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Three-dimensional temperature prediction in cylindrical turning with large-chamfer insert based on a modified slip-line field approach

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Chinese Journal of Aeronautics 2021年第10期34卷 265-281页

作者： Cheng HU Kejia ZHUANG Yuanwei TANG Jian WENG Xiaoming ZHANG Han DING Hubei Digital Manufacturing Key Laboratory School of Mechanical and Electronic EngineeringWuhan University of TechnologyWuhan 430070China Institute of Advanced Materials and Manufacturing Technology Wuhan University of TechnologyWuhan 430070China AECC Guizhou Liyang Aviation Power CO.LTD Guiyang 550000China State Key Laboratory of Digital Manufacturing Equipment and Technology Huazhong University of Science and TechnologyWuhan 430074China

Chamfered inserts have found broader applications in metal cutting process especially in high-performance machining of hard-to-cut materials for their excellent edge resistance and cutting ***,excessive heat generation and resulting high cutting temperature eventually cause severe tool wear and poor surface integrity,which simultaneously limits the optimal selection of machining *** the present study,an analytical thermal–mechanical model is proposed for the prediction of the three-dimensional(3-D)temperature field in cylindrical turning with chamfered round insert based on a modified slip-line field ***,an innovative discretization method is introduced in a general 3-D coordinate system to provide a comprehensive demonstration of the irregular cutting geometry and heat generation ***,a plasticity-theory-based slip-line field model is developed and employed to determine the intensities and geometries of every elementary heat sources in Primary Deformation Zones(PDZ),Secondary Deformation Zones(SDZ)and Dead Metal Zones(DMZ).At last,a 3-D analytical model is suggested to calculate the temperature increases caused by the entire heat sources and associated *** maximum cutting temperature region predicted is found existing upon the chip-tool contact area rather than the tool ***,the rationalities of cutting parameters employed are analyzed along with theoretical material removal rates and ensuing maximum cutting *** results indicate that the cutting conditions with large depth of cut and high cutting speed are more desirable than those with high feed *** proposed models are respectively verified through a series of 3-D Finite Element(FE)simulations and dry cutting experiments of Inconel 718 with chamfered round *** agreement has been reached between the predictions and simulations as well as the measurements,which confirms the correctness and effectiveness of the presented analy

关键词： Analytical model Chamfered round insert Dead metal zone Prediction of temperature Slip-line field

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Capacitor Voltage Balancing Strategy Based on Zero-Sequence Voltage Injection for Half-Wave Commutated Modular Multilevel Converter 10

Capacitor Voltage Balancing Strategy Based on Zero-Sequence ...

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10th IEEE International Power Electronics and Motion Control Conference, IPEMC 2024 ECCE Asia

作者： Fu, Nan Liu, Bao Xu, Yunfei Zhu, Sitong Wang, Kui Li, Yongdong Tsinghua University State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Beijing100084 China State Grid Smart Grid Research Institute Co. Ltd State Key Laboratory of Advanced Power Transmission Technology Changping Beijing China Electric Power Research Institute of State Grid Liaoning Electric Power Co. Ltd. Shenyang110000 China

ISBN: (纸本)9798350351330

Half-wave commutated modular multilevel converter (HWC-MMC) is suitable for high-voltage large-capacity AC-AC conversion, and an appropriate capacitor voltage balancing strategy is essential. This paper analyzes the condition of capacitor voltage balancing and proposes a capacitor voltage balancing strategy based on optimal zero-sequence voltage injection using the model predictive control. Finally, the simulation is carried out to verify the proposed strategy. © 2024 IEEE.

关键词： Model predictive control

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Research on Transient Characteristics of an Improved Phase-locked Loop Topology Suitable for VSC Converters

Research on Transient Characteristics of an Improved Phase-l...

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IEEE International Conference on Power and Power and Renewable Energy (ICPRE)

作者： Huaiguang Gu Jiapei Zhou Jinlong Qiu Jin Li State Key Laboratory of Advanced Power Transmission Technology Beijing China Beijing Key Laboratory of DC Power Grid Technology and Simulation Beijing China State Grid Smart Grid Research Institute Co. Ltd Beijing China

ISBN: (数字)9798350377460

ISBN: (纸本)9798350377477

To solve the problem of deteriorating performance and poor stability of traditional PLL connected to weak AC system, an improved PLL structure is proposed in this paper. By measuring the angular velocity and initial phase Angle of the system respectively, the angular velocity of the system is first stabilized to ensure the synchronization between VSC and AC power grid, and then the initial phase Angle of the system is tracked by PI link to achieve accurate estimation and fast tracking of AC power grid phase Angle value. Finally, taking a classic VSC grid-connected system as an example, the effectiveness and stability of the improved PLL are verified by simulation.

