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Computer Implementation of the Passage Arrangement for Plate-Fin Heat Exchangers According to Local Balance Principle

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Journal of Thermal Science 1997年第3期6卷 190-196页

作者： Yuan, Z.X. Ma, Y.L. Xia, G.P. tao, w.q. (School of Energy and Power Engineering, Xi’an Jiaotong University Xi’an Shaanxi 710049, China) School of Energy and Power Engineering Xi’an Jiaotong University Xi’an China

A two-step method for stacking arrangement of passages in multistream plate-fin heat exchanger is proposed. The first step (predict step) is to initialize the arrangement according to a local-balance principle, and the second step (correct step) is to resadust the arrangement according to the results of differential computation of the temperature distribution. The computer implementation process of the local balance principle is described in detail and three examples are illustrated to show the feasibility of this principle. A subroutine program is provided to facilitate the reader to adopt this principle.

关键词： passage arrangement plate-fin heat exchangers local balance principle

Some micromechanical models of elastoplastic behaviors of porous geomaterials

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Journal of Rock Mechanics and Geotechnical Engineering 2017年第1期9卷 1-17页

作者： w.q. Shen J.F. Shao Laboratory of Mechanics of Lille University of Lille I Villeneuve d’Ascq 59655 France

Some micromechanics-based constitutive models are presented in this study for porous *** micro-macro mechanical models focus on the effect of porosity and the inclusions on the macroscopic elastoplastic behaviors of porous materials. In order to consider the effect of pores and the compressibility of the matrix, some macroscopic criteria are presented firstly for ductile porous medium having one population of pores with different types of matrix(von Mises, Green type, Misese Schleicher and Druckere Prager). Based on different homogenization techniques, these models are extended to the double porous materials with two populations of pores at different scales and a Druckere Prager solid phase at the microscale. Based on these macroscopic criteria, complete constitutive models are formulated and implemented to describe the overall responses of typical porous geomaterials(sandstone,porous chalk and argillite). Comparisons between the numerical predictions and experimental data with different confining pressures or different mineralogical composites show the capabilities of these micromechanics-based models, which take into account the effects of microstructure on the macroscopic behavior and significantly improve the phenomenological ones.

关键词： Homogenization Porous geomaterials Ductile behavior Double porosity Macroscopic strength Plastic compressibility Druckere Prager solids

Effect of lamellarization on the microstructure and mechanical properties of marine 10Ni5CrMoV steel

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International Journal of Minerals,Metallurgy and Materials 2025年第2期32卷 402-413页

作者： tao Zou Yanwu Dong Zhouhua Jiang Shuyang Du Yushuo Li School of Metallurgy Northeastern UniversityShenyang 110819China Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819China Key Laboratory for Ecological Metallurgy of Multimetallic Ores(Ministry of Education) Northeastern UniversityShenyang 110819China

Multistage heat treatment involving quenching(q),lamellarizing(L),and tempering(T)is applied to marine 10Ni5CrMoV *** microstructure and mechanical properties were studied by multiscale characterizations,and the kinetics of reverse austenite transformation,strain hardening behavior,and toughening mechanism were further *** lamellarized specimens possess low yield strength but high toughness,especially cryogenic *** leads to the development of film-like reversed austenite at the martensite block and lath boundaries,refining the martensite structure and lowering the equivalent grain *** analysis of austenite reversion based on the JMAK model shows that the isothermal transformation is dominated by the growth of reversed austenite,and the maximum transformation of reversed austenite is reached at the peak temperature(750℃).The strain hardening behavior based on the modified Crussard-Jaoul analysis indicates that the reversed austenite obtained from lamellarization reduces the proportion of martensite,significantly hindering crack propagation via martensitic transformation during the *** a consequence,the qLT specimens exhibit high machinability and low yield *** with the qT specimen,the ductile-brittle transition temperature of the qLT specimens decreases from-116 to-130℃due to the low equivalent grain size and reversed austenite,which increases the cleavage force required for crack propagation and absorbs the energy of external load,*** work provides an idea to improve the cryogenic toughness of marine 10Ni5CrMoV steel and lays a theoretical foundation for its industrial application and comprehensive performance improvement.

