Flow Structure and Characteristics of Local Head Loss in Transition Channel
YAN Xu-feng 1, YI Zi-jing 1, LIU Tong-huan 2, LIU Xing-nian 1, WANG Xie-kang 1
(1.State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610065, China; 2.Yangtze River Scientific Research Institute, Wuhan 430010, China)
Abstract: The gradual change of transition channel width is a common form of natural rivers. The flow structure of transition channel was measured in the physical model by Acoustic Doppler Velocimeter (ADV). It is manifested that the flow was influenced remarkably by the streamwise velocity. Secondary circulation was induced in the gradually shrinked section and in the gradually expanded section, with the circulation effect in the former greater than the latter in an opposite direction. According to the 2-D flow simulation by SMS hydrodynamic model, the coefficient of local head loss was proved to be consistent with the measured value, and the coefficient values at flow separation zone were times larger than that in other regions.
Key words: transition channel; flow structure; SMS; coefficient of local head loss
Analysis of Sustainable Economic and Social Development in Wanzhou District by Ecological Footprint Model
CHEN Shi-jun, XIE Hui, LIANG Chuan, HE Tao, LI Ming-zhong, ZHU Fan-mao
(School of Water Resources and Hydropower, Sichuan University, Chengdu 610065, China)
Abstract : The ecological footprint, ecological carrying capacity and ecological deficit from 1990-2008 of Wanzhou District of Chongqing Municipality are analyzed by the time series analysis of Ecological Footprint Model. The per capita ecological footprint of Wanzhou district, which is located in the center of the Three Gorges Reservoir region, increased from 0.698 hm2 per person in 1990 to 1.584 hm2 per person in 2008, up 4.65% annually; whereas the ecological carrying capacity dropped gradually, consequently with ecological deficit spreading all over the district. Cultivated land, grassland, water area, land for construction and land for fossil fuels made significant contributions to the ecological footprint of this district, respectively accounting for 30.63% , 25.56% , 2.80% , 8.99%and 30.44% . Measures and suggestions are also proposed for the sustainable economic and social development of the district.
Key words: Wanzhou District of Chongqing Municipality; economy and society; sustainable development; ecological footprint; ecological carrying capacity
Extensible Evaluation for the Management Mode of Small Scale Rural Drinking Water Projects in Zhejiang Province
LI Sha, ZHANG Ren-gong
(Zhejiang Tongji Vocational College of Science and Technology, Hangzhou 310000, China)
Abstract: The management of rural drinking water projects is a hotspot in the research on rural water supply projects, while the management mode of small-scale projects receives less attention. It ' s of great importance to establish an effective evaluation mode for the management of small-scale drinking water projects. By investigations in Zhejiang province, small-scale drinking water projects at present are found to be mainly managed by the village collectively, by the water-users association, and by responsibility contracts. An extensible evaluation for the qualification degree of the management modes is presented and is applied in the extensible analysis and decision-making in the purpose of studying the correlation among the evaluation indexes by constructing correlation functions. Fifteen projects in Liandu district of Lisui municipality in Zhejiang province are evaluated to prove the feasibility of the method.
Key words: rural drinking water project; management mode; extensible evaluation; data processing
Numerical Simulation of the Dynamics of Single Bubble Behavior in Still Water
XU Ling-jun 1, CHEN Gang 1, SHAO Jian-bin 1, XUE Yang 2
(1.College of Water Conservancy and Hydropower Engineering, Xi ' an University of Technology, Xi’an 710048, China; 2.State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 62002, China)
Abstract : To study the dynamic properties of bubble rising in the water, a simulation model of single bubble under buoyancy and gravity in still water was established by CFD software. Taking hydrostatic pressure gradient into consideration, the no-slip technology was applied to deal with the boundary of flow field, and the whole structured grid technology was used to deal with the bubble and still water area. Using this model, bubbles of 2.6 mm and 4mm diameters were simulated to analyze the movement mechanism of the bubbles in still water. The numerical results were further compared with the test data. The rising route and velocity were well consistent with the test data. The approach in this study offered an effective solution to investigate the dynamic properties of bubble in water.
