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SSRN 2022年

作者： Liu, Shishuang Cao, Jingxia Zhou, Yi Hou, Chenrui Dai, Shenglong Huang, Xu Aviation Key Laboratory of Science and Technology on Advanced Titanium Alloys AECC Beijing Institute of Aeronautical Materials Beijing100095 China

The microstructure evolution and tensile behavior of a novel Ti2AlNb alloy (Ti-22Al-23Nb-1Mo-1Zr) processed by two-pass hot extrusion and two-step heat treatment were investigated. After extruding deformation in the B2 phase field, the B2 grains were refined from about 1500 μm to 50 μm through dynamic recrystallization. The microstructures subjected to solution treatment in the B2+α2 phase field and aging treatment in the B2+O phase field include B2 matrix, lamellar O, rim O and lamellar α2/O phases. The microstructure and tensile properties are sensitive to aging temperature. As the increase of the aging temperature, the content of the B2 phase and the size of the lamellar O phase increase, resulting in low strength and high ductility. The alloy aged at 800 oC has a good match of strength and ductility. It has an elongation of 6.4 % with a tensile strength as high as 1228 MPa due to the precipitation strengthening of numerous lamellar O phase and fine grain strengthening. The tensile fracture mode predominantly shows quasi-cleavage characteristics with typical cleavage facets and massive dimples, which is consistent with the good balance of tensile strength and ductility. An in-depth understanding of the relationship between microstructure and tensile properties in this study can be helpful for the engineering application of the Ti2AlNb alloy. © 2022, The Authors. All rights reserved.

关键词： Tensile strength

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Angular Deviation and Influential Factors of Burgers Orientation Relationship During Β→Α Transformation in Titanium Alloys

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SSRN 2023年

作者： Li, Mingbing Wang, Kai Wang, Bin Lv, Chao Wang, Xinnan Li, Xing Zhu, Zhishou Hou, Huilong Zhao, Xinqing School of Materials Science and Engineering Beihang University Beijing100191 China Key Laboratory of Advanced Titanium Alloys Beijing Institute of Aeronautical Materials Aero Engine Corporation of China Beijing100095 China MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials Technology Nanjing University of Science and Technology Nanjing210094 China Tianmushan Laboratory Zhejiang Provincial Laboratory for Aviation Hangzhou311312 China

The Burgers orientation relationship commonly observed during β→α transformation in titanium alloys exhibits an angular deviation in crystallographic orientation. Determining the possible angular deviations and governing factors is of great importance for controlling the microstructure and properties of alloys. Herein, we propose a calculation method to determine the angular deviations, Δθ, from the ideal Burgers orientation relationship. The calculated results show that the angular deviations exist between the β and α phases in α colonies for Ti-6Al-4V and Ti-6.5Al-2Zr-1Mo-1V alloys. The angular deviations originate from the lattice distortions by the dislocations in the α phase and β phase and their interfaces. Our work indicates that a tolerance angle could be used to determine whether the α phase and β phase obey the Burgers orientation relationship in polycrystalline titanium alloys. The proposed method offers an approach to quantify the variations of the Burgers orientation relationship and develops the understanding of crystallographic evolutions. © 2023, The Authors. All rights reserved.

关键词： Titanium alloys

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Active control of thermoacoustic instability in a lean-premixed hydrogen-enriched combustor via open-loop acoustic forcing

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Combustion and Flame 2025年 277卷

作者： Liao, Yu Choi, Yongseok Liu, Peijin Kim, Kyu Tae Guan, Yu Department of Aeronautical and Aviation Engineering The Hong Kong Polytechnic University Kowloon Hong Kong National Key Laboratory of Solid Rocket Propulsion Northwestern Polytechnical University Xi'an710072 China Department of Aerospace Engineering Korea Advanced Institute of Science and Technology Daejeon34141 Korea Republic of