关键词： 10Ni5CrMoV steel lamellarizing reversed austenite cryogenic toughness ductile-brittle transition temperature

Extension/Compression-Controlled Complete Band Gaps in 2D Chiral Square-Lattice-Like Structures

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Acta Mechanica Solida Sinica 2018年第1期31卷 51-65页

作者： Y. L. Huang N. Gao w.q. Chen R.H. Bao Department of Engineering Mechanics Zhejiang University Hangzhou 310027 China State Key Lab of CAD & CG Zhejiang University Hangzhou 310058 China Key Laboratory of Soft Machines and Smart Devices of Zhejiang Province Zhejiang University Hangzhou 310027 China Soft Matter Research Center Zhejiang University Hangzhou 310027 China

Achieving tunable band gaps in a structure by external stimuli is of great importance in acoustic applications. This paper aims to investigate the tunability of band gaps in square-lattice-like elastic periodic structures that are usually not featured with notable band gaps. Endowed with chirality, the periodic structures here are able to undergo imperfection-insensitive large deformation under extension or compression. The influences of geometric parameters on band gaps are discussed via the nonlinear finite element method. It is shown that the band gaps in such structures with curved beams can be very rich and, more importantly, can be efficiently and robustly tuned by applying appropriate mechanical loadings without inducing buckling. As expected, geometry plays a more significant role than material nonlinearity does in the evolution of band gaps. The dynamic tunability of band gaps through mechanical loading is further studied. Results show that closing, opening, and shifting of band gaps can be realized by exerting real-time global extension or compression on the structure. The proposed periodic structure with well-designed chiral symmetry can be useful in the design of particular acoustic devices.

关键词： Band gap Tunability Square-lattice-like periodic structure Chiral symmetry,Large deformation

PROPERTIES OF THREE-DIMENSIONAL MOVEMENT OF SANDY wATER DISCHARGED INTO A LAKE

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Journal of Hydrodynamics 2001年第2期13卷 72-76页

作者： Deng, Y. Li, J. Li, K.F. Zhao, w.q. State Key Lab. of High Speed Flow Sichuan Univ. Chengdu 610065 China

A Random Trajectory Model (RTM) for solid-liquid two-phase flow based on the Lagrangian Method is presented in this paper. The effects of water drag force, pressure gradient force, buoyancy and virtual mass force on the particles were included and the turbulent dispersion was modeled by random method. Three-dimensional k-Ε model was used to calculate the flow field. A pumped-storage power station, with a natural lake as its upper pool, was taken as a case for the study. Averaged movement trajectories, velocities and the volume-concentration distributions for 5 groups of sediment particles, were predicted with RTM. The possible silted locations in the lake were also predicted.

关键词： Boundary conditions Computer simulation Lakes Sand Three dimensional Two phase flow Velocity

Discussion　on　the　Network　Method　for　Calculating　Radiant　Interchange　within　an　Enclosure

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Journal of Thermal Science 1994年第2期3卷 130-135页

作者： H.J. Kang w.q. tao(School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, China) School of Energy and Power Engineering Xi’an Jiaotong University Xi’an China

In this paper the △- Y transformation of a linear electric circuit is introduced to simplify the computation of net radiant heat exchange on a surface of an enclosure with three surfaces. The illustration of the transformation is given by solving six problems taken from the textbooks. Some discussion concerning the possibility of extending the transformation method to enclosures with more than three surfaces, and the condition for applying the network method are also presented.

关键词： radiative heat transfer network method enclosure.