Key words: bubble; numerical simulation; movement mechanism
Hydraulic Characteristic of Low Practical Weir and Its Influence on Engineering
WU Guo-jun 1, LIU Xiao-ping 1, FANG Sen-song 1, SUN Wen-hong 1, HOU Bin 2
(1.School of Hydraulic Engineering, Changsha University of Science and Technology, Changsha 410076, China; 2.Infrastructure Department, China International Engineering Consulting Corporation, Beijing 100048, China)
Abstract : The flood discharge capacity and sediment transport capacity of WES weir and improved practical weir with polygonal line in a low-head hydro-junction are comparatively analyzed through physical model and mathematical model. The results indicate that the two types of weir both meet the requirements of norms and regulations for flood discharge in plain area. The discharge capacity of WES weir is better than that of the practical weir; whereas the improved practical weir is more beneficial for the normal operation of bulkhead gate and the safe running of the whole hydro-junction as it has intensified and wide weir surface turbulence, which will increase the sediment transport capacity and enable the sediment initiate easily, thus refraining from sedimentation to a certain extent. By comprehensive comparison, the improved practical weir with polygonal line is finally recommended.
Key words: hydro-junction; practical weir; flood discharge capacity; sediment transport capacity
Tests on Blocking Dam Breaches by Throwing Heavy Objects
JIA Zhi-feng, FU Fei
(School of Environmental Science and Engineering, Chang’an University, Xi’an 710054, China)
Abstract: It is of practical significance to work on the approaches of blocking breaches and delaying dam-break as floods and debris flow caused by dam-break are detrimental to the country and people ' s life and property. Nonetheless, since dam-break is non-repeatable and harmful in practice, it can only be studied theoretically by getting data from small-scale tests. In this paper, the small-scale test of blocking breaches by throwing heavy objects is performed to evaluate the results under different throwing heights and flow velocities by three throwing modes. The influencing factors and the rule of motion of the objects in the process of falling are analyzed, and the horizontal and vertical differential equations in ideal status are set up. Based on the least square method and error-revised data from small-scale tests, the parameters are obtained by Matlab programming and the location of throwing objects in simulated dam-break is calculated by using similarity criterion. The study provides theoretical basis for blocking breaches.
Key words: block the breaches; least square method; similarity criterion
Fuzzy Stochastic Reliability Analysis of Slope Engineering
WANG Yu 1, SONG Xin-long 2, ZHNAG Hang 1,WANG Can 1,YU Hong-ming 1
(1.School of Engineering, China University of Geosciences, Wuhan 430074 China; 2. Northwest Research Institute Co., Ltd of C.R.E.C, Lanzhou 730000)
Abstract : Fuzzy stochastic theory is applied to the slope reliability evaluation. Considering the fuzzy and stochastic features of random variables, the subordinate function of stability factor is introduced to perform fuzzy reliability analysis for the actual working condition of the slope. The secondary structure of fuzzy random limit state equation is proposed on the basis of combining the fuzzy stochastic theory with the response surface method. The response surface method is used on a structure firstly to obtain the reliability response surface function, based on which the complementary function of subordinate function is used as an auxiliary to carry on the secondary limit state equation to calculate the random fuzzy reliability of the slope. Rather than directly solving the fuzzy probability density function by integral calculus, which is complicated and time-consuming, this method is proved to be simple with fast convergence and high precision of calculation, thereby can be used widely. The slope stability can be reflected more accurately by the calculated reliability indexes. The method can be regarded as a new approach of studying the reliability of slopes.
Key words: fuzzy reliability; response surface method; subordinate function; performance function; reliability index
Dynamic Analysis of Loose Zone at the Sidewall of Large Underground Cavern in High Geostress Zone
ZHAO Hai-bin 1 , FU Jian-jun 1 , ZHOU Jiang-ping 2
(1.Hydrochina Zhongnan Engineering Corporation, Changsha 410014, China; 2. Ertan Hydropower Development Co., Ltd., Chengdu 610051, China)
Abstract: The loose zone is of essential importance to the supporting of underground caverns. It changes dynamically with the change of time, excavation depth, and lithology of the surrounding rock. To provide reference and guidance for alike projects, the applicability of sonic wave method in dynamically analyzing loose zone is expounded, and the loose zone at upstream sidewall of an underground powerhouse is measured and tested by the method. Curves of the loose zone versus the depth of excavation, the wave velocity of rock mass as well as the time and space are given. By analyzing the curves, the variation and distribution of loose zone are obtained, and corresponding engineering measures for the project construction are put forward.
Key words: loose zone; depth of excavation; dynamic variation; sonic wave method
Durability of Cement Grouting Curtain at Danjiangkou Dam
LI Xiao-e, LI Zhen
(Yangtze River Scientific Research Institute ,Wuhan 430010, China)
Abstract : To study the durability of impermeable curtain and to propose suggestions for the strengthening grouting of the curtain in the later stage, physical-chemical analysis and permeability test are performed on the cement stone of the impermeable curtain which is constructed at the riverbed section of Danjiangkou dam in the early stage. The structures of hydration products of cement stone from core samples in most investigated holes are manifested to be compact with no abnormal mineral or chemical compositions. These core samples with compact structure exhibit good impermeability with little CaO corroded by percolating water. The corrosion speed of CaO reduced with the permeation time extended. The effective age of the curtains with dense cement stones is estimated to exceed 100 years, which indicates that the grouted cement curtain has good durability and corrosion resistance. Strengthening grouting is required at dam sections where CaO is visibly corroded.
