检索结果-南通市图书馆

NUMERICAL SIMULATION OF transient flow AROUND A SHIP IN UNSTEADY BERTHING MOTION

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2009年第3期21卷 379-385页

作者： WANG Hua-ming ZOU Zao-jian TIAN Xi-min School of Naval Architecture Ocean and Civil Engineering Shanghai Jiao Tong University Shanghai 200240 China School of Naval Architecture Ocean and Civil Engineering Shanghai Jiao Tong University Shanghai 200240 State Key Laboratory of Ocean Engineering Shanghai Jiao Tong University Shanghai 200030 China Marine Design and Research Institute of China Shanghai 200011 China

Ship berthing is a specific maneuver operation. The flow around a berthing ship and the forces acting on the hull are quite different from those for a ship in normal navigation. By solving the unsteady Reynolds-Averaged Navier-Stokes （RANS） equations, the transient flow field around a ship undergoing unsteady lateral motion is simulated and the varying lateral hydrodynamic force acting on the hull is evaluated in this article. The numerical results obtained with different turbulence models are analyzed and compared with experimental results and other numerical results published in literature, and a turbulence model more suitable for simulation of the viscous flow around a ship undergoing unsteady berthing is determined.

关键词： ship berthing transient flow lateral hydrodynamic force numerical simulation

NUMERICAL SOLUTIONS FOR THE transient flow IN THE HOMOGENOUS CLOSED CIRCLE RESERVOIRS

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2003年第1期19卷 40-45页

作者：周蓉刘曰武周富信 State Key LNM Institute of Mechanics CAS Beijing 100080 China

There are many fault block fields in China. A fault block field consists of fault *** small fault pools can be viewed as the closed circle reservoirs in some case. In order to know the pressure change of the developed formation and provide the formation data for developing the fault block fields reasonably, the transient flow should be researched. In this paper, we use the automatic mesh generation technology and the finite element method to solve the transient flow problem for the well located in the closed circle reservoir, especially for the well located in an arbitrary position in the closed circle reservoir. The pressure diffusion process is visualized and the well-location factor concept is first proposed in this paper. The typical curves of pressure vs time for the well with different welllocation factors are presented. By comparing numerical results with the analytical solutions of the well located in the center of the closed circle reservoir, the numerical method is verified.

关键词： fluid flow in porous media transient flow closed circle reservoir numerical solution

Application of Computational Fluid Dynamics and Fluid Structure Interaction Techniques for Calculating the 3D transient flow of Journal Bearings Coupled with Rotor Systems

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2012年第5期25卷 926-932页

作者： LI Qiang YU Guichang LIU Shulian ZHENG Shuiying Institute of Chemical Machinery Zhejiang University Hangzhou 310027 China Department of Electro-mechanical Engineering Zhejiang University of Science & Technology Hangzhou 310023 China

Journal bearings are important parts to keep the high dynamic performance of rotor machinery. Some methods have already been proposed to analysis the flow field of journal bearings, and in most of these methods simplified physical model and classic Reynolds equation are always applied. While the application of the general computational fluid dynamics （CFD）-fluid structure interaction （FSI） techniques is more beneficial for analysis of the fluid field in a journal bearing when more detailed solutions are needed. This paper deals with the quasi-coupling calculation of transient fluid dynamics of oil film in journal bearings and rotor dynamics with CFD-FSI techniques. The fluid dynamics of oil film is calculated by applying the so-called ＂dynamic mesh＂ technique. A new mesh movement approacb is presented while the dynamic mesh models provided by FLUENT are not suitable for the transient oil flow in journal bearings. The proposed mesh movement approach is based on the structured mesh. When the joumal moves, the movement distance of every grid in the flow field of bearing can be calculated, and then the update of the volume mesh can be handled automatically by user defined function （UDF）. The journal displacement at each time step is obtained by solving the moving equations of the rotor-bearing system under the known oil film force condition. A case study is carried out to calculate the locus of the journal center and pressure distribution of the journal in order to prove the feasibility of this method. The calculating results indicate that the proposed method can predict the transient flow field of a journal bearing in a rotor-bearing system where more realistic models are involved. The presented calculation method provides a basis for studying the nonlinear dynamic behavior of a general rotor-bearing system.

