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Examination on behavior of tip leakage flow in a three-stage gas-liquid two-phase flow pump

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Journal of Hydrodynamics 2024年第5期36卷 843-853页

作者： Si-na Yan Xing-qi Luo Jian-jun Feng Shuai-hui Sun guo-jun Zhu Xin Wu State Key Laboratory of Eco-hydraulics in Northwest Arid Region Xi’an University of TechnologyXi’an710048China

Tip leakage flow(TLF)trajectory in a pump with gas entrainment is investigated via visualization experiments and numerical *** position of tip leakage vortex(TLV)is determined accurately by numerical *** high liquid flow rate(Q_(l))and high inlet gas volume fraction(IGVF)conditions,TLF flows from suction surface to pressure surface near the leading edge of blade,and the direction of TLF gradually changes along the chord which flows from pressure surface to suction surface near the tailing *** angle between TLF and blade mean camberline increases progressively as either Q_(l)or IGVF decreases,and starting position of TLV moves towards leading edge *** Q_(l)or IGVF decreases,value of vorticity increases and high vorticity region moves towards leading *** entropy production rate at blade tip clearance is high,and entropy diffuses from pressure surface to suction surface due to jet flow in blade tip *** greater the amount of accumulated gas there is,the greater the amount of entropy in the *** addition,when gas is entrained in pump,there are many low frequency fluctuations generated in blade tip clearance.

关键词： Gas-liquid two-phase flow multistage pump entropy production tip leakage vortex(TLV) unstable characteristics

Regulating microstructure and mechanical property of dissimilar joints by pretreatments of S31042 steel and Ni3Al-based superalloy bonding substrates

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Journal of Iron and Steel Research International 2023年第11期30卷 2328-2339页

作者： Yuan-yi Peng Chong Li Qian-ying guo hui-jun Li Yong-chang Liu State Key Lab of Hydraulic Engineering Simulation and Safety School of Materials Science and EngineeringTianjin UniversityTianjin300354China

For the bonding couple of S31042 steel and Ni3Al-based superalloy,joint microstructure regulation plays a pivotal role in improving joint *** pretreatment approaches including solution and cold rolling treatments were severally applied to the two substrates before vacuum diffusion *** rolling treatment in S31042 steel substrate before bonding promoted the coarsening and precipitation behaviors of large amounts of Z(NbCrN)phases during the bonding process so that the AlN phase decreased in the joint area because of the consumption of N atom in the Z *** solution treatment for Ni3Al-based superalloy increased the grain boundary mobility and led to the occurrence of dynamic recrystallization in the diffusion area of the joint by reducing segregation and homogenizing the microstructure within the *** a result,the bonded sample with two substrates that are pretreated exhibited a better tensile strength and elongation at 700℃.

关键词： Ni3Al-based superalloy Steel Joint Pretreatment Diffusion bonding

Microstructure and properties of AlSi7Mg alloy fabricated by selective laser melting

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China Foundry 2021年第4期18卷 416-423页

作者： Shuai Huang Shao-qing guo Biao Zhou guo-hui Zhang Xue-jun Zhang 3D Printing Research and Engineering Technology Center Beijing Institute of Aeronautical MaterialsBeijing 100095China

The AlSi7Mg alloy was fabricated by selective laser melting(SLM),and its microstructure and properties at different building directions after heat treatment were *** show that the microstructure of SLM AlSi7Mg samples containes three zones:fine grain zone,coarse grain zone,and heat affected *** fine-grain regions locate inside the molten pool,and the grains are *** coarse-grain regions locate in the overlap of molten *** T6 treatment,the microstructure at the molten pool boundary is still the network eutectic Si,but the network structure becomes discrete,and is composed of intermittent,chain-like eutectic Si *** yield strength at three directions(xy,45°,z direction)of the AlSi7Mg alloy samples fabricated by SLM is improved after T6 heat *** fracture mechanism of the samples is a mixed ductile and brittle fracture before heat treatment and ductile fracture after heat treatment.

