检索结果-南通市图书馆

two-phase SPH simulation of vertical water entry of a two-dimensional structure

Journal of Hydrodynamics 2018年第5期30卷 841-850页

作者： Lin Ma Xi Zhao Hua Liu Key Laboratory of Hydrodynamics（Ministry of Education） School of Naval ArchitectureOcean and civil EngineeringShanghai Jiao Tong UniversityShanghai200240 China State Key Laboratory of Ocean Engineering Shanghai Jiao Tong UniversityShanghai 200240China College of Ocean Science and Engineering Shanghai Maritime UniversityShanghai 200135China

In view of the fact that the SPH model is easy to handle the flows with the free surface of large deformation, a 2-D flow induced by vertical water entry of a 2-D structure is simulated using the two-phase SPH model. The local pressure of the boundary particles is obtained by pressure of the fluid particles nearby through a modified kernel approximation. To evaluate the accuracy of the method, water entry of a 2-D symmetric wedge with fixed separation point of the free surface on the wedge surface is simulated. The pressure distribution of the wedge at the initial stage agrees well with the analytical results available. Evolution of the free surface and the air flow in the cavity induced by the water entry are obtained. A higher speed air jet is found at the neck of the cavity when the neck of the cavity becomes smaller. For the case of a horizontal cylinder entering the water with an unknown separation point of flow on the model surface, the early stage of the water entry is simulated for the rigid body with different density. Evolution of the free surface deformation of the half-buoyant cylinder and neutrally buoyant cylinder water entry is compared with the experimental data. The effects of the density ratio and Froude number on the pinch-off of the cavity are discussed. It is found that the pinch-off time remains almost constant for different density ratio and Froude number. Meanwhile, for a given Froude number, the dimensionless pinch-off depth and the location of the cylinder at the time of pinch-off increase with the density ratio. Further, for a given density ratio, these two parameters increase with the Froude number and, however, the relative cavity shape appears to be a self-similar shape when Fr ≥8.35.

关键词： Smoothed particle hydrodynamics (SPH) two-phase water entry density ratio

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

two-phase Flow Patterns in a Square Mini-channel

引用

Journal of Thermal Science 2004年第2期13卷 174-178页

作者： Jianfu Zhao Gang Liu Bin Li Chinese Acad Sci Inst Mech Natl Micrograv Lab Beijing 100080 Peoples R China

This paper presents a new set of experimental data of air-water flow patterns in a channel with a cross-section of 1×1 mm2. The ranges of the gas and liquid superficial velocities are 0.1-10 m/s and 0.2~7 m/s, respectively. Bubble, bubble-slug, slug, and frothy flows are observed. The present data are compared with other data in mini-channels reported in literature, and also compared with those in normal channel at microgravity, in which the Bond number has the same order of magnitude. The slug-frothy boundary is in consistent with each other, but for the bubble-slug transition, a much smaller value for the transition quality in the drift-flux model is obtained in the present study than those predicted by the empirical relations for the case of microgravity. It’s shown that the mini-scale modeling may not be an effective way to anticipate the bubble-slug transition of two-phase flow at microgravity.

关键词： two-phase flow flow pattern mini-channel microgravity

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Characteristics of pressure drop for singlephase and two-phase flow across sudden contraction in microtubes

引用

Science China(Technological Sciences) 2008年第2期51卷 162-169页

作者： LI Zhuo YU Jian MA ChongFang Key Laboratory of Enhanced Heat Transfer and Energy Conservation Ministry of Education of ChinaKey Laboratory of Heat Transfer and Energy ConversionBeijing Education CommissionBeijing University of TechnologyBeijing 100022China

Single-phase and gas-liquid two-phase pressure drops caused by a sudden con-traction in microtubes were experimentally investigated at room temperature and atmospheric pressure,using nitrogen and water. The experimental results on pressure drop with a novel measurement method,the tiny gaps on the tubes,were used to characterize the sudden contraction pressure drop for tube diameters from 850 to 330 μm. The ranges of the gas and liquid superficial velocity were 2.55―322.08 and 0.98―9.78 m/s in the smaller tube respectively. In single-phase flow experiments,the contraction loss coefficients were larger than the experimental results from conventional tubes in the laminar flow. While in the turbulent flow,the contraction loss coefficients were slightly smaller than those from conventional tubes and predicted well by Kc=0.5×(1-σ2)0.75. In two-phase flow experiments,the slip flow model with a velocity slip ratio S=(ρL/ρG)1/3 showed a good prediction that reveals the occurrence of velocity slip. An empirical correlation for two-phase flow pressure drops caused by the sudden contraction was developed based on the proposed contraction loss coefficients correlation for single-phase flow and Mar-tinelli factor.

