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NUMERICAL SIMULATION OF CAVITATION FLOW UNDER HIGH PRESSURE AND TEMPERATURE

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Journal of Hydrodynamics 2011年第3期23卷 289-294页

作者： zhao wei-guo zhang ling-xin shao xue-ming Department of Mechanics Zhejiang University Hangzhou 310027 China State Key Laboratory of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 China

The numerical simulation of cavitation flow on a 2D NACA0015 hydrofoil under high pressure and temperature is performed. The Singhal＇s cavitation model is adopted combined with an improved RNG k-ε turbulence model to study the cavitation flow. The thermal effect in the cavitation flow is taken into account by introducing the energy equation with a source term based on the latent heat transfer. The code is validated by a case of a hydrofoil under two different temperatures in a comparison between the simulation and the experiment. Computational results show that the latent heat of vaporization has a significant impact on the cavitation process in the high temperature state, and the cavity in the high temperature state is thinner and shorter than that in a normal state with the same cavitation number, due to the fact that the heat absorption in the cavitation area reduces the local temperature and the saturated vapor pressure. This numerical study provides some guidance for the design of machineries in the High Pressure and Temperature （HPT） state.

关键词： cavitation NACA0015 thermodynamic CFD high pressure and temperature

Measurement of two-phase velocities in bubble flows using laser Doppler velocimetry

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Journal of Hydrodynamics 2022年第6期34卷 1134-1144页

作者： ling-xin zhang xin-sheng Cheng Han Tu Qi Gao xue-ming shao Xiang-wei Liao Liang zhao Department of Engineering Mechanics Zhejiang UniversityHangzhou310027China Iron and Steel Research Institutes of Ansteel Group Corporation Anshan114009China State Key Laboratory of Metal Material for Marine Equipment and Application Anshan114009China

The measurement of two-phase velocities in bubble flows using laser Doppler velocimetry(LDV)is *** key to the problem is to differentiate the LDV signals from bubbles and tracers,based on which the two-phase velocities can be *** this study,two experiments are carried ***,the bubble-chain experiment is performed to investigate the optical response of bubble surface and the corresponding LDV *** optical response shows that the light received by the LDV detector is dominated by the reflection component,which is similar to specular reflection to some *** are three typical patterns of signals of large bubbles passing through the measurement volume,all of which are with high amplitude and ***,the upward-flow experiment is conducted to study the statistical characteristics of large bubbles as well as micro tracers and micro *** results show that the amplitude of signal of millimeter bubbles is about an order of magnitude larger than that of tracers or micro *** on this significant difference of the amplitude,we propose a phase discrimination method to distinguish two-phase *** capability of the proposed method is tested in a complex bubble flow,and its reliability is verified by bubble tracking velocimetry(BTV)technology.

关键词： laser Doppler velocimetry(LDV) bubbly flow phase discrimination bubble tracking velocimetry(BTV)

Characterization of 17-4PH stainless steel powders produced by supersonic gas atomization

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International Journal of Minerals,Metallurgy and Materials 2012年第1期19卷 83-88页

作者： xin-ming zhao Jun Xu xue-xin Zhu shao-ming zhang Wen-dong zhao guo-liang Yuan National Engineering and Technological Research Center for Non-ferrous Metals Composites General Research Institute for Non-ferrous Metals Beijing 100088 China Beijing COMPO Advanced Technology Co. Ltd. Beijing 100088 China

17-4PH stainless steel powders were prepared using a supersonic nozzle in a close-coupled gas atomization system. The characteristics of powder particles were carried out by means of a laser particle size analyzer, scanning electron microscopy （SEM）, and the X-ray diffraction （XRD） technique. The results show that the mass median particle diameter is about 19.15 prn. Three main types of surface microstructures are observed in the powders： well-developed dendrite, cellular, and cellular dendrite structure. The XRD measurements show that, as the particle size decreases, the amount of fcc phase gradually decreases and that of bcc phase increases. The cooling rate is inversely related to the particle size, i.e., it decreases with an increase in particle size.

关键词： gas atomization metal powder stainless steel metal injection molding

Qualitative Analysis and Approximate Damped Oscillatory Solutions for a Kind of Nonlinear Dispersive-dissipative Equation

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Acta Mathematicae Applicatae Sinica 2017年第1期33卷 1-24页

作者： shao-wei LI wei-guo zhang Van zhao Zheng-ming LI Xiang LI Business School University of Shanghai for Science and Technology Shanghai 200093 China School of Mathematics and Information Engineering Taizhou University Taizhou 317000 China College of Science University of Shanghai for Science and Technology Shanghai 200093 China

This paper makes qualitative analysis to the bounded traveling wave solutions for a kind of nonlinear dispersive-dissipative equation, and considers its solving problem. The relation is investigated between behavior of its solution and the dissipation coefficient. Further, all approximate damped oscillatory solutions when dissipation coefficient is small are presented by utilizing the method of undetermined coefficients according to the theory of rotated vector field in planar dynamical systems. Finally, error estimate is given by establishing the integral equation which reflects the relation between approximate and exact damped oscillatory solutions applying the idea of homogenization principle.

