The flight envelope of Air Turbo Rocket(ATR)engines is broader compared to conventional aero-engines,and designing a full-envelope controller using traditional methods poses significant challenges due to a burdensome ...The flight envelope of Air Turbo Rocket(ATR)engines is broader compared to conventional aero-engines,and designing a full-envelope controller using traditional methods poses significant challenges due to a burdensome design process.To address this issue,this paper proposes a self-learning neural network controller design method based on Reinforcement Learning(RL).Additionally,a method for predictive compensation and stability rewards is proposed to reduce the system oscillation caused by actuator delay.This approach simplifies the actuator to a firstorder inertial element exhibiting pure delay.A simulation environment for the ATR engineactuator system is first established.Based on this environment,a self-learning neural network controller using a predictive compensator and the Proximal Policy Optimization(PPO)algorithm is then developed.Furthermore,the temporal difference signals from the controller output are integrated into the reward function to enhance system stability.The proposed method is validated through numerical simulations and semi-physical experiments.The numerical simulation results demonstrate that the proposed method increases the system's tolerance to delays from 20 ms to 400 ms.Under an actuator delay of 400 ms,the average steady-state error remains less than0.1%,the overshoot is limited to 1%,and the settling time does not exceed 3 s.Moreover,compared to the traditional method,the proposed method exhibits higher adaptability to model errors and variations in flight conditions.In the conducted semi-physical simulation experiments,the proposed method achieves stable control of a real electric pump.展开更多
Quantum dot systems emerge as promising platforms for studying nanoscale thermoelectric effects and quantum fluctuation phenomena.In this work,we investigate the thermodynamic performance of a Coulomb-blockaded quantu...Quantum dot systems emerge as promising platforms for studying nanoscale thermoelectric effects and quantum fluctuation phenomena.In this work,we investigate the thermodynamic performance of a Coulomb-blockaded quantum dot operating as a quantum heat engine using the quantum master equation approach.By incorporating full counting statistics,we analyze both average transport properties and current fluctuations in this nanoscale system.We demonstrate that electron-electron interactions significantly enhance thermoelectric performance by increasing both the output power and energy conversion efficiency.Furthermore,we show that Coulomb interactions suppress current fluctuations while preserving the validity of the thermodynamic uncertainty relation.Our results provide important insights into the interplay between quantum effects and thermodynamic principles in nanoscale heat engines.展开更多
Pre-chamber ignition technology can address the issue of uneven in-cylinder mixture combustion in large-bore marine engines.The impact of various pre-chamber structures on the formation of the mixture and jet flames w...Pre-chamber ignition technology can address the issue of uneven in-cylinder mixture combustion in large-bore marine engines.The impact of various pre-chamber structures on the formation of the mixture and jet flames within the pre-chamber is explored.This study performed numerical simulations on a large-bore marine ammonia/hydrogen pre-chamber engine prototype,considering pre-chamber volume,throat diameter,the distance between the hydrogen injector and the spark plug,and the hydrogen injector angle.Compared with the original engine,when the pre-chamber volume is 73.4 ml,the throat diameter is 14 mm,the distance ratio is 0.92,and the hydrogen injector angle is 80°.Moreover,the peak pressure in the pre-chamber increased by 23.1%,and that in the main chamber increased by 46.3%.The results indicate that the performance of the original engine is greatly enhanced by altering its fuel and pre-chamber structure.展开更多