Key words: Danjiangkou Dam; grouted cement curtain; durability
Theoretical Study and Tests on Relative Humidity Change of Concrete Under Self Desiccation Effect
ZHANG Deng-xiang 1, YANG Wei-jun 2
(1.School of Hydraulic Engineering, Changsha University of Science and Technology, Changsha 410076, China; 2.School of Civil Engineering and Architecture, Changsha University of Science and Technology, Changsha 410076, China)
Abstract : The functional equations of internal humidity and saturation fraction in concrete induced by self-desiccation effect are presented based on theoretical studies and tests on the relative humidity change in concrete. Digital humidity sensors are used to measure the internal relative humidity change against concrete age under sealed curing. The tests manifest that the relative humidity in concrete with low water-cement ratio decreases rapidly in the early-age, which indicates that the cracking probability of concrete with low water-cement ratio is significantly increased. There is a quite small relative error between the test values of relative humidity and the calculated values from the model proposed in the paper.
Key words: concrete; self-desiccation; relative humidity
Crack Prevention Measures for High Strength Concrete Aqueduct Constructed in Summer
ZHANG Yang 1 , WU Ai-qing 2 , HE Lei 3
(1. School of Hydraulic Science and Engineering, Yangzhou University, Yangzhou 225009, China; 2. Key Laboratory of Geotechnical Mechanics and Engineering of the Ministry of Water Resources, Yangtze River Scientific Research Institute, Wuhan 430010, China; 3. Southwest Electric Power Design Institute, Chengdu 610021, China)
Abstract: In spite of high carrying capacity, it involves great difficulty to control the temperature and prevent cracking during the construction of high strength concrete aqueduct in summer because of high heat of hydration. The finite element method for unsteady temperature field and stress field is applied to simulate the construction process in summer for a typical aqueduct structure. The cause of cracking at dangerous positions is analyzed based on the calculation results of temperature field and stress field in different cases. Corresponding measures of pipe cooling and surface thermal insulation are put forward, which will be beneficial for the design and construction of such high strength concrete structure.
Key words: aqueduct; high strength concrete; temperature control and crack prevention; finite element method
Development of Temperature Field Calculation Program on ANSYS Platform for Mass Concrete Structure
SI Zheng, LI Shou-yi, CHEN Pei-pei,YANG Jie
(School of Water Resources and Hydro-electric Engineering, Xi’an University of Technology, Xi’an 710048, China)
Abstract : Most of the temperature field calculation programs at present have certain defects. In light of the merits of ANSYS platform which has complete pretreatment function, powerful equation solver, convenient post-processing function and good openness, a more applicable simulation program of calculating the temperature field of mass concrete structure is proposed and demonstrated based on ANSYS platform. According to the actual pouring progress and thermodynamic parameters, a Roller Compacted Concrete (RCC) dam is simulated and calculated. The difference of the maximum temperature between the calculated values and the measured values at the measurement points is less than 1.8 ℃, and the relative difference is within the range from -5% to 5%, which indicates that the calculation program developed on ANSYS platform can be used to simulate and calculate the temperature field of mass concrete structure.
Key words : mass concrete structure; temperature field; ANSYS
Distributed Hydrological Model for Dongjiang Watershed Based on HSPF Model
DONG Yan-jun, DENG Jia-quan, LI Jie, ZHENG Jiang-li, MA Zhi-peng
(Pearl River Hydraulic Research Institute, Guangzhou 510611, China)
Abstract: A distributed hydrological model is established for Dongjiang watershed based on Hydrological Simulation Program-Fortran (HSPF) Model. The theory of the construction, the data preparation, the model construction and model calibration are presented in details. The watershed is divided into 51 subfields from the perspective of spatial heterogeneity; while in terms of physical heterogeneity, the land use type, soil type and slope aspect are overlaid into 29 types of underlying surfaces. The relative errors at two calibrated stations (Heyuan station and Boluo station) are less than 15% and the NASH coefficients are larger than 0.9, which indicates a favorable simulation effect.
