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Improvement of mechanical properties and investigation of strengthening mechanisms on the Ti_(3)AlC_(2) ceramic with nanosized WC addition

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Journal of Advanced Ceramics 2024年第6期13卷 861-876页

作者： Yi Zhong Ying Liu Qinkai Jiang Na Jin Zifeng Lin Jinwen Ye School of Materials Science&engineering Sichuan UniversityChengdu 610065China Yibin r&d Park Yibin Industrial Technology Research InstituteSichuan UniversityYibin 644005China

Ti_(3)AlC_(2) (TAC) has great potential for use as an ablation material in aerospace applications due to its great oxidation/ablation resistance, but its high-temperature strength and thermal shock resistance still have much room for simultaneous improvement under fast temperature variation conditions. Herein, we used Ti_(3)AlC_(2) and WC powders as raw materials and successfully fabricated textured (Ti,W)_(3)AlC_(2) ceramic with small amounts of TiC and Al_(2)O_(3), and room temperature mechanical properties such as flexural strength (1146±46.9 MPa), fracture toughness (11.78±0.44 MPa·m^(1/2)), and hardness (5.81±0.11 GPa) at 5 wt% WC addition were achieved. The high-temperature strength of the ceramic was significantly improved, and better thermal shock resistance from 298 to 1173 K was simultaneously acquired together with the regulation of the elastic modulus, thermal conductivity, and thermal expansion coefficient, providing (Ti,W)_(3)AlC_(2) with more possibilities for fast-temperature variation applications. Strengthening and toughening mechanisms were proposed. Scanning transmission electron microscopy high-angle annular dark-field imaging (STEM-HAddF) showed that W randomly replaced the Ti1 and Ti2 sites of Ti_(3)AlC_(2), providing a good reference for establishing crystal models, and further density functional theory (dFT) calculations based on these models indicated a higher fracture energy of (Ti,W)_(3)AlC_(2) along different crystal planes, providing superior resistance to transgranular fracture;a lower mismatch degree of (Ti,W)_(3)AlC_(2)/Al_(2)O_(3) resulted in stronger interface bonding, resulting in greater resistance to intergranular fracture as well as more balanced stress distributions at different interfaces.

关键词： mechanical properties solid solution MAX phase transmission electron microscopy(TEM) ceramic atomic structure

A micro-crosslinked amphoteric hydrophobic association copolymer as high temperature-and salt-resistance fluid loss reducer for water-based drilling fluids

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Petroleum Science 2024年第3期21卷 1980-1991页

作者： Jian Li Yu-Xi Ji Xiao-Xiao Ni Kai-He Lv Xian-Bin Huang Jin-Sheng Sun School of Petroleum engineering China University of Petroleum(East China)Qingdao266580ShandongChina Key Laboratory of Unconventional Oil&Gas development China University of Petroleum(East China)Qingdao26650ShandongChina Inspection and Testing Center of Huabei Oil Field Company PetroChinaRenqiu062552HebeiChina drilling fluid research institute CNPC Engineering Technology R&D Company LimitedBeijing102206China

during ultradeep oil and gas drilling,fluid loss reducers are highly important for water-based drilling fluids,while preparing high temperature-and salt-resistance fluid loss reducers with excellent rheology and filtration performance remains a ***,a micro-crosslinked amphoteric hydrophobic association copolymer(i.e.,dAdC)was synthesized using N,N-dimethyl acrylamide,diallyl dimethyl ammonium chloride,2-acrylamido-2-methylpropane sulfonic acid,hydrophobic monomer,and pentaerythritol triallyl ether *** to the synergistic effects of hydrogen bonds,electrostatic interaction,hydrophobic association,and micro-crosslinking,the dAdC copolymer exhibited outstanding temperature-and *** rheological experiments have shown that the dAdC copolymer had excellent shear dilution performance and a certain degree of salt-responsive viscosity-increasing *** dAdC copolymer could effectively adsorb on the surface of bentonite particles through electrostatic interaction and hydrogen bonds,which bring more negative charge to the bentonite,thus improving the hydration and dispersion of bentonite particles as well as the colloidal stability of the drilling ***,the drilling fluids constructed based on the dAdC copolymer exhibited satisfactory rheological and filtration properties(FLHTHP=12 m L)after aging at high temperatures(up to200℃)and high salinity(saturated salt)***,this work provided new insights into designing and fabricating high-performance drilling fluid treatment agents,demonstrating good potential applications in deep and ultradeep drilling engineering.