Actuator faults can be critical in turbofan engines as they can lead to stall,surge,loss of thrust and failure of speed control.Thus,fault diagnosis of gas turbine actuators has attracted considerable attention,from b...Actuator faults can be critical in turbofan engines as they can lead to stall,surge,loss of thrust and failure of speed control.Thus,fault diagnosis of gas turbine actuators has attracted considerable attention,from both academia and industry.However,the extensive literature that exists on this topic does not address identifying the severity of actuator faults and focuses mainly on actuator fault detection and isolation.In addition,previous studies of actuator fault identification have not dealt with multiple concurrent faults in real time,especially when these are accompanied by sudden failures under dynamic conditions.This study develops component-level models for fault identification in four typical actuators used in high-bypass ratio turbofan engines under both dynamic and steady-state conditions and these are then integrated with the engine performance model developed by the authors.The research results reported here present a novel method of quantifying actuator faults using dynamic effect compensation.The maximum error for each actuator is less than0.06%and 0.07%,with average computational time of less than 0.0058 s and 0.0086 s for steady-state and transient cases,respectively.These results confirm that the proposed method can accurately and efficiently identify concurrent actuator fault for an engine operating under either transient or steady-state conditions,even in the case of a sudden malfunction.The research results emonstrate the potential benefit to emergency response capabilities by introducing this method of monitoring the health of aero engines.展开更多
Lighters made in Shaodong,Hunan Province,are exported in bulk to Africa;Anji in Zhejiang Province turns a simple tea leaf or bamboo into an ecological commodity;Kunshan and Jiangyin in Jiangsu Province have surpassed ...Lighters made in Shaodong,Hunan Province,are exported in bulk to Africa;Anji in Zhejiang Province turns a simple tea leaf or bamboo into an ecological commodity;Kunshan and Jiangyin in Jiangsu Province have surpassed the 500 billion yuan($70 billion)GDP mark...This dynamic illustrates the diversity and vitality of the county economy in China,which is becoming an important lever for high-quality development.展开更多
Advanced propulsion systems experience critical challenges under extreme service conditions,including aerodynamic loads and thermal loads.Especially,flutter stability is a key bottleneck restricting the design and saf...Advanced propulsion systems experience critical challenges under extreme service conditions,including aerodynamic loads and thermal loads.Especially,flutter stability is a key bottleneck restricting the design and safe op⁃eration of hot structures in advanced propulsion systems employing ceramic matrix composites(CMCs).Compared to traditional nickel-based alloys,CMCs offer superior high-temperature resistance and specific strength,making them ideal for next-generation engine hot structures.The inherent anisotropy,heterogeneity,and complex nonlinear behav⁃ior of CMCs,coupled with extreme operating environments,result in strong multi-physics interactions,including aero-thermo-structural,thermo-mechanical,and damage-aeroelastic coupling.These complexities significantly com⁃plicate vibration stability and flutter analysis.The recent research progresses on these problems are systematically ex⁃amined,focusing on multi-field coupling mechanisms,material constitutive and damage evolution models,multi-scale modeling methods,coupled solution strategies,and the influence of key parameters on flutter characteristics.The current challenges are highlighted,including the complexity of high-temperature nonlinear modeling,the effi⁃ciency of multi-field coupling calculations,and the multi-scale modeling of complex weaving structures.Finally,an outlook on future development directions is presented to provide theoretical support for the design and safety assess⁃ment of hot structures of advanced CMCs.展开更多
In today’s complex and rapidly changing business environment,the traditional single-organization service model can no longer meet the needs of multi-organization collaborative processing.Based on existing business pr...In today’s complex and rapidly changing business environment,the traditional single-organization service model can no longer meet the needs of multi-organization collaborative processing.Based on existing business process engine technologies,this paper proposes a distributed heterogeneous process engine collaboration method for crossorganizational scenarios.The core of this method lies in achieving unified access and management of heterogeneous engines through a business process model adapter and a common operation interface.The key technologies include:Meta-Process Control Architecture,where the central engine(meta-process scheduler)decomposes the original process into fine-grained sub-processes and schedules their execution in a unified order,ensuring consistency with the original process logic;Process Model Adapter,which addresses the BPMN2.0 model differences among heterogeneous engines such as Flowable and Activiti through a matching-and-replacement mechanism,providing a unified process model standard for different engines;Common Operation Interface,which encapsulates the REST APIs of heterogeneous engines and offers a single,standardized interface for process deployment,instance management,and status synchronization.This method integrates multiple techniques to address API differences,process model incompatibilities,and execution order consistency issues among heterogeneous engines,delivering a unified,flexible,and scalable solution for cross-organizational process collaboration.展开更多