Key words: HSPF model; distributed hydrological model; Dongjiang watershed; hydrologic response
Design of the Mechanical Hydraulic System of Impulse Turbine Speed Governor at Bulunkou Hydropower Station
AN Gang 1, CHEN Yu-ting 2, YE Wei 2, NIE Wei 2, WANG Li-juan 2
(1. Xinjiang Water Resources and Hydropower Design Institute, Urumqi 830000, China; 2. Yangtze River Scientific Research Institute, Wuhan 430010, China)
Abstract: This paper presents a design scheme of the mechanical hydraulic system of the speed governing system of impulse turbine with 6 nozzles and 6 deflectors at Bulunkou-Gongge’er Power Station in Xinjiang Autonomous Region. In association with the research achievements of high head impulse units, advanced hydraulic control technology is adopted in the manufacturing, testing and inspection of the design, which is qualified to be applied in engineering. The design includes nozzle control unit, deflector control unit, centralized control unit for accidental shutdown, and the structure design. This paper would be referential for the design of the speed governor of large-sized impulse turbine with multi-nozzles.
Key words: impulse turbine; 6 nozzles and 6 deflectors; mechanical hydraulic system; modular construction
Configuration of Large Generator Neutral Grounding Through High Impedance Distribution Transformer
CHEN Yu-shi, TAO Yi-shou
(Yangtze River Scientific Research Institute, Wuhan 430011, China)
Abstract : The excessive fault current induced by stator single-phase earth fault and big ground capacitance of stator winding of large generator can be restricted by neutral grounding through distribution transformer. This paper introduces a configuration method of generator neutral grounding device with high impedance distribution transformer. The fault capacitive current is partly compensated by the inductive current generated from the internal reactance of the transformer, and the ground-fault current is limited within an allowable range while the fault transient overvoltage is restrained.
Key words: generator neutral; grounding device; high impedance transformer; configuration method
Quantitative Analysis on CRSRI Papers Collected in SCI, EI and ISTP from 2006 to 2010
CHEN Yuan-ming, ZHOU Li-feng, MENG Xiang-fang, NIE Wen
(Yangtze River Scientific Research Institute, Wuhan 430010, China)
Abstract : The science and technology papers written by researchers in Changjiang/Yangtze River Scientific Research Institute (CRSRI/YRSRI) collected in SCI, EI, and ISTP are quantitatively analyzed. Data from 2006 to 2010 are analyzed in terms of the total amount, authorship, subjects, periodicals, and international conference proceedings on which the articles were published. Skills and methods of increasing the rate of adoption by the three retrieval systems are also proposed for reference.
Key words: retrieval system; collected papers; information analysis; SCI; EI; ISTP
Changes of Inflow and Outflow Runoff and Sediment of Three Gorges Reservoir Before and After the Impoundment
HUANG Ren-yong, ZHANG Xi-bing
(Yangtze River Scientific Research Institute, Wuhan430010, China)
Abstract : The changes of inflow and outflow runoff and sediment of the Three Gorges Reservoir before and after the impoundment are systematically analyzed based on the observed data of hydrographic stations. The results reveal that since the 1990s, the inflow-outflow runoff and sediment have both reduced, of which the sediment discharge reduced much more remarkably than the runoff. In recent years, the inflow-outflow runoff and sediment during flood season remain above 76% and 96% of the whole year. In terms of annual distribution, the inflow runoff and sediment in flood season both exhibit a tendency of decreasing; whereas the outflow runoff tends to decrease and the outflow sediment tends to increase in flood season. After the impoundment, the inflow and outflow water and sediment decreased sharply in September and October, while increased in dry season from February to April.
Key words: Three Gorges Reservoir; water-sediment changes; annual distribution; Cuntan station; Yichang
Physical Modeling of Fluvial Process and River Regime Control in Shishou Reach of Yangtze River at the Initial Stage of Three Gorges Project
HUANG Li, ZHU Yong-hui, YAO Shi-ming
(Key Laboratory of River Regulation and Flood Control of MWR, Yangtze River Scientific Research Institute, Wuhan 430010, China)
Abstract : Physical modeling tests were performed to study the fluvial process in Shishou reach of Yangtze River in the purpose of predicting the river regime tendency and proposing river regime control plans for the changes at different stages of Three Gorges Project(TGP). The results reveal that until the end of 2022, apart from some local changes, the overall river regime of Shishou reach will generally remain the same as that at the present, which presents a braided pattern with the left branch of Xinsheng shoal, a newly developed shoal, as the dominant and with the left channel in the left branch as the main channel. The preliminary plan of river regulation projects include bank protection works, either reinforcements or new constructions to be carried out at vulnerable spots along the river bank which are close to the thalweg or heading to the main flow. Additionally, to maintain the present regime or prevent it from deteriorating, bank protection projects will be constructed at some local sandbars or beaches based on the tendency of river regime adjustment.
Key words: Changjiang River Flood Protection Model;Three Gorges Project; Shishou reach of Yangtze River; river regime control