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Slip effects on shearing flows in a porous medium

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Acta Mechanica Sinica 2008年第1期24卷 51-59页

作者： M.Khan t.Hayat y.Wang Department of Mathematics Quaid-i-Azam University Islamabad 44000 Pakistan Chair of Fluid Dynamics Department of Mechanical Engineering Darmstadt University of TechnologyHochschulstrasse 164289 Darmstadt Germany

this paper deals with the magnetohydrodynamic （MHD） flow of an Oldroyd 8-constant fluid in a porous medium when no-slip condition is no longer valid. Modified Darcy＇s law is used in the flow modelling. the non-linear differential equation with non-linear boundary conditions is solved numerically using finite difference scheme in combination with an iterative technique. Numerical results are obtained for the Couette, Poiseuille and generalized Couette flows. the effects of slip parameters on the velocity profile are discussed.

关键词： Porous medium. Magnetohydrodynamic flow Slip effect

Structural Changes ofαPhase in Furnace Cooled Eutectoid Zn-Al Based Alloy

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Journal of Materials Science & technology 2007年第3期23卷 347-352页

作者： y.H.Zhu K.C.Chan G.K.H.Pang t.M.yue W.B.lee Advanced Manufacturing technology Research Center Department of Industrial and Systems Engineering The Hong Kong Polytechnic University Hong Kong China Department of Applied Physics The Hong Kong Polytechnic University Hong Kong China

Furnace cooling is a slow cooling process. It is of importance to study structural evolution and its effects on the properties of alloys during the furnace cooling. Decomposition of aluminium rich α phase in a furnace cooled eutectoid Zn-Al based alloy was studied by transmission electron microscopy. two kinds of precipitates in the α phase were detected in the FCZA22 alloy during ageing at 170℃. One was the hcp transitional α＂ m phase which aooears as directional rods and the round precipitates. the other was the fcc α＇m phase. 〈101〉. the orientation relationship between the a phase and transitional phase α＇m was determined as （022）α＇m （fcc）//（022^-）α（fcc）, [1^-11]α＇m, （fcc）//[2^-33]α（fcc）. the non-equilibrium phase decomposition of the α phase is discussed in correlation with the equilibrium phase relationships.

关键词： Phase decomposition Microstructural evolution Zn-Al alloys

Performance and Flow Condition of Small-Sized Axial Fan and Adoption of Contra-Rotating Rotors

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Journal of thermal Science 2010年第1期19卷 1-6页

作者： t.Shigemitsu J.Fukutomi y.Okabe Institute of technology and Science The University of Tokushima2-1 Minamijyosanjima-choTokushima 770-8506JAPAN Graduate School of Advanced technology and Science The University of Tokushima2-1 Minamijyosanjima-choTokushima 770-8506JAPAN

Small-sized axial fans are used as air coolers for electric *** there is a strong demand for higher power of fans according to the increase of quantity of heat from electric ***,higher rotational speed design is conducted,although it causes the deterioration of the efficiency and the increase of *** the adoption of contra-rotating rotors for the small-sized axial fan is proposed for the improvement of the *** the present paper,the performance and the internal flow condition of the small-sized axial fan are shown as a first step of the research for the contra-rotating small-sized axial fan and the important points to apply contra-rotating rotors to the small-sized axial fan are ***,the numerical flow analysis is conducted to investigate the performance of the contra-rotating small-sized axial fan and internal flow conditions and pressure distributions are clarified and the effect of contra-rotating rotors is considered.

关键词： Small-sized axial fan Contra-rotating rotors Numerical analysis Performance Internal flow

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Summary

Chinese Physics C 2009年第12期33卷 1230-1232页

作者： t.-S. H. lee Physics Division Argonne National Laboratory Argonne IL 60439 USA Excited Baryon Analysis Center (EBAC) Thomas Jefferson National Accelerator Facility Newport News VA 23606 USA

A summary of the contributions to this workshop is given. the status and future development of N＊ physics are discussed.

关键词： PWA resonance

Development of mathematical model with a genetic algorithm for automatic arc welding process

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Acta Metallurgica Sinica(English Letters) 2010年第3期23卷 230-240页

作者： D.t.thao I.S.Kim J.W.Jeong J.H.lee J.y.Shim H.H.Kim Department of Mechanical Engineering Mokpo National University

this paper is to represent new algorithms to predict process parameters on top-bead width in robotic gas metal arc（GMA） welding *** models have been developed：linear, curvilinear and intelligent model based on full factorial design with two *** analysis was employed for optimization of the coefficients of linear and curvilinear models, while genetic algorithm（GA） was utilized to estimate the coefficients of an intelligent *** only the fitting of these models were checked and compared by using a variance test（ANOVA）, but also the prediction on top-bead width using the developed models were carried out based on the additional *** developed models were employed to investigate the characteristic between process parameters and top-bead *** solutions and graphical representation showed that the intelligent model developed can be employed for prediction of bead geometry in GMA welding process.