This work investigates the potential of low-pressure,medium-speed dual-fuel engines for cleaner maritime transportation.The thermodynamic performance of these engines is explored using three alternative fuels:liquefie...This work investigates the potential of low-pressure,medium-speed dual-fuel engines for cleaner maritime transportation.The thermodynamic performance of these engines is explored using three alternative fuels:liquefied natural gas(LNG),methanol,and ammonia.A parametric analysis examines the effect of adjustments to key engine parameters(compression ratio,boost pressure,and air-fuel ratio)on performance.Results show an initial improvement in performance with an increase in compression ratio,which reaches a peak and then declines.Similarly,increases in boost pressure and air-fuel ratio lead to linear performance gains.However,insufficient cooling reduces the amount of fuel burned,which hinders performance.Exergy analysis reveals significant exergy destruction within the engine,which ranges from 69.96%(methanol)to 78.48%(LNG).Notably,the combustion process is the leading cause of exergy loss.Among the fuels tested,methanol exhibits the lowest combustion-related exergy destruction(56.41%),followed by ammonia(62.12%)and LNG(73.77%).These findings suggest that methanol is a promising near-term alternative to LNG for marine fuel applications.展开更多
Limiting environmental pollution from exhaust emissions from internal combustion engines includes many measures,including encouraging biofuel use because biofuel is environmentally friendly and renewable.A mixture of ...Limiting environmental pollution from exhaust emissions from internal combustion engines includes many measures,including encouraging biofuel use because biofuel is environmentally friendly and renewable.A mixture of diesel fuel and vegetable oil is a form of biofuel.However,some properties of the mixed fuel,such as viscosity and density,are higher than those of traditional diesel fuel,affecting the injection and combustion process and reducing power and non-optimal toxic emissions,especially soot emissions.This study uses Kiva-3V software to simulate the combustion process of a diesel-vegetable oil mixture in the combustion chamber of a fishing vessel diesel engine with changes in fuel injection timing.The results show that when increasing the fuel injection timing of a diesel-vegetable oil mixture about 1–2 degrees of crankshaft rotation angle before the top dead center compared to diesel fuel injection timing,the engine power increases,and soot emissions decrease compared to no adjustment.The above simulation research results will help orient the experiments conveniently and reduce costs in the future experimental research process to quantify the fuel system adjustment of fishing vessels’diesel engines when using biofuels,including diesel-vegetable oil mixtures.Thus,the engine’s economic indicators will improve,and emissions that pollute the environment will be limited.展开更多
Liquid rocket engine(LRE)fault diagnosis is critical for successful space launch missions,enabling timely avoidance of safety hazards,while accurate post-failure analysis prevents subsequent economic losses.However,th...Liquid rocket engine(LRE)fault diagnosis is critical for successful space launch missions,enabling timely avoidance of safety hazards,while accurate post-failure analysis prevents subsequent economic losses.However,the complexity of LRE systems and the“black-box”nature of current deep learning-based diagnostic methods hinder interpretable fault diagnosis.This paper establishes Granger causality(GC)extraction-based component-wise multi-layer perceptron(GCMLP),achieving high fault diagnosis accuracy while leveraging GC to enhance diagnostic interpretability.First,component-wise MLP networks are constructed for distinct LRE variables to extract inter-variable GC relationships.Second,dedicated predictors are designed for each variable,leveraging historical data and GC relationships to forecast future states,thereby ensuring GC reliability.Finally,the extracted GC features are utilized for fault classification,guaranteeing feature discriminability and diagnosis accuracy.This study simulates six critical fault modes in LRE using Simulink.Based on the generated simulation data,GCMLP demonstrates superior fault localization accuracy compared to benchmark methods,validating its efficacy and robustness.展开更多
