have the capability of diagnosing marine gear faults in the earlier phases,and thus have application importance.
文摘A new marine propulsion system is proposed . A small liquid sodium cooled reactor acts as prime mover; alkali-metal thermal-to-electric conversion ( AMTEC) cells are employed to convert the heat energy to electricity; superconducting magneto-hydrodynamic thruster combined with spray-water thruster works as pr opulsion. The configuration and characteristics of this system are described. Such a nuclear-powered propulsion system is not only free of noise, but also has high reliability and efficiency. It would be a preferable propulsion system for ships in the future.
基金This work was supported by the National Natural Science Foundation of China(No.50106005)
文摘Fault diagnosis of liquid rocket propulsion systems （LRPSs） is a very important issue in space launch activities particularly when manned space missions are accompanied, since the safety and reliability can be significantly enhanced by exploiting an efficient fault diagnosis system. Currently, inverse problem-based diagnosis has attracted a great deal of research attention in fault diagnosis domain. This methodology provides a new strategy to model-based fault diagnosis for monitoring the health of propulsion systems. To solve the inverse problems arising from the fault diagnosis of LRPSs, GAs have been adopted in recent years as the first and effective choice of available numerical optimization tools. However, the GA has many control parameters to be chosen in advance and there still lack sound theoretical tools to analyze the effects of these parameters on diagnostic performance analytically. In this paper a comparative study of the influence of GA parameters on diagnostic results is conducted by performing a series of numerical experiments. The objective of this study is to investigate the contribution of individual algorithm parameter to final diagnostic result and provide reasonable estimates for choosing GA parameters in the inverse problem-based fault diagnosis of LRPSs. Some constructive remarks are made in conclusion and will be helpful for the implementation of GA to the fault diagnosis practice of LRPSs in the future.
基金the National Natural Science Foundation of China under Grant 52007071 and 51907073the China Postdoctoral Science Foundation under Grant 3004131154 and 2020M672355the Applied Basic Frontier Program of Wuhan under Grant 2020010601012207。
文摘To lower the difficulty of fault protection,a doubly-fed induction machine based shipboard propulsion system(DFIM-SPS)that is partially power decoupled is presented.In such an intrinsically safe SPS architecture,a synchronous generator(SG)is employed for power generation,and the accuracy of the parameters of power generation unit(PGU)plays an important role in SPS stable operation.In this paper,the PGU parameter deviations are studied to evaluate the effects on system performance.The models of salient-pole SG,type DC1A excitation system(EXS)and DFIM are illustrated first.Besides,the corresponding control scheme is explained.For the 16 important parameters of PGU,up to 40%of parameter deviations are applied to implement parameter sensitivity analysis.Then,simulation studies are carried out to evaluate the parameter deviation effects on system performance in detail.By defining three parameter deviation effect indicators(PDEIs),the effects on the PGU output variables,which are the terminal voltage and output active power,are studied.Moreover,the increasing rates of PDEIs with different degrees of parameter deviations for the key parameters are analyzed.Furthermore,the overall system performance is investigated for the two most influential PGU parameters.This paper provides some vital clues on SG and EXS parameter identification for DFIM-SPS.
基金supported by National Natural Science Foundation of China(Grant No. 50575027)Ministry of Transportation and Communications Foundation of China (Grant No. 200332922502)
文摘As the development tends towards high-speed, large-scale and high-power, power of the ship main engine becomes larger and larger. This make the engine design and cabin arrangement become more and more difficult. Ship maneuverability becomes bad. A new ship propulsion system, integrated hydraulic propulsion （IHP）, is put forward to meet the development of modem ship. Principle of IHP system is discussed. Working condition matching characteristic of IHP ship is studied based on its matching characteristic charts. According to their propulsion principle, dynamic mathematic models of IHP ship and direct propulsion （DP） ship are developed. These two models are verified by test sailing and test stand data. Based on the software Matlab/Simulink, comparison research between IHP ship and DP ship is conducted. The results show that cabin arrangement of IHP ship is very flexible, working condition matching characteristic of IHP ship is good, the ratio of power to weight of IHP ship is larger than DP ship, and maneuverability is excellent. IHP system is suitable for engineering ship, superpower ship and warship, etc.
文摘Modern satellite propulsion systems are generally designed to fulfill multiphase-missions.Traditional reliability modelling methods have problems of inadequate depict capacity considering complex systems such as satellite propulsion system.An extended object-oriented Petri net(EOOPN)method was proposed to facilitate the reliability modelling of satellite propulsion system in the paper.The proposed method was specified for modelling of phased mission system,and it could be implemented by generating combination of Petri net(PN)principles and object-oriented(OO)programming.The effectiveness of the proposed method was demonstrated through the reliability modelling of a satellite propulsion system with EOOPN.The major advantage of the proposed method is that the dimension of net model can be reduced significantly,and phased mission system at system,phase,or component levels can be respectively depicted.Furthermore,the state-space explosion problem is solved by the proposed EOOPN model efficiently.
