检索结果-南通市图书馆

An analytical model of hot rolling force for a thick plate by combining globally optimal approximation yield criterion and egg-circular velocity field

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2024年第3期31卷 647-659页

作者： Shun-hu Zhang Yi Zhang Wen-hao Tian Yan Li Shagang School of Iron and Steel Soochow UniversitySuzhou 215021JiangsuChina

For the sake of solving the problem that it is difficult to be integrated for the Mises specific plastic power due to its nonlinearity,a new linear criterion,named the globally optimal approximation criterion,is constructed by the polygonal approximation to the Mises *** new criterion is proved to be the linear function of the principal stress componentsσ1,σ2 andσ3 and the trajectory of it on theπ-plane is a non-equiangular but equilateral dodecagon intersecting the Mises *** theoretical results of the current criterion described by the Lode stress parameters are in excellent accordance with the experimental ***,according to the trend that the metallic flow velocity between rollers aggrandizes gradually from the inlet to the outlet during the hot rolling of a thick plate,a biomimetic velocity field is proposed in which the horizontal velocity component fits the egg-circular curve *** velocity field and its simulated results agree quite ***,using the determined linear criterion,energy analysis of the constructed velocity field is utilized to obtain the interior deformation power,while the vector decomposition approach is utilized to obtain the frictional power and shear *** this basis,the overall power is obtained and the analytical solutions are generated for the rolling torque,rolling force and the coefficient of the stress state under different egg curves by minimizing the neutral ***,the parameter optimization of the characteristic parameterρwhich affects the slope of the egg-circular curve is carried out and the best egg-circular curve which can minimize the energy consumption is *** best agreement between the theoretical and observed values of rolling force and rolling torque is under this curve,and the mean relative errors of the rolling torque and rolling force are no more than 2.93%,while the maximum error is no more than 8.35%.

关键词： Yield criterion Plastic deformation Rolling force velocity field Analytical solution

Experimental studies on flow visualization and velocity field of compression ramp with different incoming boundary layers

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 Physics B 2014年第11期23卷 384-395页

作者：武宇易仕和何霖陈植朱杨柱 College of Aerospace Science and Engineering National University of Defense Technology

Experimental studies which focus on flow visualization and the velocity field of a supersonic laminar/turbulent flow over a compression ramp were carried out in a Mach 3.0 wind tunnel. Fine flow structures and velocity field structures were obtained via NPLS （nanoparticle-tracer planar laser scattering） and PIV （particle image velocimetry） techniques, time- averaged flow structures were researched, and spatiotemporal evolutions of transient flow structures were analyzed. The flow visualization results indicated that when the ramp angles were 25~, a typical separation occurred in the laminar flow, some typical flow structures such as shock induced by the boundary layer, separation shock, reversed flow and reattachment shock were visible clearly. While a certain extent separation occurred in turbulent flow, the separation region was much smaller. When the ramp angles were 28~, laminar flow separated further, and the separation region expanded evidently, flow structures in the separation region were complex. While a typical separation occurred in turbulent flow, reversed flow structures were significant, flow structures in the separation region were relatively simple. The experimental results of velocity field were corresponding to flow visualization, and the velocity field structures of both compression ramp flows agreed with the flow structures well. There were three layered structures in the U component velocity, and the V component velocity appeared like an oblique ＂v＂. Some differences between these two compression ramp flows can be observed in the velocity profiles of the shear layer and the shearing intensity.

关键词： compression ramp incoming boundary layer fine flow structure velocity field

AN ASYMPTOTIC SOLUTION OF velocity field IN SHIP WAVES

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2006年第4期18卷 387-392页

作者： WU Yun-gang TAO Ming-de Department of Mechanics and Engineering Science and The Key Laboratory of Wave Scattering and RemoteSensing Information Fudan University Shanghai 200433 China

The stationary phase method in conventional Lighthill＇s two-stage scheme to get the expressions of the velocity field was given up in this paper. The method that Ursell had used in deducing the elevation expression of ship wave was adopted, and an asymptotic solution of velocity field of ship waves on an inviscid fluid that is perfectly fit for the region inside and outside the critical lines was obtained. It is very convenient to be used in SAR technique.

关键词： ship waves velocity field remote sensing,asymptotic solution

Face stability of shield tunnels considering a kinematically admissible velocity field of soil arching

在线全文

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2022年第2期14卷 505-526页

作者： Wei Li Chengping Zhang Dingli Zhang Zijian Ye Zhibiao Tan Key Laboratory for Urban Underground Engineering of the Ministry of Education Beijing Jiaotong UniversityBeijing100044China School of Civil Engineering Beijing Jiaotong UniversityBeijing100044China

Existing mechanism of simulating soil movement at tunnel face is generally based on the translational or rotational velocity field,which is,to some extent,different from the real soil movement in the arching *** simulations are carried out first to investigate the characteristics of the velocity distribution at tunnel face and above tunnel *** a new kinematically admissible velocity field is proposed to improve the description of the soil movement according to the results of the numerical *** on the proposed velocity field,an improved failure mechanism is constructed adopting the spatial discretization technique,which takes into account soil arching effect and plastic deformation within soil ***,the critical face pressure and the proposed mechanism are compared with the results of the numerical simulation,existing analytical studies and experimental tests to verify the accuracy and improvement of the presented *** proposed mechanism can serve as an alternative approach for the face stability analysis.