关键词： microtube sudden contraction pressure measurement loss coefficients single-and two-phase flow

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

two-phase flow in anode flow field of a small direct methanol fuel cell in different gravities

引用

Science China(Technological Sciences) 2009年第6期52卷 1576-1582页

作者： GUO Hang WU Feng YE Fang ZHAO JianFu WAN ShiXin LüCuiPing MA ChongFang Key Laboratory of Enhanced Heat Transfer and Energy Conservation Ministry of Education of ChinaCollege of Environmental and Energy EngineeringBeijing University of TechnologyBeijing 100124China Key Laboratory of Heat Transfer and Energy Conversion Beijing MunicipalityBeijing University of TechnologyBeijing 100124China Institute of Mechanics Chinese Academy of SciencesBeijing 100080China

An in-situ visualization of two-phase flow inside anode flow bed of a small liquid fed direct methanol fuel cells in normal and reduced gravity has been conducted in a drop *** anode flow bed con-sists of 11 parallel straight *** length,width and depth of single channel,which had rec-tangular cross section,are 48.0,2.5 and 2.0mm,*** rib width was *** experi-mental results indicated that when the fuel cell orientation is vertical,two-phase flow pattern in anode channels can evolve from bubbly flow in normal gravity into slug flow in *** size of bub-bles in the reduced gravity is also *** microgravity,the bubbles rising speed in vertical channels is obviously slower than that in normal *** the fuel cell orientation is horizontal,the slug flow in the reduced gravity has almost the same characteristic with that in normal *** implies that the effect of gravity on two-phase flow is small and the bubbles removal is governed by viscous *** the gas slugs or gas columns occupy channels,the performance of liquid fed direct methanol fuel cells is failing *** infers that in long-term microgravity,flow bed and operating condition should be optimized to avoid concentration polarization of fuel cells.

关键词： direct methanol fuel cells microgravity two-phase flow visualization bubble behavior

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

two-phase Flow Patterns and Heat Transfer in Parallel Microchannels

引用

Journal of Thermal Science 2002年第4期11卷 353-358页

作者： AlainDegiovanni BenjaminRemy StephanéAndre Department of Mechanical Engineering Technion- Israel Institute of TechnologyDepartment of Mechanical Engineering Technion- Israel Institute of TechnologyDepartment of Mechanical Engineering Technion- Israel Institute of Technology

MicroChannel heat sinks with two-phase flow can satisfy the increasing heat removal requirements of modern micro electronic devices. One of the important aspects associated with two- phase flows in microchannels is to study the bubble behavior. However, in the literature most of the reports present data of only a single channel. This does not account for flow mixing and hydrodynamic instability that occurs in parallel microchannels, connected by common inlet and outlet collectors. In the present study, experiments were performed for air- water and steam- water flow in parallel triangular microchannels with a base of 200-300μ m. The experimental study is based on systematic measurements of temperature and flow pattern by infrared radiometry and high-speed digital video imaging. In air-water flow, different flow patterns were observed simultaneously in the various microchannels at a fixed values of water and gas flow rates. In steam-water flow, instability in uniformly heated microchannels was observed.

关键词： two-phase flow heat transfer microchannels dryout.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Experimental study and correlation development for the two-phase frictional pressure drop of flow boiling in copper foam fin microchannels

引用

Science China(Technological Sciences) 2024年第9期67卷 2758-2776页

作者： FU Kai XU XiangHua LIANG XinGang School of Aerospace Engineering Tsinghua UniversityBeijing 100084China

Flow boiling in microchannels with porous walls has received extensive attention in recent years. Compared with the emphasis on heat transfer, there is a lack of research on the effect of the porous wall structures on the pressure drop characteristics. In this study, systematic experiments are performed to measure the pressure drop of water-vapor two-phase flow in five microchannels with copper foam fins, which consist of nine or six channels and fins of copper foam. The porosities of the foam fins range from0.78 to 0.82 and ratios of fin width to channel width range from 0.5 to 2. The channels are approximately 0.5 or 1 mm in width and 1 mm in height. Both adiabatic and flow boiling experiments are conducted with water at mass fluxes ranging from 66 to 407 kg/(m^(2)s). In the adiabatic experiments, the average quality in channels is between 0.017 and 0.846. In the flow boiling experiments, the outlet quality of channels is between 0.040 and 0.863. Slug flow, churn flow, annular flow, and wispy-annular flow are observed in adiabatic experiments. A two-phase frictional pressure drop correlation based on the Lockhart-Martinelli model is developed for copper foam fin microchannels by introducing the effects of the mass flux, porosity, ratio of fin width to channel width, and heating condition step by step. The mean absolute percentage errors of the new correlation are 7.53% for 325data points under adiabatic conditions and 5.51% for 268 data points under flow boiling conditions, respectively. This work provides insight into the correlations of frictional pressure drop in microchannels with porous walls.

