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A Time-Marching Throughflow Model and its Application in Transonic Axial Compressor

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Journal of Thermal Science 2010年第6期19卷 519-525页

作者： jin Hai-liang jin dong-hai LI Xiao-juan GUI Xing-min Aeroengine Numerical Simulation Research Center Beihang University Beijing China The College of Engineering Peking University Beijing China

A throughflow model based on the time-marching finite volume approach is described in this paper. The governing equations are derived by circumferentially averaging the three-dimensional Navier-Stokes equations neglecting the circumferentially non-uniform and viscous terms. An inviscid blade force model similar to the Large-particle method is derived. The viscous blade force has been modeled by the distributed loss model. The convective fluxes of the governing equation are discretized with the Edward’s low-diffusion flux-splitting (LDFSS) scheme. And a point-iterative Symmetric Gauss-Seidel (SGS) scheme is used in the temporal discretization. The throughflow model has been applied to the NASA Rotor 67 and a high-load transonic fan stage ATS-2. The reasonable good agreements with the experiments and the 3D viscous computations show the potential of the method.

关键词： throughflow model time marching transonic axial compressor

Numerical investigation of the influence of companion drops on drop-on-demand ink jetting

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2012年第8期13卷 584-595页

作者： Hai-yun ZHANG jin WANG Guo-dong LU Institution of Engineering and Computer Graphics Zhejiang UniversityHangzhou 310027China

In this study we characterized and investigated the specific phenomenon of "companion drops" in the drop-ondemand(DoD) ink jetting process.A series of simulations based on a piezoelectric DoD printhead system is presented,adapting the volume-of-fluid(VoF) interface-capturing method to track the boundary evolution and model the interfacial *** results illustrate the causality between the generation of companion drops and droplet deviation behavior,as well as their close correlations with ink jetting straightness and printing *** characteristics of companion drops are summarized and compared with those of satellite ***,a theoretical mechanism for the generation of companion drops is presented,and their effects and behaviors are analyzed and ***,the effects of critical factors on the generation of companion drops are investigated and characterized based on variations in the printable pressure *** are given for the suppression of companion drops and for the improvement of printing accuracy.

关键词： Drop-on-demand (DoD) ink jetting Droplet deviation Companion drops Computational fluid dynamics (CFD) Volume-of-fluid (VoF) method

Normal Contact Model for Elastic and Plastic Mechanics of Rough Surfaces

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Acta Mechanica Solida Sinica 2019年第2期32卷 148-159页

作者： dong Wang Zhousuo Zhang Fan jin Xuanhua Fan State Key Laboratory for Manufacturing and Systems Engineering School of Mechanical Engineering XVan Jiaotong University Xi'an 710049 China Institute of Systems Engineering China Academy of Engineering Physics Mianyang 621999 China

An elastic and plastic mechanical model is proposed to characterize the normal contact of rough surfaces. The contact process is considered as three separated contact regimes, i.e., the fully elastic, mixed elastic一plastic and fully plastic ones. The Hertzian elastic contact solutions and the classical fully plastic contact model of Abbott and Fires tone are used to model the contact behaviors of fully elastically deformed asperities and fully plastically deformed ones, respectively. For the mixed elastic-plastic regime, an improved Hermit interpolation method is applied to enforce the continuity and smoothness at the critical contact interference, and to decrease the interpolation waving effect by transforming the physical quantities of contact load into logarithmic coordinates. The contac t model of rough surfaces is formula ted by using the Greenwood and Williamson^ statistics analysis. Comparisons with the CEB, ZMC and KE models are then performed to examine the effects of plasticity index and mean separation. Agreeing well with the ZMC model, our results show that the total contact load of rough surfaces decreases with the increase in mean separation, and the difference between the prediction results of elastic models and the plastic ones also decreases, indicating that the contact behaviors mainly dominated by plastically deformed asperities have been changed to be controlled by elastically deformed ones. Larger plasticity index represents more plastically deformed asperities, inducing normal contact behaviors mainly dominated by plastic solutions.