关键词： mesh movement transient flow computational fluid dynamics (CFD) fluid-structure interaction (FSI) journal bearing

A new method for studying the 3D transient flow of misaligned journal bearings in flexible rotor-bearing systems

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2012年第4期13卷 293-310页

作者： Qiang LI Shu-lian LIU Xiao-hong PAN Shui-ying ZHENG Institute of Chemical Machinery Zhejiang UniversityHangzhou 310027China Department of Electro-Mechanical Engneering Zhejiang University of Science and TechnologyHangzhou 310023China Institute of Modern Manufacture Engineering Zhejiang UniversityHangzhou 310027China

The effects of journal misalignment on the transient flow of a finite grooved journal bearing are presented in this study. A new 3D computational fluid dynamics (CFD) analysis method is applied. Also, the quasi-coupling calculation of transient fluid dynamics of oil film in journal bearing and rotor dynamics is considered in the analysis. Based on the structured mesh, a new approach for mesh movement is proposed to update the mesh volume when the journal moves during the fluid dynamics simula- tion of an oil film. Existing dynamic mesh models provided by FLUENT are not suitable for the transient oil flow in journal bearings. The movement of the journal is obtained by solving the moving equations of the rotor-bearing system with the calculated film pressure as the boundary condition of the load. The data exchange between fluid dynamics and rotor dynamics is realized by data files. Results obtained from the CFD model were consistent with previous experimental results on misaligned journal bearings. Film pressure, oil film force, friction torque, misalignment moment and attitude angle were calculated and compared for mis- aligned and aligned journal bearings. The results indicate that bearing performances are greatly affected by misalignment which is caused by unbalanced excitation, and the CFD method based on the fluid-structure interaction (FSI) technique can effectively predict the transient flow field of a misaligned journal bearing in a rotor-bearing system.

关键词： Misalignment transient flow Computational fluid dynamics (CFD) Fluid-structure interaction (FSI) Journalbearing

Simulations of the transient flow Generated from a Started Flat Plate

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2012年第6期25卷 1190-1197页

作者： WANG Leqin MA Xudan LI Zhifeng WU Peng WU Dazhuan Institute of Process Equipment Zhejiang UniversityHangzhou 310027China Engineering Research Center of High Pressure Process Equipment and Safety Ministry of EducationHangzhou 310027China

transient operations are commonly founded in fluid machineries such as the starting, stopping, and variations of rotor speeds, etc. flow generated from a started fiat plate is of fundamental importance. Experiments have been done to observe the flow evolution in current researches. And in order to explore the flow in more detailed scale, some vortex methods with high resolution and other numerical methods were developed to solve various related problems by some researchers. But the promotion of vortex method to engineering application is rare due to its complexity and difficulty in specifying the boundary conditions. In order to build up a method of numerical study for such problems, a simplified model is built up with a flat plate. The development of two-dimensional viscous incompressible flow generated from an impulsively started and uniformly accelerated infinitesimally thin flat plate is simulated numerically. A dynamic mesh（DM） method based on the spring analogue and local remeshing is applied to realize the mesh motion caused by the started plate. Researches show that the mesh quality will decline under large grid shear force during the updating process. To conquer this problem, a region near the plate is separated to guarantee the mesh quality at location of interest which is the innovation of the present paper. All computations at least cover a period during which the plate translates 6 times its length. The simulated instantaneous velocity profiles, flow structures and drag coefficients under several Reynolds numbers （20 ≤ Re ≤ 126） and accelerations （20 m/s2≤ a ≤ 152 m/s2） are presented and compared with existing results in literatures. Comparisons are found to be satisfactory, confirming the validity of the current proposed method（region separated DM）. The proposed DM method is firstly used to study the transient flow generated from a started flat plate and can be used in further study of transient characteristics during transient operations of turbo mach