关键词： Renewable energy sources Power measurement Power system stability Stability analysis Angular velocity Topology Velocity measurement Synchronization Phase locked loops Transient analysis

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Creating Ferroelectricity in Monoclinic (HfO2)1/(CeO2)1 Superlattices

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Physical Review Letters 2024年第25期132卷 256801-256801页

作者： Hong Jian Zhao Yuhao Fu Longju Yu Yanchao Wang Yurong Yang Laurent Bellaiche Yanming Ma Key Laboratory of Material Simulation Methods and Software of Ministry of Education College of Physics Key Laboratory of Physics and Technology for Advanced Batteries (Ministry of Education) College of Physics International Center of Future Science State Key Laboratory of Superhard Materials College of Physics National Laboratory of Solid State Microstructures and Jiangsu Key Laboratory of Artificial Functional Materials Department of Materials Science and Engineering Smart Ferroic Materials Center Physics Department and Institute for Nanoscience and Engineering

Ferroelectricity in CMOS-compatible hafnia (HfO2) is crucial for the fabrication of high-integration nonvolatile memory devices. However, the capture of ferroelectricity in HfO2 requires the stabilization of thermodynamically metastable orthorhombic or rhombohedral phases, which entails the introduction of defects (e.g., dopants and vacancies) and pays the price of crystal imperfections, causing unpleasant wake-up and fatigue effects. Here, we report a theoretical strategy on the realization of robust ferroelectricity in HfO2-based ferroelectrics by designing a series of epitaxial (HfO2)1/(CeO2)1 superlattices. The designed ferroelectric superlattices are defects free, and most importantly, on the base of the thermodynamically stable monoclinic phase of HfO2. Consequently, this allows the creation of superior ferroelectric properties with an electric polarization >25 μC/cm2 and an ultralow polarization-switching energy barrier at ∼2.5 meV/atom. Our work may open an avenue toward the fabrication of high-performance HfO2-based ferroelectric devices.

关键词： Epitaxial strain Ferroelectricity Order parameters Oxides First-principles calculations

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基于晶体塑性的辐照金属材料局部化颈缩和吕德斯带的模拟研究

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Acta Mechanica Sinica 2023年第4期39卷 132-146页

作者：付家琪刘文斌隋昊男程杨洋段慧玲 State Key Laboratory for Turbulence and Complex System Department of Mechanics and Engineering ScienceThe Beijing Innovation Center for Engineering Science and Advanced TechnologyCollege of EngineeringPeking UniversityBeijing100871China Key Laboratory of High Energy Density Physics Simulation Center for Applied Physics and Technologyand Inertial Fusion Sciences and ApplicationsCollaborative Innovation Center of Ministry of EducationPeking UniversityBeijing100871China

金属材料中,颈缩失稳通常由表面缺陷或材料不均匀性等潜在扰动引起并随着微结构的演化进一步发展.本文将构型扰动法与考虑辐照效应的晶体塑性本构关系相结合,模拟了辐照前后局部化颈缩和吕德斯带等现象.通过考虑模拟局部化变形中扰动的... 详细信息

金属材料中,颈缩失稳通常由表面缺陷或材料不均匀性等潜在扰动引起并随着微结构的演化进一步发展.本文将构型扰动法与考虑辐照效应的晶体塑性本构关系相结合,模拟了辐照前后局部化颈缩和吕德斯带等现象.通过考虑模拟局部化变形中扰动的必要性,发现了外在的几何缺陷和内禀的微结构演化在颈缩过程中的竞争关系.此外,以纯金属铜和奥氏体不锈钢为例研究了辐照硬化效应对颈缩失稳的影响.结果表明,流动应力的增加和功硬化能力的降低是均匀延伸率下降的原因,辐照效应导致的织构软化作用可以忽略.为了解释辐照后低碳钢下屈服点和吕德斯应变同时增加的现象,一种位错脱钉扎和位错与辐照缺陷的交互作用相耦合的塑性变形机制被提出并结合修正的流动方程,很好地模拟出包含屈服下降、应力平台、应变扩展和应变硬化等特征的吕德斯带现象.其中,位错与辐照缺陷的相互作用也可以解释辐照后纯金属材料中发现的扩散颈缩现象.我们的模拟结果既阐明了几何缺陷在颈缩失稳中的重要作用,也为辐照金属中常见的宏观塑性失稳现象提供了清晰的物理图像.