关键词： Rough surfaces Elastic plastic Asperity contact Logarithm transformation Statistics analysis

Formation of coherent BCC/B2 microstructure and mechanical properties of Al-Ti-Zr-Nb-Ta-Cr/Mo light-weight refractory high-entropy alloys

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Rare Metals 2022年第8期41卷 2886-2893页

作者： dong-Ming jin Zhen-Hua Wang jin-Feng Li Ben Niu Qing Wang Engineering Research Center of High Entropy Alloy Materials(Liaoning Province) Key Laboratory of Materials Modification by LaserIon and Electron Beams(Ministry of Education)School of Materials Science and EngineeringDalian University of TechnologyDalian116024China Institute of Materials China Academy of Engineering PhysicsMianyang621908China

The present work investigated the formation of coherent body-centered-cubic(BCC)/B2 microstructure in Al-Ti-Zr-Nb-Ta-Cr/Mo refractory high-entropy alloy system,in which three alloys with the composition of Al_(2)Ti_(6) Zr_(2)Nb_(3)Ta_(2)(Cr/Mo)_(1)were *** as-cast alloy ingots were homogenized at 1573 K for 2 h and then aged at different temperatures for 24 *** is found that the BCC/B2 coherent microstructure with cuboidal BCC nanoprecipitates into the B2 matrix would be formed in873 K-aged Al_(2)Ti_(6) Zr_(2)Nb_(3)Ta_(2)Cr_(0.5)Mo_(0.5)alloy with half Cr and half Mo,which is ascribed to a moderate lattice misfit(ε=0.94%)between BCC and B2 *** is due to the special coherent microstructure that results in a prominent mechanical property with the highest compressive yield strength(σ_(yS)=1314 MPa)and good plasticity among these alloys,while coarse Cr2 Ti and Zr_(5)Al_(3)particles are existed in 873 K-aged alloy with *** 1073 K aging,all these alloys with Cr_(1),Cr_(0.5)Mo_(0.5)and Mo_(1)consist of BCC,B2 and Zr_(5)Al_(3),in which BCC/B2 coherent microstructure is *** strengthening mechanism of BCC/B2 coherent microstructure in 873 K-aged alloy with Cr_(0.5)Mo_(0.5)was also discussed.

关键词： High entropy alloys Coherent precipitation Microstructure Lattice misfit Precipitation strengthening

The development,performances and applications of the monochromatic X-rays facilities in(0.218–301)keV at NIM,China

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Nuclear Science and Techniques 2021年第6期32卷 108-121页

作者： Si-Ming Guo jin-Jie Wu dong-Jie Hou National Institute of Metrology BeijingChina

Space scientific exploration is rapidly becoming the primary battlefield for humankind to explore the *** worldwide have launched numerous space exploration *** calibration of the detectors on the ground is a crucial element for space science satellites to obtain observational *** the purpose of providing calibration for various satellite-borne detectors,multiple monochromatic X-rays facilities have been built at the National Institute of Metrology,***(NIM).These facilities mainly pertain to grating diffraction and Bragg diffraction,and the energy range of the produced monochromatic X-rays is 0.218–301 ke *** facilities have a high performance in terms of energy stability,monochromaticity,and flux *** monochromaticity was greater than 3.0%.The energy stability.of the facility is 0.02%at 25 ke V over 8 h,and the flux stability was within 1.0%at 25 ke V over 8 *** experiments on the properties of satellite-borne detectors,such as energy linearity,energy resolution,detection efficiency,and temperature response,can be conducted at the *** far,the calibration of two satellites has been completed by the authors,and the work on three other satellites is in *** study will contribute to the advancement of X-ray astronomy the development of Chinese space science.

关键词： Monochromatic X-rays Monochromator Bragg diffraction Energy spectra Calibration

Numerical study via total Lagrangian smoothed particle hydrodynamics on chip formation in micro cutting

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Advances in Manufacturing 2020年第2期8卷 144-159页

作者： jin-Shi Wang Xiao-dong Zhang Feng-Zhou Fang State Key Laboratory.of Precision Measuring Technology and Instruments Centre of Micro/Nano Manufacturing Technology(MNMT)Tianjin UniversityTianjin 300072People's Republic of China Centre of Micro/Nano Manufacturing Technology(MNMT-Dublin) University College DublinDublinIreland

Numerical simulation is an effective approach in studying cutting *** widely used methods for cutting simulation include finite element analysis and molecular ***,there exist some intrinsic shortcomings when using a mesh-based formulation,and the capable scale of molecular dynamics is extremely *** contrast,smoothed particle hydrodynamics(SPH)is a candidate to combine the advantages of *** is a particle method which is suitable for simulating the large deformation process,and is formulated based on continuum mechanics so that large scale problems can be handled in *** a result,SPH has also become a main way for the cutting *** some issues arise while using conventional SPH to handle solid materials,the total Lagrangian smoothed particle hydrodynamics(TLSPH)is *** instabilities would still occur during the cutting,which is a critical issue to *** paper studies the effects of TLSPH settings and cutting model parameters on the numerical instability,as well as the chip formation *** deformation,stress field and cutting forces are analyzed as *** shows that the hourglass coefficient,critical pairwise deformation and time step are three important parameters to control the stability.of the simulation,and a strategy.on how to adjust them is provided.