In liquid rocket engines,regenerative cooling technology is essential for preserving structural integrity under extreme thermal loads.However,non-uniform coolant flow distribution within the cooling channels often lea...In liquid rocket engines,regenerative cooling technology is essential for preserving structural integrity under extreme thermal loads.However,non-uniform coolant flow distribution within the cooling channels often leads to localized overheating,posing serious risks to engine reliability and operational lifespan.This study employs a three-dimensional fluid–thermal coupled numerical model to systematically investigate the influence of geometric parameters-specifically the number of inlets,the number of channels,and inlet manifold configurations-on flow uniformity and thermal distribution in non-pyrolysis zones.Key findings reveal that increasing the number of inlets from one to three significantly enhances flow uniformity,reducing mass flow rate deviation from 1.2%to below 0.3%.However,further increasing the inlets to five yields only marginal improvements indicating diminishing(<0.1%),returns beyond three inlets.Additionally,temperature non-uniformity at the combustion chamber throat decreases by 37%-from 3050 K with 18 channels to 1915 K with 30 channels-highlighting the critical role of channel density in effective thermal regulation.Notably,while higher channel counts improve cooling efficiency,they also result in increased pressure losses of approximately 18%–22%,emphasizing the need to balance thermal performance against hydraulic resistance.An optimal configuration comprising 24 channels and three inlets was identified,providing minimal temperature gradients while maintaining acceptable pressure losses.The inlet manifold structure also plays a pivotal role in determining flow distribution.Configuration 3(Config-3),which features an enlarged manifold and reduced inlet velocity,achieves a 40%reduction in velocity fluctuations compared to Configuration 1(Config-1).This improvement leads to a more uniform mass flow distribution,with a relative standard deviation(RSD)of less than 0.15%.Furthermore,this design effectively mitigates localized hot spots near the nozzle-where temperature gradients are most severe-achieving a reduction of approximately 1135 K.展开更多
Powder engine as a novel type of engine using high-energy metal powder as fuel and gas,liquid,or solid as oxidizer.These engines exhibit remarkable adaptability,flexible thrust regulation,and multi-pulse start-stop,wh...Powder engine as a novel type of engine using high-energy metal powder as fuel and gas,liquid,or solid as oxidizer.These engines exhibit remarkable adaptability,flexible thrust regulation,and multi-pulse start-stop,which have significant application potentials in the fields of near-Earth space development,space propulsion systems,and deep-sea exploration.The scope of this review encompasses the classification and application of powder engines,the classification of powdered fuel supply systems,and the prospective trajectories and pivotal challenges of powder engines and fuel supply technologies.This work points out that although certain ground-based experimental challenges on powder engines have been solved,the relative technology remains in the nascent stages of feasibility demonstration and testing.The pneumatic and motor-driven piston methods currently dominate as the primary means for supplying fuel,and the structure of the piston and intake should be further optimized in the future to promote fuel fluidization and delivery efficiency.The adaptability of powder engines and powdered fuels under different pre-treatment and loading methods should be evaluated.Furthermore,the stability of powdered fuel delivery across varying operational environments,the accuracy of CFD modeling,and the precision of mass flow rate measurement and prediction technologies necessitate further enhancement and refinement.These advancements are crucial for the maturation of powder engine technology and its integration into practical applications.展开更多
