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Numerical exploration on the thermal invasion characteristics of two typical gap-cavity structures subjected to hypersonic airflow

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Chinese Journal of Aeronautics 2020年第6期33卷 1589-1601页

作者： zhenhuan li Xinlin XIA Xiaolei li Chuang SUN Key Laboratory of Aerospace Thermophysics of Ministry of Industry and Information Technology School of Energy Science and EngineeringHarbin Institute of TechnologyHarbin 150001China

In this paper,numerical investigation of hypersonic gas flow over two typical gap-cavity structures is carried out using all-speed preconditioned density-based *** structures filled with porous seal in the gap are often present at the joint locations of control surfaces of the hypersonic ***-domain approach is adopted to integrate the governing equations for both porous and fluid *** basic thermal invasion characteristic is first illustrated using the maze gap-cavity structure without ***,the influence of seal filling depth on the thermal invasion characteristic is investigated for the structure with ***,a comparison of thermal invasion characteristics between maze and straight gap-cavity structures is performed to examine the influence of gap *** show that the main source of hot airflow invading into the gap is from the millimeter scale gas layer within the boundary *** the invasion characteristic presents approximate stationary behavior.A primary vortex occurs in the gap adjacent to the leeward wall,which is ascribed to the impinging effect between the separate boundary flow and the windward *** effect is also the main driving force of thermal invasion.A treatment of filling the seal in certain depth inside the gap can significantly reduce the thermal load of seal and maintain an acceptable level of the invading mass flow ***,it is found that the gap bending exerts a limited block effect on the thermal invasion without sealing,and this effect can be ignored with *** results can provide a reference for optimizing the seal gap-cavity structure configuration.

关键词： Gap-cavity structure Heat transfer Hypersonic flow Porous material Thermal invasion

Highly stable aqueous rechargeable Zn-ion battery:The synergistic effect between NaV_(6)O_(15) and V_(2)O_(5) in skin-core heterostructured nanowires cathode

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Journal of Energy Chemistry 2021年第4期30卷 25-33页

作者： Lanlan Fan zhenhuan li Weimin Kang Bowen Cheng State Key Laboratory of Separation Membranes and Membrane Processes National Center for International Joint Research on Separation MembranesTiangong UniversityTianjin 300387China School of Materials Science and EngineeringTiangong UniversityTianjin 300387China School of Textiles Tiangong UniversityTianjin 300387China

The aqueous rechargeable Zn-ion batteries based on the safe,low cost and environmental benignity aqueous electrolytes are one of the most compelling candidates for large scale energy storage ***,pursuing suitable insertion materials may be a great challenge due to the strong electrostatic interaction between Zn^(^(2+))and cathode ***,a novel NaV_(6)O_(15)/V_(2)O_(5) skin-core heterostructure nanowire is reported via a one-step hydrothermal method and subsequent calcination for high-stable aqueous Zn-ion batteries(ZIBs).The NaV_(6)O_(15)/V_(2)O_(5) cathode delivers high specific capacity of 390 m Ah/g at 0.3 A/g and outstanding cycling stability of 267 m Ah/g at 5 A/g with high capacity retention over 92.3%after 3000 *** superior electrochemical performances are attributed to the synergistic effect of skin-core heterostructured NaV_(6)O_(15)/V_(2)O_(5),in which the sheath of NaV_(6)O_(15) possesses high stability and conductivity,and the V_(2)O_(5) endows high specific ***,the heterojunction structure not only accelerates intercalation kinetics of Zn^(2+)transport but also further consolidates the stability of the layers of V_(2)O_(5) during the cyclic *** work provides a new perspective in developing feasible insertion materials for rechargeable aqueous ZIBs.

