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Effect of cavity flame holder configuration on combustion flow field performance of integrated hypersonic vehicle

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Science China(Technological Sciences) 2010年第10期53卷 2725-2733页

作者： HUANG Wei, LUO ShiBin, LIU Jun & WANG ZhenGuo institute of Aerospace & Materials Engineering, National University of defense technology, Changsha 410073, China 1. institute of Aerospace & Materials Engineering National University of Defense Technology Changsha 410073 China

As one of the most common methods to be used as the flame holding mechanism in the propulsion system of the integrated hypersonic vehicle,the research of cavity flame holder has drawn an ever increasing attention of many researchers. The two-dimensional coupled implicit NS equations,the standard k-ε turbulent models and the finite-rate/eddy-dissipation reaction model were employed to simulate the experimental items arranged by the orthogonal design,and the variance analysis method was used to investigate the effects of the geometric parameters of the cavity flame holder on the aero-propulsive performance of the integrated hypersonic vehicle,namely the depth,the ratio of length-to-depth and the sweepback angle. The obtained results show that the geometric parameters make only a little difference to the aero-propulsive performance of the vehicle in the range considered in this paper,and the cavity flame holder with its sweepback angle 45° can satisfy the performance requirement of the integrated hypersonic vehicle further. The hydrogen injected from the upper stream of the cavity makes the boundary layer separate on the lower wall of the engine,and a separate region appears in the upper stream and down stream of the injection slot,respectively.

关键词： aerospace propulsion system integrated hypersonic vehicle cavity flame holder variance analysis orthogonal design aero-propulsive performance

Laser-Chirp Controlled Terahertz Wave Generation from Air Plasma

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Chinese Physics Letters 2023年第4期40卷 34-39页

作者：徐行黄崟东张喆林刘金磊娄菁高明鑫吴世有方广有赵增秀陈燕萍盛政明常超 Aerospace Information Research institute Chinese Academy of SciencesBeijing 100094China innovation Laboratory of Terahertz Biophysics National Innovation Institute of Defense TechnologyBeijing 100071China Key Laboratory of Electromagnetic Radiation and Sensing technology Chinese Academy of SciencesBeijing 100190China School of Electronic Electrical and Communication EngineeringUniversity of Chinese Academy of SciencesBeijing 100049China Tsung-Dao Lee institute Shanghai Jiao Tong UniversityShanghai 200240China Key Laboratory for Laser Plasmas School of Physics and AstronomyShanghai Jiao Tong UniversityShanghai 200240China Collaborative innovation Center of IFSA Shanghai Jiao Tong UniversityShanghai 200240China Department of Physics College of SciencesNational University of Defense TechnologyChangsha 410073China

We report the laser-chirp controlled terahertz(THz) wave generation from two-color-laser-induced air *** experimental results reveal that the THz wave is affected by both the laser energy and chirp,leading to radiation minima that can be quantitatively reconstructed using the linear-dipole-array *** phase difference between the two colors,determined by the chirp and intensity of the laser,can account for the radiation ***,we observe an asynchronous variation in the generated THz spectrum,which suggests a THz frequency-dependent phase matching between the laser pulse and THz *** results highlight the importance of laser chirp during the THz wave generation and demonstrate the possibility of modulating the THz yields and spectrum through chirping the incident laser *** work can provide valuable insights into the mechanism of plasma-based THz wave generation and offer a unique means to control THz emissions.

关键词： spectrum matching dipole

Review of atomization mechanism and spray characteristics of a liquid jet in supersonic crossflow

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Chinese Journal of Aeronautics 2023年第8期36卷 1-23页

作者： Yaozhi ZHOU Zun CAI Qinglian LI Chenyang LI Mingbo SUN Peibo LI Hongbo WANG College of Aerospace Science and Engineering National University of Defense TechnologyChangsha 410073China Beijing institute of Tracking and Telecommunication technology Beijing 100094China