关键词： selective laser melting AlSi7Mg alloy microstructure mechanical property

BIFURCATION AND DYNAMICS OF THIN SLIPPING FILMS UNDER THE INFLUENCE OF INTERMOLECULAR FORCES

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Journal of Hydrodynamics 2006年第2期18卷 248-252页

作者： HU guo-hui Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 China

The effects of the Born repulsive force on the stability and dynamics of ultra-thin slipping films under the influences of intermolecular forces are investigated with bifurcation theory and numerical simulation. Results show that the repulsive force has a stabilizing effect on the development of perturbations, and can suppress the rupture process induced by the van der Waals attractive force. Although slippage will enhance the growth of disturbances, it does not have influence on the linear cutoff wave number and the final shape of the film thickness as time approaches to infinity.

关键词： ultra-thin film dewetting Navier slip boundary condition

Design,synthesis and antifungal activities in vitro of novel tetralin compounds

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Chinese Chemical Letters 2008年第3期19卷 264-268页

作者： hui Tang You jun Zhou Yao Wu Li Jia guo Lv Can hui Zheng jun Chen Ju Zhu Department of Medicinal Chemistry School of Pharmacy Second Military Medical University Shanghai 200433 China

Novel chiral tetralin compounds were designed and synthesized, and their antifungal activities in vitro were tested. The results showed that all of target compounds had potent antifungal activities, and were stronger than that of control compounds tetrahydroisoquinolines. The binding model of lead molecules in the active site of CYP51 of Candida albicans showed that lead compound specifically interacted with the amino acids residues in the active site, without binding with the heme of CYP51, which was different from azole antifungal drugs. The present study might afford a novel lead molecule to develop non-azole CYP51 inhihitars of fungi.

关键词： Antifungal Chiral tetralins Lanosterol 14α-demethylase Design Synthesis

Designing solid-state interfaces on lithium-metal anodes: a review

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Science China Chemistry 2019年第10期62卷 1286-1299页

作者： Chen-Zi Zhao hui Duan Jia-Qi Huang Juan Zhang Qiang Zhang Yu-guo guo Li-jun Wan Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology Department of Chemical EngineeringTsinghua UniversityBeijing 100084China CAS Key Laboratory of Molecular Nanostructure and Nanotechnology CAS Research/Education Center for Excellence in Molecular SciencesBeijing National Laboratory for Molecular SciencesInstitute of ChemistryChinese Academy of SciencesBeijing 100190China Advanced Research Institute of Multidisciplinary Science Beijing Institute of TechnologyBeijing 100081China University of Chinese Academy of Sciences Beijing 100049China

Li-metal anodes are one of the most promising energy storage systems that can considerably exceed the current technology to meet the ever-increasing demand of power applications. The apparent cycling performances and dendrite challenges of Li-metal anodes are highly influenced by the interface layer on the Li-metal anode because the intrinsic high reactivity of metallic Li results in an inevitable solid-state interface layer between the Li-metal and electrolytes. In this review, we summarize the recent progress on the interfacial chemistry regarding the interactions between electrolytes and ion migration through dynamic interfaces. The critical factors that affect the interface formation for constructing a stable interface with a low resistance are reviewed. Moreover, we review emerging strategies for rationally designing multiple-structured solid-state electrolytes and their interfaces, including the interfacial properties within hybrid electrolytes and the solid electrolyte/electrode interface. Finally, we present scientific issues and perspectives associated with Li-metal anode interfaces toward a practical Li-metal battery.

关键词： lithium-metal anode solid-state electrolyte energy chemistry rechargeable lithium-metal batteries solid electrolyte/electrode interface

An iterative blending integrating grinding force model considering grain size and dislocation density evolution

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Advances in Manufacturing 2023年第3期11卷 428-443页

作者： Zi-Shan Ding Yun-hui Zhao Miao-Xian guo Wei-Cheng guo Chong-jun Wu Steven Y.Liang School of Mechanical Engineering University of Shanghai for Science and TechnologyShanghai 200093People's Republicof China College of Mechanical Engineering Donghua UniversityShanghai 201620People's Republic of China George W.Woodruff School of Mechanical Engineering Georgia Institute of TechnologyAtlanta 30332USA

The dynamic force load in grinding process is considered as a crucial factor affecting the quality of parts,and a better understanding of the mechanism of force generation is conducive to revealing the evolution of material microstructure more *** this study,an iterative blending integrating grinding force model that comprehensively considers the impact of grain size and dislocation density evolution of the material is *** to the grinding kinematics,the interaction of grit-workpiece is divided into rubbing,plowing,and chip formation stages in each grinding *** this basis,the evolution of material microstructure in the current chip formation stage will affect the rubbing force in the next grinding arc through flow stresses,which in turn will influence the total grinding ***,the flow stress models in rubbing and chip formation stages are firstly established,and then the dislocation density prediction model is established experimentally based on the characteristics of grain *** effects of the evolution of grain size and dislocation density on the grinding forces during the grinding process are studied by means of iterative *** results indicate that the implementation of an iterative blending scheme is instrumental in obtaining a higher accurate prediction of the grinding force and a deeper insight of the influence mechanisms of materials microstructure on grinding process.