关键词： fluid loss reducer Temperature-and salt-resistance Hydrophobic association Amphoteric Micro-crosslinking

Progress in the application of graphene material in oilfield chemistry:A review

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Petroleum 2024年第2期10卷 175-190页

作者： Jinsheng Sun Yuanwei Sun Yong Lai Li Li Gang Yang Kaihe Lv Taifeng Zhang Xianfa Zhang Zonglun Wang Zhe Xu Zhiwen dai Jingping Liu School of Petroleum engineering China University of Petroleum (East China) CNPC engineering Technology r&d Company Limited Nanchong Vocational and Technical College Oil & Gas Technology research institute of Changqing Oilfield Company CNPC Greatwall drilling fluids Company

Graphene is a single atom thick crystal composed of carbon atoms. It is the lightest, thinnest, strongest material that conducts heat and electricity well heretofore. In terms of application, by introducing oxygen-containing groups, graphene can be well dispersed in solvents, can be chemically modified and functionalized, or connected with other electroactive substances through covalent bond or non-covalent bond to form composite materials, which is conducive to further processing and promotion. The application of graphene in oilfield chemistry started late, but developed rapidly. Graphene has played an active role in drilling fluid, cementing fluid, fracturing fluid, displacement fluid and other oilfield working fluids. It can enhance the temperature and salt resistance of working fluid and improve the effect of working fluid. In this paper, several directions of graphene applications in oilfield chemistry, such as modified graphene, graphene copolymers and graphene nanoparticles, are reviewed in detail from the synthesis methods, action mechanisms and effects of graphene and its derivatives, and the frontier cases at this stage are given. On the basis of the existing research, suggestions for the development direction of graphene materials in oilfield chemistry are given for a variety of graphene materials, aiming to provide guidance for the application of graphene in oilfield chemistry.

关键词： Oilfield chemistry Graphene Action mechanism Application Prospect

Heat Transfer and Friction Characteristics of Printed Circuit Heat Exchangers with different Channel Structures for S-CO_(2) Power System

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Journal of Thermal Science 2024年第3期33卷 1132-1147页

作者： JIANG Tao LI Mingjia Key Laboratory of Thermo-fluid Science and engineering of Ministry of Education School of Energy and Power EngineeringXi’an Jiaotong UniversityXi’an710049China School of Mechanical engineering Beijing Institute of TechnologyBeijing100081China

Printed circuit heat exchanger(PCHE)has been widely used in supercritical carbon dioxide(S-CO_(2))power systems because of its high heat transfer efficiency and good ***,due to the large variety of PCHE configurations,channel selection in practical applications lacks a ***,this paper discussed the heat transfer and friction characteristics and the synergy of three fields in the channel under the guidance of the field synergy principle for four typical PCHE ***,the comprehensive performance of four channels was ***,the heat transfer and friction factor correlations for S-CO_(2)in four channels were *** findings demonstrate that the synergy of velocity and pressure fields of the straight channel PCHE is better(β≈180°),so its resistance loss is relatively *** zigzag and sinusoidal wavy channels and the airfoil fins can reduce the angle a between the temperature gradient and velocity,thus enhancing the heat *** sinusoidal wavy channel can reduce flow resistance compared to the zigzag channel due to the rounded *** streamlined airfoil structure can guide the flow and reduce backflow,thus reducing resistance *** the range of re studied in this paper,the maximum error of the proposed heat transfer and friction factor correlations of PCHE is 7.0%,which shows good fitting *** research in this paper can provide a reference for the selection and design of PCHE with different channel configurations.

