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EMERGENCE ANGLE OF FLOW OVER AN AERATOR

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Journal of Hydrodynamics 2007年第5期19卷 601-606页

作者： wu jian-hua RUAN Shi-ping College of Water Conservancy and Hydropower Engineering Hohai University Nanjing 210098 China

Aerator is an important device for release works of hydraulic structures with high-speed flow in order to protect them from cavitation damage. This kind of protecting effect is related closely to cavity length below the aerator, while the cavity length is dominated by the emergence angle over the aerator. Therefore it is crucial to determine this angle accurately. In the present paper the affecting intensities of flow depth and the fluctuating velocity on this angle were analyzed through two introduced parameters. Furthermore, the improved expressions of emergence angle estimation, for both ramp-type and step-type aerators, were presented by means of 68 sets of experimental data from 6 projects based on error theory. The results showed that the present method has higher accuracy than the previously reported methods.

关键词： aerator cavitation damage cavity length,emergence angle flow depth fluctuating velocity

FLOWS THROUGH ENERGY DISSIPATERS WITH SUDDEN REDUCTION AND SUDDEN ENLARGEMENT FORMS

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Journal of Hydrodynamics 2010年第3期22卷 360-365页

作者： wu jian-hua AI Wan-zheng College of Water Conservancy and Hydropower Engineering Hohai University Nanjing 210098 China

The energy dissipation of flood discharges has been one of important problems that affect directly the safety of hydropower projects. The energy dissipater with sudden reduction and sudden enlargement forms, used widely in large-scale projects has been a kind of effective structure for energy dissipation. The concept of critical thickness was defined, which is related to both the geometric parameters and the hydraulic parameters of the energy dissipater, and the factors affecting the critical thickness, were analzsed by means of dimensional analysis. The empirical expression about the critical thickness was obtained and could be used as the criterion to distinguish the flows through the energy dissipater, i.e., the plug flow and the orifice plate flow. The error analysis showed that the critical thickness calculated by the expression has the errors of smaller than 10% in the estimation of the flows for the energy dissipater mentioned above.

关键词： critical thickness energy dissipater orifice plate plug reduction ratio sudden reduction sudden enlargement

ANALYSIS OF WATER QUALITY IN SHALLOW LAKES WITH A TWO-DIMENSIONAL FLOW-SEDIMENT MODEL

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Journal of Hydrodynamics 2007年第4期19卷 501-508页

作者： JI Yong ZhANG Jie YAO ei ZHAO Di-hua Nanchang institute of Technology Nanchang 330099 China College of Environmental Science and Engineering Hohai University Nanjing 210098 China nanjing hydraulic research institute Nanjing 210098 China

The governing equation for sediment pollutions was derived based on the turbulent diffusion of pollutants in shallow lakes. Coupled with shallow water equations, a depth-averaged 2-D flow and water quality model was developed. By means of the conservation law, a proposed differential equation for the change of sediment pollutants was linked to the 2-D equations. Under the framework of the finite volume method, the Osher approximate Riemann solver was employed to solve the equations. An analytical resolution was used to examine the model capabilities. Simulated results matched the exact solutions especially well. As an example, the simulation of CODMn in the wuli Lake, a part of the Taihu lake, was conducted, which led to reasonable results. This study provides a new approach and a practical tool for the simulation of flow and water quality in shallow lakes.

关键词： sediment falling velocity turbulence flow and water quality model finite volume method approximate Riemann solver shallow water equation advection-dispersion equation

hydraulic CHARACTERISTICS OF WATER-WINGS FOR THE MIDDLE-PIER OF A DISCHARGE TUNNEL

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Journal of Hydrodynamics 2006年第5期18卷 567-571页

作者： wu jian-hua CAI Chang-guang JI Wei RUAN Shi-ping College of Water Conservancy and Hydropower Engineering Hohai University Nanjing 210098 China china Hydropower Mid-South Design and research institute Changsha 410014 China

Water-wings, induced by the middle-pier placed in the inlet of a discharge tunnel, have harmful effects on the operation of the discharge tunnel. Based on dimensional analysis and physical model tests, the hydraulic characteristics of water-wings were investigated and their causes were analyzed in this study. The results show that the height and length of the water-wings increased with the increase of three factors, i.e., the Froude number Frd of the outlet of the pressure section, the depth Hc of the water surface concave at the end of the middle-pier, and the impact length Li of the two flows after this end.

关键词： water-wing dimensional analysis discharge tunnel middle-pier

THE RISK AND ECONOMY ANALYSIS OF ENERGY DISSIPATORS

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Journal of Hydrodynamics 1991年第4期3卷 1-7页

作者： Guo Zi-zhong Xu Zu-xin Hohai University,nanjing 210024,P.R chinawu jian-hua nanjing hydraulic research institute,nanjing 210024,P.R.china

According to the analysis results of risk,economy and practical experiences for many years,the paper demonstrates that the great economic benifits can be got by reducing the design flood standard of energy dissipators and that the reduction of design flood standard is significant for reducing project investment and speeding project construction.

