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Experimental Study on Geometry Characteristics of Turbulent Premixed Flames for Natural Gas/Air Mixtures

Journal of Thermal Science 2025年第1期 268-282页

作者： ZHENG Weilin WANG Qijiao XIAO Huahua CHEN Xiaoxiao XIE Fan ZENG Wen Liaoning key Lab of advanced Test technology for Aerospace Propulsion System Shenyang Aerospace University State key laboratory of Fire Science University of science and Technology of China AVIC Shenyang aircraft design and Research Institute

In this study,focusing on the geometry characteristics of spherical expanding flame,the turbulent premixed flames of natural gas/air mixtures were investigated in a fan-stirred turbulent *** effects of initial temperature（T=300-400 K）,initial pressure（P=0.1-0.3 MPa）,turbulence intensity（u'=1.0-2.7 m/s）,oxygen volumetric percentage(φ（O2）=15%-21%) and carbon dioxide volumetric percentage(φ（CO2）=0-20%)were delved *** flame profile under the Cartesian coordinate system was derived from the schlieren images taken by the high-speed ***,from both macroscopic and microscopic perspectives,the influence of experimental conditions on the flame geometry characteristics was explored through flame front extraction,wavelet decomposition and network *** results demonstrate that for significant flame wrinkling,changes in species concentrations and turbulence intensity have more pronounced effects on the flame wrinkling *** wrinkling of the flame front maintains a certain degree of similarity,as evidenced by the locally concentrated distribution of the angles of the maximum fluctuation *** disturbance energy under large-scale（D6-D8） disturbances exhibits relatively high values with a similar trend,exerting a significant impact on the geometry characteristics of the flame *** peaks of correlation degree are scattered either with the decomposition scale or the development of flame radius,indicating no linear correlation between different detail ***,the probability distribution of node degrees in key wrinkled regions exhibits different trends with that of large-scale wrinkling and disturbance energy,especially with changes in initial *** occurs because the number of key wrinkles varies based on the perturbation's strength or the region's ***,an increase in the fluctuation frequency of the flame's local radius may not necessarily lead to an increase in the number of key folded regions.

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Multi-objective optimization of aircraft design for emission and cost reductions

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Chinese Journal of Aeronautics 2014年第1期27卷 52-58页

作者： Wang Yu Yin Hailian Zhang Shuai Yu Xiongqing key laboratory of Fundamental Science for national defense Advanced Design Technology of Flight VehicleNanjing University of Aeronautics and Astronautics

Pollutant gases emitted from the civil jet are doing more and more harm to the environ- ment with the rapid development of the global commercial aviation transport. Low environmental impact has become a new requirement for aircraft design. In this paper, estimation method for emis- sion in aircraft conceptual design stage is improved based on the International Civil Aviation Orga- nization （ICAO） aircraft engine emissions databank and the polynomial curve fitting methods. The greenhouse gas emission （CO2 equivalent） per seat per kilometer is proposed to measure the emis- sions. An approximate sensitive analysis and a multi-objective optimization of aircraft design for tradeoff between greenhouse effect and direct operating cost （DOC） are performed with five geom- etry variables of wing configuration and two flight operational parameters. The results indicate that reducing the cruise altitude and Mach number may result in a decrease of the greenhouse effect but an increase of DOC. And the two flight operational parameters have more effects on the emissions than the wing configuration. The Pareto-optimal front shows that a decrease of 29.8% in DOC is attained at the expense of an increase of 10.8% in greenhouse gases.