关键词： nonlinear dispersive-dissipative equation qualitative analysis solitary wave solution dampedoscillatory solution error estimate

Rational design of superior catalysts from topological semimetals with nontrivial energy window

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Rare Metals 2024年第5期43卷 1956-1964页

作者： Min zhao Li-Rong Wang wei Liu ming-Hang Li Ying Liu xue-Fang Dai guo-Dong Liu Xiao-ming zhang Key Laboratory of Reliability and Intelligence of Electrical Equipment School of Materials Science and Engineering ManufacturingHebei University of TechnologyTianjin 300130China

Materials featuring topological energy bands and nontrivial surface states hold significant promise in unlocking unprecedented opportunities for innovating electrocatalytic ***,it remains a challenge to realize superior topological catalysts which can carry both high catalytic activity and excellent catalytic ***,we propose that a family of Ni-based binary materials hosting fantasying topological conjunct-nodalpoint state and a large nontrivial energy window(NEWD)represents an ideal choice for such superior topological catalysts in hydrogen evolution *** presence of conjunct-nodal-points ensures long Fermi arcs on the surface,thereby enabling an extremely high catalytic *** NEWD plays a crucial role in stabilizing the high catalytic activity against external perturbations,such as strain and electron/hole *** roles for conjunctnodal-points and NEWD are substantiated by the observable weakening of catalytic performance during topological phase transitions,which result in the removal of the conjunct-nodal-points,NEWD and their corresponding long Fermi *** work unveils a hidden mechanism and opens a feasible route for developing superior quantum catalysts from novel topology point of view.

关键词： First-principles modeling Topological semimetal Nontrivial surface states Hydrogen evolution reaction

A thermodynamic model of calculating mass action concentrations for structural units or ion couples in NaClO_4-H_2O and NaF-H_2O binary solutions and NaClO_4-NaF-H_2O ternary solution

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International Journal of Minerals,Metallurgy and Materials 2010年第5期17卷 546-557页

作者： xue-min Yang wei-jie zhao Han-jie guo Qiang zhang Jian zhang State Key Lab of Multiphase Complex System Institute of Process Engineering Chinese Academy of Sciences Beijing 100190 China School of Metallurgical and Ecological Engineering University of Science and Technology Beijing Beijing 100083 China Beijing Metallurgical Equipment Research ＆ Design Corporation Ltd. China Metallurgical Group Corporation Beijing 100029 China

A thermodynamic model of calculating mass action concentrations for structural units or ion couples in NaClO4-H2O and NaF-H2O binary solutions and NaClO4-NaF-H2O ternary strong electrolyte aqueous solutions was developed based on the ion and molecule coexistence theory （IMCT）. A transformation coefficient was needed to compare the calculated mass action concentration and the reported activity, because they were usually obtained at different standard states and concentration units. The results show that transformation coefficients between the calculated mass action concentrations and the reported activities of the same components change in a very narrow range. The transformed mass action concentrations of structural units or ion couples in NaClO4-H2O and NaF-H2O binary solutions agree well with the reported activities. The transformed mass action concentrations of structural units or ion couples in NaClO4-NaF-H2O ternary solution are also in good agreement with the reported activities in a total ionic strength range from 0.1 to 0.9 mol/kg H2O by the 0.1 mol/kg step with different ionic strength fractions of 0, 0.2, 0.4, 0.5, 0.6, 0.8, and 1, respectively. The results indicate that the developed thermodynamic model can reveal the structural characteristics of binary and ternary strong electrolyte aqueous solutions, and the calculated mass action concentrations of structural units or ion couples also strictly follow the mass action law.