Open-loop control is proven effective in mitigating self-excited oscillations in conventional hydrocarbon-fueled combustors, but its effectiveness in hydrogen-fueled combustors remains unknown. This study experimentally investigates the effectiveness of open-loop acoustic forcing in mitigating self-excited periodic thermoacoustic oscillations in a lean-premixed, hydrogen-enriched turbulent combustor. We conducted experiments across a range of hydrogen volume fractions (20% to 50%), varying both the frequencies and amplitudes of the acoustic forcing introduced via three loudspeakers positioned upstream of the combustor. For the first time, we have demonstrated the effectiveness of open-loop acoustic forcing in mitigating self-excited periodic thermoacoustic oscillations in a hydrogen-enriched combustor, with suppression effects becoming more pronounced as the hydrogen content increases. We achieve up to a 90% reduction in pressure amplitude with minimal energy input—less than 1% of the combustor's thermal power. At lower hydrogen fractions, the acoustic forcing fails to effectively decouple the flame dynamics from the acoustic field, resulting in significant oscillation amplification, with natural mode amplitudes increasing by over 2000%. A critical transition from global amplification to suppression occurs at a hydrogen volume fraction of 40%, where successful decoupling between the flame dynamics from the acoustic field is observed. These findings highlight the potential of open-loop control for mitigating thermoacoustic oscillations in hydrogen-enriched combustion systems, offering a promising approach to aid the decarbonization of gas turbines. Novelty and significance statement This study provides the first experimental evidence that open-loop acoustic forcing can effectively suppress thermoacoustic oscillations in hydrogen-enriched turbulent combustors. We show that increasing hydrogen volume fraction (20% to 50%) in the reactant mixtures enhances oscillation s

关键词： Combustors

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Symmetry-oriented enumeration method for molecular crystal structure prediction and its application

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Physical Review B 2025年第13期111卷 134112-134112页

作者： Yu Xin Zhuohang Xie Yongshuo Chen Pengyue Gao Hong Jian Zhao Jian Lv Yanchao Wang Yanming Ma Key Laboratory of Material Simulation Methods and Software of Ministry of Education College of Physics Jilin University Changchun 130012 China International Center of Future Science Jilin University Changchun 130012 China Key Laboratory of Physics and Technology for Advanced Batteries (Ministry of Education) College of Physics Jilin University Changchun 130012 China State Key Laboratory of High Pressure and Superhard Materials College of Physics Jilin University Changchun 130012 China

Predicting the thermodynamically stable arrangements of molecular building blocks is crucial for understanding the properties and behaviors of crystalline molecular compounds. Several molecular structure prediction methods have been proposed, leading to successful applications. However, some evolutionary approaches that involve direct sampling within the infinite atomic coordinate space, without symmetry-preserving constraints, tend to suffer from biased sampling, where structures with P1 symmetry become disproportionately dominant. To overcome this limitation, we propose a method that utilizes a finite set of symmetrically inequivalent Wyckoff encodes to sparsely represent the search space of crystalline molecular compounds, thereby improving the coverage of the search space. This method can be used to predict the molecular crystal structures with varying numbers of molecules in the asymmetric unit, from fractional to multiple integers. The applications of this method to three-dimensional molecular crystals of ammonia dihydrate, the NH3−H2O−CH4 mixture, and two-dimensional layered ices revealed a series of energetically quasidegenerate structures with diverse crystal packing motifs. This method expands the scope and utility of molecular building blocks for designing stable molecular crystals, providing a robust framework for achieving extensive tunability in molecular materials design.

关键词： Molecular crystals

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Towards Three-dimensional Mapping of Skyrmionic Spin Textures in an FeGe Nanodisk Using Off-axis Electron Holography

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Microscopy and microanalysis : the official journal of Microscopy Society of America, Microbeam Analysis Society, Microscopical Society of Canada 2023年第1期29卷 1396-1397页

作者： Zheng, Fengshan Caron, Jan Savchenko, Andrii S. Wang, Shasha Wang, Weiwei Denneulin, Thibaud Kovács, András Du, Hongchu Du, Haifeng Kiselev, Nikolai S. Blügel, Stefan Dunin-Borkowski, Rafal E. Electron Microscopy Center School of Physics and Optoelectronics State Key Laboratory of Luminescent Materials and Devices Guangdong-Hong Kong-Macao Joint Laboratory of Optoelectronic and Magnetic Functional Materials South China University of Technology Guangzhou China Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute Forschungszentrum Jülich Jülich Germany Peter Grünberg Institute and Institute for Advanced Simulation Forschungszentrum Jülich and JARA Jülich Germany Anhui Key Laboratory of Condensed Matter Physics at Extreme Conditions High Magnetic Field Laboratory Chinese Academy of Sciences Hefei Anhui China Information Materials and Intelligent Sensing Laboratory of Anhui Province Key Laboratory of Structure and Functional Regulation of Hybrid Materials of Ministry of Education Institutes of Physical Science and Information Technology Anhui University Hefei China

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核子电磁形状因子振荡行为的新视角

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science Bulletin 2023年第22期68卷 2729-2733,M0005页

