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Mesoscale study on explosion-induced formation and thermochemical response of PTFE/Al granular jet

Defence technology（防务技术） 2023年第5期23卷 112-125页

作者： Yuan-feng Zheng Zhi-jian Zheng Guan-cheng Lu Hai-fu Wang Huan-guo Guo State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing100081China

The dynamic formation,shock-induced inhomogeneous temperature rise and corresponding chemical reaction behaviors of PTFE/Al reactive liner shaped charge jet(RLSCJ)are investigated by the combination of mesoscale simulation,reaction kinetics and chemical energy release test.A two-dimensional granular model is developed with the randomly normal distribution of aluminum particle sizes and the particle delivery ***,the granular model is employed to study the shock-induced thermal behavior during the formation and extension processes of RLSCJ,as well as the temperature history curves of aluminum *** simulation results visualize the motion and temperature responses of the RLSCJ at the grain level,and further indicate that the aluminum particles are more likely to gather in the last two-thirds of the jet along its *** analysis shows that the shock,collision,friction and deformation behaviors are all responsible for the steep temperature rise of the reactive *** addition,a shock-induced chemical reaction extent model of RLSCJ is built based on the combination of the Arrhenius model and the Avrami-Erofeev kinetic model,by which the chemical reaction growth behavior during the formation and extension stages is described *** model indicates the reaction extent highly corresponds to the aluminum particle temperature history at the formation and extension *** last,a manometry chamber and the corresponding energy release model are used together to study the macroscopic chemical energy release characteristics of RLSCJ,by which the reaction extent model is verified.

关键词： Reactive materials Shaped charge Mesoscale simulation Formation Thermochemical response

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Coupling effect on the thermal hazard assessment of hazardous chemical materials via calorimetric technologies and simulation approaches

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Defence technology（防务技术） 2024年第2期32卷 644-654页

作者： Yabei Xu Jiankun Shao Wei Wang Shengliang Xu Dongping Chen State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China Science and Technology on Aerospace Chemical Power Laboratory Hubei Institute of Aerospace ChemotechnologyXiangyang 441003China

The coupling effect of heat absorption and release exists in the thermal decomposition of a few chemical ***,the impact of the above coupling on thermal hazard assessment is not considered in the literature *** this work,nitroguanidine(NQ)and 1,3,5-trinitro-1,3,5-triazine(RDX)are selected as representative materials to explore the influence of the coupling effect on the thermal hazard assessment of chemical *** linear heating experiments of NQ and RDX are carried out by a microcalorimeter and synchronous thermal *** thermal decomposition curves are decoupled by advanced thermokinetics *** thermal decomposition and kinetic parameters before and after decoupling are *** results of TG experiment show that both NQ and RDX began to lose mass during the endothermic *** endothermic melting and exothermic decomposition of NQ and RDX are coupled within this *** coupling effect has different degrees of influence on its initial decomposition temperature and safety *** with the parameters in the coupling state,the initial decomposition temperature and adiabatic induction period after decoupling *** self-accelerating decomposition temperature increases,and internal thermal runaway time *** the thermal hazard assessment of chemical materials with coupling effects,the calculated parameters after decoupling should be taken as an important safety index。

关键词： Calorimetric technologies Kinetics thermal hazard Phase transformation thermal decomposition

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Electromagnetic radiation of granite under dynamic compression

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International Journal of Mining science and technology 2024年第10期34卷 1427-1441页

作者： Juncheng Li Qingming Zhang Zhixiang Liu Renrong Long Xianzhe Zhong Wenjin Liu Mingze Wu Xin Hu Jinlong Xu Jiankang Ren Wei Wei Qiang Liu Keqin Zheng Haozhe Liang State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China Taiyuan University of Technology Taiyuan 030024China

To elucidate the characteristics and mechanism of electromagnetic radiation in granite under impact loading,based on the quasi-static compression tests,this paper conducts dynamic compression experiments on granite using Hopkinson pressure bar and one-stage light-gas gun as loading *** with experimental and theoretical analyses,the relationship between mechanical and electromagnetic responses under impact loads of different intensities,and the time-domain signals of electromagnetic radiation generated by a single crack under different strain rates are *** intensity and frequency of electromagnetic radiation increase with the increasing compressive strain *** to the thermal activation theory,it reveals the microscopic mechanism of the transition from intergranular microcracks to transgranular microcracks in terms of strain *** also serves as the physical basis for the increase in electromagnetic radiation intensity amplitude and frequency with increasing compressive strain *** microcracks are the primary cause of electromagnetic radiation generated by fractures.

