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NUMERICAL ANALYSIS OF LEAKAGE FLOW THROUGH TWO LABYRINTH SEALS

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Journal of Hydrodynamics 2007年第1期19卷 107-112页

作者： WANG Wei-zhe LIU Ying-zheng JIANG Pu-ning CHEN Han-ping School of Mechanical and Power engineering Shanghai Jiaotong University Shanghai 200030 China shanghai Turbine LTD Shanghai 200240 China

The leakage flow through two labyrinth seals, e.g the interlocking seal and the stepped seal, was numerically investigated. Preliminary calculation of the seal-cavity averaged pressure by using the one-dimensional control volume method showed favorable agreement with the experimental measurements. Subsequently, in-depth understanding of the fluid flow through the labyrinth seals was obtained by employing Computational Fluid Dynamics （CFD） and k -ε turbulence model, which resulted in a potential wealth of information like the streamline pattern, velocity vector field, and distribution of turbulent kinetic energy and static pressure. At the clearance of the seal the turbulent kinetic energy reached the peak value, while in the bulk region of the cavities it decayed fast. The static pressure rapidly dropped as the fluid flow went through the clearance; no distinct difference of the static pressure was inspected in the cavities. Also noted from the numerical results was that the stepped seal showed better sealing performance than the interlocking seal.

关键词： labyrinth seal leakage flow,turbomachinery Computational Fluid Dynamics (CFD)

An Expert system in FRP Composite Material Design

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Journal of Materials Science & Technology 2001年第5期17卷 556-560页

作者： Qingfen LI, Zhaoxia CUI and Weimin WANG College of Mechanical & Electrical engineering, Harbin engineering University, Harbin 150001, china Jianhua GAO Department of Mechanical engineering, shanghai Jiao Tong University, shanghai 200030, china Harbin Engn Univ Coll Mech & Elect Engn Harbin 150001 Peoples R China shanghai Jiao Tong Univ Dept Mech Engn Shanghai 200030 Peoples R China

An expert system prototype for fibre-reinforced plastic matrix (FRP) composite material design, ESFRP, has been developed. The system consists of seven main functional parts: a general inference engine, a set of knowledge bases, a material properties algorithm base, an explanation engine, various data bases, several function models and the user interface. The ESFRP can simulate human experts to make design scheme for fibre-reinforced plastics design, FRP layered plates design and FRP typical engineering components design. It can also predict the material properties and make strength analysis according to the micro and macro mechanics of composite materials. A satisfied result can be gained through the reiterative design.

关键词： An Expert system in FRP Composite Material Design FRP

A GENERAL CONSTITUTIVE RELATION FOR FATIGUE CRACK GROWTH ANALYSIS OF METAL STRUCTURES

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Acta Metallurgica Sinica(English Letters) 2003年第5期16卷 342-354页

作者： W.C. Cui and X.P. HuangSchool of Naval Architecture & Ocean engineering, shanghai Jiaotong University, shanghai 200030, china School of Naval Architecture & Ocean engineering Shanghai Jiaotong University

Crack growth rate curves are the fundamental material property for metal structures under fatigue loading. Although there are many crack growth rate curves available in the literature, few of them showed the capability to explain various special phenomena observed in tests. A modified constitutive relation recently proposed by McEvily and his co-workers showed very promising capability. This modified constitutive relation is further generalized by (1) introducing an unstable fracture condition; (2) defining a virtual strength to replace the yield stress; and (3) defining an overload and underload parameter. The performances of this general constitutive relation for fatigue crack growth is extensively studied and it is found that this general constitutive relation is able to explain various phenomena observed with particular strong capability on load sequence effect.

关键词： metal fatigue S-N curve crack growth rate general constitutive relation mean stress effect load sequence effect

Effect of Elastic Constitutive Laws on the Deformation of Two-dimensional Red Blood Cell

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Journal of shanghai Jiaotong university(Science) 2009年第1期14卷 76-80页

作者：宫兆新鲁传敬 School of Mechanical engineering Shanghai Jiaotong UniversityShanghai 200240China State Key Laboratory of Ocean engineering Shanghai Jiaotong UniversityShanghai 200240China

Deformation of two-dimensional red blood cell in linear shear flow is simulated using the immersed boundary method,in which the cell is modeled as a force source instead of a real *** effect of three constitutive laws,***,Neo-Hookean and Skalak elasticity,on the deformation is studied by simulating the cell movement in two linear shear *** results show that the effect of the constitutive laws gets more obvious as the shear rate *** the aspect ratio and the inclination of the steady shapes get bigger, and the differences between the periods of the cell tank-treading motion become *** the same shear flow, the period with Hookean elasticity is less than the period with Neo-Hookean elasticity and bigger than the period with Skalak elasticity.

关键词： red blood cell immersed boundary method constitutive law. tank-treading motion

Preparation and Magnetic Properties of Mn-Zn Ferrites by the Co-precipitation Method

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Journal of Wuhan University of Technology(Materials Science) 2009年第6期24卷 875-878页

作者：李雪张俊喜 School of Environmental and Chemical engineering Shanghai University Electrochemical Research Group Shanghai University of Electric PowerKey Laboratory of State Power Corporation of China

Mn-Zn ferrites （Mn1-xZnxFe2O4） with different compositions were prepared by the coprecipitation method, and the influences of such synthesis conditions as pH value, composition and volume ratio （R） of the mixed solution and NH4HCO3 solution on their microstructures and magnetic properties were discussed. The samples were characterized by X-ray diffraction （XRD） and magnetization measurement instrument. Lattice parameters and average crystalline size of the synthesized materials were calculated from the corresponding XRD patterns with the related software Jade.5. For samples of different pH values, only one phase was found when pH values were 7.0, 8.0 and 9.0. The sample with pH value of 7.0 exhibited the highest saturation magnetic induction, the lowest coercive force, and crystallized best. For samples of different R values with pH value of 7.0, only one phase was observed in all samples, and the sample with R value of 2.3 exhibited the highest saturation magnetic induction and the lowest coercive force. The composition has mainly afected the magnetic properties, and the saturation magnetic induction increases with the increase of the content of Zn （x）, but decreases when x is beyond 0.6. The trend of coercive force is on the contrary. However, no magnetism is exhibited when the x value is up to 0.8.