关键词： Aqueous zinc ion battery Heterojunction structure High specific capacity Stable long cycle Synergistic effect

Selective excitation of two-wave structure depending on crystal orientation under shock compression

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Science China(Physics,Mechanics & Astronomy) 2020年第11期63卷 59-71页

作者： Qilin Xiong Takahiro Shimada Takayuki Kitamura zhenhuan li Department of Mechanics Huazhong University of Science&TechnologyWuhan 430074China Hubei Key Laboratory of Engineering Structural Analysis and Safety Assessment Wuhan 430074China Department of Mechanical Engineering and Science Kyoto UniversityKyoto 615-8540Japan

Single crystals subjected to shock compression exhibit responses with distinct two-wave structures for certain crystal ***,little is known to date regarding how the shock response depends on crystal orientation,and especially why the two-wave structure depends on the crystal *** this work,molecular dynamics simulations of shock compressions in copper single crystals are performed to investigate the orientation dependence of shock responses and the corresponding deformation *** copper single crystals with[001],[011],[012],and[123]crystal orientations along the depth direction are ***[011],[012],and[123]crystal orientations of copper single crystals show distinct two-wave structures in their shock responses,while such a two-wave structure in the shock response is not seen for those orientations having a[001]crystal *** potential causes are analyzed by considering the propagation velocities of both elastic and plastic *** develop a technique for identifying twin structures in face-centered cubic crystals and this technique can effectively identify the twin *** morphology of shock-induced defects(e.g.,dislocations and twins)shows the significant dependence of crystal orientation and the mechanisms behind these are discussed in ***,the Johnson-Cook constitutive model describing dynamic deformations at high temperatures and high strain rates is used to analyze the relationships between the shock responses and microscopic *** predictions of the Johnson-Cook constitutive model are consistent with the results of the molecular dynamics simulations.

关键词： orientation-dependent two-wave structure shock compression copper molecular dynamics

Quantitative study on interactions between interfacial misfit dislocation networks and matrix dislocations in Ni-based single crystal superalloys

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Acta Mechanica Solida Sinica 2017年第4期30卷 345-353页

作者： Jun Xiong Yaxin Zhu zhenhuan li Minsheng Huang Department of Mechanics Huazhong University of Science and Technology State Key Laboratory of Digital Manufacturing Equipment and Technology Huazhong University of Science and Technology Hubei Key Laboratory of Engineering Structural Analysis and Safety Assessment

The interactions between the moving dislocation within matrix channel and the interfacial misfit dislocation networks on the two-phase interfaces in Ni-based single crystal superalloys are studied carefully via atomic modeling, with special focus on the factors influ- encing the critical bowing stress of moving dislocations in the matrix channel. The results show that the moving matrix dislocation type and its position with respect to the interfacial misfit dislocation segments have considerable influences on the interactions. If the moving matrix dislocation is pure screw, it reacts with the interracial misfit dislocation segments toward dislocation linear energy reduction, which decreases the critical bowing stress of screw dislocation due to dislocation linear energy release during the dislocation reactions. If the moving matrix dislocation is of 60^-mixed type, it is obstructed by the interaction between the mixed matrix dislocations and the misfit interfacial dislocation segments. As a result, the critical bowing stress increases significantly because extra interactive energy needs to be overcome. These two different effects on the critical bowing stress become in- creasingly significant when the moving matrix dislocation is very close to the interracial misfit dislocation segments. In addition, the matrix channel width also has a significant influence on the critical bowing stress, i.e. the narrower the matrix channel is, the higher the critical bowing stress is. The classical Orowan formula is modified to predict these effects on the critical bowing stress of moving matrix dislocation, which is in good agreement with the computational results.

关键词： Dislocation interaction Misfit dislocation networks Molecular dynamics Matrix dislocation Ni-based single crystal superalloys

Effect of Hydrogen on Dislocation Nucleation and Motion:Nanoindentation Experiment and Discrete Dislocation Dynamics Simulation

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Acta Mechanica Solida Sinica 2022年第1期35卷 1-14页

作者： Jian Wang Lv Zhao Minsheng Huang Yaxin Zhu zhenhuan li Department of Mechanics Huazhong University of Science and TechnologyWuhan 430074China Hubei Key Laboratory of Engineering Structural Analysis and Safety Assessment 1037 Luoyu RoadWuhan 430074China