关键词： THE RISK AND ECONOMY ANALYSIS OF ENERGY DISSIPATORS length than QS

ON FRACTAL MECHANISM OF COASTLINE-A Case Study of china

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Chinese Geographical Science 2002年第2期12卷 142-145页

作者： ZHU Xiao hua, WANG jian(College of Geographical Science,nanjing Normal University,nanjing 210097,P.R.china) College of Geographical Science Nanjing Normal University Nanjing 210097 College of Geographical Science Nanjing Normal University Nanjing

MANDELBROT enunciated the uncertainty of the length of a coastline in his paper"How long is the coastline of Britain?"published in "Science" in 1967. The fractal concept was presented for the first time in that paper and has been applied to many fields ever since. According to the fractal theory and conditions of fractal research of coastline,the controls of faults and biologic function on the fractal character of coastline are preliminarily discussed on the basis of GIS in this paper . Finally,some significant conclusions are drawn:1)the faults control the basic trends of coastlines of two study areas;2)the fractal dimension of coastline of Taiwan is smaller than that of Changle-Lufeng,because the faults of Taiwan more intensely control the trend and fractal dimension of the coastline;3)the larger the fractal dimension of the faults or the major faults,the more the controlling effect of them on the trend and fractal dimension of coastline; 4)the larger fractal dimension of the coastline of Changle-Lufeng indicates that the biologic function intensely shapes the coastline. In a word,the controls of faults and biologic function on the fractal character of coastline are discussed with a case study of china in this paper,it can be seen that faults and biologic function both have influence over the trend and fractal dimension of coastline,the fractal mechanism of coastline of two study areas may be so.

关键词： fractal fractal dimension GIS faults biologic function coastline

旋涡孔板消能工的初步研究──一种新型无空蚀消能工

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水动力学研究与进展（A辑） 1996年第6期11卷 698-706页

作者：吴建华南京水力科学研究院

在大型导流洞改建为永久利用泄洪洞方面，泄洪、消能和空化之间的协调是最重要的问题之一。在以往的设计中，在满足较大的泄量和消能量条件下，通常泄洪洞还要满足σｆ＞σｉ，以免发生空化空蚀。本文提出的一种新型无空蚀旋涡孔板消能... 详细信息

在大型导流洞改建为永久利用泄洪洞方面，泄洪、消能和空化之间的协调是最重要的问题之一。在以往的设计中，在满足较大的泄量和消能量条件下，通常泄洪洞还要满足σｆ＞σｉ，以免发生空化空蚀。本文提出的一种新型无空蚀旋涡孔板消能工，通过对水体的控制，允许空化仅在水体内部存在而不致对洞壁空蚀破坏，因此，可以加大消能量，提高泄流能力，使工程设计更为经济安全。本文对此种消能工（共６种方案）进行了研究，包括Ｑ～Ｈ关系，μ～Ｈ关系，空化和消能特性等，取得了较好的成果。

关键词：消能工旋涡孔板空化泄洪洞

A STUDY ON NUMERICAL METHOD OF NAVIER-STOKES EQUATION AND NON-LINEAR EVOLUTION OF THE COHERENT STRUCTURES IN A LAMINAR BOUNDARY LAYER

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Journal of Hydrodynamics 2006年第3期18卷 372-377页

作者： LU Chang-gen CAO Wei-dong QIAN jian-hua State KeyLaboratory of Hydrology-Water Resources and hydraulic Engineering and College of Environmental Science and Engineering Hohai University Nanjing 210098 China College of Environmental Science and Engineering Hohai University Nanjing 210098 China

A new method for direct numerical simulation of incompressible Navier-Stokes equations is studied in the paper. The compact finite difference and the non-linear terms upwind compact finite difference schemes on non-uniform meshes in x and y directions are developed respectively. With the Fourier spectral expansion in the spanwise direction, three-dimensional N-S equation are converted to a system of two-dimensional explicit-implicit The treatment of equations. The third-order mixed scheme is employed the three-dimensional for time integration. non-reflecting outflow boundary conditions is presented, which is important for the numerical simulations of the problem of transition in boundary layers, jets, and mixing layer. The numerical results indicate that high accuracy, stabilization and efficiency are achieved by the proposed numerical method. In addition, a theory model for the coherent structure in a laminar boundary layer is also proposed, based on which the numerical method is implemented to the non-linear evolution of coherent structure. It is found that the numerical results of the distribution of Reynolds stress, the formation of high shear layer, and the event of ejection and sweeping, match well with the observed characteristics of the coherent structures in a turbulence boundary layer.

关键词： non-uniform meshes compact finite differences scheme Fourier spectral expansion coherent structure boundary layer

EFFECTS OF hydraulic AND GEOMETRIC PARAMETERS ON DOWNSTREAM CAVITY LENGTH OF DISCHARGE TUNNEL SERVICE GATE

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Journal of Hydrodynamics 2009年第6期21卷 774-778页

作者： MOHAGHEGH A College of Water Conservancy and Hydropower Engineering Hohai University

Aerators on discharge tunnel outlets may be regarded as an effective protection against cavitation erosion. The air entrainment of aerators is governed by a number of independent parameters, including the bottom slope of releasing free-surface flow tunnel downstream of service gate, the end top slope of pressure tunnel, the height of step, and the Froude number at take-off. During eight phases of experiments, the effects of above-mentioned parameters were observed on the cavity length downstream of the fully open operating service gate of a discharge tunnel. The results show that, the bottom slope of releasing free-surface flow tunnel has obvious effect on the cavity length as well as the Froude number at gate take-off. The effect of the step height variations on the cavity length could be considered for higher discharges and steeper tunnel top slope, particularly in higher discharges, resulting in shorter cavity length downstream of service gate.

关键词： cavitation erosion cavity length discharge tunnel service gate