关键词： printed circuit heat exchanger supercritical carbon dioxide typical channel structure field synergy analysis

A 3d-printed microhemispherical shell resonator with electrostatic tuning for a Coriolis vibratory gyroscope

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Microsystems & Nanoengineering 2024年第2期10卷 25-35页

作者： Baoyin Hou Ye Zhu Chaofan He Weidong Wang Zhi ding Wen He Yong He Lufeng Che College of Information Science and Electronic engineering Zhejiang UniversityHangzhou310027China Center for Microelectronics Shaoxing InstituteZhejiang UniversityShaoxing312035China State Key Laboratory of fluid Power and Mechatronic Systems Zhejiang UniversityHangzhou310058China School of Mechanical engineering Zhejiang UniversityHangzhou310058China

The emergence of microhemispherical resonant gyroscopes,which integrate the advantages of exceptional stability and long lifetime with miniaturization,has afforded new possibilities for the development of whole-angle ***,existing methods used for manufacturing microhemispherical resonant gyroscopes based on MEMS technology face the primary drawback of intricate and costly ***,we report the design,fabrication,and characterization of the first 3d-printable microhemispherical shell resonator for a Coriolis vibrating *** remarkably achieve fabrication in just two steps bypassing the dozen or so steps required in traditional *** utilizing the intricate shaping capability and ultrahigh precision offered by projection microstereolithography,we fabricate 3d high-aspect-ratio resonant structures and controllable capacitive air gaps,both of which are extremely difficult to obtain via MEMS *** addition,the resonance frequency of the fabricated resonators can be tuned by electrostatic forces,and the fabricated resonators exhibit a higher quality factor in air than do typical MEMS microhemispherical *** work demonstrates the feasibility of rapidly batch-manufacturing microhemispherical shell resonators,paving the way for the development of microhemispherical resonator gyroscopes for portable inertial ***,this particular design concept could be further applied to increase uptake of resonator tools in the MEMS community.

关键词： resonator tuning electrostatic

Statistics and dynamics of coherent structures in compressible wall-bounded turbulence

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Science China(Physics,Mechanics & Astronomy) 2024年

作者： Ming Yu SiWei dong XianXu Yuan ChunXiao Xu State Key Laboratory of Aerodynamics Key Laboratory of Applied Mechanics Institute of Fluid Mechanics Department of Engineering Mechanics Tsinghua University

Compressible wall-bounded turbulence is ubiquitously encountered in modern aerospace and mechanical industries. In this review, we summarize the current state of the literature on the flow physics of compressible wall-bounded turbulence with simple flow geometry and boundary constraints, focusing on the statistics and dynamics of coherent structures, the seemingly organized flow patterns hidden amidst the nonlinear chaotic random processes. We summarize the conclusions brought by recent year studies regarding the influences of the Mach number and wall temperature on the velocity streaks, quasi-streamwise vortices and dilatational motions in the near-wall region, and the large-scale and very-large-scale motions in the outer region, from both statistical and dynamical point of view, with the primary concern of the similarities with and disparities from those in incompressible flows.

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Experimental and Numerical Evaluation of the Cavitation Performances of Self-Excited Oscillating Jets

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fluid dynamics & Materials Processing 2024年第8期20卷 1883-1901页

作者： Yuanyuan Zhao Fujian Zhao Guohui Li Wei Xu Xiuli Wang School of the Environment and Safety engineering Jiangsu UniversityZhenjiang212013China research Center of fluid Machinery engineering and Technology Jiangsu UniversityZhenjiang212013China GongQing institute of Science and Technology Jiujiang332020China School of Energy and Power engineering Jiangsu UniversityZhenjiang212013China

Self-excited oscillating jets(SOJ)are used in several practical *** performances are significantly affected by structural parameters and the target *** this study,a geometric model of the SOJ nozzle accounting for multiple structural parameters is introduced,then the related cavitation performances and the optimal target distance are investigated using a Large-Eddy Simulation(LES)*** are also provided about an experiment,which was conducted to validate the simulation *** analyzing the evolution of the vapor volume fraction at the nozzle outlet,a discussion is presented about the effect of the aforementioned structural parameters on the cavitation performances and the target *** is shown that the distribution of cavitation clouds at the outlet of the SOJ nozzle displays a non-monotonic trend(first increasing,then decreasing).Under working conditions with an inlet pressure of 4 MPa,a SOJ nozzle outlet/inlet diameter ratio(d_(1)/d_(2))of 1.2,and a chamber diameter ratio(d/L)close to 1.8,the nozzle outlet cavitation performance attains a *** optimal structural parameters correspond to the optimal target distance,which is near 50 *** experiments have revealed that the SOJ nozzle with the above parameters displays a good cavitation erosion effect at the target distance of 50 mm,in satisfactory agreement with the numerical simulation results.

