No.06 1999
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No.06 1999 |
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Coupling mechanism of turbulence and suspended sediment
Ni Jinren, Liao Qian |
Zhou Donghuo |
(Dep. of Urban & Environmental Sciences,Peking University) |
(American KEANE Co.Ltd) |
Abstract Based on the perturbation theory,the interaction between turbulent water and suspended sediment is described quantitatively.The formula of the vertical distribution of sediment concentration is applied to the analysis of additional Reynolds stress and the distribution of perturbation velocity is obtained.As a result, the mean velocity profile is reported, which is almost the same as that proposed and verified by Ni & Hui(1998).The analysis demonstrates that the interaction and coupling of the phases is in a systematic manner.It provides the basis for the study on the effect of suspension on the mean velocity distribution and helps improving the understanding of the complicated mechanism of low concentration solid-liquid two-phase flow.
Key words solid-liquid two-phase flow,turbulence,sediment.
Simulation on phreatic evaporation during soil freezing
Lei Zhidong, Shang Songhao, Yang Shixiu |
Wang Yi, Zhao Dongmei |
(Tsinghua University) |
(Inner Mongolia Institute of Water Resources Research) |
Abstract As an application of the model of simultaneous moisture and heat transfer during soil freezing,the process of phreatic evaporation during the freezing period from November 1990 to March 1991 in Hetao Irrigation Area,Inner Mongolia Municipality is simulated.The simulated values of soil water storage and phreatic evaporation agreed well with the observed data.Moreover,phreatic evaporation under different accumulated negative temperature and water table depth is simulated to analyze their effects on phreatic evaporation.Based on the analysis,the concept of converted coefficient of phreatic evaporation during the freezing period is proposed.The converted coefficient of phreatic evaporation is not related to accumulated negative temperature,and thus will make contribution to the analysis and application of the patterns about phreatic evaporation during soil freezing.
Key words Soil freezing,phreatic evaporation,converted coefficient of phreatic evaporation,numerical simulation.
Experiment on material model of steel spiral case and surrounding
reinforced concrete of Ertan Hydropower Station
Qin Jinzhang, Ma Shanding, Wu Hegao, Kuang Huijian
(Wuhan University of Hydraulic and Electric Engineering)
Abstract The experimental result of the model test for steel spiral case and surrounding reinforced concrete of Ertan Hydropower Station is presented.It shows that the method of placing concrete encasement of steel spiral case by keeping constant pressure is feasible for large scale hydropower project which brings the capability of steel spiral case into fully play in bearing internal pressure and mitigates the effect of internal pressure on surrounding reinforced concrete.
Key words spiral case,stress measure,model test,strength.
Application of Optimum Control Theory to dynamic optimization of arch dam
Xie Nenggang, Wang Dexing
(Hohai University)
Abstract The Optimum Control Theory is applied to establish the double-objective model and energy model for dynamic optimization of arch dam.By using these two models the safety,economy and stability of arch dam can be comprehensively studied.The reasonableness and feasibility of the models are witnessed by the computational result of arch dam in Xaiowan Hydropower project.
Key words optimum control,arch dam,dynamic optimization,double-objective model,energy model.
Random Seismic Response Analysis of Arch Dams Based on
Non-Stationary Random Earthquake Motion Field
Liang Aihu, Du Xiuli, Chen Houqun
(China Institute of Water Resources and Hydropower Research)
Abstract Based on the non-homogeneous earthquake motion input and 3-D dynamic finite elemnt method,a random seismic response analysis method for arch dams excited by non-stationary random earthquake motion field is proposed.An example is given for illustration.The calculated result of response is compared with that based on stationary field.
Key words arch dam,non-stationary,random earthquake motion field.
Characteristics of Stoneley waves in fluid solid media
Xia Tangdai, Wu Shiming
(Zhejiang University)
Abstract The secular equation and displacement equations of Stoneley waves in two infinite fluid solid media are deduced by using analytical method in this paper. The secular equation of Stonelye wave in layered fluid solid media is also established by using finite element analytical method. The characteristics of Stoneley wave and the law of its displacement distribution in fluidsolid media are discussed.
Key words Stoneley wave, secular equation, dispersion characteristics, fluid solid media.
Numerical simulation of turbulent buoyancy flow in natural open channel
Part ¢ò: Mathematical model and its application in cooling water engineering
Hao Ruixia ,Chen Huiquan |
Zhou Lixing |
(China Institute of Water Resources and Hydropower Research) |
(Tsinghua University) |
Abstract This paper is the second part of the research finding of 3 D turbulent buoyant flow study. A modified k-¦Å model is established. The study on cooling water circulation of Zhuzhou Power Plant is used to illustrate the application of the model adopted. The computation program 3TBF is applied to simulate the flow field and thermal field in the adjacent of the power plant. The result is in agreement with the data obtained from field observation and model test.