Reliability evaluation for aircraft engines is difficult because of the scarcity of failure data. But aircraft engine data are available from a variety of sources. Data fusion has the function of maximizing the amount...Reliability evaluation for aircraft engines is difficult because of the scarcity of failure data. But aircraft engine data are available from a variety of sources. Data fusion has the function of maximizing the amount of valu- able information extracted from disparate data sources to obtain the comprehensive reliability knowledge. Consid- ering the degradation failure and the catastrophic failure simultaneously, which are competing risks and can affect the reliability, a reliability evaluation model based on data fusion for aircraft engines is developed, Above the characteristics of the proposed model, reliability evaluation is more feasible than that by only utilizing failure data alone, and is also more accurate than that by only considering single failure mode. Example shows the effective- ness of the proposed model.展开更多
基金co-supported by the National Science and Technology Major Project(No.J2019-Ⅲ-0010-0054)the National Natural Science Foundation of China(No.52336002)。
文摘The flight envelope of Air Turbo Rocket(ATR)engines is broader compared to conventional aero-engines,and designing a full-envelope controller using traditional methods poses significant challenges due to a burdensome design process.To address this issue,this paper proposes a self-learning neural network controller design method based on Reinforcement Learning(RL).Additionally,a method for predictive compensation and stability rewards is proposed to reduce the system oscillation caused by actuator delay.This approach simplifies the actuator to a firstorder inertial element exhibiting pure delay.A simulation environment for the ATR engineactuator system is first established.Based on this environment,a self-learning neural network controller using a predictive compensator and the Proximal Policy Optimization(PPO)algorithm is then developed.Furthermore,the temporal difference signals from the controller output are integrated into the reward function to enhance system stability.The proposed method is validated through numerical simulations and semi-physical experiments.The numerical simulation results demonstrate that the proposed method increases the system's tolerance to delays from 20 ms to 400 ms.Under an actuator delay of 400 ms,the average steady-state error remains less than0.1%,the overshoot is limited to 1%,and the settling time does not exceed 3 s.Moreover,compared to the traditional method,the proposed method exhibits higher adaptability to model errors and variations in flight conditions.In the conducted semi-physical simulation experiments,the proposed method achieves stable control of a real electric pump.
基金supported by the National Natural Science Foundation of China(Grant No.12305050)the Natural Science Foundation of Jiangsu Higher Education Institutions of China(Grant No.23KJB140017)the Zhejiang Provincial Natural Science Foundation of China(Grant No.LZ25A050001)。
文摘Quantum dot systems emerge as promising platforms for studying nanoscale thermoelectric effects and quantum fluctuation phenomena.In this work,we investigate the thermodynamic performance of a Coulomb-blockaded quantum dot operating as a quantum heat engine using the quantum master equation approach.By incorporating full counting statistics,we analyze both average transport properties and current fluctuations in this nanoscale system.We demonstrate that electron-electron interactions significantly enhance thermoelectric performance by increasing both the output power and energy conversion efficiency.Furthermore,we show that Coulomb interactions suppress current fluctuations while preserving the validity of the thermodynamic uncertainty relation.Our results provide important insights into the interplay between quantum effects and thermodynamic principles in nanoscale heat engines.
基金Supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions under Grant No.014000319/2018-00391.
文摘Pre-chamber ignition technology can address the issue of uneven in-cylinder mixture combustion in large-bore marine engines.The impact of various pre-chamber structures on the formation of the mixture and jet flames within the pre-chamber is explored.This study performed numerical simulations on a large-bore marine ammonia/hydrogen pre-chamber engine prototype,considering pre-chamber volume,throat diameter,the distance between the hydrogen injector and the spark plug,and the hydrogen injector angle.Compared with the original engine,when the pre-chamber volume is 73.4 ml,the throat diameter is 14 mm,the distance ratio is 0.92,and the hydrogen injector angle is 80°.Moreover,the peak pressure in the pre-chamber increased by 23.1%,and that in the main chamber increased by 46.3%.The results indicate that the performance of the original engine is greatly enhanced by altering its fuel and pre-chamber structure.
