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2022 CSAA/IET International Conference on Aircraft Utility systems, AUS 2022

作者： Wang, Chenchen Wang, Yangyang Li, Chaoyue AVIC Nanjing Engineering Institute of Aircraft Systems The Aviation Electromechanical System Integration of Aviation Science and Technology Key Laboratory Nanjing211106 China School of Mechanical and Electrical Engineering Jinling Institute of Technology Nanjing211169 China

ISBN: (数字)9781839537769

ISBN: (纸本)9781839537769

According to the inert gas filling requirements of a certain type of aircraft fuel tank, three different inlet and outlet layout plans are designed. Based on CFD, the simulation calculation of the inert gas filling effect of the fuel tank under different inlet and outlet layout plans is calculated. The changes of the oxygen volume fraction (Vo2) in the gas space in the tank under different inert gas flow rates, concentrations and fuel load are analyzed. The calculations show that with the increase of inerting time, the average Vo2 in the tank decreases, and finally tends to the Vo2 of inert gas. Considering the overall average Vo2 of the tank and the uniform distribution of inert gas in the gas space of each tank, it can be seen that the best inerting performance can be achieved by adopting the inlet and outlet layout plan 3. The calculation results can provide a basis for the optimization of the gas distribution design of the tank inerting system. © 2022 IET Conference Proceedings. All rights reserved.

关键词： Volume fraction

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Instability threshold analysis and optimization of a rotor system considering the Alford force 57

Instability threshold analysis and optimization of a rotor s...

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57th International Conference on Vibroengineering

作者： Fu, Yao Wang, Fei AVIC Jincheng Nanjing Engineering Institute of Aircraft Systems Nanjing211106 China China Aviation Key Laboratory of Science and Technology on Aero Electromechanical System Integration Nanjing211106 China College of Aircraft Engineering Nanchang Hangkong University Nanchang China

Under certain circumstances, the Alford force might induce instability of the rotor system. The mechanism and influence factors of the Alford force induced instability were analyzed with the Jeffcott rotor. Then a method for calculating the instability threshold was proposed. Finally, the optimization model of a high-speed micro-turbojet engine was established to optimize the instability threshold. The results show that the anisotropy of support stiffness and the damping ratio can both improve the threshold of instability. The instability threshold can be greatly improved by optimizing bearing stiffness and diameter of the rotor system. Copyright © 2022 Yao Fu, et al.

关键词： Stability

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Measurement-based Path Loss Prediction and Analysis in Water Scenarios

Measurement-based Path Loss Prediction and Analysis in Water...

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IEEE International Conference on Computational Electromagnetics (ICCEM)

作者： Hanpeng Li Xiaomin Chen Hangang Li Jian Ma Xuchao Ye Lixin Song Taotao Zhang Weizhi Zhong Qiuming Zhu College of Electronic and Information Engineering Nanjing University of Aeronautics and Astronautics Nanjing China Aviation Key Laboratory of Science and Technology on Aero Electromechanical System Integration Nanjing China State Key Laboratory of Complex Electromagnetic Environment Effects on Electronics and Information System Luoyang China

ISBN: (数字)9798350383317

ISBN: (纸本)9798350383324

Unmanned aerial vehicles (UAVs) have enabled the unmanned management of water areas. Path loss (PL) serves as a critical factor that affects the UAV communication quality. In this work, a PL model for UAV channel in water scenarios is proposed, aiming to explore the multidimensional relationship between transceiver distance, carrier frequency, UAV height, and PL by constructing an Artificial Neural Network (ANN). Moreover, channel measurements are conducted in a river area, and the obtained data are analyzed using the proposed ANN model as well as the close-in (CI) model. The analysis results demonstrates that the PL increases initially and then declines as the UAV height increases. The proposed ANN model has higher prediction accuracy than the classic empirical model, and can achieve precise prediction of the PL in water scenarios.

关键词： Analytical models Accuracy Computational modeling Artificial neural networks Predictive models Autonomous aerial vehicles Data models

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Channel Fading Emulation for Highly Dynamic Communication Scenarios

Channel Fading Emulation for Highly Dynamic Communication Sc...

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IEEE International Conference on Computational Electromagnetics (ICCEM)

作者： Sheng Fang Ling Yang Jian Ma Yuetian Xie Maozhong Song Lixin Song Boyu Hua Qiuming Zhu Dan Shi College of Electronic and Information Engineering Nanjing University of Aeronautics and Astronautics Nanjing China Aviation Key Laboratory of Science and Technology on Aero Electromechanical System Integration Nanjing China Electronic Science and Technology Beijing University of Posts & Telecommunications Beijing China

ISBN: (数字)9798350383317

ISBN: (纸本)9798350383324

Highly dynamic communication terminals have a crucial role in future communication networks. In this article, a channel emulator is designed and implemented on a Field Programmable Gate Array (FPGA) platform to generate channel fading for highly dynamic communication. To reproduce the fast time-varying channel characteristics, a hardware time-evolution method of channel parameters based on scenario-dependent information is proposed. The measurement results indicate that the proposed channel emulator achieves continuity in the time evolution of channel parameters, and the Doppler power spectral density of the emulated channel match the theoretical results, validating the effectiveness of the emulator.