The injection and atomization process of a liquid fuel jet is critical for an ignition start of a scramjet ***-mounted crossflow injection strategy is widely used in scramjet combustors,avoiding high total pressure loss and allowing the liquid fuel to rapidly undergo atomization,mixing,and *** this review,research progress on a liquid jet in supersonic crossflow was evaluated from aspects of atomization mechanism and spray *** a liquid jet is injected into a supersonic crossflow,primary and secondary breakups occur *** surface instability of liquid can significantly affect the breakup *** review discusses the current understanding of the breakup process and spray characteristics of a liquid jet in supersonic crossflow including the mechanism of atomization and the characteristics of distribution and *** development of windward Rayleigh-Taylor(R-T)unstable waves is the main factor in column *** development of Kelvin-Helmholtz(K-H)unstable waves along the circumferential direction of the jet or droplets is the main factor of surface and droplet *** liquid-gas momentum ratio is the most important factor affecting the penetration *** span width of the liquid jet is affected by the windward *** and coalescence lead to a transformation of the size distribution of droplets from S-or C-shaped to I-shaped,and the velocity distribution of the droplets on the central symmetry plane has a mirrored *** droplet distribution on the spanwise cross-section retains a structure similar to an“Ω”*** last,some promising recommendations have been proposed,namely a theoretical predictive model which can describe the breakup mechanism of a liquid jet,the distribution characteristics and droplets size distribution of a liquid jet under a cavity combustion chamber,especially for enthalpy flows with complex wave structures.

关键词： Atomization Liquid fuels Spraynozzles Supersonicflow Two phase flow

Extended ambiguity function for bistatic MIMO radar

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Journal of Systems Engineering and Electronics 2012年第2期23卷 195-200页

作者： Haowen Chen Yiping Chen Zhaocheng Yang Xiang Li institute of Space Electronic Information technology School of Electronic Science and EngineeringNational University of Defense TechnologyChangsha 410073P.R.China

This paper derives the extended ambiguity function for a bistatic multiple-input multiple-output （MIMO） radar system, which includes the whole radar system parameters： geometric sensor configuration, waveforms, range, range rate, target scattering and noise characteristics. Recent research indicates the potential pa- rameter estimate performance of bistatic MIMO radars. And this ambiguity function can be used to analyze the parameter estimate performance for the relationship with the Cramer-Rao bounds of the estimated parameters. Finally, some examples are given to demonstrate the good parameter estimate performance of the bistatic MIMO radar, using the quasi-orthogonal waveforms based on Lorenz chaotic systems.

关键词： bistatic multiple-input multiple-output (MIMO) radar ambiguity function parameter estimate Cramer-Rao bound (CRB) quasi-orthogonal waveforms.

Joint Trajectory and Passive Beamforming Optimization in IRS-UAV Enhanced Anti-Jamming Communication Networks

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China Communications 2022年第5期19卷 191-205页

作者： Zhifeng Hou Jin Chen Yuzhen Huang Yijie Luo Ximing Wang Jiangchun Gu Yifan Xu Kailing Yao PLA Army Engineering University Nanjing 210007China Artificial Intelligence Research Center Defense Innovation InstituteBeijing 100166China School of Information and Communication Beijing University of Posts and TelecommunicationsBeijing 100876China College of Information and Communication National University of Defense TechnologyWuhan 430010China

This paper investigates the anti-jamming communication scenario where an intelligent reflecting surface(IRS)is mounted on the unmanned aerial vehicle(UAV)to resist the malicious jamming *** from existing works,we consider the dynamic deployment of IRS-UAV in the environment of the mobile user and unknown ***,a joint trajectory and passive beamforming optimization approach is proposed in the IRS-UAV enhanced *** detail,the optimization problem is firstly formulated into a Markov decision process(MDP).Then,a dueling double deep Q networks multi-step learning algorithm is proposed to tackle the complex and coupling decision-making ***,simulation results show that the proposed scheme can significantly improve the anti-jamming communication performance of the mobile user.

关键词： intelligent reflecting surface unmanned aerial vehicle deep reinforcement learning trajectory optimization

Architecture for Cellular Enabled Integrated Communication and Sensing Services

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China Communications 2023年第9期20卷 59-77页

作者： Bo Liu Qixun Zhang Zheng Jiang Dongsheng Xue Chenlong Xu Bowen Wang Xiaoming She Jinlin Peng School of Information and Communication Engineering Beijing University of Posts and TelecommunicationsBeijing 100876China China Telecom Corporation Limited Beijing Research institute Beijing 102209China Artificial Intelligence Research Center National Innovation Institute of Defense TechnologyBeijingChina

There is growing interest in the integrated sensing and communication(ISAC)to extend the 5G+/6G network capabilities by introducing sensing *** the solutions for mono-static or bi-static ISAC have shown feasibility and benefits based on existing 5G physical layer design,whether and how to coordinate multiple ISAC devices to better exert networking performance are rarely discussed.3 rd Partnership Project(3GPP)has initiated the ISAC use cases study,and the follow-up studies for network architecture could be *** this article,we focus on gNB-based sensing mode and propose ISAC functional framework with given of highlevel service procedures to enable cellular based ISAC *** the proposed ISAC framework,three types of network functions for sensing service as Sensing Function(SF),lightweight-Edge Sensing Function(ESF)and full-version-ESF are designed with interaction with network nodes to fulfill the latency requirements of ISAC use ***,with simulation evaluations and hardware testbed results,we further verify the performance benefit and feasibility to enable ISAC in 5G for the gNB-based sensing mode with new design on SF and related signaling protocols.