关键词： Grinding force Grain size Dislocation density Iterative loop

Corrosion and impact-abrasion-corrosion behaviors of quenching- tempering martensitic Fe-Cr alloy steels

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Journal of Iron and Steel Research International 2022年第11期29卷 1853-1863页

作者： Zhi-bin Zheng jun Long Yi guo hui Li Kai-hong Zheng Yan-xin Qiao Institute of New Materials Guangdong Academy of SciencesGuangdong Provincial Key Laboratory of Metal Toughening Technology and ApplicationGuangzhou 510650GuangdongChina Guangdong Provincial Iron Matrix Composite Engineering Research Center Guangzhou 510650GuangdongChina Jiangmen Guangjin Casting and Forging Co. Ltd.Jiangmen 529000GuangdongChina School of Materials Science and Engineering Jiangsu University of Science and TechnologyZhenjiang 212003JiangsuChina

The corrosion and impact-abrasion-corrosion behaviors of quenching-tempering Fe-Cr martensitic steels for ball mill liner were investigated in the corrosive slurry of a copper mine compared with high manganese *** is found that the corrosion resistance and the protectiveness of the passive film of Fe-Cr martensitic steels became worse when the carbon content *** quenching-tempering Fe-Cr martensitic steel showed better impact-abrasion-corrosion resistance in the corrosive slurry compared with the high manganese steel,especially the alloy steel with the carbon content of 0.3 wt.%.The synergistic effect between mechanics and corrosion has also been analyzed to further reveal the impact-abrasion-corrosion mechanism of the *** damage from pure mechanics accounted for the largest percentage(over 65%)for all steels,demonstrating that mechanical damage played the most important role in the impact-abrasion-corrosion behaviors of the *** impact and cracking resistance of the steel should also be paid special attention during the development of new materials for ball mill liner.

关键词： Mining Abrasive wear Corrosive wear Impact wear Martensitic steel

Spring snow-albedo feedback from satellite observation,reanalysis and model simulations over the Northern Hemisphere

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Science China Earth Sciences 2022年第8期65卷 1463-1476页

作者： hui guo Yuting YANG State Key Laboratory of Hydroscience and Engineering Department of Hydraulic EngineeringTsinghua UniversityBeijing100084China

The snow-albedo feedback(SAF)is one of the key processes that lead to rapid temperature increases at high latitude and altitude ***,we examine the strength of SAF in the Northern Hemisphere(NH,30°-90°N)from satellite-based observation,climate reanalysis(i.e.,ERA5)and climate model projections(i.e.,CMIP5 and CMIP6).Using satellite-derived estimates as an observational reference,our results show that the strength of SAF is considerably overestimated by both climate reanalysis and climate models throughout the *** positive bias is mainly caused by a much higher month-to-month changing rate of surface albedo simulated by climate reanalysis and climate models,compared with satellite-based *** addition,we find that the strength of SAF is primarily controlled by changes in snow cover fraction(SNC)while the snow metamorphosis effect only plays a secondary role at the hemispheric scale and the regional ***,we demonstrate that there exists an emergent relationship between historical SAF and future SAF in climate model projections,which is then used to constrain modeled SAF in both CMIP5 and CMIP6 under various climate change *** constraining,the magnitude of modeled SAF is reduced to be more consistent with satellite-based estimates and the uncertainties of the modeled SAF are reduced by 10-50%for 13 sub-regions of the *** results highlight the need for improving the representation of surface albedo and snow cover fraction in climate reanalysis and models and the advantage of combining observation and model predictions such that to achieve a more realistic quantification of SAF and a better understanding of the impacts of SAF on the climate system.

关键词： Snow-albedo feedback Satellite observation Climate reanalysis Climate model Emergent constraint