关键词： Fading channels Accuracy Power measurement Emulation Time-varying channels Hardware Time measurement

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Probabilistic RUL Prediction based on Nonlinear Wiener Process and Monte Carlo Simulation 15

Probabilistic RUL Prediction based on Nonlinear Wiener Proce...

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15th IEEE Global Reliability and Prognostics and Health Management Conference, PHM-Beijing 2024

作者： Huang, Bing Cao, Liang Liu, Ying Yao, Xiaohan Jiang, Fan Li, Qingyang Shan, Tianmin Wang, Jinglin Aviation Key Laboratory of Science and Technology on Fault Diagnosis and Health Management AVIC United Technology Center for Basic Research on Aircraft System Fault Diagnosis and Health Management AVIC Shanghai Aero Measurement & Controlling Research Institute Shanghai China

ISBN: (纸本)9798350354010

Remaining useful life (RUL) prediction is the core of intelligent operation and maintenance, improving operation and maintenance efficiency and reducing maintenance costs. Aiming at the limitations of RUL prediction methods based on mathematical derivation in terms of adaptability and flexibility, this paper proposes a probabilistic RUL simulation method for complex systems or complex degradation processes. The method constructs a degradation model using a complex nonlinear Wiener process, estimates the model parameters using maximum likelihood estimation, and updates the stochastic parameters based on the Bayesian updating strategy. On this basis, the prediction of probabilistic RUL is realized by the simulation algorithm. Compared with the mathematical derivation method, the prediction of the method proposed in this paper is accurate, which verifies the effectiveness and practicality of the simulation method. In a complex system or complex degradation process, the method in this paper can construct the probabilistic RUL prediction model faster. © 2024 IEEE.

关键词： Prediction models

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Research on Aircraft system Anomaly Detection Method Based on MHAVGAE Model 15

Research on Aircraft System Anomaly Detection Method Based o...

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15th IEEE Global Reliability and Prognostics and Health Management Conference, PHM-Beijing 2024

作者： Jiang, Fan Huang, Bing Yao, Xiaohan Li, Qinyang Cao, Liang Aviation Key Laboratory of Science and Technology on Fault Diagnosis and Health Management AVIC United Technology Center for Basic Research on Aircraft System Fault Diagnosis and Health Management AVIC Shanghai Aero Measurement & Controlling Research Institute Shanghai China

ISBN: (纸本)9798350354010

With the increasing complexity of aircraft systems, there are different degrees of correlation in monitoring aircraft systems, which brings great challenges to anomaly detection in complex systems. In this paper, the method of anomaly detection for complex aircraft systems is studied, and an anomaly detection model based on variational graph autoencoder considering multi-variable coupling is established. Firstly, the detrended correlation quantification system is used to monitor the coupling relationship between variables, and the coupling relationship network is constructed. Secondly, the multi-head attention mechanism is introduced into the variogram autoencoder anomaly detection model to fully extract the hidden features of the network nodes, and quantitatively analyze the changes of the coupling relationship network during the operation of the aircraft system to accurately characterize the system health state. The reconstruction probability is taken as the evaluation index of system running state, and the threshold value of fault warning is determined by the criterion of Gauss distribution theory to realize the timely detection of system anomalies. © 2024 IEEE.

关键词： Aircraft detection

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Overview and Design of Central Maintenance system for Civil Aircraft 15

Overview and Design of Central Maintenance System for Civil ...

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15th IEEE Global Reliability and Prognostics and Health Management Conference, PHM-Beijing 2024

作者： Cao, Liang Wang, Jinglin Li, Qinyang Jiang, Fan Yao, Xiaohan Zhou, Sheng Aviation Key Laboratory of Science and Technology on Fault Diagnosis and Health Management AVIC United Technology Center for Basic Research on Aircraft System Fault Diagnosis and Health Management AVIC Shanghai Aero Measurement & Controlling Research Institute Shanghai China

ISBN: (纸本)9798350354010

In order to ensure the maintenance and support capability level of large-scale aviation equipment, the central maintenance system of large-scale aviation equipment is crucial. It is required to accurately grasp the health status of equipment, conduct real-time monitoring, and timely formulate corresponding maintenance and support strategies based on the fault status of aviation equipment and its various subsystems, combined with ground maintenance and support resources, to achieve precise fault localization. It is of great significance to improve the operational safety of large-scale aviation equipment, reduce maintenance and support costs, and enhance maintenance and support efficiency. It is a landmark system in the intelligent development trend of large-scale aviation equipment and a key subsystem essential for various types of key equipment. © 2024 IEEE.

