检索结果-内蒙古大学图书馆

Measurement of laminar burning velocities and analysis of flame stabilities for hydrogen-air-diluent premixed mixtures

引用

Chinese Science Bulletin 2009年第5期54卷 846-857页

作者： HU ErJiang HUANG ZuoHua HE JiaJia JIN Chun MIAO HaiYan WANG XiBin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

The laminar burning velocities and Markstein lengths of the hydrogen-air-diluent mixtures were meas-ured at different equivalence ratios (0.4―1.5), different diluents (N2, CO2 and 15%CO2+85%N2) and di-lution ratios (0, 0.05, 0.10 and 0.15) by using the outwardly expanding flame. The influences of flame stretch rate on the flame propagation characteristics were analyzed. The results show that both the laminar burning velocities and the Markstein lengths of the hydrogen-air-diluent mixtures decrease with the increase of dilution ratio. The decrease in Markstein lengths means that adding diluents into the hydrogen-air mixtures will decrease the diffusional-thermal instability of the flame front. For a specified dilution ratio, the laminar burning velocities give their maximum values at an equivalence ratio of 1.8. The Markstein lengths increase with the increase of the equivalence ratio monotonously regardless of the diluents. The study shows that CO2 as the diluent has a greater impact on the laminar flame speed and the flame front stability than N2 as the diluent.

关键词：氢气空气混合火焰特性燃烧速度稳定性

来源：评论

学校读者我要写书评

暂无评论

A numerical model of thermal analysis for woven wire screen matrix heat exchanger

引用

Cryogenics 2009年第9期49卷 482-489页

作者： Shuangtao, Chen Yu, Hou Hongli, Zhao Lan, Xi State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

Woven wire screen matrix heat exchanger (WSMHE) is a kind of compact, light-weight and high-efficiency matrix heat exchanger (MHE) for cryogenic applications. This paper presented a numerical model for the design and thermal analysis of WSMHE. The influence of wall thermal resistance, axial conduction, parasitic heat load and properties variation was taken into account, which is neglected in the traditional effectiveness-NTU method but important for compact cryogenic heat exchangers. The proposed numerical method is verified by effectiveness-NTU method under specific conditions, then it is tested according to experiment data, and a well agreement was obtained. Based on this model, a detailed analysis was performed on WSMHEs. The analysis results show that the axial conduction might result in evident decrease of effectiveness at low flow rate region;the effectiveness of WSMHEs with large flow rate could be remarkably enhanced by increasing its length;the influence of parasitic heat load varied little throughout of the flow rate region. Furthermore, the numerical model presented in this paper can be developed to the design and thermal analysis of small partition wall type heat exchangers. © 2009 Elsevier Ltd. All rights reserved.

关键词： Thermoanalysis

来源：评论

学校读者我要写书评

暂无评论

Implementation of an efficient segregated algorithm-IDEAL on 3D collocated grid system

引用

Chinese Science Bulletin 2009年第6期54卷 929-942页

作者： SUN DongLiang QU ZhiGuo HE YaLing Tao WenQuan State Key Laboratory of Multiphase Flow in Power Engineering School of Energy & Power Engineering Xi'an Jiaotong University Xi'an 710049 China

The segregated algorithm-IDEAL (inner doubly-iterative efficient algorithm for linked-equations) is an efficient and stable algorithm. In this algorithm, there exist inner doubly-iterative processes for pres-sure equation, which almost completely overcome two approximations in SIMPLE algorithm. Thus the coupling between velocity and pressure is fully guaranteed, greatly enhancing the convergence rate and stability of iteration process. In this paper, implementation of the IDEAL algorithm on a 3D collo-cated grid system is conducted. The interface velocity is calculated by the modified momentum inter-polation method (MMIM), by which the converged result is independent of the under-relaxation factor. Finally, five three-dimensional incompressible fluid flow and heat transfer problems are provided to compare the convergence rate and robustness between the IDEAL and three other most widely-used algorithms (SIMPLER, SIMPLEC and PISO). By the comparison it can be concluded that the IDEAL al-gorithm is more robust and efficient than the three other algorithms.