基金support by the National Natural Science Foundation of China(Grant No.52402520)。
文摘Actuator faults can be critical in turbofan engines as they can lead to stall,surge,loss of thrust and failure of speed control.Thus,fault diagnosis of gas turbine actuators has attracted considerable attention,from both academia and industry.However,the extensive literature that exists on this topic does not address identifying the severity of actuator faults and focuses mainly on actuator fault detection and isolation.In addition,previous studies of actuator fault identification have not dealt with multiple concurrent faults in real time,especially when these are accompanied by sudden failures under dynamic conditions.This study develops component-level models for fault identification in four typical actuators used in high-bypass ratio turbofan engines under both dynamic and steady-state conditions and these are then integrated with the engine performance model developed by the authors.The research results reported here present a novel method of quantifying actuator faults using dynamic effect compensation.The maximum error for each actuator is less than0.06%and 0.07%,with average computational time of less than 0.0058 s and 0.0086 s for steady-state and transient cases,respectively.These results confirm that the proposed method can accurately and efficiently identify concurrent actuator fault for an engine operating under either transient or steady-state conditions,even in the case of a sudden malfunction.The research results emonstrate the potential benefit to emergency response capabilities by introducing this method of monitoring the health of aero engines.
文摘Lighters made in Shaodong,Hunan Province,are exported in bulk to Africa;Anji in Zhejiang Province turns a simple tea leaf or bamboo into an ecological commodity;Kunshan and Jiangyin in Jiangsu Province have surpassed the 500 billion yuan($70 billion)GDP mark...This dynamic illustrates the diversity and vitality of the county economy in China,which is becoming an important lever for high-quality development.
基金supported by the Na⁃tional Science and Technology Major Project(No.Y2019-Ⅰ⁃0018-0017)the National Natural Science Foundation of China(No.U24A2051)+2 种基金the Natural Science Foundation of Jiangsu Province(No.BK20232037)the Foundation of Key Laboratory of Aero-engine Thermal Environment and Structure,Ministry of Industry and Information Technology(No.CEPE2024002)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KY⁃CX24_0605)。
文摘Advanced propulsion systems experience critical challenges under extreme service conditions,including aerodynamic loads and thermal loads.Especially,flutter stability is a key bottleneck restricting the design and safe op⁃eration of hot structures in advanced propulsion systems employing ceramic matrix composites(CMCs).Compared to traditional nickel-based alloys,CMCs offer superior high-temperature resistance and specific strength,making them ideal for next-generation engine hot structures.The inherent anisotropy,heterogeneity,and complex nonlinear behav⁃ior of CMCs,coupled with extreme operating environments,result in strong multi-physics interactions,including aero-thermo-structural,thermo-mechanical,and damage-aeroelastic coupling.These complexities significantly com⁃plicate vibration stability and flutter analysis.The recent research progresses on these problems are systematically ex⁃amined,focusing on multi-field coupling mechanisms,material constitutive and damage evolution models,multi-scale modeling methods,coupled solution strategies,and the influence of key parameters on flutter characteristics.The current challenges are highlighted,including the complexity of high-temperature nonlinear modeling,the effi⁃ciency of multi-field coupling calculations,and the multi-scale modeling of complex weaving structures.Finally,an outlook on future development directions is presented to provide theoretical support for the design and safety assess⁃ment of hot structures of advanced CMCs.
文摘In today’s complex and rapidly changing business environment,the traditional single-organization service model can no longer meet the needs of multi-organization collaborative processing.Based on existing business process engine technologies,this paper proposes a distributed heterogeneous process engine collaboration method for crossorganizational scenarios.The core of this method lies in achieving unified access and management of heterogeneous engines through a business process model adapter and a common operation interface.The key technologies include:Meta-Process Control Architecture,where the central engine(meta-process scheduler)decomposes the original process into fine-grained sub-processes and schedules their execution in a unified order,ensuring consistency with the original process logic;Process Model Adapter,which addresses the BPMN2.0 model differences among heterogeneous engines such as Flowable and Activiti through a matching-and-replacement mechanism,providing a unified process model standard for different engines;Common Operation Interface,which encapsulates the REST APIs of heterogeneous engines and offers a single,standardized interface for process deployment,instance management,and status synchronization.This method integrates multiple techniques to address API differences,process model incompatibilities,and execution order consistency issues among heterogeneous engines,delivering a unified,flexible,and scalable solution for cross-organizational process collaboration.