关键词： top-bead width Genetic algorithm Multiple regression Robotic arc welding GMA welding

Relationship between Primary Crystal temperature and Carbon Equivalent in Cast Iron

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Journal of Materials Science & technology 2008年第3期24卷 325-326页

作者： t.Kanno t.Kikuchi K.Hayashi y.Maruyama Kimura Chuzosho Co.Ltd. 1157 Nagasawa Shimizu-choShizuoka-ken

CE （=%C＋（1/3）x（%Si）） does not suit experiment results in many cases. In this work, the effect of alloy elements on primary crystal temperature was measured and the relationship between primary crystal temperature （tc） and carbon equivalent （CEL） was investigated. the results show that tc （Celsius degree） = 1650-110 × （%C） -25 × （%Si）＋3 × （%Mn） -35 × （%P） -71 × （%5）-2 × （%Ni） -7 × （%Cr）; CEL=%C ＋ 0.23×（%Si）-0.03× （%Mn）＋0.32×（%P）＋0.64×（%S）＋0.02×（%Ni）＋0.06×（%Cr）. that is, in hypo eutectic composition, carbon equivalent should be calculated with CEL=%C＋ 0.23×（%Si）, not with CE=%C＋（1/3） x（%Si）.

关键词： Carbon equivalent Cast iron Primary crystal temperature Hypo eutectic composition

Numerical simulation of a sheet metal extrusion process by using thermal-mechanical coupling EAS FEM

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Journal of University of Science and technology Beijing 2002年第5期9卷 378-382页

作者： ZhanghuaChen t.C.lee 等 AppliedScienceSchool UniversityofScienceandTechnologyBeijingBeijing100083China DepartmentofIndustrialsystemEngineering TheHongKongPolytechnicunivetsityChina

the thermal-mechanical coupling finite element method(FEM)was usedto simulate a non-isothermal sheet metal extrusion process. On thebasis of the finite plasticity consistent with multiplicativedecomposition of the deformation gradient, the enhanced as- sumedstrain(EAS)FEM was applied to carry out the numerical simulation. Inorder to make the computation reliable ad avoid hour- glass mode inthe EAS element under large compressive strains, an alterative formof the original enhanced deformation gradient was employed. Inaddition, reduced factors were used in the computation of the elementlocal internal parameters and the enhanced part of elementalstiffness.

关键词： enhanced assumed strain element thermal-mechanical coupling process houyrglass mode

Improved thermal performance of a hydronic radiant panel heating system by the optimization of tube shapes

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2011年第6期12卷 428-437页

作者： young t.CHAE Kwang Ho lee Jae Sung PARK School of Architecture University of Illinois at Urbana-Champaign Department of Architectural Engineering Hanbat National University Department of Mechanical Engineering University of Illinois at Urbana-Champaign

the thermal performance enhancement of the hydronic radiant floor heating system by tube shape refinements is investigated in this *** analytical and detailed numerical modelings are carried out to predict the performance of the radiant *** the simple analytical model briefly investigates the possibility of the effect of the tube shape improvement with the parametric analysis,the commercial computational fluid dynamics(CFD) code(Ansys/CFX) is used to perform the detailed 3D analysis under different tube shape *** fin thickness,the number of fins,and the tube thermal conductivity turn out to have significant effects on the radiant system *** potential energy saving impacts of the tube shape refinements are also *** tube shape improvement turns out to increase the floor surface temperature and to decrease the hot water temperature drop across the system,resulting in heating energy savings.

关键词： Radiant panel system Analytical modeling Computational fluid dynamics(CFD) tube shape Energy saving

Steady vortex force theory and slender-wing flow diagnosis

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Acta Mechanica Sinica 2007年第6期23卷 609-619页

作者： y.t.yang R.K.Zhang y.R.An J.Z.Wu State Key Laboratory for turbulence and Complex Systems College of EngineeringPeking UniversityBeijing 100871China

the concept vortex force in aerodynamics is sys- tematically examined based on a new steady vortex-force theory （Wu et al., Vorticity and vortex dynamics, Springer, 2006） which expresses the aerodynamic force （and moment） by the volume and boundary integrals of the Lamb vector. In this paper, the underlying physics of this theory is explored, including the general role of the Lamb vector in non- linear aerodynamics, its initial formation, and its relevance to the total-pressure non-uniformity. As a typical example, the theory is applied to the flow over a slender delta wing at a large angle of attack. the highly localized flow structures with high Lamb-vector peaks are identified in terms of their net contribution to various constituents of the total aerody-namic force. this vortex-force diagnosis sheds new light on the flow control and configuration optimization.

关键词： Vortex force - Delta-wing - Flow control