检索结果-南通市图书馆

Computational theory of cavitating flows for hydraulic turbomachinery with consideration of influence of water quality

引用

Science china(Technological Sciences) 2010年第12期53卷 3341-3348页

作者： WANG Lei1,2 & CHANG JinShi2 1 Huadian Electric Power Research Institute, Hangzhou 310030, china 2 college of water conservancy and civil engineering, china agricultural university, beijing 100083, china Huadian Electric Power Research Institute Hangzhou China college of water conservancy and civil engineering China Agricultural University Beijing China

Previously it was assumed that the pressure within the cavity or on the cavity surface remained constant and the vapor pressure of clean water at 20°C and 0 m altitude was utilized as the computational boundary for cavitating flows in hydraulic turbomachinery. Cavitation was confused with vaporization, and the effect of water quality on cavitation pressure characteristics was not taken into account. In recent years, lots of experiments of cavitation pressure characteristics of different water qualities including different sand concentrations of sand water and different altitudes of clean water have been performed by the authors, and the important influences of water quality on cavitation pressure characteristic have been validated. Thus the water quality should be involved in the cavitating flows computation. In the present paper, the effect of water quality on the cavitation pressure characteristic is analyzed and the computational method and theory of cavitating flows for hydraulic turbomachinery that considers the influence of water quality are proposed. The theory is suitable for both the potential flow method and the two-phase flow method for cavitating flows simulation. Finally, the validation results for cavitating flows in a hydraulic tur- bine indicate the significant influences of water quality on the cavitating flow performance.

关键词： cavitating flows cavitation pressure water quality hydraulic turbomachinery

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

A general finite element model for numerical simulation of structure dynamics

引用

Science china(Physics,Mechanics & Astronomy) 2006年第4期49卷 440-450页

作者： WANG Fujun1, LI Yaojun1, Han K.2 & Feng Y.T.2 1. college of water conservancy and civil engineering, china agricultural university, beijing 100083, china 2. civil & Computational engineering Centre, university of Wales Swansea, Swansea SA2 8PP, U.K. college of water conservancy and civil engineering China Agricultural University Beijing China civil & Computational engineering Centre University of Wales Swansea Swansea UK

A finite element model used to simulate the dynamics with continuum and discontinuum is presented. This new approach is conducted by constructing the general contact model. The conventional discrete element is treated as a standard finite element with one node in this new method. The one-node element has the same features as other finite elements, such as element stress and strain. Thus, a general finite element model that is consistent with the existed finite element model is set up. This new model is simple in mathematical concept and is straightforward to be combined into the existing standard finite element code. Numerical example demonstrates that this new approach is more effective to perform the dynamic process analysis in which the interactions among a large number of discrete bodies and continuum objects are included.

关键词： finite element method, discrete element method, structure dynamics, numerical simulation.

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

烟气脱硫副产物改良碱性土壤过程中化学指标变化规律的研究

引用

土壤学报 2005年第1期42卷 98-105页

作者：王金满杨培岭任树梅项光明中国农业大学水利与土木工程学院北京100083 清华大学热能工程系北京100084

通过土柱淋洗试验的方法,研究了脱硫副产物在改良碱性土壤过程中对碱性土壤化学指标(代换性钠、ESP、SAR、pH值)的影响。本研究采用两种碱性土壤(强度碱化土和碱土),两种土壤各分两个脱硫副产物施用水平(强度碱化土为3 g kg-1和3 6 g kg... 详细信息

通过土柱淋洗试验的方法,研究了脱硫副产物在改良碱性土壤过程中对碱性土壤化学指标(代换性钠、ESP、SAR、pH值)的影响。本研究采用两种碱性土壤(强度碱化土和碱土),两种土壤各分两个脱硫副产物施用水平(强度碱化土为3 g kg-1和3 6 g kg-1;碱土为7 g kg-1和8 4 g kg-1)。结果表明,经过施加烟气脱硫副产物和淋洗各种试验处理的代换性钠、ESP、SAR和pH值都有了明显的降低,碱性土壤得到了改良;同时,高烟气脱硫副产物施加水平的碱性土壤改良效果要优于低施加水平的碱性土壤;强度碱化土和碱土分别施加3 6 g kg-1、8 4 g kg-1烟气脱硫副产物后,在强度碱化土表层(0~40 cm)和碱土表层(0~20 cm)ESP<15、SAR<13和pH<8 5,已经降至中度碱化土水平,改良效果显著。

