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Numerical simulation of transient characteristics in a bulb turbine during the load rejection process

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Journal of Hydrodynamics 2024年第1期36卷 170-183页

作者： Yue Lu Yu-quan Zhang zhong-wei He Yuan Zheng College of Water Conservancy and Hydropower Engineering Hohai UniversityNanjing210098China College of Energy and Electrical Engineering Hohai UniversityNanjing210098China Huadong Engineering Corporation Ltd. Hangzhou311122China

To evaluate the safety of the bulb tubular turbine,the dynamic hydraulic characteristics of a hydropower station system during the load rejection process are studied through numerical simulations and a prototype *** the developed model,a dynamic grid technology(DGT)controls the closure of the guide vane and the blade,whilst the moment balance equation and the user-defined function(UDF)provide the runner’s rotation *** 3-D transient simulation method can well predict the rotation speed and mass flow curves in the state of load *** simulation outcomes of the system performance are basically consistent with the measurement data of the *** observed,the runner is subjected to the reversely increased torque and axial force,the system is in a braking phase,and the maximum speed peaks at 144.6%of the rated ***,the internal flow of the runner is greatly affected by the closure of the guide vane,and the draft tube forms an eccentric spiral vortex *** breaks downstream,aggravating the instability of the draft ***,the transient characteristics span for the first five seconds,demonstrating the importance of establishing an efficient governing *** obtained results are useful for designing the turbine’s flow channel with a double regulating function and comprehending the turbine’s transient characteristics.

关键词： Bulb tubular turbine load rejection numerical simulation dynamic grid prototype test

Investigations on High-Speed Flash Boiling Atomization of Fuel Based on Numerical Simulations

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Computer Modeling in Engineering & Sciences 2024年第5期139卷 1427-1453页

作者： wei zhong Zhenfang Xin Lihua Wang Haiping Liu School of Aerospace Engineering and Applied Mechanics Tongji UniversityShanghai200092China Beijing Mechanical Equipment Research Institute Beijing100854China

Flash boiling atomization(FBA)is a promising approach for enhancing spray atomization,which can generate a fine and more evenly distributed spray by increasing the fuel injection temperature or reducing the ambient ***,when the outlet speed of the nozzle exceeds 400 m/s,investigating high-speed flash boiling atomization(HFBA)becomes quite *** difficulty arises fromthe involvement ofmany complex physical processes and the requirement for a very fine mesh in numerical *** this study,an HFBA model for gasoline direct injection(GDI)is *** model incorporates primary and secondary atomization,as well as vaporization and boilingmodels,to describe the development process of the flash boiling *** to lowspeed FBA,these physical processes significantly impact *** this model,the Eulerian description is utilized for modeling the gas,and the Lagrangian description is applied to model the droplets,which effectively captures the movement of the droplets and avoids excessive mesh in the Eulerian *** various conditions,numerical solutions of the Sauter mean diameter(SMD)for GDI show good agreement with experimental data,validating the proposed model’s *** based on this HFBA model investigate the influences of fuel injection temperature and ambient pressure on the atomization *** analyses of the velocity field,temperature field,vapor mass fraction distribution,particle size distribution,and spray penetration length under different superheat degrees reveal that high injection temperature or low ambient pressure significantly affects the formation of small and dispersed droplet *** effect is conducive to the refinement of spray particles and enhances atomization.

关键词： High-speed flash boiling atomization numerical simulations Eulerian description Lagrangian description gasoline direct injection

Uptrend of the Western North Pacific Tropical Cyclone Outflow Height during 1959-2021

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Journal of Meteorological Research 2024年第2期38卷 339-350页

作者： Yuan SUN Zhihao FENG wei zhong Panmao ZHAI Yanluan LIN Shuo LYU College of Advanced Interdisciplinary Studies National University of Defense TechnologyNanjing 211100 College of Meteorology and Oceanography National University of Defense TechnologyChangsha 410073 State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesChina Meteorological AdministrationBeijing 100081 Ministry of Education Key Laboratory for Earth System Modeling Department of Earth System ScienceTsinghua UniversityBeijing 100084

Relatively little is known about the impact of global warming on the tropical cyclone(TC)outflow,despite its large contribution to TC *** this study,based on the International Best Track Archive for Climate Stewardship(IBTrACS)dataset and ERA5 reanalysis data,we show that the TC outflow height has risen significantly(48.20±22.18 m decades-1)in the past decades(1959-2021)over the western North Pacific,and the rising trend tends to be sharper for stronger TCs(the uptrend of severe typhoon is 61.09±40.92 m decades-1).This rising trend of the outflow height explains the contradiction between the decrease trend of the TC outflow temperature and the increase trend of the atmospheric troposphere ***,possible contribution of the TC outflow height uptrend to TC intensity has also been *** results show that the rise of outflow height leads to the decrease of outflow temperature,and thus an increased difference between underlying sea surface temperature(SST)and TC outflow temperature,which eventually favors the increase of TC intensity.