关键词： Impact load Granite Electromagnetic radiation Transgranular microcracks

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Environment-adaptive phase-separation-porous fluorofilm for highperformance passive radiation cooling

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Nano Research 2024年第6期17卷 5636-5644页

作者： Weiming Tang Yong Li Xue Meng Shutao Wang Ziguang Zhao School of Future Technology University of Chinese Academy of SciencesBeijing 100049China CAS Key Laboratory of Bio-inspired Materials and Interfacial Science Technical Institute of Physics and ChemistryChinese Academy of SciencesBeijing 100190China CAS Key Laboratory of Cryogenics Technical Institute of Physics and ChemistryChinese Academy of SciencesBeijing 100190China

Passive radiative cooling is widely recognized as an environmentally sustainable method for achieving significant cooling ***,the mechanical properties and environmental adaptability of current radiative cooling materials are not sufficient to maintain high cooling performance in external *** we reported an environment-adaptive phase-separation-porous fluorofilm for high-performance passive radiation *** to the homogenous fluoro-porous network with limited scattering efficiencies,we modulated the porous structure of the fluorofilm to achieve a strong emissivity of 95.2%(8-13μm)and a high reflectivity of 97.1%(0.3-2.5μm).The fluorofilm demonstrates a temperature drop of 10.5°C and an average cooling power of 81 W·m^(−2)under a sunlight power of 770 W·m^(−2).The high mechanical performance and environmental adaptability of fluorofilms are also *** its significant radiative cooling capability and robust environmental adaptability,the fluorofilm is expected to have a promising future in radiative temperature regulation.

关键词： fluorofilm passive radiation cooling porous optimization thermal regulation

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Shock response of cyclotetramethylene tetranitramine(HMX)single crystal at elevated temperatures

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Defence technology（防务技术） 2023年第3期21卷 147-163页

作者： Kai Ding Xin-Jie Wang Zhuo-Ping Duan Yan-Qing Wu Feng-Lei Huang State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing100081PR China

To investigate the shock response of cyclotetramethylene tetranitramine(HMX)single crystals at elevated temperatures(below the phase transition point),plate impact experiments at elevated temperatures were designed and *** HMX/window interface particle velocities at temperatures of 300 K,373 K,and 423 K were measured by the velocity interferometry system for any reflector(VISAR)*** further analyze the related mesoscale deformation mechanisms,a nonlinear thermoelastic-viscoplastic model was developed,which considers thermal activation and phonon drag dislocation slip *** proposed model could well reproduce the measured thermal hardening behavior of Hugoniot elastic limit(HEL)of HMX single *** elevated temperatures,the reduced dislocation mobility was observed,which stems from both phonon scattering and radiative damping *** speaking,radiative damping contributes less than phonon scattering to thermal hardening *** calibrated model was further used to predict shock response of HMX single crystals with different thicknesses at different initial *** the stress relaxation and elastic precursor decrease with thickness are mainly due to the rapid dislocation *** insights shed light on the interplay between dislocation motion and dislocation generation in thermal hardening behavior,stress relaxation,and elastic precursor decay,which serves to reveal the mesoscale deformation mechanisms at elevated temperatures.