关键词：碱化改良效果淋洗施用变化规律土壤试验烟气脱硫副产物土柱

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

昌黎县水资源问题及其可持续利用研究

引用

水土保持研究 2007年第5期14卷 279-281页

作者：赵会芝任树梅河北科技师范学院园艺园林系河北昌黎066600 中国农业大学水利与土木工程学院北京100083

介绍了昌黎县的自然、地理及水资源概况,分析了昌黎县水资源开发利用中存在的问题,并提出了促进水资源可持续开发利用的具体策略,即：节约用水、进一步退耕还林、提高区域供水能力及加强管理与保护。

关键词：昌黎县水资源可持续利用

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

层次分析法在衡水湖环境功能区划方案遴选中的应用

引用

水资源保护 2005年第1期21卷 27-28,44页

作者：潘增辉刘文娟周清张晓燕河北省水利科学研究院河北石家庄050051 中国农业大学水利与土木工程学院北京100083 宁夏水利学校宁夏银川750004

通过对环境、社会和技术经济的综合分析,利用层次分析法对衡水湖环境功能区划备选方案进行遴选,确定了最佳方案为:东洼蓄当地水,西洼蓄引江水,不建中隔堤,提高了评价结果的直观性和可操作性。

关键词：层次分析法湖泊功能区划衡水湖

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

Decisive influence of the ionization strength of cosmic rays on the cavitation characteristics of pure water

引用

Science china(Technological Sciences) 2009年第6期52卷 1804-1808页

作者： CHANG JinShi college of water conservancy & civil engineering,china agricultural university,beijing 100083,china college of water conservancy & civil engineering China Agricultural University Beijing China

The experiment result in this article shows that the initial and critical cavitation pressure of pure water are both increasing along with the increase of height above sea level,and the ionization strength of cosmic rays in the lower aerosphere is the crucial factor which influences the cavitation pressure of pure *** author concludes the relationship between the cavitaion pressure of pure water and the height above sea ***,air particles in water caused by the radiation of cosmic rays can exist in the water for a long time and will not escape.

关键词： initial cavitaiton pressure critical cavitation pressure ionization strength of cosmic rays height above sea level

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

Integrating MODFLOW and GIS technologies for assessing impacts of irrigation management and groundwater use in the Hetao Irrigation District,Yellow River basin

引用

Science china(Technological Sciences) 2009年第11期52卷 3257-3263页

作者： XU Xu1,2, HUANG GuanHua1,2 & QU ZhongYi3 1 Center for Agriculture water Research, china agricultural university, beijing 100083, china 2 Chinese-Israeli International Center for Research and Training in Agriculture, china agricultural university, beijing 100083, china 3 water conservancy and civil engineering college, Inner Mongolia agricultural university, Hohhot 010018, china Center for Agriculture water Research China Agricultural University Beijing China Chinese-Israeli International Center for Research and Training in Agriculture China Agricultural University Beijing China water conservancy and civil engineering college Inner Mongolia Agricultural University Hohhot China

Due to severe water scarcity, water resources used in agricultural sector have been reduced markedly in Hetao irrigation district. Application of water-saving practices (WSPs) is required for the sustainable agricultural development. The human activities including WSPs and increase of groundwater abstraction can lower down the groundwater table, which is helpful to the salinity control. Meanwhile, an excessively large groundwater table depth may result in negative impact on crop growth and fragile ecological environment. In this paper, the Jiefangzha irrigation system in Hetao irrigation district was selected as a typical area, a groundwater flow model based on ArcInfo Geographic Information System (GIS) was developed and implemented to quantify the effect of human activities on the groundwater system in this area. The preand post-processing of model data was performed efficiently by using the available GIS tools. The time-variant data in boundary conditions was further edited in Microsoft Excel with programs of Visual Basic for Application (VBA). The model was calibrated and validated with independent data sets. Application of the model indicated that it can well describe the effect of human activities on groundwater dynamics in Jiefangzha irrigation system.