关键词： tropical cyclone outflow height global warming western North Pacific

Regulation of aqueous electrolyte interface via electrolyte strategies for uniform zinc deposition

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Nano Research 2024年第10期17卷 8678-8693页

作者： wei zhong Chaoqiang Tan Laixi Li Shichao Zhang Xinyang Wang Hao Cheng Yingying Lu Institute of Wenzhou Zhejiang UniversityWenzhou 325006China State Key Laboratory of Chemical Engineering Institute of Pharmaceutical EngineeringCollege of Chemical and Biological EngineeringZhejiang UniversityHangzhou 310027China ZJU-Hangzhou Global Scientific and Technological Innovation Center Zhejiang UniversityHangzhou 311215China Zhejiang Huayou Cobalt Company Limited Tongxiang 314500China

Aqueous zinc ion batteries(AZIBs),renowned for their high theoretical energy density,safety,cost-effectiveness and ecofriendliness,offer immense potential in the realm of energy storage and conversion,finding applications in renewable energy and portable ***,the development of AZIBs still faces several challenges related to the electrochemical behavior of zinc anodes in aqueous electrolytes,primarily zinc dendrite formation,which emphasize the critical need for a fundamental understanding of the interfacial phenomena between the electrode and *** review focuses on the three models:the electric double layer(EDL)model,the solvation structure model,and the Zn/electrolyte interface *** guide the design of the electrolyte system in *** models provide a comprehensive understanding of the interactions between the electrode,electrolyte,and the solvated ions in the *** optimizing the salt types,salt concentrations,solvents and additives based on these models,it is possible to enhance the performance of AZIBs,including their energy density,cycle life,and *** review also highlights recent research progress in electrolyte modification of AZIBs for understanding battery behavior,along with perspectives for the direction of further investigations.

关键词： aqueous zinc ion batteries electric double layer solvation structure electrolyte optimization

Cross-level steam load smoothing and optimization in industrial parks using data-driven approaches

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Energy and AI 2024年第2期16卷 69-83页

作者： Xiaojie Lin Xueru Lin wei zhong Feiyun Cong Yi Zhou Zhejiang Key Laboratory of Clean Energy and Carbon Neutrality Zhejiang UniversityHangzhouChina Shanghai Institute for Advanced Study Zhejiang UniversityShanghaiChina College of Energy Engineering Zhejiang UniversityHangzhouChina Jiaxing Research Institute Zhejiang UniversityJiaxingChina School of Mechanical Engineering Zhejiang UniversityHangzhouChina

This study focuses on the integrated energy production system in industrial parks, addressing the problem of stable load dispatch of equipment under demand fluctuations. A cross-level method for steam load smoothing and optimization is proposed, aiming to achieve stable production and optimal economic performance through three levels of integration: load forecasting, load dispatch, and load regulation. Unlike traditional methods that directly use load forecasting values, heat network elasticity is presented as a buffer between demand and supply. Constraints for minimal changes in equipment load and operational parameters are established for smooth regulation. Industrial cases demonstrate that the load forecasting model has mean absolute percentage errors of 2.44% and 1.68% for medium-pressure and low-pressure steam, respectively, meeting accuracy requirements. The modified supply-side load smoothness is effectively improved by considering heat network elasticity. The method increases boiler efficiency by 1.92%, reducing average coal consumption by 0.92 t/h. Compared to manual operation, the proposed model leads to an average increase of 5.69 MW in power generation and an average reduction of 10.81% in coal-to-electricity ratio. This study verifies the importance of smooth integration across different levels and analyzes the effective response of the proposed method to the uncertainty in load forecasting. The method demonstrates the enormous potential of data-driven methods in achieving safe, economical, and sustainable production in industrial parks.