关键词： two-phase flow boiling pressure drop correlation microchannel copper foam porous wall

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

two-phase Flow in Porous Electrodes of Proton Exchange Membrane Fuel Cell

引用

Transactions of Tianjin University 2020年第3期26卷 197-207页

作者： Daokuan Jiao Kui Jiao Qing Du State Key Laboratory of Engines Tianjin University135 Yaguan RoadTianjin 300350China

Water management in porous electrodes bears significance due to its strong potential in determining the performance of proton exchange membrane fuel *** terms of porous electrodes,internal water distribution and removal process have extensively attracted attention in both experimental and numerical ***,the structural difference among the catalyst layer(CL),microporous layer(MPL),and gas diffusion layer(GDL)leads to significant challenges in studying the two-phase flow *** the different porosities and pore scales of the CL,MPL,and GDL,the model scales in simulating each component are *** review emphasizes the numerical simulation related to porous electrodes in the water transport process and evaluates the effectiveness and weakness of the conventional methods used during the *** limitations of existing models include the following:(i)The reconstruction of geometric models is difficult to achieve when using the real characteristics of the components;(ii)the computational domain size is limited due to massive computational loads in three-dimensional(3 D)simulations;(iii)numerical associations among 3 D models are lacking because of the separate studies for each component;(iv)the effects of vapor condensation and heat transfer on the two-phase flow are disregarded;(v)compressive deformation during assembly and vibration in road conditions should be considered in two-phase flow studies given the real operating ***,this review is aimed at critical research gaps which need further *** potential research directions are also suggested for future improvements.

关键词： PEMFC Porous electrodes two-phase flow Water management

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Recovery of Dyestuffs from Dilute Solution with two-phase Electrophoresis

引用

Chinese Journal of Chemical Engineering 2000年第1期8卷 80-84页

作者：骆广生吕阳成朱慎林戴猷元清华大学北京 100084

two-phase electrophoresis was used to separate the dyestuffs from their dilute solutions. Several dyestuffs (naphthol green B, acid-chrome blue K, methyl blue and direct fast torquoise blue GL, and n-butanol) were treated in a self-designed experimental setup and the mass transfer characteristics in this process were studied. The results confirm the potential of this technique for recovering dyestuffs from their dilute solutions.

关键词： dyestuff two-phase electrophoresis separation

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Experimental study on the flow pattern and pressure gradient of air-water two-phase flow in a horizontal circular mini-channel

引用

Journal of Hydrodynamics 2019年第1期31卷 102-116页

作者： Sudaija Aqli Haq Deendarlianto Indarto Adhika Widyaparaga Departement of Mechanical and Industrial Engineering Gadjah Mada UniversityYogyakartaIndonesia Centre for Energy Studies Gadjah Mada UniversitySekip K-1A Kampus UGMYogyakartaIndonesia Departement of Mechanical Engineering Universitas Muhammadiyah YogyakartaYogyakartaIndonesia

Experimental studies on the flow pattern and the pressure gradient of gas-liquid co-current two-phase flow in a mini-channel were *** test section was a transparent circular channel of 1.6 mm inner *** working fluids were air and *** superficial velocities of gas and liquid were in the range of 0.025-66.300 m/s and 0.033-4.935 m/s,*** the present work,the flow pattern and the pressure gradient data were obtained by analyzing the flow images captured by a high-speed camera,and by using the pressure transducer,*** a result,it was found that (1) the obtained flow patterns were bubbly,plug,slug-annular,annular,and chum flows,(2) new experimental correlations on the bubble and plug lengths were proposed,whereas the lengths are the function of the homogeneous void fraction,(3) both gas and liquid superficial velocities affect proportionally to the pressure gradient,whereas it increases with the increase both of JG,*** addition,the obtained flow patterns are in a good agreement with that of the available flow pattern maps in the open literatures,such as,Triplett et al.(1999) and Chung and Kawaji (2004).

关键词： two-phase flow mini channel flow pattern pressure gradient plug length

来源：

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

CONDENSING HEAT TRANSFER IN AN ADVANCED two-phase CLOSED THERMOSYPHON

引用

Chinese Journal of Chemical Engineering 1996年第1期4卷 88-92页

作者：李修伦闻建平单岩昆黄鸿鼎天津大学化学工程系天津

1 INTRODUCTIONClosed thermosyphon has been developed to enhance heat transfer and recover wasteheat in various process industries [1,2].Stimulated by this success,a new type oftwo-phase closed thermosyphon was designed by inserting respectively two inner tubesinto the thermosyphon,one in the boiling section and the other in the condensing *** two-phase flow boiling heat transfer coefficient was calculated successfully onthe basis of Chen’s dual-mechanism [3].A boiling heat transfer model for thetwo-phase closed thermosyphon with an inner tube in the boiling section was pro-

关键词： two-phase closed thermosyphon heat transfer narrow annulus

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：