文摘This work investigates the potential of low-pressure,medium-speed dual-fuel engines for cleaner maritime transportation.The thermodynamic performance of these engines is explored using three alternative fuels:liquefied natural gas(LNG),methanol,and ammonia.A parametric analysis examines the effect of adjustments to key engine parameters(compression ratio,boost pressure,and air-fuel ratio)on performance.Results show an initial improvement in performance with an increase in compression ratio,which reaches a peak and then declines.Similarly,increases in boost pressure and air-fuel ratio lead to linear performance gains.However,insufficient cooling reduces the amount of fuel burned,which hinders performance.Exergy analysis reveals significant exergy destruction within the engine,which ranges from 69.96%(methanol)to 78.48%(LNG).Notably,the combustion process is the leading cause of exergy loss.Among the fuels tested,methanol exhibits the lowest combustion-related exergy destruction(56.41%),followed by ammonia(62.12%)and LNG(73.77%).These findings suggest that methanol is a promising near-term alternative to LNG for marine fuel applications.
文摘Limiting environmental pollution from exhaust emissions from internal combustion engines includes many measures,including encouraging biofuel use because biofuel is environmentally friendly and renewable.A mixture of diesel fuel and vegetable oil is a form of biofuel.However,some properties of the mixed fuel,such as viscosity and density,are higher than those of traditional diesel fuel,affecting the injection and combustion process and reducing power and non-optimal toxic emissions,especially soot emissions.This study uses Kiva-3V software to simulate the combustion process of a diesel-vegetable oil mixture in the combustion chamber of a fishing vessel diesel engine with changes in fuel injection timing.The results show that when increasing the fuel injection timing of a diesel-vegetable oil mixture about 1–2 degrees of crankshaft rotation angle before the top dead center compared to diesel fuel injection timing,the engine power increases,and soot emissions decrease compared to no adjustment.The above simulation research results will help orient the experiments conveniently and reduce costs in the future experimental research process to quantify the fuel system adjustment of fishing vessels’diesel engines when using biofuels,including diesel-vegetable oil mixtures.Thus,the engine’s economic indicators will improve,and emissions that pollute the environment will be limited.
文摘Liquid rocket engine(LRE)fault diagnosis is critical for successful space launch missions,enabling timely avoidance of safety hazards,while accurate post-failure analysis prevents subsequent economic losses.However,the complexity of LRE systems and the“black-box”nature of current deep learning-based diagnostic methods hinder interpretable fault diagnosis.This paper establishes Granger causality(GC)extraction-based component-wise multi-layer perceptron(GCMLP),achieving high fault diagnosis accuracy while leveraging GC to enhance diagnostic interpretability.First,component-wise MLP networks are constructed for distinct LRE variables to extract inter-variable GC relationships.Second,dedicated predictors are designed for each variable,leveraging historical data and GC relationships to forecast future states,thereby ensuring GC reliability.Finally,the extracted GC features are utilized for fault classification,guaranteeing feature discriminability and diagnosis accuracy.This study simulates six critical fault modes in LRE using Simulink.Based on the generated simulation data,GCMLP demonstrates superior fault localization accuracy compared to benchmark methods,validating its efficacy and robustness.
基金supported by the Key project of Hunan Provincial Education Department(Grant Number:22A0485)The Natural Science Foundation of Hunan(Grant Number:2024JJ5293)The Key project of Hunan University of Arts and Science(Grant Number:23ZZ08).