文摘The paper presents a technical solution which provides energy saving at full speed, as well as duplication of screw propeller and main propulsion system incase it＇s out of order. The description of the corresponding device, designed for transport refrigerator ship, is shown as well as its location on board. Value of energy saving from the use of contra propeller is estimated. The results of the assessment required power to move the ship at low speed by the action of the contra propeller operating in the reactive mode are demonstrated. It is shown, that the ship equipped with the proposed device will get the additional class notation related to the redundancy or duplication of the propulsion system of Russian Maritime Register of Shipping.
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Developed by the Academy of Aerospace Liquid Propulsion Technology (AALPT), the propulsion system for the new-generation light-lift liquid launch vehicle passed its first ground test firing on November 27, 2012 at the Beijing Institute of Aerospace Testing Technology. The event signifies that this is the only domestic static test-firing facility for rocket propulsion systems that can meet the development requirements for new-generation launch vehicles,
基金Supported by the Natural Science Foundation of China under Grant No.50675162the Program of Introducing Talents of Discipline to Universities under Grant No.B08031the Key Project of Hubei Province Science & Technology Fund under Grant No.2008CAD027
文摘Thrust bearing is a key component of the propulsion system of a ship. It transfers the propulsive forces from the propeller to the ship＇s hull, allowing the propeller to push the ship ahead. The performance of a thrust bearing pad is critical. When the thrust bearing becomes damaged, it can cause the ship to lose power and can also affect its operational safety. For this paper, the distribution of the pressure field of a thrust pad was calculated with numerical method, applying Reynolds equation. Thrust bearing properties for loads were analyzed, given variations in outlet thickness of the pad and variations between the load and the slope of the pad. It was noticed that the distribution of pressure was uneven. As a result, increases of both the outlet thickness and the slope coefficient of the pad were able to improve load beating capability.
文摘The fundamental performance analysis of an advanced concept ramjet propulsion system using antimatter is presented. Antimatter is generated by ultra-intense laser pulses incident on a gold target. The scientific foundation for the generation of antimatter by an ultra-intense laser was established in the early 1970’s and later demonstrated at Lawrence Livermore National Laboratory from 2008 to 2009. Antimatter on the scale of 2 × 1010 positrons were generated through a ~1 ps pulse from the Lawrence Livermore National Laboratory Titan laser that has an intensity of ~1020 W/cm2. The predominant mechanism is the Bethe-Heitler process, which involves high-energy bremsstrahlung photons as a result of electron-nuclei interaction. Propulsion involving lasers through chemical rather than non-chemical interaction has been previously advocated by Phipps. The major utilities of the ultra-intense laser derived antimatter ramjet are the capability to generate antimatter without a complex storage system and the ability to decouple the antimatter ramjet propulsion system from the energy source. For instance the ultra-intense laser and energy source could be terrestrial, while the ramjet could be mounted to a UAV as a propulsion system. With the extrapolation of current technologies, a sufficient number of pulses by ultra-intense lasers are eventually anticipated for the generation of antimatter to heat the propulsive flow of a ramjet. Fundamental performance analysis is provided based on an ideal ramjet derivation that is modified to address the proposed antimatter ramjet architecture.
文摘Antimatter has been generated in large quantities by the Lawrence Livermore National Laboratory Titan laser. The Titan laser is an ultra-intense laser system on the order of approximately 1020W/cm2 with pulse durations of roughly 1ps. With the Titan laser incident on a high atomic number target, such as gold, antimatter on the scale of 2 × 1010 positrons are generated. Roughly 90% of the generated positrons are ejected anisotropic and aft to the respective target. The mechanisms for the laser-derived positron antimatter generation involve electron interaction with the nuclei based on bremsstrahlung photons that yield electron-positron pairs as a consequence of the Bethe-Heitler process, which predominates the Trident process. Given the constraints of the current and near future technology space, a pulsed space propulsion configuration is advocated for antimatter derived space propulsion, similar in concept to pulsed radioisotope propulsion. Antimatter is generated through an ultra-intense laser on the scale of a Titan laser incident on a gold target and annihilated in a closed chamber, representative of a combustion chamber. Upon reaching a temperature threshold, the closed chamber opens, producing a pulse of thrust. The implication of the pulsed space propulsion antimatter architecture is that the energy source for the antimatter propulsion system can be decoupled from the actual spacecraft. In contrast to conventional chemical propulsion systems, which require storage of its respective propulsive chemical potential energy, the proposed antimatter propulsion architecture may have the energy source at a disparate location from the spacecraft. The ultra-intense laser could convey its laser energy over a distance to the actual spacecraft equipped with the positron antimatter pulsed space propulsion system. Hydrogen is considered as the propulsive fluid, in light of its low molecular weight. Fundamental analysis is applied to preliminarily define the performance of the positron antimatter derived pulsed space propulsion system. The fundamental performance analysis of the antimatter pulsed space propulsion system successfully reveals the architecture is viable for further evaluation.
