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An integration method based on a novel combined flow for aerodynamic configuration of strutjet engine

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Chinese Journal of Aeronautics 2021年第9期34卷 156-167页

作者： Longsheng XUE Chuan cheng chengpeng WANG keming cheng College of Aerospace Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China Key Laboratory of Unsteady Aerodynamics and Flow Control Ministry of Industry and Information TechnologyNanjing University of Aeronautics and AstronauticsNanjing 210016China Aerospace System Engineering Shanghai Shanghai 201100China

In this paper a novel design method of aerodynamic configuration is proposed to integrate forebody,strut and inlet for strutjet engine,and a model at design point of Mach number6 is generated to investigate the aerodynamic performance by both simulations and experiments.The basic flow field employed by proposed method is a combined flow named IBB,which is combined by Internal Conical Flow A(ICFA),truncated Busemann flow I(BI)for external section,and truncated Busemann flow II(BII)for internal section.The model configuration is generated by streamline tracing method from basic flow field,in which the forebody section is traced from ICFA and BI flows,and the inlet as well as strut section is traced from BII flow.The simulations in Mach number 4,5,and 6 demonstrate uniform starting flow fields with relatively high total pressure recovery,which agree well with experiments in wind tunnel.Additionally,in low Mach number cases,this inlet could start at Mach number 3 while it is unstarted at Mach number 2.7;in high Mach number cases,a uniform flow could still exist in Mach number 6.5 while a relatively strong shock wave boundary layer interaction is found in cowl area of Mach number 7 case,indicating the inlet designed by proposed method works in a relatively wide Mach number range.

关键词： Airframe-propulsion integration Busemann flow Combined flow Hypersonics Wind tunnel test

The model of hydrocarbon generation and evolution for coal and macerals in the Tuha Basin

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Chinese Science Bulletin 1998年第21期43卷 1826-1830页

作者： Changyi Zhao keming cheng China Natl Petr Corp Res Inst Petr Explorat & Dev Beijing 100083 Peoples R China

By means of Py-GC, 13C NMR and fluorescent analysis, the properties of hydrocarbon generation of macerals are determined, and the evolution model of hydrocarbon generation is established for macerals and coal of the Tuha Basin. There are two stages of oil generation for the coal of the Tuha Basin, whose R+o values are 0.40-0.80 and 0.90-1.20 respectively.

关键词： Tuha Basin hydrocarbon from coal hydrocarbon generation and evolution.

Numerical and experimental investigation into hypersonic boundary layer transition induced by roughness elements

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Chinese Journal of Aeronautics 2019年第3期32卷 559-567页

作者： Hao DONG Shicheng LIU Xi GENG Song LIU Liming YANG keming cheng Department of Aerodynamics Nanjing University of Aeronautics and Aeronautics Department of Mechanical Engineering National University of Singapore

In this work, the Direct Numerical Simulation(DNS) and Oil-Film Interferometry(OFI)technique are used to investigate the hypersonic boundary layer transition induced by single and double roughness elements at Mach number 5. For single roughness, the DNS results showed that both horseshoe vortices and hairpin vortices caused by shear layer instability can affect the boundary layer instability. The generation of the near-wall unstable structure is the key point of boundary layer transition behind the roughness element. At the downstream of the roughness element, the interaction between horseshoe vortices and hairpin vortices will spread in the spanwise direction.For double roughness elements, the effect of the spacing between roughness elements on the transition is studied. It is found that the case of higher spacing between roughness elements is more effective for inducing transition than the lower one. The interaction between two adjacent roughness elements can suppress the evolution of horseshoe vortices in the downstream and trigger the instability of shear layer. Thus, the transition will be suppressed accordingly.

关键词： Boundary layer transition Hypersonic Direct numerical simulation (DNS) Oil-film interferometry Roughness elements

Woody plant cell walls:Fundamentals and utilization

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Molecular Plant 2024年第1期17卷 112-140页

作者： Wei Li Ying-Chung Jimmy Lin Ying-Lan Chen chenguang Zhou Shuang Li Nette De Ridder Dyoni M.Oliveira Lanjun Zhange Baocai Zhang Jack P.Wang Changzheng Xu Xiaokang Fu keming Luo Ai-Min Wu Taku Demura Meng-Zhu Lu Yihua Zhou Laigeng Li Toshiaki Umezawa Wout Boerjan Vincent L.Chiang State Key Laboratory of Tree Genetics and Breeding Northeast Forestry UniversityHarbin 150040China Department of Life Science National Taiwan UniversityTaipeiTaiwanChina Department of Biotechnology and Bioindustry Sciences College of Bioscience and BiotechnologyNational Cheng Kung UniversityTainanTaiwanChina Department of Plant Biotechnology and Bioinformatics Ghent UniversityTechnologiepark 719052 GhentBelgium VIB Center for Plant Systems Biology Technologiepark 719052 GhentBelgium State Key Laboratory of Plant Genomics Insttute of Genetics and Developmental Biology Chinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China Forest Biotechnology Group Department of Forestry and Environmental ResourcesNorth Carolina State UniversityRaleighNC 27695USA Chongqing Key Laboratory of Plant Resource Conservation and Germplasm Innovation Integrative Science Center of Germplasm CreationSchool of Life SciencesSouthwest UniversityChongqing 400715China Guangdong Key Laboratory for Innovative Developmentand Utilization of Forest Plant Germplasm College of Forestry and Landscape ArchitecturesSouth China Agricultural UniversityGuangzhou510642China Center for Digital Green-innovation Nara Institute of Science and TechnologykomaNara 630-0192Japan State Key Laboratory of Subtropical Siviculture College of Forestry and BiotechnologyZhejang A&F UniversityHangzhou 311300China CAS Center for Excellence in Molecular Plant Sciences Chinese Academy of Sciences300 Fenglin RoadShanghai 200032China Laboratoryof MetabolicScienceofForest Plants and Microorganisms Rsearch Institute for Sustainable HumanosphereKyoto UniversityUjiKyoto 611-0011 Japan