文摘In liquid rocket engines,regenerative cooling technology is essential for preserving structural integrity under extreme thermal loads.However,non-uniform coolant flow distribution within the cooling channels often leads to localized overheating,posing serious risks to engine reliability and operational lifespan.This study employs a three-dimensional fluid–thermal coupled numerical model to systematically investigate the influence of geometric parameters-specifically the number of inlets,the number of channels,and inlet manifold configurations-on flow uniformity and thermal distribution in non-pyrolysis zones.Key findings reveal that increasing the number of inlets from one to three significantly enhances flow uniformity,reducing mass flow rate deviation from 1.2%to below 0.3%.However,further increasing the inlets to five yields only marginal improvements indicating diminishing(<0.1%),returns beyond three inlets.Additionally,temperature non-uniformity at the combustion chamber throat decreases by 37%-from 3050 K with 18 channels to 1915 K with 30 channels-highlighting the critical role of channel density in effective thermal regulation.Notably,while higher channel counts improve cooling efficiency,they also result in increased pressure losses of approximately 18%–22%,emphasizing the need to balance thermal performance against hydraulic resistance.An optimal configuration comprising 24 channels and three inlets was identified,providing minimal temperature gradients while maintaining acceptable pressure losses.The inlet manifold structure also plays a pivotal role in determining flow distribution.Configuration 3(Config-3),which features an enlarged manifold and reduced inlet velocity,achieves a 40%reduction in velocity fluctuations compared to Configuration 1(Config-1).This improvement leads to a more uniform mass flow distribution,with a relative standard deviation(RSD)of less than 0.15%.Furthermore,this design effectively mitigates localized hot spots near the nozzle-where temperature gradients are most severe-achieving a reduction of approximately 1135 K.
基金supported by the National Natural Science Foundation of China(grant number:12102161)the Key Research and Development Program of Jiangxi Province,China(grant number:20232BBE50005)the Natural Science Foundation of Jiangxi Province,China(grant number:20224BAB214060)。
文摘Powder engine as a novel type of engine using high-energy metal powder as fuel and gas,liquid,or solid as oxidizer.These engines exhibit remarkable adaptability,flexible thrust regulation,and multi-pulse start-stop,which have significant application potentials in the fields of near-Earth space development,space propulsion systems,and deep-sea exploration.The scope of this review encompasses the classification and application of powder engines,the classification of powdered fuel supply systems,and the prospective trajectories and pivotal challenges of powder engines and fuel supply technologies.This work points out that although certain ground-based experimental challenges on powder engines have been solved,the relative technology remains in the nascent stages of feasibility demonstration and testing.The pneumatic and motor-driven piston methods currently dominate as the primary means for supplying fuel,and the structure of the piston and intake should be further optimized in the future to promote fuel fluidization and delivery efficiency.The adaptability of powder engines and powdered fuels under different pre-treatment and loading methods should be evaluated.Furthermore,the stability of powdered fuel delivery across varying operational environments,the accuracy of CFD modeling,and the precision of mass flow rate measurement and prediction technologies necessitate further enhancement and refinement.These advancements are crucial for the maturation of powder engine technology and its integration into practical applications.
基金Supported by the National Natural Science Foundation of China and Aviation Fund(60879001)the Natural Science Foundation of Jiangsu Province(BK2009378)+1 种基金the Fundamental Research Fund of Nanjing University of Aeronautics and Astronautics(NS2010179)the Qinglan Project of Jiangsu Province~~
文摘Reliability evaluation for aircraft engines is difficult because of the scarcity of failure data. But aircraft engine data are available from a variety of sources. Data fusion has the function of maximizing the amount of valu- able information extracted from disparate data sources to obtain the comprehensive reliability knowledge. Consid- ering the degradation failure and the catastrophic failure simultaneously, which are competing risks and can affect the reliability, a reliability evaluation model based on data fusion for aircraft engines is developed, Above the characteristics of the proposed model, reliability evaluation is more feasible than that by only utilizing failure data alone, and is also more accurate than that by only considering single failure mode. Example shows the effective- ness of the proposed model.