文摘Photofission enables a unique capability for the domain of non-chemical space propulsion. An ultra-intense laser enables the capacity to induce nuclear fission through the development of bre- msstrahlung photons. A fundamental architecture and performance analysis of a photofission pulsed space propulsion system through the operation of an ultra-intense laser is presented. A historical perspective of previous conceptual nuclear fission propulsion systems is addressed. These applications use neutron derived nuclear fission;however, there is inherent complexity that has precluded further development. The background of photofission is detailed. The conceptual architecture of photofission pulsed space propulsion and fundamental performance parameters are established. The implications are the energy source and ultra-intense laser can be situated far remote from the propulsion system. Advances in supporting laser technologies are anticipated to increase the potential for photofission pulsed space propulsion. The fundamental performance analysis of the photofission pulsed space propulsion system indicates the architecture is feasible for further evaluation.
基金supported by the Western-Caucasus Research Center
文摘The main aim of this research is to get a better knowledge and understanding of the micro-scale oscillatory networks behavior in the solid propellants reactionary zones. Fundamental understanding of the micro-and nano-scale combustion mechanisms is essential to the development and further improvement of the next-generation technologies for extreme control of the solid propellant thrust. Both experiments and theory confirm that the micro-and nano-scale oscillatory networks excitation in the solid propellants reactionary zones is a rather universal phenomenon. In accordance with our concept,the micro-and nano-scale structures form both the fractal and self-organized wave patterns in the solid propellants reactionary zones. Control by the shape, the sizes and spacial orientation of the wave patterns allows manipulate by the energy exchange and release in the reactionary zones. A novel strategy for enhanced extreme thrust control in solid propulsion systems are based on manipulation by selforganization of the micro-and nano-scale oscillatory networks and self-organized patterns formation in the reactionary zones with use of the system of acoustic waves and electro-magnetic fields, generated by special kind of ring-shaped electric discharges along with resonance laser radiation. Application of special kind of the ring-shaped electric discharges demands the minimum expenses of energy and opens prospects for almost inertia-free control by combustion processes. Nano-sized additives will enhance self-organizing and self-synchronization of the micro-and nano-scale oscillatory networks on the nanometer scale. Suggested novel strategy opens the door for completely new ways for enhanced extreme thrust control of the solid propulsion systems.
文摘The aim of this project is to design and analyze the propulsion system for a tugboat for optimum performance. In so doing, certain approved procedures were followed;these procedures included getting the desired tugboat dimension, using ITTC methods, Gertlers charts, Bp charts etc. to estimate the bare hull resistance of the tugboat, estimating the effective power that must be employed to overcome this tug resistance. Numerical software code was developed to determine the various performance indicators of the propulsion system. The effective power was used as a basis for selecting the main engine and designing of a suitable propeller capable of propelling the tugboat for the various sea state were evaluated. Propeller cavitation was also put into consideration during this design. Hence in matching the engine to the propeller a series of calculations were done across a speed range of 300 - 500 rpm in other to effectively ascertain the engine-propeller matching point. The result shows that the point of engine-propeller matching is at 335 rpm and 2550 KW respectively. This provides a guide for the selection of a main engine with an acceptable sea service margins. All designs were done in accordance to classification organization and regulations.
文摘The inverter-fed induction motor drive system may become unstable at low frequencies and light load, and phase current and speed of the induction motor may oscillate periodically, which will threaten safety and reliability of the system. This paper chooses nine-phase induction motor simulated propulsion system as the research object, small disturbance model of three-phase induction motor is built, and average equivalent model of the converter is built by introducing switch function. On the basis above, small disturbance mathematic model of the whole system is obtained. As for the limitation of parameters adjustment method of restrain low-frequency oscillation, the restrain method combining current close-loop with dead-time compensation is put forward. Finally, the proposed restrain method is verified respectively on the built simulation and experimental analogue platform. And the simulation and experimental results indicate that the proposed method can not only satisfy the requirement of low-frequency oscillation restraining, but also be expanded widely, and the stability of the system can get improved greatly.
文摘The 200mm class ion propulsion system(LIPS-200)developed by CAST subsidiary Lanzhou Institute of Vacuum Physics(LIP)has passed its 6000-hour accumulative ground test recently with 3000 times on-off switching throughout the test.It is capable of ensuring reliable in-orbit operation of a satellite for 15 years.China’s indigenous state-of-the-art electric propulsion system is ready to apply on spacecraft meeting the requirement for the