关键词： Industrial parks Heat network elasticity Load regulation Integrated optimization Load forecasting Production stability

Dynamic recrystallization behavior and strengthening mechanism of a novel Mo-Ti_(3)AlC_(2) alloy at ultrahigh temperature

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Rare Metals 2024年第8期43卷 3946-3960页

作者： Lu Yang Xin-Yuan Zheng Yang Zhao Xi-Ran Wang Fang-Nao Xiao Shi-zhong wei School of Materials Science and Engineering Henan University of Science and TechnologyLuoyang 471023China National Joint Engineering Research Center for Abrasion Control and Molding of Metal Materials Henan University of Science and TechnologyLuoyang 471003China Department of Applied Mechanics Univ.Bourgogne FrancheComteFEMTO-ST InstituteCNRS/UF/ENSMM/UTBM25000BesangonFrance

Increasing the recrystallization temperature to achieve better high-temperature performance is critical in the development of molybdenum alloys for ultrahightemperature applications,such as the newest generation of multitype high-temperature nuclear *** this study,an innovative strategy was proposed to improve the performance of molybdenum alloys at high temperature by using the two-dimensional MAX(where M is an early transition metal,A is an A-group element and X is C or N)ceramic material Ti_(3)AlC_(2).The relationships between flow stress,strain rate and temperature were *** microstructure,distribution of misorientation and evolution of dislocations in the Mo-Ti_(3)AlC_(2) alloy were *** microscopic mechanism of the Ti_(3)AlC_(2) phase in the molybdenum alloy at high temperatures was *** experimental results showed that the peak flow stress of Mo-Ti_(3)AlC_(2) at 1600℃ reached 155 MPa,which was161.8% greater than that of pure *** activation energy of thermal deformation of Mo-Ti_(3)AlC_(2) was as large as537 kJ·mol~(-1),which was 17.6% more than that of pure *** recrystallization temperature reached 1600℃ or even *** topological reaction of the Ti_(3)AlC_(2) phase consumed a large amount of energy at high temperatures,resulting in increases in the deformation activation *** structures of AlTi_3 and Ti-O Magneli-phase oxides(Ti_nO_(2n-1)) were formed in-situ,which relied on kink bands and interlayer slip,resulting in many dislocations during ***,the special two-dimensional of the structure Ti_(3)AlC_(2) ceramic inhibited the recrystallization behavior of the Mo *** results of this study can provide theoretical guidance for the development of a new generation of molybdenum alloys for use in ultrahigh-temperature environments.

关键词： Mo alloy Two-dimensional reinforcement Dynamic recrystallization behavior Hot deformation Mechanical properties

A novel profile modification HPF-Co gel satisfied with fractured low permeability reservoirs in high temperature and high salinity

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Petroleum Science 2024年第1期21卷 683-693页

作者： Ya-Kai Li Ji-Rui Hou wei-Peng Wu Ming Qu Tuo Liang wei-Xin zhong Yu-Chen Wen Hai-Tong Sun Yi-Nuo Pan China University of Petroleum Beijing Beijing102249China PetroChina Tarim Oilfield Company Korla 841000XinjiangChina Key Laboratory of Improving Oil and Gas Recovery of Ministry of Education Northeast Petroleum University Daqing 163318HeilongjiangChina Xi'an Shiyou University Xi'an 710065ShaanxiChina Northwest Oilfield Company SINOPECUrumqi 830011XinjiangChina

Conformance control and water plugging are a widely used EOR method in mature ***,majority of conformance control and water plugging agents are unavoidable dehydrated situation in high-temperature and high-salinity low permeability ***,a novel conformance control system HPF-Co gel,based on high-temperature stabilizer(CoCl_(2)·H_(2)O,CCH)is *** HPF-Co bulk gel has better performances with high temperature(120℃)and high salinity(1×10^(5)mg/L).According to Sydansk coding system,the gel strength of HPF-Co with CCH is increased to code *** dehydration rate of HPF-Co gel is 32.0%after aging for 150 d at 120℃,showing excellent thermal *** rheological properties of HPF gel and HPF-Co gel are also *** results show that the storage modulus(G′)of HPF-Co gel is always greater than that of HPF *** effect of CCH on the microstructure of the gel is *** results show that the HPF-Co gel with CCH has a denser gel network,and the diameter of the three-dimensional network skeleton is 1.5-3.5μ*** 90 d of aging,HPF-Co gel still has a good three-dimensional *** spectroscopy results show that CCH forms coordination bonds with N and O atoms in the gel amide group,which can suppress the vibration of cross-linked sites and improve the stability at high *** core plugging test determines the optimized polymer gel injection strategy and injection velocity with HPF-Co bulk gel system,plugging rate exceeding 98%.Moreover,the results of subsequent waterflooding recovery can be improved by 17%.