关键词：隔离算法网格系统理想 SIMPLE算法 3D 压力方程收敛速度迭代过程

来源：评论

学校读者我要写书评

暂无评论

Drop deformation and breakup with diffuse interface method

引用

AIP Conference Proceedings 2010年第1期1207卷

作者： S. L. Chen C. Z. Lin L. J. Guo Y. S. Wang State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an 710049 China

Two‐dimensional numerical simulation of the deformation and breakup of an isolated liquid drop suspended in immiscible viscous fluid under shear flow was performed with the diffuse interface method. The governing equations of the model were described by Navier—Stokes—Cahn—Hilliard equations. The surface tension was treated as a modified stress. In the paper, the critical Capillary number was plotted as a function of viscosity ratios with the method of approximation. Besides, From the numerical observations, the breakup of the droplets occurred by three mechanisms, namely, necking, end pinching, and capillary instability. Quantitative results for the deformation and breakup of drop are presented.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Simulation of combustion in spark-ignition engine fuelled with natural gas-hydrogen blends combined with EGR

引用

中国高等学校学术文摘·能源与动力工程 2009年第2期3卷 204-211页

作者： Jie WANG Zuohua HUANG Bing LIU Xibin WANG State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

A numerical simulation of the influence of different hydrogen fractions, excess air ratios and EGR mass fractions in a spark-ignition engine was conducted. Good agreement between the calculated and measured in-cylinder pressure traces as well as pollutant formation trends was obtained. The simulation results show that NO concentration has an exponential relationship with temperature and increases sharply as hydrogen is added. EGR introduction strongly influences the gas temperature and NO concentration in the cylinder. The difference in temperature will lead to even greater difference in NO concentration. Thus, EGR can effectively decrease NO concentration. NO concentration reaches its peak value at the excess air ratio of 1.1 regardless of EGR mass fraction. The study shows that natural gas-hydrogen blend combined with EGR can realize a stable combustion and low NO emission in a spark-ignition engine.

关键词： natural gas hydrogen NO exhaust gas recirculation numerical simulation

来源：评论

学校读者我要写书评

暂无评论

Modeling of water and temperature distribution in PEM fuel cell

引用

Kung Cheng Je Wu Li Hsueh Pao/Journal of engineering Thermophysics 2010年第12期31卷 2051-2056页

作者： Ma, Li-Zhong Shen, Shuang-Lin Jia, Fei Liu, Hong-Tan Guo, Lie-Jin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China Dept. of Mechanical and Aerospace Engineering University of Miami Coral Gables FL 33124 United States

A two-phase flow, non-isothermal, three dimensional model was developed to study the transport phenomena in proton exchange membrane (PEM) fuel cell. Modeling results of water distribution and temperature distribution are presented in this paper. The modeling results show that water and temperature distributions are non-uniform. Along the flow direction, water concentration in anode is decreasing while that in cathode is increasing which liquid water present in cathode;in the cross section perpendicular to the flow direction, both water concentration and liquid water saturation under the shoulder are higher than that under the channel;liquid water distribution across cathode GDL is different at different discharging voltages. Local temperature is decreasing along the flow direction, with even higher gradient when the reactant gas is insufficient;temperatures under the shoulder are lower than those under the channel;in the direction across MEA, the highest temperature is in cathode catalyst layer, and temperature gradient increases as the discharging voltage decreases;at the same discharging voltage, the thicker the PEM is, the lower the local temperatures and the temperature gradient across MEA are.

关键词： Temperature distribution

来源：评论

学校读者我要写书评

暂无评论

A MODEL FOR LIQUID SLUG LENGTH DISTRIBUTION IN VERTICAL GAS-LIQUID SLUG flow

引用

Journal of Hydrodynamics 2009年第4期21卷 491-498页

作者： XIA Guo-dong CUI Zhen-zhen LIU Qing ZHOU Fang-de HU Ming-sheng College of Environmental and Energy Engineering Beijing University of Technology Beijing 100124 China State Key Laboratory of Multiphase Flow in Power Engineering Xi＇an Jiaotong University Xi＇an 710049 China

The slug length and the trailing Taylor bubble velocity in an upward vertical slug flow were measured by using the optical probes and the EKTAPRO 1000 high speed motion analyzer. The correlation between the trailing bubble velocity and the length of liquid slug ahead of that bubble is derived from the experimental data. Based on this correlation as well as the bubble overtaking mechanism, a model for the slug length distribution at any designated locations along the pipe is proposed. The predicted results are in agreement with the experimental data.