Key words modified k-¦Åturbulence model, numerical simulation, natural open channel.
Field water balance modeling with the dynamic parameters of soil hydraulic properties taken into consideration
Xu Di |
R.Schmid and A. Mermoud |
(China Insitute of Water Resources and Hydropower Research) |
(Swiss Federal Institute of Technology) |
Abstract A simulation model with time varying soil hydraulic parameters is use to predict the effects of conventional tillage(CT),no tillage(NT) and subsoiling tillage(ST) practices on the components of field water balance during the summer maize growth season for different hydrologic years in North China¡£The differences in potential for filtration, deep percolation, water storage, transpiration and evaporation of these tillage practices are to be modeled. The results show that ST changes the hydraulic behavior of the soil significantly and the simulation based on dynamic parameters is remarkably differed from that of CT.
Key words dynamic hydraulic parameters, time varying, tillage practices, filed water balance.
Measurement of evaporation from wheat field and
bare soil by using micro lysimeters
Liu Yu |
R. M. Fernando L. S. Pereira |
(China Institute of Water Resources and Hydropower Research) |
(Institute of Agriculture, Technical University of Lisbon) |
Abstract The method for measuring the soil evaporation from wheat field and bare soil surface by means of two types of micro lysimeter is described¡£The ratio between soil evaporation and crop evapotranspiration in each month and in the whole growing period of winter wheat are obtained from observed evolution of soil evaporation rate in the field. The relationship between soil evaporation and soil water content and the relationship between soil evaporation and leaf area index are analyzed. The advantages of measurement by means of these two types of microlysimeter and main problems pending for further improved are pointed out accordingly.
Key words micro lysimeter, soil evaporation, winter wheat.
Threshold auto-regressive model based on genetic algorithm and its application
to forecasting the shallow groundwater level
Jin Juliang£¬ Ding Jing |
Wei Yiming |
(Sichuan University) |
(Institute of Policy & Management,Chinese Academy of Sciences) |
Abstract A simple and universal scheme is suggested to deduce the threshold auto-regressive model.Both threshold values and auto-regressive parameters can be optimized with genetic algorithm.The example shows that the scheme is practical and effective.The method can be applied to the forecasting of time series in various engineering practices.
Key words groundwater level,threshold auto-regressive model,forecasting, genetic algorithm.
The simplified formulas for shock wave in open channel
Liu Hansheng£¬ Ni Hangen
(Dalin University)
Abstract According to Ippen's theory for oblique jump,this paper derived a new simplified formula for shock wave.Based on Von Karman's formula of integration,a simplified formula of integration for flat shock wave is established.These two formulas are simple in form,convenient to use and wide in their scope of application.
Key words oblique hydraulic jump, flat shock wave, specific energy.
Study on economic pipe diameter of network
Zhao Yunde
(Gansu Agricultural University)
Abstract In this paper, the generalized brief gradient method is applied to establish a method for design of optimal pipe diameter without discharge assumption. Example is given for illustration.
Key words generalized and brief gradient method, pipe, economic diameter, network.
On the formation of shoal in river
Gao Jin
(Xiangtan Polytechnic University)
Abstract The formula for estimating the length of shoal in river with rhomb shape or isosceles triangle shape is deduced. The irregular shoals are generalized as diamond shape shoals. Examples are given for demonstration.
Key words evolution of riverbed, shoal, circumfluence, principle of least resistance.
Axial bucking analysis for top-pinned and bottom-fixed pile
Yang Weihao, Song Lei
(China University of Mining & Technology)
Abstract On the basis of energy method,studies on axial stability of top-pinned and bottom-fixed pile acted by lateral friction and top load is carried out.A series of formulas for solving stability problems are developed and critical slenderness ratio of the pile is solved by numerical method. According to the results of data processing,an approximate formula for calculating critical slenderness ratio of the pile is obtained.
Key words pile, buckling analysis, energy method.
The optimization mathematical model of the pile forces
for offshore piled breasting dolphin
Zhou Xireng, Gao Yuechun, Wang Hui
(Tianjin University)
Abstract The optimization mathematical model of the pile forces for offshore piled breasting dolphin is presented in this paper.The forces acting on the pile under various conditions are analyzed.The optimum layout of the least number of piles is calculated by the method of sequential quadratic programming (SQP).Several project examples have been calculated by using this model and compared with the traditional design method.It is shown that the number of piles can be reduced at least by 10-20% and the qorces acting on the pile ane im poroved obriously.
Key words piled dolphin, sequential quadratic programming, optimum of design.