关键词：吕德斯带金属材料奥氏体不锈钢晶体塑性下屈服点流动应力几何缺陷均匀延伸率

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Influence Factors of Frictional Heat between Bristles and Rotor for a Multi-Stage Brush Seal

SSRN

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SSRN 2024年

作者： Sun, Dan Yang, Yixiao Zhao, Huan Zhang, Jieyi Yang, Zemin Zhang, Jinghan Key Laboratory of Turbomachinery Advanced Seal Technology Shenyang Shenyang Aerospace University Shenyang110136 China Liaoning Key Laboratory of Advanced Measurement and Test Technology for Aviation Propulsion System Shenyang Aerospace University Shenyang110136 China Key Laboratory for Power Transmission of Aero Engine Aero Engine Corporation of China Shenyang110115 China

In multi-stage brush seals (MBS), frictional heat generates at frictional surface, which leads to early failure of the seal The frictional heat was accumulated at the downstream stages caused by transfer of the heat from upstream stage to downstream one with flow of the airflow. A three-dimensional tube bundle model of the MBS was established to study change of heat flux on the frictional heat between bristles and rotor among stages. Increasing height of backing plate to rotor could not only balance the pressure drops but also reduce the bristle temperature at downstream stage. decreasing interference amount and decreasing axial width of bristle pack stage by stage, which had a higher impact on bristle temperature at downstage stages. © 2024, The Authors. All rights reserved.

关键词： Heat flux

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key technologies and development trends of VSC-HVDC transmission for offshore wind power

Renewable Energy System and Equipment

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Renewable Energy System and Equipment 2025年第1期1卷 35-49页

作者： Zhiyuan He Jie Yang Guangfu Tang Yuexi Yang Zhenyu Du Sheng Zhang State Key Laboratory of Advanced Power Transmission Technology (China Electric Power Research Institute Co. Ltd.) Beijing 100192 China Beijing Huairou Laboratory Huairou District Beijing 101400 China China Beijing Key Laboratory of DC Grid Technology and Simulation (China Electric Power Research Institute Co. Ltd.) Beijing 100192 China

Developing offshore wind power, particularly in deep waters, is recognized as a vital approach to tackling the energy crisis and facilitating a low-carbon transition. VSC-HVDC transmission, leveraging its technological prowess, has emerged as the principal means for transmitting large-scale, remotely located offshore wind energy. In recent years, numerous VSC-HVDC grid interconnection projects for offshore wind farms have been commissioned globally, with the technology itself continually advancing and improving. This paper, in light of prevailing technological trends, provides a comprehensive overview of the advancements in key technologies within VSC-HVDC transmission tailored to the requirements of offshore wind power evacuation, encompassing system topology, operating modes, control and protection systems, essential equipment, and platform configurations. It further details the profiles of representative offshore wind power VSC-HVDC transmission and grid connection projects currently operational or under construction, and delves into the prospective development trajectories and future research avenues for offshore wind power VSC-HVDC transmission technology.

关键词： VSC-HVDC Offshore wind power System topology Control and protection Core equipment Offshore platform

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Application of a Bipolar Trriger System With Nanosecond Quasi-Rectangular Ouptut Pulse For Jitter Reduction of a 3-MV Marx Generator

Application of a Bipolar Trriger System With Nanosecond Quas...

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IEEE International Conference on Plasma Science (ICOPS)

作者： L. Cheng H. Wang G. Wu J. Hua Z. Jia K. Mei W. Wu Z. Zhang College of Advanced Interdisciplinary Studies National University of Defense Technology Changsha China National Key Laboratory of Intense Pulsed Radiation Simulation and Effect Northwest Institute of Nuclear Technology Xi’an China

ISBN: (数字)9798350360912

ISBN: (纸本)9798350360929

In the primary drive sources of large-scale pulsed power devices, such as the Marx generators and linear transformer drivers (LTDs), the gas switch remains the predominant choice for energy conversion. The performance of trigger pulse plays a pivotal role in ensuring stable conduction of the gas switch, thereby influencing the overall operational characteristics of the pulsed power source. Generally speaking, fast rising time and high voltage amplitude are of great advantage for enhancing the trigger performance. Particularly in pulses operating in parallel synthesis mode, there is a heightened requirement for minimal delay jitter and superior repeatability within the trigger system.