关键词： aircraft design Direct Operating Cost(DOC) Emission Global warming potential(GWP) Greenhouse effect

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Aerodynamic/Stealthy/Structural Multidisciplinary design Optimization of Unmanned Combat Air Vehicle

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Chinese Journal of Aeronautics 2009年第4期22卷 380-386页

作者： Hu Tianyuan,Yu Xiongqing key laboratory of Fundamental Science for national defense-advanced design technology of Flight Vehicle,Nanjing University of Aeronautics and Astronautics,Nanjing 210016,China [a]key laboratory of Fundamental Science for national defense-advanced design technology of Flight Vehicle Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

An optimization strategy is proposed to deal with the aerodynamic/stealthy/structural multidisciplinary design optimization （MDO） issue of unmanned combat air vehicle （UCAV）. In applying the strategy, the MDO process is divided into two levels, i.e. system level optimization and subsystem level optimization. The system level optimization is to achieve optimized system objective （or multi-objective） through the adjustment of global external configuration design variables. The subsystem level optimization consists of the aerodynamic/stealthy integrated design and the structural optimization. The aerodynamic/stealthy integrated design aims at achieving the minimum aerodynamic drag coefficient under the constraint of stealthy requirement through the adjustment of local external configuration design variables. The structural optimization is to minimize the structural weight by adjusting the dimefisions of structural components. A flowchart to implement this strategy is presented. The MDO for a flying-wing configuration of UCAV is employed to illustrate the detailed process of the optimization. The results indicate that the overall process of the surrogate-based two-level optimization strategy can be implemented automatically, and quite reasonable results are obtained.

关键词： aircraft design multidisciplinary design optimization aerodynamics radar cross section structure

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Structural reliability analysis using a hybrid HDMR-ANN method

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Journal of Central South University 2017年第11期24卷 2532-2541页

作者： Bhaw Nath Jha LI Hong-shuang key laboratory of Fundamental Science for national defense-advanced design technology of Flight Vehicles Nanjing University of Aeronautics and AstronauticsNanjing 210016China

A new hybrid method is proposed to estimate the failure probability of a structure subject to random parameters. The high dimensional model representation(HDMR) combined with artificial neural network(ANN) is used to approximate implicit limit state functions in structural reliability analysis. HDMR facilitates the lower dimensional approximation of the original limit states function. For evaluating the failure probability, a first-order HDMR approximation is constructed by deploying sampling points along each random variable axis and hence obtaining the structural responses. To reduce the computational effort of the evaluation of limit state function, an ANN surrogate is trained based on the sampling points from HDMR. The component of the approximated function in HDMR can be regarded as the input of the ANN and the response of limit state function can be regarded as the target for training an ANN surrogate. This trained ANN surrogate is used to obtain structural outputs instead of directly calling the numerical model of a structure. After generating the ANN surrogate, Monte Carlo simulation(MCS) is performed to obtain the failure probability, based on the trained ANN surrogate. Three numerical examples are used to illustrate the accuracy and efficiency of the proposed method.

关键词： high dimensional model representation structural reliability artificial neural network failure probability

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Two Degree-of-Freedom Dynamic Theoretical Model on Tile Thermal Protection System

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Transactions of Nanjing University of Aeronautics and Astronautics 2019年第1期36卷 139-145页

作者： HUANG Jie YAO Weixing KONG Bin YANG Jiayong WANG Man ZHANG Qingmao key laboratory of Fundamental Science for national defense-advanced design technology of Flight Vehicle Nanjing University of Aeronautics and Astronautics State key laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and Astronautics AVIC Chengdu aircraft design and Research Institute

In order to study the dynamic behaviors of the thermal protection system(TPS)and dynamic strength of the strain-isolation-pad(SIP),a two degree-of-freedom dynamic theoretical model is presented under the acoustic excitation and base excitation. The tile and SIP are both considered as the elastic body and simplified as a mass point,a linear spring and a damping element. The theoretical solutions are derived,and the reasonability of theoretical model is verified by comparing the theoretical results with the numerical results. Finally,the influences on the dynamic responses of TPS by the structural damping coefficient of TPS,elasticity modulus and thickness of SIP are *** results show that the material with higher damping,and SIP with thicker size and lower elastic modulus should be considered to reduce the dynamic responses and intensify the security of TPS. The researches provide a theoretical reference for studying the dynamic behaviors of TPS and the dynamic strength of SIP. Besides,the dynamic theoretical model can be used as a quick analysis tool for analyzing the dynamic responses of TPS during the initial design phase.