关键词： Self-excited oscillating nozzle cavitating jet target distant LES cavitation

Numerical Analysis of Perforation during Hydraulic Fracture Initiation Based on Continuous-discontinuous Element Method

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Computer Modeling in engineering & Sciences 2024年第8期140卷 2103-2129页

作者： rui Zhang Lixiang Wang Jing Li Chun Feng Yiming Zhang School of Civil and Transportation engineering Hebei University of TechnologyTianjin300401China Key Laboratory for Mechanics in fluid Solid Coupling Systems Institute of MechanicsChinese Academy of SciencesBeijing100190China School of Civil engineering and Architecture Zhejiang Sci-Tech UniversityHangzhou310018China Jinyun institute Zhejiang Sci-Tech UniversityLishui321400China

Perforation is a pivotal technique employed to establish main flow channels within the reservoir formation at the outset of hydraulic fracturing *** perforation designs is critical for augmenting the efficacy of hydraulic fracturing and boosting oil or gas *** this study,we employ a hybrid finite-discrete element method,known as the continuous–discontinuous element method(CdEM),to simulate the initiation of post-perforation hydraulic fractures and to derive enhanced design *** model incorporates the four most prevalent perforation geometries,as delineated in an engineering technical ***-world perforations deviate from the ideal cylindrical shape,exhibiting variable cross-sectional profiles that typically manifest as an initial constriction followed by an expansion,a feature consistent across all four perforation *** simulations take into account variations in perforation hole geometries,cross-sectional diameters,and perforation *** findings show that perforations generated by the 39g dP3 HMX perforating bullet yield the lowest breakdown pressure,which inversely correlates with increases in sectional diameter and perforation ***,this study reveals the relationship between breakdown pressure and fracture degree,providing valuable insights for engineers and designers to refine perforation strategies.

关键词： Hydraulic fracturing real perforation shape breakdown pressure perforation layout design CdEM

Analytical solutions of turbulent boundary layer beneath forward-leaning waves

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Applied Mathematics and Mechanics(English Edition) 2024年第4期45卷 695-710页

作者： Yiqin XIE Jifu ZHOU Xu WANG Jinlong dUAN Yongjun LU Shouqian LI Laboratory for Mechanics in fluid Solid Coupling Systems Institute of MechanicsChinese Academy of SciencesBeijing 100190China State Key Laboratory of Simulation and regulation of Water Cycle in river Basin China Institute of Water Resources and Hydropower ResearchBeijing 100038China School of engineering Sciences University of Chinese Academy of SciencesBeijing 100049China State Key Laboratory of Hydrology-Water resources and Hydraulic engineering Nanjing Hydraulic Research InstituteNanjing 210024China

As a typical nonlinear wave,forward-leaning waves can be frequently encountered in the near-shore areas,which can impact coastal sediment transport ***,it is of significance to describe the characteristics of the boundary layer beneath forward-leaning waves accurately,especially for the turbulent boundary *** this work,the linearized turbulent boundary layer model with a linear turbulent viscosity coefficient is applied,and the novel expression of the near-bed orbital velocity that has been worked out by the authors for forward-leaning waves of arbitrary forward-leaning degrees is further used to specify the free stream boundary condition of the bottom boundary ***,a variable transformation is found so as to make the equation of the turbulent boundary layer model be solved analytically through a modified Bessel ***,an explicit analytical solution of the turbulent boundary layer beneath forward-leaning waves is derived by means of variable separation and variable *** analytical solutions of the velocity profile and bottom shear stress of the turbulent boundary layer beneath forward-leaning waves are verified by comparing the present analytical results with typical experimental data available in the previous literature.

关键词： forward-leaning wave turbulent boundary layer velocity profile bottom shear stress