关键词： integrated sensing and communication(ISAC) network architecture 5G system

Active formatting modulation of electromagnetically induced transparency in metamaterials

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Chinese Optics Letters 2020年第9期18卷 64-68页

作者： Hao Sun Yuhua Tang Yuze Hu Jie You Hengzhu Liu Xin Zheng College of Computer National University of Defense TechnologyChangsha 410073China College of Advanced Interdisciplinary Studies National University of Defense TechnologyChangsha 410073China National innovation institute of defense technology Beijing 100010China

We experimentally demonstrate for the first time an active all-optical ultrafast modulation of electromagnetically induced transparency-like effect in a hybrid device of sapphire/Si/metamaterial. From numerical simulations, it can be deducted that the tuning process is attributed to the coupling between the dark mode existing in split-ring resonators and the bright mode existing in cut wire resonators. The transmission amplitude modulation is accompanied by the slow-light effect. In addition, the ultrafast formation process is measured to be as fast as 2 ps. This work should make an important contribution to novel chip-scale photonic devices and terahertz communications.

关键词： terahertz metamaterials ultrafast photoswitching electromagnetically induced transparency all-optical device

Research status of key techniques for shock-induced combustion ramjet(shcramjet) engine

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Science China(Technological Sciences) 2010年第1期53卷 220-226页

作者： HUANG Wei,QIN Hui,LUO ShiBin & WANG ZhenGuo institute of Aerospace & Materials Engineering,National University of defense technology,Changsha 410073,China 1. institute of Aerospace & Materials Engineering National University of Defense Technology Changsha 410073 China

As one of the most promising propulsion systems in the future,shock-induced combustion ramjet engine can remedy the disadvantages in the integrated design of scramjet engine and *** can shorten the length of the combustor,lighten the structure weight of the engine and keep better performance in a broad range of flight Mach *** elementary principle of shock-induced combustion ramjet engine is *** key technologies of this kind of propulsion system are described,while their research status is presented in *** on the development of shcramjet engine in China is put forward.

关键词： aerospace propulsion system shock-induced combustion ramjet engine premature ignition premixed efficiency denotation

Enhanced high-temperature strength of HfNbTaTiZrV refractory high-entropy alloy via Al_(2)O_(3)reinforcement

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Journal of Materials Science & technology 2022年第28期123卷 191-200页

作者： Bingjie Wang Qianqian Wang Nan Lu Xiubing Liang Baolong Shen School of Materials Science and Engineering Jiangsu Key Laboratory for Advanced Metallic MaterialsSoutheast UniversityNanjing 211189China School of Materials Science and Engineering Jiangsu Key Laboratory of Advanced Structural Materials and Application TechnologyNanjing Institute of TechnologyNanjing 211167China defense innovation institute Academy of Military ScienceBeijing 100071China

Novel composites of HfNbTaTiZrV refractory high-entropy alloy(RHEA)reinforced with 0–4 vol.%Al_(2)O_(3)particles have been synthesized by vacuum arc *** microstructure evolution,compressive mechanical properties at room and elevated temperatures,as well as strengthening mechanism of the composites were *** HfNbTaTiZrV RHEA reinforced with 4 vol.%Al_(2)O_(3)displayed excellent phase stability at elevated temperatures.A superior compressive yield strength of 2700 MPa at room temperature,1392 MPa at 800°C,and 693 MPa at 1000°C was obtained for this *** improved yield strength resulted from multiple strengthening mechanisms caused by Al_(2)O_(3)addition,including solution strengthening,interstitial strengthening,grain boundary strengthening,and dispersion ***,the effects of interstitial strengthening increased with temperature and was the main strengthening mechanism at elevated *** findings not only promote the development of oxidereinforced RHEAs for challenging engineering applications but also provide guidelines for the design of light refractory materials with multiple strengthening mechanisms.

关键词： Al_(2)O_(3)-reinforcement HfNbTaTiZrV Refractory high-entropy alloy Interstitial strengthening