关键词： thermal protection system dynamic theoretical model acoustic excitation base excitation

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Integrated optimization on aerodynamics-structure coupling and flight stability of a large airplane in preliminary design

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Chinese Journal of Aeronautics 2018年第6期31卷 1258-1272页

作者： Xiaozhe WANG Zhiqiang WAN Zhu LIU Chao YANG School of Aeronautic Science and Engineering Beihang University key laboratory of aircraft advanced design technology Ministry of Industry and Information

The preliminary phase is significant during the whole design process of a large airplane because of its enormous potential in enhancing the overall performance. However, classical sequential designs can hardly adapt to modern airplanes, due to their repeated iterations, long periods, and massive computational burdens. Multidisciplinary analysis and optimization demonstrates the capability to tackle such complex design issues. In this paper, an integrated optimization method for the preliminary design of a large airplane is proposed, accounting for aerodynamics, structure, and stability. Aeroelastic responses are computed by a rapid three-dimensional flight load analysis method combining the high-order panel method and the structural elasticity correction. The flow field is determined by the viscous/inviscid iteration method, and the cruise stability is evaluated by the linear small-disturbance theory. Parametric optimization is carried out using genetic algorithm to seek the minimal weight of a simplified plate-beam wing structure in the cruise trim condition subject to aeroelastic, aerodynamic, and stability constraints, and the optimal wing geometry shape, front/rear spar positions, and structural sizes are obtained simultaneously. To reduce the computational burden of the static aeroelasticity analysis in the optimization process, the Kriging method is employed to predict aerodynamic influence coefficient matrices of different aerodynamic shapes. The multidisciplinary analyses guarantee computational accuracy and efficiency, and the integrated optimization considers the coupling effect sufficiently between different disciplines to improve the overall performance, avoiding the limitations of sequential approaches utilized currently.

关键词： Aeroelasticity Integrated optimization Multidisciptinary analysis Large airplane Preliminary design

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Integration of Manufacturing Cost into Structural Optimization of Composite Wings

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Chinese Journal of Aeronautics 2010年第6期23卷 670-676页

作者： Yin Hailian Yu Xiongqing Research Institute of Unmanned aircraft Nanjing University of Aeronautics and Astronautics Nanjing 210016 China key laboratory of Fundamental Science for national defense--advanced design technology of Flight Vehicle Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

The manufacturing cost is a significant factor that must be considered in the structural design of a composite wing. A multi-objective optimization method for the tradeoff between manufacturing cost and weight of composite wing structure is de- veloped by integrating the manufacturing cost model into the traditional wing structural optimization. A two-level optimization method is proposed to carry out the tradeoff between manufacturing cost and weight, in which the design variables include both structural layout and dimensions and a cost model is incorporated into structural optimization. The manufacturing cost model for a composite wing and the detail procedure for solving this tradeoff problem are presented. The application of the method to the composite wing structural design of an unmanned aerial vehicle is illustrated to verify the method. The application indicates that the method is able to find the Pareto optimal set of minimum structural weight and manufacturing cost. Based on the Pareto optimal set, one can conduct the tradeoff between manufacturing cost and weight of wing structures.