关键词： groundwater flow modeling MODFLOW GIS water-saving practices irrigation district

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

NUMERICAL INVESTIGATION OF PERFORMANCE OF AN AXIAL-FLOW PUMP WITH INDUCER

引用

Journal of Hydrodynamics 2007年第6期19卷 705-711页

作者： LI Yao-jun WANG Fu-jun college of water conservancy and civil engineering China Agricultural University Beijing 100083 China

The interaction of flow through the inducer and impeller of an axial-flow pump equipped with an inducer has significant effect on its performance. This article presents a recent numerical investigation on this topic. The studied pump has an inducer with 3 blades mounted on a conical hub and a 6-blade impeller. The blade angle of the impeller is adjustable to generate different relative circumferential angles between the inducer blade trailing edge and the impeller blade leading edge. A computational fluid dynamics code was used to investigate the flow characteristics and performance of the axial-flow pump. For turbulence closure, the RNG k-ε model was applied with an unstructured grid system. The rotor-stator interaction was treated with a Multiple Reference Frame （MRF） strategy. Computations were performed in different cases： 7 different relative circumferential angles （ Δθ ） between the inducer blade trailing edge and the impeller blade leading edge, and 3 different axial gaps （G） between the inducer and the impeller. The variation of the hydraulic loss in the rotator was obtained by changing Δθ . The numerical results show that the pressure generated is minimum in the case of （ G = 3%D）, which indicates that the interference between inducer and impeller is strong if the axial gap is small. The pump performances were predicted and compared to the experimental measurements. Recommendations for future modifications and improvements to the pump design were also given.

关键词： axial-flow pump inducer CFD numerical simulation of 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

One-dimensional numerical simulation of non-uniform sediment transport under unsteady flows

引用

International Journal of Sediment Research 2008年第4期23卷 316-328页

作者： Hongwei FANG 1,Minghong CHEN 2,and Qianhai CHEN 31 Prof.,Dept.of Hydraulic engineering,Tsinghua Univ.,State Key Laboratory of Hydroscience and engineering,beijing,100084,china 2 PhD,college of water conservancy and civil engineering,china agricultural Univ.,beijing 100083,china.3 Engineer,Institute of the Yangtze River Research,Wuhan,430010,china Prof. Dept. of Hydraulic Engineering Tsinghua Univ. State Key Laboratory of Hydroscience and Engineering Beijing 100084 China PhD College of Water Conservancy and Civil Engineering China Agricultural Univ. Beijing 100083 China Engineer Institute of the Yangtze River Research Wuhan 430010 China

One-dimensional numerical models are popularly used in sediment transport research because they can be easily programmed and cost less time compared with two-and three-dimensional numerical *** particular,they possess greater capacity to be applied in large river basins with many *** paper presents a one-dimensional numerical model capable of calculating total-load sediment *** cross-section-averaged sediment transport capacity and recovery coefficient are addressed in the suspended load *** one-dimensional model,therefore,can be applied to fine suspended loads and to hyperconcentrated flows in the Yellow ***,a new discretization scheme for the equation of unsteady non-uniform suspended sediment transport is *** model is calibrated using data measured from the Yantan Reservoir on the Hongshui River and the Sanmenxia Reservoir on the Yellow River.A comparison of the calculated water level and river bed deformation with field measurements shows that the improved numerical model is capable of predicting flow,sediment transport,bed changes,and bed-material sorting in various situations,with reasonable accuracy and reliability.

关键词： One-dimensional numerical model Sediment transport capacity Recovery coefficient Adaptation length Unsteady flow

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

A PARTIALLY-AVERAGED NAVIER-STOKES MODEL FOR HILL AND CURVED DUCT FLOW

引用

Journal of Hydrodynamics 2011年第4期23卷 466-475页

作者： MA Jia-mei WANG Fu-jun YU Xin LIU Zhu-qing college of water conservancy and civil engineering China Agricultural University Beijing 100083 China

Turbulent flows past hill and curved ducts exist in many engineering applications. Simulations of the turbulent flow arc carried out based on a newly developed technique, the Partially-Averaged Navier-Stokes （PANS） model, including separation, recirculation, reattachment, turbulent vortex mechanism. The focus is on how to accurately predict typical separating, reattaching and secondary motion at a reasonable computational expense. The effect of the parameter, the unresolved-to-total ratio of kinetic energy （ fk ）, is examined with a given unresolved-to-total ratio of dissipation （ fE ） for the hill flow with a much coarser grid system than required by the LES. An optimal value of fk can be obtained to predict the separation and reattachment locations and for more accurate simulation of the resolved turbulence. In addition, the turbulent secondary motions are captured by a smaller fi as compared with the RANS method with the same grid.

关键词： Partially-Averaged Navier-Stokes (PANS) flow separation recirculation reattachment resolved turbulence

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：