关键词： co-precipitation method microstructure magnetic property Mn-Zn ferrite

Homotopic mapping solving method for gain fluency of a laser pulse amplifier

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Science china(Physics,Mechanics & Astronomy) 2009年第7期52卷 1007-1010页

作者： MO JiaQi1,2 1 Anhui Normal University, Wuhu 241000, china 2 Division of Computational Science, E-Institutes of shanghai Universities, at SJTU, shanghai 200240, china Anhui Normal University Wuhu 241000 China Division of Computational Science E-Institutes of Shanghai Universities at SJTU Shanghai 200240 China

The model for gain fluency of a laser pulse amplifier is studied. Using the homotopic mapping method, firstly, the system of the original model is packed up standardization; secondly, introducing a homotopic mapping, taking the property of the mapping, inducing a contrived parameter, the solving of a nonlinear problem translates into the solving of a linear problem. Then the approximate expressions of the solution for the corresponding model are obtained. And the precision for the approximate solution is compared. It illuminates that the obtained approximate solution using the homotopic mapping method possesses higher approximate degree. At one time, the expansion of solution through the homotopic mapping method can be kept in the analytic operation. Thus it also enables us through differential and integral operations to obtain other physics behavior for the gain fluency of laser pulse amplifier.

关键词： nonlinear homotopic mapping laser pulse amplifier

LARGE-EDDY SIMULATION OF THREE-DIMENSIONAL VORTICAL STRUCTURES FOR AN IMPINGING TRANSVERSE JET IN THE NEAR REGION

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Journal of Hydrodynamics 2007年第3期19卷 314-321页

作者： FAN Jing-yu ZHANG Yan WANG Dao-zeng shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 China Key Laboratory of Advanced Display and system Applications （shanghai University） Ministry of Education and SMIT Center Shanghai University Shanghai 200072 China Department of Applied Mechanics Chalmers University of Technology SE-412 96 Gothenburg Sweden shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 China

The three-dimensional vortical structures for an impinging transverse jet in the near region were numerically investigated by means of Large-Eddy Simulation （LES）. The LES results reproduced the skewed jet shear layer vortices close to the jet nozzle and the scarf vortex in the near-wall zone in good agreement with the experimental observations. Different vortical modes in the skewed jet shear layer close to the jet nozzle were identified depending upon the velocity ratio between jet and crossflow, namely changing from an approximately axisymmetric mode to a helical one with the velocity ratios varying from 20 to 8. Moreover, the scarf vortex wrapped around the impinging jet in the near-wall zone showed distinct asymmetry with regard to its bilateral spiral legs within the near region. And the entrainment of the ambient crossflow fluids by the scarf vortex in the near-wall zone was appreciably influenced by its asymmetry and in a large part occurred on the surface of the spiral roller structures in the course of spreading downstream.

关键词： Large-Eddy Simulation (LES) impinging jet crossflow vortical structure entrainment

IDENTIFICATION OF ABKOWITZ MODEL FOR SHIP MANOEUVRING MOTION USING ε-SUPPORT VECTOR REGRESSION

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Journal of Hydrodynamics 2011年第3期23卷 353-360页

作者： ZHANG Xin-guang ZOU Zao-jian School of Naval Architecture Ocean and Civil Engineering Shanghai Jiao Tong University Shanghai 200240 China School of Naval Architecture Ocean and Civil Engineering and State Key Laboratory of Ocean Engineering Shanghai Jiao Tong University Shanghai 200240 China

By analyzing the data of longitudinal speed, transverse speed and rudder angle etc. in the simulated 10°/10°zigzag test, the hydrodynamic derivatives in the Abkowitz model for ship manoeuvring motion are identified by using e-Support Vector Regression （ε -SVR）. To damp the extent of parameter drift, a series of random numbers are added into the training samples to reconstruct the training samples. The identification results of the hydrodynamic derivatives are compared with the Planar Motion Mechanism （PMM） test results to verify the identification method. By using the identified Abkowitz model, 20°/20° zigzag test is numerically simulated. The simulated results are compared with those obtained by using the Abkowitz model where the hydrodynamic derivatives are obtained from PMM tests. The agreement is satisfactory, which shows that the regressive Abkowitz model has a good generalization performance.

关键词： ship manoeuvring Abkowitz model parameter identification e -Support Vector Regression ( ~ -SVR)

Embed-Solitons and Their Evolutional Behaviors of (3+1)-Dimensional Burgers system

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Communications in Theoretical Physics 2007年第7期48卷 57-62页

作者： ZHU Hai-Ping ZHENG Chun-Long College of Mathematics and Physics,Lishui University,Zhejiang 323000,china2 shanghai Institute of Applied Mathematics and Mechanics,shanghai University,shanghai 200072,china College of Mathematics and Physics Lishui University Zhejiang 323000 China

With the help of an extended mapping approach and a linear variable separation method,new families ofvariable separation solutions with arbitrary functions for the(3+1)-dimensional Burgers system are *** onthe derived exact solutions, some novel and interesting localized coherent excitations such as embed-solitons are revealedby selecting appropriate boundary conditions and/or initial *** time evolutional properties of the novellocalized excitation are also briefly investigated.

关键词： extended mapping method (3+1)-dimensional Burgers system embed-soliton evolutional behavior