Cell walls in plants,particularly forest trees,are the major carbon sink of the terrestrial ecosystem.Chemical and biosynthetic features of plant cell walls were revealed early on,focusing mostly on herbaceous model species.Recent developments in genomics,transcriptomics,epigenomics,transgenesis,and associated analytical techniques are enabling novel insights into formation of woody cell walls.Here,we review multilevel regulation of cell wall biosynthesis in forest tree species.We highlight current approaches to engineering cell walls as potential feedstock for materials and energy and survey reported field tests of such engineered transgenic trees.We outline opportunities and challenges in future research to better understand cell type biogenesis for more efficient wood cell wall modification and utilization for biomaterials or for enhanced carbon capture and storage.

关键词： regulation of cell wall formation biosynthesis of cell wall components lignin cellulose hemicellulose cell wall utilization

MXene-GaN van der Waals metal-semiconductor junctions for high performance multiple quantum well photodetectors

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Light(Science & Applications) 2021年第10期10卷 1829-1839页

作者： Lingzhi Luo Yixuan Huang keming cheng Abdullah Alhassan Mahdi Alqahtani Libin Tang Zhiming Wang Jiang Wu Institute of Fundamental and Frontier Sciences University of Electronic Science and Technology of China610054 ChengduChina Materials Department University of CaliforniaSanta BarbaraCalifornia 93106USA King Abdulaziz City for Science and Technology(KACST) RiyadhSaudi Arabia Kunming Institute of Physics 650223 KunmingYunnanChina State Key Laboratory of Electronic Thin Films and Integrated Devices University of Electronic Science and Technology of China610054 ChengduSichuanChina

A MXene-GaN-MXene based multiple quantum well photodetector was prepared on patterned sapphire substrate by facile drop casting.The use of MXene electrodes improves the responsivity and reduces dark current,compared with traditional Metal-Semiconductor-Metal(MSM)photodetectors using Cr/Au electrodes.Dark current of the device using MXene-GaN van der Waals junctions is reduced by three orders of magnitude and its noise spectral intensity shows distinct improvement compared with the traditional Cr/Au–GaN–Cr/Au MSM photodetector.The improved device performance is attributed to low-defect MXene-GaN van der Waals interfaces.Thanks to the high quality MXene-GaN interfaces,it is possible to verify that the patterned substrate can locally improve both light extraction and photocurrent collection.The measured responsivity and specific detectivity reach as high as 64.6 A/W and 1.93×1012 Jones,respectively,making it a potential candidate for underwater optical detection and communication.The simple fabrication of MXene-GaN-MXene photodetectors spearheaded the way to high performance photodetection by combining the advantages of emerging 2D MXene materials with the conventional III-V materials.

关键词： junctions sapphire performance

Experimental investigation of influence of strake wings on self-induced roll motion at high angles of attack

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Chinese Journal of Aeronautics 2016年第6期29卷 1591-1601页

作者： Geng Xi Shi Zhiwei cheng keming College of Aerospace Engineering Nanjing University of Aeronautics and Astronautics

The modern high performance air vehicles are required to have extreme maneuverability,which includes the ability of controlled maneuvers at high angle of attack. However, the nonlinear and unsteady aerodynamic phenomena, such as flow separation, vortices interaction, and vortices breaking down, will occur during the flight at high angle of attack, which could induce the uncommanded motions for the air vehicles. For the high maneuverable and agile air missile, the nonlinear roll motions would occur at the high angle of attack. The present work is focused on the selfinduced nonlinear roll motion for a missile configuration and discusses the influence of the strake wings on the roll motion according to the results from free-to-roll test and PIV measurement using the models assembled with different strake wings at a = 60°. The free-to-roll results show that the model with whole strake wings(baseline), the model assembled with three strake wings(Case A)and the model assembled with two opposite strake wings(Case C) experience the spinning, while the model assembled with two adjacent strake wings(Case B), the model assembled with one strake wing(Case D) and the model with no strake wing(Case E) trim or slightly vibrate at a certain "×"rolling angle, which mean that the rolling stability can be improved by dismantling certain strake wings. The flow field results from PIV measurement show that the leeward asymmetric vortices are induced by the windward strake wings. The vortices would interact the strake wings and induce crossflow on the downstream fins to degrade the rolling stability of the model. This could be the main reason for the self-induced roll motion of the model at a = 60°.