关键词： wings composite materials costs structure optimization

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Internal phase control of fiber laser array based on photodetector array

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Chinese Physics B 2024年第7期33卷 320-326页

作者：靳凯凯龙金虎常洪祥粟荣涛张嘉怡陈思雨马阎星周朴 College of advanced Interdisciplinary Studies National University of Defense TechnologyChangsha 410073China Nanhu Laser laboratory National University of Defense TechnologyChangsha 410073China Hunan Provincial key laboratory of High Energy Laser technology National University of Defense TechnologyChangsha 410073China

Coherent beam combining(CBC) of fiber laser array is a promising technique to realize high output power while maintaining near diffraction-limited beam quality. To implement CBC, an appropriate phase control feedback structure should be established to realize phase-locking. In this paper, an innovative internal active phase control CBC fiber laser array based on photodetector array is proposed. The dynamic phase noises of the laser amplifiers are compensated before being emitted into free space. And the static phase difference compensation of emitting laser array is realized by interference measurement based on photodetector array. The principle of the technique is illustrated and corresponding simulations are carried out, and a CBC system with four laser channels is built to verify the technique. When the phase controllers are turned on, the phase deviation of the laser array is less than λ/20, and ~ 95% fringe contrast of the irradiation distribution is obtained. The technique proposed in this paper could provide a reference for the system design of a massive high-power CBC system.

关键词： fiber laser laser array coherent beam combining internal phase control

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Multi-scale strength analysis of bolted connections used in integral thermal protection system

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Chinese Journal of Aeronautics 2018年第8期31卷 1728-1740页

作者： Heng LIANG Yuqing WANG Mingbo TONG Junhua ZHANG College of Aerospace Engineering Ministerial Key Discipline Laboratory of Advanced Design Technology of Aircraft Nanjing University of Aeronautics & Astronautics Nanjing 210016 China Shanghai aircraft design and Research Institute Shanghai 201210 China

Efficient and accurate strength analysis of bolted connections is essential in analyzing the integral thermal protection system（ITPS） of hypersonic vehicles, since the system bears severe loads and structural failures usually occur at the connections. Investigations of composite mechanical properties used in ITPS are still in progress as the architecture of the composites is complex. A new method is proposed in this paper for strength analysis of bolted connections by investigating the elastic behavior and failure strength of three-dimensional C/C orthogonal composites used in ITPS. In this method a multi-scale finite element method incorporating the global–local method is established to ensure high efficiency in macro-scale and precision in meso-scale in *** results reveal that predictions of material properties show reasonable accuracy compared with test results. And the multi-scale method can analyze the strength of connections efficiently and accurately.

关键词： Bolted connection Composite Multi-scale method Strength analysis Thermal Protection System

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Bioinspired sensing-memory-computing integrated vision systems: biomimetic mechanisms, design principles, and applications

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Science China(Information Sciences) 2024年第5期67卷 5-27页

作者： Yujie HUANG Yinlong TAN Yan KANG Yabo CHEN Yuhua TANG Tian JIANG Institute for Quantum Information and State key laboratory of High Performance Computing College of Computer National University of Defense Technology College of advanced Interdisciplinary Studies National University of Defense Technology Institute for Quantum Science and technology College of ScienceNational University of Defense Technology

With the explosion of sensory data in the Internet of Things(Io T) era, conventional machine vision systems are becoming increasingly difficult to meet the requirements of high efficiency, low energy consumption, and low latency due to their inherent shortcomings of separate sensing, memory, and computing units. Inspired by the retina and neuromorphic computing, the sensing-memory-computing integrated vision system(SMCVS) that features low power consumption, low latency, and high parallelism has been considered a promising technology to surpass the von Neumann architecture and realize strong artificial ***, novel materials like two-dimensional semiconductors and quantum dots with novel optoelectronic performance provide hardware carriers for implementing integrated sensing-memory-computing architectures,attracting considerable attention. This paper reviews the recent research progress in bioinspired vision systems in terms of biomimetic mechanisms, design principles, computational architectures, and ***, the biomimetic mechanisms are illustrated to guide the design of high-performance artificial visual perception systems. Then the research progress of optoelectronic-synapse-based bioinspired vision systems in the device principles and applications including image filtering, color recognition, visual adaptation, and motion detection are summarized. Finally, the challenges and future developing directions of the SMCVS are provided regarding bionic application, architecture design, and device fabrication.

关键词： sensing-memory-computing architecture neuromorphic computing retinomorphic device image recognition visual system

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