关键词： Low permeability reservoir High-temperature resistant gel Complexation reaction Polymer gel injection strategy Plugging rate Enhanced oil recovery

Room-temperature ferromagnetism and piezoelectricity in metalfree 2D semiconductor crystalline carbon nitride

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Nano Research 2024年第6期17卷 5670-5679页

作者： Yong Wang Dingyi Yang wei Xu Yongjie Xu Yu Zhang Zixuan Cheng Yizhang Wu Xuetao Gan wei zhong Yan Liu Genquan Han Yue Hao Wide Bandgap Semiconductor Technology Disciplines State Key Laboratory School of MicroelectronicsAcademy of Advanced Interdisciplinary ResearchXidian UniversityXi’an 710071China Emerging Device and Chip Laboratory Hangzhou Institute of TechnologyXidian UniversityHangzhou 311200China INRS Centre for Energy Materials and Telecommunications1650 Boul.Lionel BouletVarennesQC J3X 1P7Canada National Laboratory of Solid State Microstructures Collaborative Innovation Center of Advanced Microstructures and Jiangsu Provincial Key Laboratory for NanotechnologyNanjing UniversityNanjing 210093China School of Education Jiangsu Open UniversityNanjing 210036China Department of Physics Shaanxi University of Science and TechnologyXi’an 710021China Department of Applied Physical Sciences The University of North Carolina at Chapel HillChapel HillNC 27514USA Key Laboratory of Light Field Manipulation and Information Acquisition Ministry of Industry and Information Technologyand Shaanxi Key Laboratory of Optical Information TechnologySchool of Physical Science and TechnologyNorthwestern Polytechnical UniversityXi'an 710129 China

Two-dimensional(2D)materials that combine ferromagnetic,semiconductor,and piezoelectric properties hold significant potential for both fundamental research and spin electronic ***,the majority of reported 2D ferromagnetic-semiconductor-piezoelectric materials rely on d-electron systems,which limits their practical applications due to a Curie temperature lower than room temperature(RT).Here,we report a high-crystallinity carbon nitride(CCN)material based on sp-electrons using a chemical vapor deposition *** exhibits a band gap of 1.8 eV and has been confirmed to possess substantial in-plane and out-of-plane ***,we acquired clear evidences of ferromagnetic behavior at room *** structural characterizations combined with theoretical calculations reveal that incorporating structural oxygen into the highly ordered heptazine structure causes partial substitution of nitrogen sites,which is primarily responsible for generating room-temperature ferromagnetism and *** a result,the strain in wrinkles can effectively modulate the domain behavior and piezoelectric potential at room *** addition of RT ferromagnetic-semiconductor-piezoelectric material based on sp-electrons to the family of two-dimensional materials opens up numerous possibilities for novel applications in fundamental research and spin electronic devices.

关键词： crystallinity carbon nitride room-temperature ferromagnetism piezoelectricity magnetic force microscopy density functional theory(DFT)calculations

Recent Advances in the Electrochemical Defluorinative Transformations of C-F Bonds

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Chinese Journal of Chemistry 2024年第16期42卷 1913-1928页

作者： Qinhui Wan Rui-Xue Liu zhongyi Zhang Xia-Die Wu zhong-wei Hou Lei Wang Advanced Research Institute and Schoolof Pharmaceutical Sciences Taizhou UniversityJiaojiangZhejiang 318000China Department of Chemistry Southern University of Science and TechnologyhenzhenGuangdong 518055China College of Material Chemistry and Chemical Engineering Key Laboratory of Organosilicon Chemistry and Material Technology Ministryof EducationHangzhou Normal UniversityHangzhouZhejiang 311121China

Organic fluorine compounds are ubiquitous and pivotally important organic molecules,yet their activation and transformation have long been a formidable challenge due to the high energy and low reactivity of C-F *** electrosynthesis,an environmentally benign synthetic method in organic chemistry,enables a myriad of chemical transformations without the need for external redox *** recent years,organic electrochemistry has emerged as a powerful tool for achieving the activation and transformation of C-F bonds in fluorine-containing *** review aims to succinctly recapitulate the latest advancements in the electrochemical defluorinative transformations of C-F bonds and to delve into the reaction design,mechanistic insights,and developmental prospects ofthese methods.

关键词： Organic electrochemistry Electroreduction Defluorination C-F bond activation Organic fluorine compounds