关键词： binary systems ternary systems thermodynamic model activity coefficient structural unit

Investigation on the Structure and Performance of Polypropylene Sheets and Bi-axially Oriented Polypropylene Films for Capacitors

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Chinese Journal of Polymer Science 2022年第12期40卷 1688-1696,I0011页

作者： Chong zhang Xi-Ying Dai zhao-Liang xing shao-wei guo Fei Li xin Chen Jian-Jun Zhou Lin Li State Key Laboratory of Advanced Power Transmission Technology Global Energy Interconnection Research Institute Co.Ltd.Beijing 102209China Beijing Key Laboratory of Energy Conversion and Storage Materials College of ChemistryBeijing Normal UniversityBeijing 100875China

Polypropylene(PP) sheets are cast with various chill roll temperatures and rates, which are studied with differential scanning calorimetry, wide angel X-ray diffraction, scanning electronic microscopy and dielectric withstand voltage test system. The results show that increasing the chill roll temperature and cast rate can promote the increase of crystallinity and the growth of β-form. The PP sheets have asymmetric skin layer structures. The lower the chill roll temperature, the thicker the skin layer, the smaller the spherulite size. The electric breakdown strength(Eb) of PP sheets is mainly affected by the crystallinity but not the morphology. The PP sheets are further stretched to prepare bi-axially oriented PP(BOPP) films with various heat setting time. Our results indicate that the structure of PP sheets affects the properties of BOPP films. The as prepared BOPP films from the sheets cast at high chill roll temperature and rate have the highest crystallinity and Eb. Heat setting time has profound effect on the crystallinity and Eb, which increase first and then decrease with the heat setting time. It is expected that our study can provide guidance for optimizing process parameters.

关键词： BOPP film Polypropylene sheet Electric breakdown strength Crystallinity Heat set

CTL Responses to Regulatory Proteins Tat and Rev in HIV-1 B’/C Virus-Infected Individuals

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Biomedical and Environmental Sciences 2008年第4期21卷 314-318页

作者： ming-ming JIA KUN-xue HONG JIAN-PING CHEN HONG-wei LIU SHA LIU XIAO-QING zhang HONG-JING zhao YI-ming shao Branch of AIDS State Key Laboratory for Infectious Diseases Prevention and Control National Center for AIDS/STD Control and Prevention Chinese Center for Disease Control and Prevention Beijing 100050 China

Objective To characterize HIV-1 specific CTL responses to regulatory proteins Tat and Rev in HIV-B＇/C virus-infected ART-naive individuals. Methods HIV-1-specific CTL responses were analyzed by IFN-7 ELISPOT assay using overlapping peptides spanning the consensus sequences of HIV-1 clade C Tat and Rev proteins. Statistical analysis and graphical presentation were performed using SIGMAPLOT 10.0 and SIGMASTAT 3.5. For samples with a positive response, the magnitude of CTL responses was compared between HIV-1 C proteins by Wilcoxon rank sum test, and the significance threshold was P〈0.05. Results Tat and Rev were frequently recognized, with 23% and 52% of the tested individuals having detectable responses to these proteins, respectively. Several immunodominant regions were detected in Rev. No significant correlation was observed between the magnitude and breadth of CTL responses to regulatory proteins and the control of virus replication in this study. Conclusion Tat and Rev can serve as targets for HIV-l-specific CTL, and several immunodominant regions are detectable in Rev. Further characterization of epitopes and their role in virus control may shed light on pathogenesis of HIV- 1 natural infection and also be useful for the design and testing of candidate vaccines.

关键词： HIV-1 Immune responses ELISPOT Cytotoxic T-lymphocytes

Structure, magnetic properties, and thermal stability of Sm(1-x)Tm_xCo_5compounds

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Rare Metals 2014年第2期33卷 176-179页

作者： Jian-Hua Zuo ming Yue Qing-Mei Lu Dong-Tao zhang xue-Xu Gao Jiu-xing zhang zhao-Hui guo wei Li College of Materials Science and Engineering Beijing University of Technology State Key Laboratory of Advanced Metals and Materials University of Science and Technology Beijing Division of Functional Materials Central Iron and Steel Research Institute

Structure, magnetic properties, and thermal stability of ternary Sm1-xTmxCo5 compounds were studied via X-ray diffraction（XRD）, thermal magnetic analysis（TMA）, and magnetic measurements. XRD results show that all the compounds have a main phase of hexagonal CaCu5-type crystal structure with small amount of impurity phases; increasing Tm content is associated with contraction of the hexagonal unit cell in the direction of the c axis and expansion of the a and b parameters. TMA results indicate that the Curie temperature（TC） of Sm1-xTmxCo5 compounds gets higher with the increase in Tm *** measurements show that both the magnetic anisotropy field（HA） and the magnetization at an applied field of 7 T（M7 T） decrease with the increase of Tm content. However, the thermal stability of both the HAand M7 Tof all the Tm doped compounds is remarkably improved compared with that of the pure SmCo5 compound, leading to the result that both the M7 Tand HAof Sm0.8Tm0.2Co5 .2are higher than those of SmCo5 compound at 473 K, which indicates the good potential of Tm doped compound in the practical applications at elevated temperature.

关键词： Sm1-xTmxCo5 compounds Crystal structure Intrinsic magnetic property Thermal stability