关键词： deformation elevated dislocation

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Selective hydrodeoxygenation of guaiacol to cyclohexanol using activated hydrochar-supported Ru catalysts

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Frontiers of Chemical science and Engineering 2024年第5期18卷 13-22页

作者： Kaile Li Shijie Yu Qinghai Li Yanguo Zhang Hui Zhou Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Beijing Key Laboratory of CO_(2) Utilization and Reduction TechnologyDepartment of Energy and Power EngineeringTsinghua UniversityBeijing 100084China Department of Chemical and Biomolecular Engineering National University of SingaporeSingapore117585Singapore

Lignin,an abundant aromatic polymer in nature,has received significant attention for its potential in the production of bio-oils and chemicals owing to increased resource availability and environmental *** hydrodeoxygenation of guaiacol,a lignin-derived monomer,can produce cyclohexanol,a nylon precursor,in a carbon-negative and environmentally friendly *** study explored the porous properties and the effects of activation methods on the Ru-based catalyst supported by environmentally friendly and cost-effective *** selective cleavage of C_(ary)-O bonds was achieved under mild conditions(160°C,0.2 MPa H_(2),and 4 h),and alkali activation further improved the catalytic *** characterization methods revealedthat hydrothermal treatment and alkali activation relatively contributed to the excellent performance of the catalysts and influenced their porous structure and Ru dispersion.X-ray photoelectron spectroscopy results revealed an increased formation of metallic ruthenium,indicating the effective regulation of interaction between active sites and *** synergistic approach used in this study,involving the valorization of cellulose-derived hydrochar and the selective production of nylon precursors from lignin-derived guaiacol,indicated the comprehensive and sustainable utilization of biomass resources.

关键词： hydrochar guaiacol cyclohexanol activation full-component utilization

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Effect of operational and geometric parameters on the hydrodynamics of a Wurster coater:A CFD-DEM study

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Particuology 2024年第2期85卷 62-76页

作者： Yinqiang Song Tuo Zhou Ruiqi Bai Man Zhang Hairui Yang Department of Energy and Power Engineering Tsinghua UniversityBeijing100084China Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Tsinghua UniversityBeijing100084China State Key Laboratory of Power System and Generation Equipment Tsinghua UniversityBeijing100084China

A coupled CFD-DEM method was used to study the hydrodynamics of a Wurster ***,the CFD part of the model was validated by the accurate prediction of the pressure drops over a pseudo-2D fluidized bed under various gas *** effect of gas velocity,gap height,tube length and batch volume of the particles on the cycle time and the residence time of the particles was thoroughly *** central jet gas velocity ui was found to speed up the particle cycle but undermine the coating *** gas velocity at the horizontal transport zone u2 was able to promote the horizontal transport of the particles but should not be too high,otherwise,it would obstruct the normal falling back of the particles in the downward *** gap heights would decrease the coating efficiency but tube length had little impact on *** increment of batch volume would commonly abase the cycle time and the working efficiency under a given *** de-fluidization problem arose when the batch volume increased to 550 ***,this problem could be swept out by the optimization of u1 and *** a mixture of different sizes,the coarse particles enjoyed higher coating efficiency and could travel closer to the *** may shield the fine particles from getting enough coating liquids,and thus coarse particles and fine particles were not recommended to get coated in the same batch.

关键词： Numerical simulation CFD-DEM Wurster coater Hydrodynamics Cycle time Residence time

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Study on the effects of combustion characteristics of pyrotechnic charges on pyrotechnic shocks

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Defence technology(防务技术) 2025年第4期46卷 79-98页

作者： Jingcheng Wang Shihui Xiong Huina Mu Xiaogang Li Yuquan Wen State Key Laboratory of Explosion Science and Safety Protection Beijing Institute of TechnologyBeijing 100081China CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern MechanicsUniversity of Science and Technology of ChinaHefei 230027China

This study calculates the combustion characteristics of various gas-generating and micro gas pyrotechnic charges,including aluminium/potassium perchlorate,boron/potassium nitrate,carbon black/potassium nitrate,and silicon-based delay compositions,using thermodynamic software.A multiphase flowthermal-solid coupling model was established,and the combustion process of the pyrotechnic charges within a closed bomb was *** pyrotechnic shock generated by combustion was *** combustion pressures and pyrotechnic shocks were *** simulation results demonstrated good agreement with experimental ***,the mechanism of shock generation by the combustion of pyrotechnic charges in the closed bomb was *** effects of the combustion characteristics of the pyrotechnic charges on the resulting pyrotechnic shocks were systematically ***,the shock response spectrum of the gas-generating pyrotechnic charges is greater than that of the micro gas compositions at most frequencies,particularly in the mid-field pyrotechnic shocks(3-10 kHz).Furthermore,the pyrotechnic shocks increase approximately linearly with the impulse of the gas-generating pyrotechnic charges.