关键词： numerical simulation flat plate start transient flow region separated dynamic mesh

THEORETIC SOLUTION OF transient flow OF LIQUID IN THE PIPE WITH FLUID MACHINERY

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 1992年第4期4卷 119-126页

作者： Chen Jin-e Shanghai Institute of Electric Power,Shanghai 200090,P.R.China

The transient flow of liquid in the pipe with fluid machinery is analysed in this pa- *** theoretic solution of the transient flow produced due to the regulation of fluid machin- ery is found by use of the method of t... 详细信息

关键词： transient flow liquid fluid machinery

Computational fluid dynamic(CFD)modelling of transient flow in the intermittent gas lift

在线全文

学校读者我要写书评

暂无评论

Petroleum Research 2020年第2期5卷 144-153页

作者： Nagham Amer Sami Zoltan Turzo Petroleum and Natural Gas Institute Faculty of Earth Science and EngineeringUniversity of Miskolc3515MiskolcHungary Department of Petroleum Engineering College of EngineeringUniversity of BaghdadAljadrea10071BaghdadIraq

A computational fluid dynamics model(CFD)is developed for intermittent gas lift *** simulation is conducted for a test section of 18 m vertical tube with 0.076 m in diameter using air as injection gas and oil as a formation *** results obtained from the CFD model are validated with the experiment results from the *** current study shows that computational modeling is a proven simulation program for predicting intermittent gas lift characteristics and the transient flow parameters that are changing with time and position in the coordinate *** model can predict the slug velocity behavior for different injection *** slug velocity profile shows three regions;the first region is the rapid acceleration at the initial time of injection,the second region shows the nearly constant velocity until the slug reaches the surface and the third region is again the rapid acceleration when the liquid starts to ***,the results obtained from this model show that as the gas injection pressure increases,the liquid slug velocity increase,and the region of the constant velocity *** effect of the injection time on the liquid production rate has been studied for two different gas injection pressures of 40 psig and 50 *** developed model shows that more than 50%of the liquid production is coming from after flow period.

关键词： Intermittent gas lift Slug velocity transient flow CFD Artificial lift

Numerical simulation of transient flow in horizontal drainage systems

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Water Science and Engineering 2009年第1期2卷 74-85页

作者： Ze-yu MAO Han XIAO Ying LIU Ying-jun HU Department of Hydraulic Engineering Tsinghua University Beijing 100084 P. R. China

A numerical simulation model based on the characteristic-based finite-difference method with a time-line interpolation scheme was developed for predicting transient free surface flow in horizontal drainage systems. The fundamental accuracy of the numerical model was first clarified by comparison with the experimental results for a single drainage pipe. Boundary conditions for junctions and bends, which are often encountered in drainage systems, were studied both experimentally and numerically. The numerical model was applied to an actual drainage system. Comparison with a full-scale model experiment indicates that the model can be used to accurately predict flow characteristics in actual drainage networks.

关键词： transient flow drainage systems time-line interpolation urbanization

THE transient ELLIPTIC flow OF POWER-LAW FLUID IN FRACTAL POROUS MEDIA

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2002年第8期23卷 875-880页

作者： SONG Fu-quan(宋付权) LIU Ci-qun(刘慈群) Institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 P R China Institute of Porous Flow and Fluid Mechanics Academia Sinica Langfang Hebei 065007 P R China

The steady oil production and pressure distribution formulae of vertically fractured well for power-law non-Newtonian fluid were derived on the basis of the elliptic flow model in fractal reservoirs. The corresponding transient flow in fractal reservoirs was studied by numerical differentiation method: the influence of fractal index to transient pressure of vertically fractured well was analyzed. Finally the approximate analytical solution of transient flow was given by average mass conservation law. The study shows that using elliptic flow method to analyze the flow of vertically fractured well is a simple method.

关键词： fractal media vertically fractured well transient flow power-law fluid