The hydrogen effect on the nucleation and motion of dislocations in single-crystal bcc Fe with(110)surface was investigated by both nanoindentation experiments and discrete dislocation dynamics(DDD)*** results of nanoindentation experiments showed that the pop-in load decreased evidently for the electrochemical hydrogen charging specimen,indicating that the dislocation nucleation strength might be reduced by *** addition,the decrease of hardness due to hydrogen charging was also captured,implying that the dislocation motion might be promoted by *** incorporating the effect of hydrogen on dislocation core energy,a DDD model was specifically proposed to investigate the influence of hydrogen on dislocation nucleation and *** results of DDD simulation revealed that under the effect of hydrogen,the dislocation nucleation strength is decreased and the motion of dislocation is promoted.

关键词： Hydrogen Nanoindentation Homogeneous dislocation nucleation Discrete dislocation dynamics

Rational design of hollow oxygen deficiency-enriched NiFe_(2)O_(4)@N/rGO as bifunctional electrocatalysts for overall water splitting

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Journal of Energy Chemistry 2021年第3期30卷 595-603页

作者： Lei Cao zhenhuan li Kunmei Su Maliang Zhang Bowen Cheng State Key Laboratory of Separation Membranes and Membrane Processes/National Center for International Joint Research on Separation Membranes School of Materials Science and EngineeringTiangong UniversityTianjin 300387China School of Environment Science and Chemistry Engineering Tiangong UniversityTianjin 300160China

Bimetallic metal organic framework(MOF)as a precursor to prepare catalysts with bifunctional catalytic activity of oxygen evolution reaction(OER)and hydrogen evolution reaction(HER)attracts more and more ***,hollow oxygen deficiency-enriched NiFe_(2)O_(4) is synthesized by pyrolytic FeNi bimetallic *** defects of rGO during carbonization can act as nucleation sites for FeNi *** nucleation and N doping,the FeNi particles were served as catalysts for the deposition of dissolved carbon in the defects of the N/*** deposited carbon,like a bridge,connect N/rGO and hollow oxygen deficiency-enriched NiFe_(2)O_(4) together,which giving full play to the advantages of N/rGO in fast electron transfer,thereby improving its catalytic *** resultant NiFe_(2)O_(4)@N/rGO-800 exhibits a low overpotential of 252 mV at 20 mA cm^(-2) for OER and 157 mV at 10 mA cm^(-2) for HER in 1 M KOH,*** used as bifunctional electrodes for overall water splitting,it also shows low cell voltage of 1.60 V and 1.67 V at 10 and 20 mA cm^(-2),respectively.

关键词： Oxygen deficiency Hollow NiFe_(2)O_(4) N/rGO Bifunctional electrocatalyst Overall water splitting

CYCliC HARDENING BEHAVIOR OF POLYCRYSTALS WITH PENETRABLE GRAIN BOUNDARIES:TWO-DIMENSIONAL DISCRETE DISLOCATION DYNAMICS SIMULATION

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Acta Mechanica Solida Sinica 2009年第4期22卷 295-306页

作者： Chuantao Hou zhenhuan li Minsheng Huang Chaojun Ouyang Department of Mechanics Huazhong University of Science and Technology Wuhan 430074 China

A two-dimensional discrete dislocation dynamics （DDD） technology by Giessen and Needleman （1995）, which has been extended by integrating a dislocation-grain boundary interaction model, is used to computationally analyze the micro-cyclic plastic response of polycrystals containing micron-sized grains, with special attentions to significant influence of dislocationpenetrable grain boundaries （GBs） on the micro-plastic cyclic responses of polycrystals and underlying dislocation mechanism. Toward this end, a typical polycrystalline rectangular specimen under simple tension-compression loading is considered. Results show that, with the increase of cycle accumulative strain, continual dislocation accumulation and enhanced dislocation-dislocation interactions induce the cyclic hardening behavior; however, when a dynamic balance among dislocation nucleation, penetration through GB and dislocation annihilation is approximately established, cyclic stress gradually tends to saturate. In addition, other factors, including the grain size, cyclic strain amplitude and its history, also have considerable influences on the cyclic hardening and saturation.