Three－Dimensional　Numerical　Simulation　of　Natural　Convection　Heat　Transfer　in　an　Inclined　Cylindrical　Annulus

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Journal of Thermal Science 1996年第3期5卷 175-183页

作者： J.G. wei w.q. tao (School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, China) School of Energy and Power Engineering Xi’an Jiaotong University Xi’san China

A numerical study of natural convection heat transfer in an inclined cylindrical annulus has been conducted. The inner cylinder of the annulus is maintained at uniform heat flux and the outer cylinder at constant temperature. The two end walls are assumed to be insulated. A numerical code has been developed to calculate the steady state three-dimensional natural convection in an inclined cylindrical annulus, and the research emphasis is placed on the influences of inclination angle or and modified Rayleigh number Ra on the natural convection heat transfer in the annulus. Computations were carried out in the ranges of 0°α 90*, 2.5×105 Ra* and Pr=0.7 with fixed aspect ratio of H=28.97 and radius ratio of K= 3.33. The numerical results are compared with the experimental correlations from the literature and the inclination angle effect on heat transfer is found to be insignificant. Detailed results of heat transfer rate, temperature, and velocity fields are presented for the case of or α=45° and discussion is also made concerning the comparison between the numerical and experimental results for the specific case of α=90°.

关键词： enclosure flows natural convection numerical methods

Pressure　Loss　Through　Sharp　180　deg　Turn　in　a　Relatively　Short　Two－Pass　Smooth　and　Rib－Roughened　Channel

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Journal of Thermal Science 1995年第2期4卷 109-116页

作者： C.Y. Zhao w.q. tao(School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, China) School of Energy and Power Engineering Xi’an Jiaotong University Xi’an China

The local pressure distributions and resistance coefficients (f1 and f2) through the sharp 180 deg turn in a relatively short (L/De = 4) two-pass smooth and rib-roughened channel were investigated for a Reynolds number range of 1.0 × 103 - 9.0 × 103. The rib pitch-to-height ratios (p/e) were 5,10, and 20. The rib height-to-hydraulic diameter ratios (e/De) were 0.025, 0.050 and 0.10, and the rib angles of attack (α) were 90, 45, 60, -45, and -60 deg. Ribs were installed not only in before and after turn regions but also in turn region. The results show that the resistance coefficients remain approximately constant when Reynolds number is more than 3.0×104. The effects of the rib condguration (rib spacing, rib height, and rib orientation) on the inlet straight duct resistance coefficient (f2) were significant, however, their effects on the overall resistance coefficient (f1) were diluted by the sharp-180 turn. For this relatively short channel (L/De=4), the overall resistance coefficient (f1) was greatly affected by the sharp turn. Correlations for the overall resistance (f1) and inlet straight duct resistance coefficient (f2) are presented.

关键词： resistance cofficient rib-roughened channel.

MICROSTRUCTURE AND MACROSEGREGATION OF Al-7%Si ALLOY SOLIDIFIED UNDER COMPLEX EFFECTS OF ELECTROMAGNETIC AND CENTRIFUGAL FORCES

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Acta Metallurgica Sinica(English Letters) 1997年第2期10卷 105-114页

作者： Y.F. Zhu w.q. Zhang Y.S. Yang q.M. Liu and Z.q. Hu (State Key Lab. of RSA, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110015,Chilla) Inst of Metal Research Chinese Acad of Sciences Shenyang China

Macrosegregations and microstructures of Al-7%Si alloy solidified under complex of fects of magnetic field and centrifugal forces are studied by means of a set of selfdesigned electromagnetic centrifugal casting (EMCC) device. It is shown that electromagnetic field (EMF) has an important effect on the macrosegregation of centrifugal casting specimen of Al-7%Si alloy in two respects: one is that there exists always a kind of convection in the liquid in front of the S/L interface caused by effect ofthe electromagnetic force; the other is that different atomic clusters of solidparticles with different physical characteristics are subjected to quite different electromagnetic (Lorentz) force. Therefore, their movements get changed. In addition, the formation process of a complex band structure consisting of primary α-Al dendrites and (α-Al+β-Si) eutectics in hypoeutectic Al-Si alloys during EMCC and the effect of EMF are discussed.

关键词： electromagnetic field (EMF) centrifugal force Al-7%Si alloy macrosegregation solidification microstructure convection