作者：杨勤鹤郭棣戴凌云 Johann Haidenbauer 康现伟 Ulf-GMeiner School of Physics and Electronics Hunan UniversityChangsha 410082China Hunan Provincial Key Laboratory of High-Energy Scale Physics and Applications Hunan UniversityChangsha 410082China Institute for Advanced Simulation Institut für Kernphysik and Jülich Center for Hadron PhysicsForschungszentrum JülichJülich D-52425Germany Key Laboratory of Beam Technology of the Ministry of Education College of Nuclear Science and TechnologyBeijing Normal UniversityBeijing 100875China Institute of Radiation Technology Beijing Academy of Science and TechnologyBeijing 100875China Helmholtz Institut für Strahlen-und Kernphysik and Bethe Center for Theoretical Physics Universität BonnBonn D-53115Germany Tbilisi State University Tbilisi 0186Georgia

本文研究了质子和中子的类时电磁形状因子.作者基于手征有效场论,通过求解李普曼-施温格方程得到了核子-反核子对散射振幅.以此为输入,利用扭曲波恩近似方法描述了核子末态相互作用,计算了正负电子湮灭到正反核子对的过程.通过拟合相移... 详细信息

本文研究了质子和中子的类时电磁形状因子.作者基于手征有效场论,通过求解李普曼-施温格方程得到了核子-反核子对散射振幅.以此为输入,利用扭曲波恩近似方法描述了核子末态相互作用,计算了正负电子湮灭到正反核子对的过程.通过拟合相移、截面以及微分截面等实验数据,定下了有效场论的未知耦合常数.进一步研究发现,可以利用两个分数振荡振子来描述核子电磁类时形状因子的振荡行为:一个表现为过阻尼振荡,在阈值附近占主导地位;另一个类似于欠阻尼振荡,在高能区起到重要作用.这种振荡行为对理解硬光子诱导的核子内部极化电荷的分布起着至关重要的作用.

关键词： Electromagnetic form factors Fractional oscillator Chiral effective field theory Lippmann-Schwinger equation Distorted wave Born approximation

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Evaluation on elevated-temperature stability of modified 718-type alloys with varied phase configurations

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International Journal of Minerals,Metallurgy and Materials 2020年第8期27卷 1123-1132页

作者： Zhan Qiao Chong Li Hong-jun Zhang Hong-yan Liang Yong-chang Liu Yong Zhang State Key Lab of Hydraulic Engineering Simulation and Safety School of Materials Science&EngineeringTianjin UniversityTianjin 300354China Key Laboratory of the Ministry of Education for Modern Metallurgy Technology North China University of Science and TechnologyTangshan 063210China Science and Technology on Advanced High Temperature Structural Materials Laboratory AEEC Beijing Institute of Aeronautical MaterialsBeijing 100095China

Inconel 718 is a Ni–Fe-based superalloy widely used in aerospace engines because of its excellent mechanical ***,the inferior stability of theγ″phase limits the application of Inconel 718,which coarsens rapidly at temperatures greater than 650°*** improving the temperature tolerance of Inconel 718 requires optimization of the phase configuration via modification of the alloy’s chemical *** the aforementioned objective,this work was conducted to study the precipitation behavior and thermal stability of the strengthening phases with various structures in modified Inconel 718 alloys by tailoring the Al/Ti *** increasing Al/Ti ratio,three particle configurations were formed:γ′/γ″composite,isolatedγ′,andγ′/γ″/γ′composite *** results of aging tests demonstrate that the isolatedγ′and theγ′/γ″/γ′composite structure exhibited better thermal stability at temperature as high as 800°*** isolatedγ′exhibited a reduced coarsening rate compared with theγ′/γ″/γ′composite particles because the isolatedγ′phase was rich in Al,Ti,and ***,theγ′/γ″composite particles coarsened and decomposed rapidly during aging at temperatures greater than 700°C because of the lower stability resulting from the larger number ofγ″*** obtained results provide necessary data for the compositional optimization of novel 718-type alloys.

关键词： Inconel 718 structure thermal stability interface

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Conjugated Bond-Based Peridynamic Model of Laminated Composite Materials with Arbitrary Poisson's Ratio and Shear Modulus

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SSRN 2023年

作者： Liu, Shuo Che, Lu Fang, Guodong Liang, Jun Institute of Advanced Structure Technology Beijing Institute of Technology Beijing100081 China School of Civil Aviation Northwestern Polytechnical University Xi’an710072 China Yangtze River Delta Research Institute of NPU Taicang215400 China Science and Technology on Advanced Composites in Special Environments Key Laboratory Harbin Institute of Technology Harbin150001 China

The bond-based peridynamic (BB-PD) theory is inadequate in describing the four independent engineering material constants of composite lamina, which results in fixed values its Poisson’s ratios and shear moduli. This study presents a novel lamina conjugated BB-PD model encompasses not only the fiber bond and matrix bond, but also the transverse bond and conjugated bond pair. By defining these four basic PD bonds, the improved conjugated BB-PD model can overcome the restriction of material properties. The determination of the four basic PD micro-modulus parameters is achieved through the utilization of the equivalent relationship of strain energy density. In addition, the lamina conjugated BB-PD model is extended to deal with composite laminates with different stacking sequences. The present study validates the accuracy and applicability of the conjugated BB-PD model for composite materials by conducting simulations of the elastic deformation and progressive damage behavior of unidirectional laminae and laminates. Moreover, the proposed model provides an elucidation of the damage modes and failure mechanisms of laminated composite materials subjected to uniaxial loading. © 2023, The Authors. All rights reserved.