关键词： discrete dislocation dynamics simulation cyclic micro-plasticity size effect polycrystals grain boundary penetrability

Synergistic coupling of Ni_(3)ZnC_(0.7)decorated with homogeneous multimetal CoNiCuFe nitrogen-codoped carbon matrix as high-entropy catalysts for efficient overall water splitting

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Journal of Materials Science & Technology 2023年第4期135卷 26-33页

作者： Xi Du Leilei Yin WenJun Zhang Maliang Zhang Kunmei Su zhenhuan li State Key Laboratory of Separation Membranes and Membrane Processes Tiangong UniversityTianjin 300387China Tianjin Key Laboratory of Advanced Fibers and Energy Storage School of Materials Science and EngineeringTiangong UniversityTianjin 300387China School of Chemistry and Chemical Engineering Tiangong UniversityTianjin 300387China

Due to unique electrical properties and high catalytic efficiency,transition metal nitrogen-codoped car-bide(TM-N-C)has attracted tremendous interest as a multifunctional electrocatalyst for water *** traditional single-source modification,herein a novel pomegranate-like high-entropy(HE)elec-trocatalyst of Ni_(3)ZnC_(0.7)decorated with homogeneous multimetal(Fe,Co,Cu,and Ni)nitrogen-codoped carbon matrix(Ni_(3)ZnC_(0.7)@CoNiCuFe-NC)is *** can be implemented by the simple thermal an-nealing method of multimetal codoped zeolitic imidazolate framework(ZIF).Benefiting from the syn-ergistic effects of plentiful TM-N-C species,template effect of ZIF and distinct nanoporous structure,HE electrocatalyst Ni_(3)ZnC_(0.7)@CoNiCuFe-NC exhibits outstanding electrocatalytic *** ap-plied in strong alkaline electrolyte(1.0 M KOH),the overpotentials of Ni_(3)ZnC_(0.7)@CoNiCuFe-NC present as low as 202 and 97 mV for oxygen evolution reaction(OER)and hydrogen evolution reaction(HER)at 10 mA cm^(−2)current *** as a bifunctional electrode,it can achieve the low cell voltage of 1.53 V at 10 mA cm^(−2)current density for overall water splitting,which is comparable to conventional IrO_(2)||Pt/C electrode and superior to the recently reported analogous bifunctional ***,the work proposes the direction for the rational design of homogeneous distribution of TM-N-C material for water splitting in the green hydrogen energy industry.

关键词： Homogeneous multimetal Zeolitic imidazolate framework High-entropy electrocatalyst Synergistic effect Overall water splitting

INFLUENCES OF MICROSCOPE SIZE EFFECT OF MATRIX ON PLASTIC POTENTIAL AND VOID GROWTH OF POROUS MATERIALS

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Acta Mechanica Solida Sinica 2002年第4期15卷 283-293页

作者： Huang Minsheng li zhenhuan Wang Cheng Chen Chuanyao Huazhong Univ Sci & Technol Dept Mech Wuhan 430074 Peoples R China

Based on approximate theoretical analyses on a typical spherical cellcontaining a spherical rnicrovoid, the influences of matrix materials' microscopic scale on themacroscopic constitutive potential theory of porous material and microvoid growth have beeninvestigated in detail. By assuming that the plastic: deformation behavior of matrix materialsfollows the strain gradient (SG) plastic theory involving the stretch and rotation gradients , theratio (λ = l/a) of the matrix materials' intrinsic characteristic length l to the micro-void radiusa is introduced into the plastic constitutive potential and the void growth law. The presentresults indicate that, when the radius a of microvoids is comparable with the intrinsiccharacteristic length l of the matrix materials, the influence of microscopic size effect on neitherthe constitutive potential nor the micro-void evolution predicted can be ignored. And when the voidradius a is much lager than the intrinsic characteristic length l of the matrix materials, thepresent model can retrogress automatically to the improved Gur-son model that takes into account thestrain hardening effect of matrix materials.

关键词： strain gradient plasticity scale effect constitutive potential boidgrowth damage theory