关键词： gas-liquid two-phase flow slug flow Taylor bubble liquid slug

来源：评论

学校读者我要写书评

暂无评论

Comments on Three-point explicit compact difference scheme with arbitrary order of accuracy and its application in CFD

引用

Applied Mathematics and Mechanics(English Edition) 2009年第5期30卷 669-676页

作者：张红娜宇波王艺魏进家李凤臣 Beijing Key Laboratory of Urban Oil and Gas Distribution Technology China University of Petroleum School of Energy Science and Engineering Harbin Institute of Technology State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University

The explicit compact difference scheme, proposed in Three-point explicit compact difference scheme with arbitrary order of accuracy and its application in CFD by Lin et al., published in Applied Mathematics and Mechanics （English Edition）, 2007, 28（7）, 943-953, has the same performance as the conventional finite difference schemes. It is just another expression of the conventional finite difference schemes. The proposed expression does not have the advantages of a compact difference scheme. Nonetheless, we can more easily obtain and implement compared with the conventional expression in which the coefficients can only be obtained by solving equations, especially for higher accurate schemes.

关键词： explicit compact difference scheme conventional finite difference scheme central difference scheme upwind difference scheme

来源：评论

学校读者我要写书评

暂无评论

Edge detection based on wavelet analysis with Gaussian filter and application in multiphase flow

Edge detection based on wavelet analysis with Gaussian filte...

引用

2008 ASME Summer Heat Transfer Conference, HT 2008

作者： Chen, Bin Yang, Fude Guo Ning, Yahui Tao State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University China

ISBN: (纸本)9780791848487

In this paper an edge detection algorithm based on wavelet transform with Gaussian filter was proposed. In this algorithm original images are firstly converted into gray images and then each pixel was analyzed using wavelet transform to find the local maximum of the gray gradient of each pixel along the phase angle direction and compared with a given threshold value, through which real edge can be kept and fake ones will be eliminated. In the computation of local maximum, the gray gradients computed in eight directions, which can improve precision of edge detection. After the investigation of influence of filter length, scale and threshold value on the edge detection and validation by comparison with N.L. Fenandez-Garcia's Minimean and Minimax methods for 100 real color images, we applied this algorithm to bubbly gas-liquid two-phase flow. Compared with Canny operator, present result is more close to real bubble shape and can distinguish very close bubbles, which indicates the algorithm is effective and can be used to study the interaction between different phases and flow field in multiphase flow. Copyright © 2008 by ASME.

关键词： Edge detection

来源：评论

学校读者我要写书评

暂无评论

The dust emission law in the wind erosion process on soil surface

引用

Science China(Physics,Mechanics & Astronomy) 2009年第2期52卷 258-269页

作者： XING Mao1 & GUO LieJin2 1 Mining Technology Institute, Taiyuan University of Technology, Taiyuan 030024, China 2 state key laboratory of multiphase flow in power engineering, Xi’an Jiaotong University, Xi’an 710049, China Mining Technology Institute Taiyuan University of Technology Taiyuan 030024 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an 710049 China

The dust emission models to date cannot describe the relation between the transport rate of different sized grains and their grain size composition in soil surface, so Aeolian grain transport on a soil-like bed composed of fine sand and silt powder was measured in a wind tunnel. Six types of soil-like beds with different silt fractions have been tested in this experiment. The mass flux profiles of silt dust and sand grains are much different due to their different motion modes. Analysis of the vertical distribution of the powder and sand grains reveals that for a given soil bed, the ratio of the horizontal dust flux to the horizontal sand flux is directly proportional to their mass ratio in the bed. The dust flux is closely linked to the sand flux by the bombardment mechanism. For a given wind velocity and grain size of the bed, the slopes of the vertical mass flux profiles of sand grains larger than 100 μm are nearly equal in a log-linear plot and the ratio between the fraction of transport rate of each size group to the whole transport rate and the mass fraction of each size group in the bed is a constant only dependent on grain size. With this law, the transport rate of dust and different sized grains can be related with the grain size composition in the soil surface.

关键词： wind erosion dust transport rate grain size

来源：评论

学校读者我要写书评

暂无评论

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

请选择保存的检索档案：

请选择收藏分类：

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

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

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：