关键词： Maintenance

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Thermal Management of Turbine Disc Cavity system Using Ffbpnn and Nsga Ii Algorithm

SSRN

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SSRN 2024年

作者： He, Zhenzong Zuo, Min Liang, Shuang Mao, Junkui College of Energy and Power Engineering Nanjing University of Aeronautics and Astronautics Nanjing210016 China Collaborative Innovation Center for Advanced Aero-Engine Beijing100191 China Aviation Key Laboratory of Science and Technology on Aero Electromechanical System Integration Nanjing211106 China

This study addresses the thermal management of the turbine disc cavity system (TDCS) by combining the feed-forward backward propagation neural network (FFBPNN) with the non-dominated sorting genetic algorithm II (NSGA II). First, the heat transfer analysis of the TDCS is carried out using the 1D fluid network method and the 2D finite element method. The impact of different cooling air inlet conditions on the heat transfer performance of the TDCS is investigated. The results show that changing the inlet pressure and temperature significantly affects the heat transfer performance of the TDCS, and the TDCS temperature field can be regulated by the inlet parameters. Then, the prediction model based on the FFBPNN is established to predict the heat transfer performance of the TDCS, and satisfactory result is obtained with mean relative error lower than 1.5% and a coefficient of determination higher than 0.998. Finally, the NSGA II is employed to optimize the cool air inlet condition to achieve thermal management of the TDCS. The Pareto solution set and the optimal solution are obtained. The results indicate that the most comprehensive improvement in the heat transfer performance of the TDCS can be achieved by the present technology. © 2024, The Authors. All rights reserved.

关键词： Temperature control

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Application of WSGSA Model in Predicting Temperature and Soot in C_(2)H_(4)/Air Turbulent Diffusion Flame

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Transactions of Nanjing University of aeronautics and Astronautics 2022年第4期39卷 482-492页

作者： HE Zhenzong ZHU Ruihan DONG Chuanhui MAO Junkui FU Yao College of Energy and Power Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016P.R.China Aviation Key Laboratory of Science and Technology on Aero Electromechanical System Integration Nanjing 211106P.R.China

Soot,a product of insufficient combustion,is usually in the form of aggregate. The multi-scattering of soot fractal aggregates has been proved to play an important role in studying the soot radiative properties,which is rarely considered in predicting the radiative heat transfer in combustion flame. In the present study,based on the weighted sum of gray soot fractal aggregate(WSGSA) model,which is used to predict the temperature field and soot aggregates in turbulent diffusion flame,the flame temperature distribution and soot volume fraction distribution under the conditions of the model without considering radiation,the default radiation model in Fluent software and the WSGSA model are calculated respectively. The results show that the flame temperature will be seriously overestimated without considering radiation and the maximum relative discrepancy of flame centerline temperature is about 64.5%. The accuracy will be improved by the default radiation model in the Fluent software,but the flame temperature is still overestimated and the maximum relative discrepancy of flame centerline temperature is about 42.1%. However,more satisfactory results can be obtained by the WSGSA model,and the maximum relative discrepancy of flame centerline temperature is no more than 15.3%. Similar conclusions can also be obtained in studying the temperature distribution along different flame heights. Moreover,the soot volume fraction can be predicted more accurately with the application of the WSGSA model. Both without considering radiation and using the default radiation model in the Fluent software will result in the underestimating of soot volume fraction. All the results reveal that the WSGSA model can be used to predict the temperature and soot aggregates in the CH/air turbulent diffusion flame.

关键词： radiative heat transfer WSGSA model soot radiation turbulent diffusion flame soot aggregate

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Learning to Update Engine Models with Deep Reinforcement Learning

Learning to Update Engine Models with Deep Reinforcement Lea...

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International Symposium on Autonomous systems (ISAS)

作者： RuoYan Yu Bei Li SuMu Shi Cong Peng YuNan Zhou XiangYu Du School of Automation Nanjing University of Aeronautics and Astronautics Nanjing China Aviation Key Laboratory of Science and Technology on Aero Electromechanical System Integration Nanjing Engineering Institute of Aircraft Systems Nanjing China

Model updating can reduce the reality gap between the digital space and physical space, which is essential for accurately building digital models of aviation equipment. However, with data requirements and the complexity of application environments continue to increase, traditional update techniques show great limitations. The main reason is that traditional update technologies are limited by computational efficiency, resulting in the inability to balance accuracy and real-time. In this work, we propose a model update method based on reinforcement learning to infer model parameters. The proposed method does not require any ground truth parameters. Experimental results on the twin-rotor turbofan engine model verify the superiority of the proposed method compared with other state-of-the-art methods.

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