关键词： Tunnel face stability velocity field Failure pattern Improved failure mechanism Critical face pressure

PRESSURE DISTRIBUTION DETERMINED BY USING MEASURED velocity field DATA AND RANS EQUATIONS

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 1997年第1期9卷 102-110页

作者： Dong Shi-tang, Ji Zhi-ye, Zhou Wei-xinChina Ship Scientific Research Center, P. O. Box 116, Wuxi, 214082, P. R. China China Ship Scientific Research Cent Wuxi China

The current paper presents the result of a study on determining the pressure distribution along the surface of a foil section by using measured velocity field data and the Reynolds Averaged Navier-Stokes equations. The results are compared with the measured pressure data and show its satisfaction. It is a try to find a new way to determine pressure by combining the experimental data and CFD method.

关键词： pressure distribution velocity field RANS equations

A Study of Lift Force and Instantaneous velocity field Around an Oscillating Circular Cylinder

在线全文

学校读者我要写书评

暂无评论

China Ocean Engineering 1997年第4期12卷 419-430页

作者： C.A.Greated Department of Physics and Astronomy University of Edinburgh

Force measurements of oscillatory flow acting on a single circular cylinder have been carried out. The experiments were done by oscillating a circular cylinder in still water. Instantaneous forces and velocity fields around the cylinder were measured by Particle Image Velocimetry (PIV). The Keulegan-Carpenter number (KC) varied in the range from 5 to 20 and the viscous parameter beta = Re / KC was set at 500 (Re is Reynolds number). It was found that the strength and frequency of the lift force increased with KC number, the main frequency of the lift force being three times the frequency of the oscillatory flow at KC = 20. The movement and strength of the vortices around the cylinder are discussed for different KC numbers.

关键词： particle image velocimetry oscillatory polo single circular cylinder force measurement lift force velocity field vortex pattern vorticity

An Analytical Solution of the Potential velocity field Induced by a Growing Bubble from a Plate Orifice

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 1993年第3期2卷 158-164页

作者： ZhiTao NingKang Division402 BeijingUniversityofAeronautics＆AstronauticsBeijing100083China Division506 BeijingUniver

An analytical solution is derived with the mirror image method of the velocity field of an inviscid liquid induced by a growing bubble from a plate orifice. The flow is assumed potential, and the bubble shape is idealised as spherical. In deriving the motion equation, the spherical image of a point source, which is a combination of a point source and a line source, is proved approximate to a double source. This approximation enables continuation of the effectiveness of mirror image method to the case studied in this paper. The derived velocity potential equation is verified for the boundary conditions on the bubble surface and the orifice plate. The streamlines of the velocity field are presented and compared with experimental results in the literature.

关键词： bubble formation bubble detachment bubble collapse plate orifice velocity field

Effects of Surface Etch Hole Fault on the velocity field in Microchannel Reactors

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2009年第6期17卷 919-924页

作者：尤学一李胜华 School of Environmental Science and Engineering Tianjin University Tianjin 300072 China School of Chemical Engineering Tianjin University Tianjin 300072 China

Microchannel reactors are commonly used in micro-chemical technology. The performance of microreactors is greatly affected by the velocity field in the microchannel. The flow field is disturbed by the cylindrical etch holes caused by air dust on the microchannel surface during its processing procedure. In this approach, a two-dimensional computational fluid dynamics （CFD） model is put forward to study the effect of etch holes on flow field. The influenced area of single or two concave etch holes is studied for the case of laminar flow. The hole diameter, the Reynolds number and the distance between the center of holes are found to have influences on the flow field. Numerical results indicate that the effects of etch hole on the flow field should be evaluated and the way of choosing the economic class of cleanroom for microreactor manufacture is presented.

关键词： microchannel processing faults etch holes computational fluid dynamics velocity field

A Laboratory Modeling of the velocity field in the Convective Boundary Layer with the Particle Image Velocimetry Technique

在线全文

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2003年第4期20卷 631-637页

作者：李萍阳蒋维楣孙鉴泞袁仁民 Department of Atmospheric Sciences Nanjing UniversityNanjing 210093 National Meteorological Center of ChinaBeijing 100081 Department of Atmospheric Sciences Nanjing UniversityNanjing 210093 Department of Earth and Space Sciences University of Science and Technology of ChinaHefei 230026

Based on the research of the convective boundary layer (CBL) temperature field in a convective tank, this paper studies the characteristics of the CBL velocity field in the convective tank. Aluminium powder (400 orders) is used as a tracer particle in the application of the particle image velocimetry (PIV) technique. The experiment demonstrates: the velocity distribution in the mixed layer clearly possesses the characteristics of CBL thermals; the velocity distribution in the top zone of the mixed layer shows entrainment layer characteristics; the vertical distribution of turbulent characteristic variables is reasonable, which is similar to field observations and other tank results; the error analysis demonstrates the validity of aluminium powder, which implies the reliability of the results.

关键词： velocity field convective boundary layer (CBL) convective water tank PIV technique