关键词： Cruciform fins High angle of attack PIV Roll motion Strake wing

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低速湍流边界层DBD控制机制

西华大学学报（自然科学版） 2024年第2期43卷 10-17页

作者：王浩宇孙志坤耿玺史志伟程克明吴继飞南京航空航天大学航空学院江苏南京210016 非定常空气动力学与流动控制工业和信息化部重点实验室江苏南京210016 中国空气动力研究与发展中心高速所四川绵阳622762

介质阻挡放电(DBD)激励器具有重量轻、无运动部件、易用及响应快等优势,在流动控制应用中受到广泛关注。等离子体湍流边界层减阻是DBD流动控制诸多应用之一,但DBD湍流减阻机制还需进一步探究。文章通过试验研究来流速度为10 m/s时DBD激... 详细信息

介质阻挡放电(DBD)激励器具有重量轻、无运动部件、易用及响应快等优势,在流动控制应用中受到广泛关注。等离子体湍流边界层减阻是DBD流动控制诸多应用之一,但DBD湍流减阻机制还需进一步探究。文章通过试验研究来流速度为10 m/s时DBD激励对平板湍流边界层摩擦阻力的影响。试验使用油膜干涉法测量摩阻的变化,利用热线风速仪和粒子图像测速系统(PIV)得到边界层内速度分布。其结果显示,在等离子体激励的作用下,测得的壁面摩擦因数减小。等离子体激励通过减小边界层缓冲层和对数区的速度,减少雷诺切应力以及湍动能,抑制了相干结构的发展,从而达到减阻的效果。

关键词：流动控制湍流边界层平板等离子体激励器减阻

The internal efficiency in higher education:An analysis based on economies of scope

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Frontiers of Education in China 2008年第1期3卷 79-96页

作者： cheng Gang WU keming Capital Research Institute of Basic Education Beijing Normal UniversityBeijing 100875China School of Administration Central China Normal UniversityWuhan 430079China

已有的关于中国高校效率的文献多集中于研究高校的规模(规模经济),更深层次的关于高校内部运行效率尤其是内部产出组合效率(范围经济)的研究寥寥无几。中国高校的教学和科研资源是否互补、本科生教育和研究生培养资源是否共享等重大问... 详细信息

已有的关于中国高校效率的文献多集中于研究高校的规模(规模经济),更深层次的关于高校内部运行效率尤其是内部产出组合效率(范围经济)的研究寥寥无几。中国高校的教学和科研资源是否互补、本科生教育和研究生培养资源是否共享等重大问题缺少理论探讨和经验研究。在高等教育资源稀缺的现实背景下,研究高校范围经济对于实现中国高等教育内涵式发展意义重大。使用多产出成本函数,并利用教育部直属高校数据对中国高校的本科生教育、研究生培养和科研活动之间的资源互补状况进行的研究发现:中国高校提供这些产出时未充分共享资源,其中研究生的培养较为孤立,范围不经济程度较高;在考虑中国高校的教学和科研质量后,高校产出间的资源不共享程度更为加大。反思范围不经济的原因,主要在于中国高校的设备、师资、图书的条块分割和内部管理体制的交叉重叠,同时,现行的研究生培养方式导致了研究生培养的相对割裂。因此,有关部门在制定高等教育管理政策时应充分考虑到高校内部资源的共享和互补,还应重视学校的类型和办学地点对高校内部资源配置的影响。

关键词：成本函数高等教育范围经济

Drag Reduction Effect for Hypersonic Lifting-Body Vehicle with Counterflowing Jet

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Transactions of Nanjing University of Aeronautics and Astronautics 2018年第5期35卷 789-799页

作者： Dong Hao Deng Fan Xie Feng Geng Xi cheng keming College of Aerospace Engineering Nanjing University of Aeronautics and Astronautics General Control Department Space Transportation Technology CO.Ltd. Hypervelocity Aerodynamics Institute China Aerodynamics Research and Development Center

This study takes the novel approach of using a counterflowing jet positioned on the nose of a lifting-body vehicle to explore its drag reduction effect at a range of angles of attack.Numerical studies are conducted at a freestream Mach number of 8 in standard atmospheric conditions corresponding to the altitude of 40 km.The effects of jet pressure ratio and flying angles of attack on drag reduction of the model are systematically investigated.Considering the reverse thrust generated from the counterflowing jet,the drag on the nose at hypersonic speeds could be reduced up to 66%.The maximum lift-to-drag ratio of the model is obtained at 6°;meanwhile,the counterflowing jet produces a drag reduction of 8.8%for the whole model.In addition to the nose,the counterflowing jet influences the drag by increasing the pressure drag of the model and reducing the skin friction drag of the first cone within 8°.The results show that the potential of the counterflowing jet as a means of active flow control for drag reduction is significant in the engineering application on hypersonic lifting-body vehicles.

关键词： hypersonic lifting-body counterflowing jet drag numerical simulation