关键词： Elastic moduli

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DC Overvoltage Analysis of GFM-controlled Wind Farm Connected via MMC-HVDC System Caused by Receiving-end AC Faults

DC Overvoltage Analysis of GFM-controlled Wind Farm Connecte...

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International Conference on Power Electronics and Motion Control (IPEMC)

作者： Siying Chen Min Cheng Yingbiao Li Jiawei Yu Yihua Zhu Mingkang Wu Jiabing Hu Jianan Yan State Key Laboratory of Advanced Electromagnetic Technology and School of Electrical and Electronic Engineering Huazhong University of Science and Technology China Yunnan Power Grid China CSG Key Laboratory for Power System Simulation (Electric Power Research Institute China Southern Power Grid) State Key Laboratory of HVDC (Electric Power Research Institute China Southern Power Grid) National Energy Power Grid Technology R&D Centre Guangdong Provincial Key Laboratory of Intelligent Operation and Control for New Energy Power System China

ISBN: (数字)9798350351330

ISBN: (纸本)9798350351347

DC overvoltage occurs when short circuit fault exists at the receiving-end and is harmful to the safety of the system where wind farms are connected to the grid through high-voltage direct current (HVDC) transmission based on the modular multilevel converter (MMC). To address this issue, this paper first analyzed the mechanism of the DC overvoltage and innovatively proposed a strategy in which grid-forming-controlled wind farms are integrated into the AC grid through MMC-HVDC, whose sending-end applies grid-following control and constant DC voltage control. However, secondary DC overvoltage appears during the fault recovery stage and is mainly caused by the saturation of the PI controller of constant active power control. simulations are carried out on a test with MATLAB/Simulink, and results verify the efficacy of the proposed methods in suppressing DC overvoltage that appeared during receiving-end faults and their recovery stage.

关键词： PI control simulation Power control Wind farms Robustness Wind turbines Safety

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Film cooling effectiveness in the presence of internal hole random roughness: A comprehensive analysis

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International Communications in Heat and Mass Transfer 2025年 165卷

作者： Wang, Xinyu Ye, Lin Li, Wei Zheng, Tianyi Liang, Xiyuan Liu, Cunliang School of Power and Energy Northwestern Polytechnical University Shaanxi Xi'an710129 China State Key Laboratory for Strength and Vibration of Mechanical Structures Xi'an Jiaotong University Shaanxi Xi'an710049 China Science and Technology on Altitude Simulation Laboratory Sichuan Mianyang621000 China Hunan Aviation Powerplant Research Institute Aero Engine Corporation of China Hunan Zhuzhou412002 China

Film cooling, with its excellent cooling performance, is widely applied in the active thermal protection design of aerospace propulsion systems. However, during manufacturing and service, film holes are affected by drilling processes and particle deposition, leading to significant deviations between the actual cooling structures and the original design. These deviations primarily manifest as hole blockage and increased surface roughness, which may cause cooling degradation. Therefore, it is essential to investigate the film cooling performance under structural damage and the jet-mainstream mixing mechanisms of damaged holes. This study focuses on internal roughness as a form of structural damage by investigating three levels of hole roughness—Ra = 3.1 μm (Film hole I), Ra = 35.9 μm (Film hole II), and Ra = 64.9 μm (Film hole III). The selected roughness levels and blowing ratios correspond to the practical range encountered in turbine cooling. The film cooling effectiveness distribution is measured using pressure-sensitive paint technology, and numerical simulations are conducted to analyze the flow field and support the experimental results. The results indicate that cooling degradation caused by internal roughness is mainly reflected in the reduction of high cooling effectiveness areas and the deterioration of cooling performance near the film hole exit. However, increased roughness also leads to an expansion of the film coverage in the spanwise, enhancing cooling performance downstream. Flow field analysis reveals that internal roughness increases the inhomogeneity of coolant velocity distribution inside the hole, strengthening the counter-rotating vortex pair and causing jet lift-off, which reduces the high cooling effectiveness area. Additionally, roughness-induced disturbances enhance turbulence intensity, promoting jet-mainstream mixing and increasing the overall film coverage. © 2025

关键词： Solar sails

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