关键词： Pyrotechnic charges Pyroshock Closed bomb tests Combustion characteristics Multiphase flow-thermal-solid coupling

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Experimental Study on Hydrodynamic Behavior of Falling Film over Vertical Tube

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Journal of thermal science 2023年第4期32卷 1512-1522页

作者： YUE Yunkai ZHANG Zhentao ZHANG Hailun YANG Junling LI Xiaoqiong ZHANG Yu Key Laboratory of Cryogenics Technical Institute of Physics and ChemistryChinese Academy of SciencesBeijing100190China University of Chinese Academy of Sciences Beijing100049China Key Laboratory of Technology on Space Energy Conversion Technical Institute of Physics and ChemistryChinese Academy of ScienceBeijing100190China

Falling film configurations play an important role in characterizing the heat transfer due to changes in hydrodynamic *** purpose of this study is to establish a novel film distributor to investigate the hydrodynamic behavior of the falling film on the vertical *** falling film thickness and flow patterns on the vertical tube were analyzed at a feed water temperature of 30℃ for film Re ranged from 53 to 4544 and the heat fluxes ranged from 1.33 to 49.45 kW/m^(2).The correlation between the average falling film thickness and the film Re was fitted;the maximum deviation between the experimental data and the predicted values was 7.58%.Additionally,the film thickness changed sharply when the heat flux increased to a certain *** the further increase of the heat flux,dry patches appeared on the surface of the experimental *** was Marangoni effect on vertical tube and the falling film thickness and flow patterns were significantly affected by *** interval value of the critical heat flux with film Re was *** with the porous film distributor reported in the literature,the critical heat flux of the new film distributor increased by 3.72%-56.95%.

关键词： falling film film distributor Marangoni effect film thickness

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thermal Stability and Strengthening Effect of Coherent Precipitates in a (FeCoNi)_(92)Al_(2.5)Ti_(5.5) High Entropy Alloy

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Acta Metallurgica Sinica(English Letters) 2024年第9期37卷 1491-1500页

作者： Yuqi Liu Feng Wang Songyang Chen Hui Wang Zhiping Xiong Khurram Yaqoob Zhangwei Wang Min Song tate Key Laboratory of Powder Metallurgy Central South UniversityChangsha410083China State Key Laboratory for Advance Metals and Materials University of Science and Technology BeijingBeijing100083China National Key Laboratory of Science and Technology on Materials Under Shock and Impact Beijing100081China School of Chemical and Materials Engineering National University of Sciences and TechnologyH-12Islamabad44000Pakistan

The coarsening behavior and strengthening effect of L1_(2)-Ni_(3)(Ti,Al)precipitates in a face-centered-cubic(FCC)(FeCoNi)_(92)Al_(2.5)Ti_(5.5) high entropy alloy have been systematically *** coherent L1_(2) precipitates,uniformly distributed throughout the FCC matrix,consistently retain a spherical *** coarsening rate coefficient of precipitate is determined by employing the Philippe-Voorhees(PV)model,suggesting excellent thermal ***,the elemental partitioning and compositional evolution of the L1_(2) precipitates is analyzed by atom probe tomography,which identify aluminum(Al)as the slowest diffusion species during the coarsening *** addition,the precipitation strengthening effect is quantified to ascertain the optimal size of the *** study enhances the understanding of precipitate coarsening in high entropy alloys,presenting valuable insights into their thermal stability and mechanical properties.

关键词： High entropy alloy L1_(2)precipitates Coarsening kinetics Precipitation hardening

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