关键词： Cutting Total Lagrangian smoothed particle hydrodynamics(TLSPH) Numerical instability Chip formation

A New Strategy for Restraining Dynamic Strain Aging in GH4169 Alloy During Tensile Deformation at High Temperature

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Acta Metallurgica Sinica(English Letters) 2022年第11期35卷 1895-1902页

作者： Xin-Tong Lian jin-Lan An Lei Wang Han dong School of Materials Scienceand Engineering Shanghai UniversityShanghai 200444China Key Laboratory.of Fundamental Science for National Defense of Aeronautical Digital Manufacturing Process Shenyang Aerospace UniversityShenyang 110136China Key Lab for Anisotropy and Texture of Materials Ministry of EducationNortheastern UniversityShenyang 110819China

The dynamic strain aging(DSA) behavior was investigated in GH4169 alloy during tensile deforming with electric-pulse current(EPC) at 750 ℃.The results show that DSA is restrained in the alloy when deformed with 40 *** size ofγ " phase inner grains increases obviously and δ phase is facilitated to precipitate on grain boundary in the alloy applied with EPC,due to the promotion effect of EPC on the diffusion and segregation of *** electron microscopy(TEM)results indicate that dislocations can cut through small γ" precipitate with the size of less than 10 nm,while dislocations can only bypass dislocations when γ " precipitate grow up over 20 *** growth of precipitates consumes large amounts of atoms as well as the velocity.of dislocation increase,which makes dislocations difficult to be ***,when γ" precipitates grow up to a large size more than the critical size of dislocation pinning,DSA is significantly restrained in the alloy after necking deformed with EPC.

关键词： GH4169 alloy Electric-pulse current Dynamic strain aging Microstructure

Influence of the electrolyte conductivity.on the critical current density and the breakdown voltage

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Chinese Journal of Chemical Engineering 2023年第7期59卷 169-175页

作者： Hae-Kyun Park dong-Hyuk Park Bum-jin Chung Department of Nuclear Engineering Kyung Hee University 1732 Deogyeong-daeroGiheung-guYongin-siGyeonggi-do 17104Korea

The work investigates influence of the electrolyte conductivity.on the onset of partial contact glow discharge electrolysis(CGDE)in a water *** current density(CCD)and breakdown voltage were measured together with in situ observation of hydrogen bubble behavior,whose influence has not been focused *** a fixed current during normal electrolysis,hydrogen coalescence adjacent to cathode surface was invigorated at a lower *** analyses elucidated the hydrogen coalescence characteristics by quantifying size and population of detached hydrogen *** CCD increased about 104% within given range of conductivity(11.50-127.48 mS·cm^(-1))due to impaired bubble coalescence,which delays hydrogen film formation on the ***,decreasing trend of breakdown voltage was measured with increased conductivity showing maximum drop of 74%.It is concluded that onset of partial CGDE is directly affected by hydrodynamic bubble behaviors,whereas the electrolyte conductivity affects the bubble formation characteristics adjacent to cathode electrode.

关键词： Water electrolysis Critical current density Breakdown voltage Electrolyte conductivity Hydrogen bubble behavior

Pattern design on 3D triangular garment surfaces

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第10期8卷 1642-1649页

作者： WANG jin LU Guo-dong LI Ji-tuo CHEN Long ZHANG dong-liang State Key Lab. of CAD ＆ CG Zhejiang University Hangzhou 310027 China Institute of Automation Chinese Academy of Sciences Beijing 100080 China Digital Fashion Ltd. Osaka 5410053 Japan

This paper focuses on a pattern design method for a 3D triangular garment surface. Firstly, some definitions of 3D style lines are proposed for designing the boundaries of patterns as drawing straight lines or splines on the triangular surface. Additionally some commonly used style lines are automatically generated to enhance design efficiency. Secondly, after style lines are preprocessed, a searching method is presented for quickly.obtaining the boundaries and patches of a pattern on the 3D trian- gular surface. Finally a new pattern design reuse method is introduced by encoding/decoding the style line information. After style lines are encoded, the pattern design information can be saved in a pattern template and when decoding this template on a new garment surface, it automates the pattern generation for made-to-measure apparel products.

关键词： Pattern design Style lines 3D patch searching Encoding/decoding Design reuse