关键词： Performance evaluation Switches High-voltage techniques Energy conversion Jitter Transformers Generators

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Analysis And Calculation Of The Short-Circuit Current Of Xiamen VSC-HVDC Project 5

Analysis And Calculation Of The Short-Circuit Current Of Xia...

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5th IEEE Conference on Energy Internet and Energy System Integration, EI2 2021

作者： Zhu, Lin Gu, Huaiguang Li, Fangyuan Kou, Longze Liu, Dong State Key Laboratory of Advanced Power Transmission Technology Beijing Key Laboratory of DC Grid Technology and Simulation Global Energy Interconnection Research Institute Beijing China State Key Laboratory of Advanced Power Transmission Technology Global Energy Interconnection Research Institute Beijing China

ISBN: (纸本)9781665434256

For the heavy load urban power grid, the short-circuit current is closed to the breaking capacity of the AC breaker. After the voltage sourced converter high voltage direct current (VSC-HVDC) is connected, the short-circuit current of VSC-HVDC will be provided during the fault period, which will cause the short-circuit current exceed the standard value and affect the normal operation of the power grid. Taking the Xiamen VSC-HVDC project as an example, this paper analyses the VSC-HVDC control mode, obtains the short-circuit current calculation method. The Xiamen AC/DC hybrid model is built, and the correctness of the proposed method is verified by simulation. The results show that the amplitude and phase angle of the VSC-HVDC short-circuit current have great influence on the total short-circuit current, and the amplitude is easily controlled by the current limiting controller, so the phase angle control should be emphasized. For Point of Common Coupling (PCC), the short-circuit current of single-phase grounding fault may be larger than three-phase grounding fault, which should be taken into account. The ideas provided in this paper have practical engineering significance for the city power supply by VSC-HVDC. © 2021 IEEE

关键词： Short circuit currents

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Numerical and experimental study on the effect of the stage number on the characteristics of leakage flow and heat transfer in brush seal

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Hangkong Dongli Xuebao/Journal of Aerospace Power 2025年第6期40卷

作者： Lin, Xiyue Sun, Dan Guo, Hailong Li, Yu Yang, Yixiao Zhang, Jinghan Liaoning Key Lab of Advanced Test Technology for Aerospace Propulsion System School of Aero-engine Shenyang Aerospace University Shenyang110136 China Key Laboratory of Turbomachinery Advanced Seal Technology Shenyang Aerospace University Shenyang110136 China Hunan Aviation Powerplant Research Institute Aero Engine Corporation of China Zhuzhou410315 China

For multi-stage brush seal,stage number has a great influence on the characteristics of leakage flow and heat transfer. The theoretical formula,which explains how the stage number affects the characteristics of leakage flow and heat transfer in multi-stage brush seal,was derived. The solution model of multi-stage brush seal was established and the numerical simulation was carried out based on the fluid-solid-thermal coupling calculation method. The leakage and pressure distribution measurement experiment of multi-stage brush seal was designed. The experimental device of leakage and pressure distribution characteristics of multi-stage brush seal was built. The experimental results were compared with the numerical results to verify the accuracy of the numerical simulation. The distribution characteristics of flow field and temperature field between different series brush seals were analyzed and compared. The influences of series on the leakage characteristics,flow characteristics and heat transfer characteristics of brush seal were studied. The results showed that under the same pressure ratio,from one to three stages brush seals,for each additional level,the pressure drop value borne by each stage of brush tows decreased, and the maximum pressure drop of brush tows decreased by 30.0%—36.3%. The maximum velocity of the flow field appeared below the rear baffle of the last stage brush tow,and the maximum velocity of the flow field decreased with the increase of stage number. Under the same pressure ratio,with the increase of stage number,the sealing performance of the brush seal was enhanced. For each additional stage,the leakage was reduced by 15.7%—22.0%. Under the same pressure ratio,the maximum temperature increased with the increase of stage number,and the maximum temperature increased by 3.7%—9.1% for each additional stage. © 2025 Beijing University of Aeronautics and Astronautics (BUAA). All rights reserved.

关键词： Electric heating

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