Influence of Longitudinal Fluctuation in Long Corridor Surge Tank on Hydraulic Transients

2009 ◽  
Author(s):  
Jian Zhang ◽  
Weihua Lu ◽  
Xiaodong Yu ◽  
Yu Zheng
Keyword(s):  
Water Level ◽  
Influence Factors ◽  
High Water ◽  
Water Diversion ◽  
Width Ratio ◽  
Surge Tank ◽  
Hydraulic Transients ◽  
Length Width ◽  
Water Conveyance ◽  
Simulation Results

Since the length-width ratio of large long corridor surge tank is big, longitudinal flow appears obviously, which influences the safety of water diversion system. Based on the water conveyance system of hydropower station with long corridor surge tank, influence of longitudinal fluctuation on hydraulic transients is analyzed, which is contrasted with the results without consideration of longitudinal fluctuation, and corresponding model test is also carried out. It is shown that numerical simulation results, without consideration of longitudinal fluctuation, are more dangerous and those considering longitudinal fluctuation relatively conform to reality. Further more, influence factors on longitudinal fluctuation are studied, the bigger the length-width ratio of surge tank and the lower the operation water level, the severer the longitudinal fluctuation. In order to decrease longitudinal fluctuation, surge tank with small length-width ratio should be designed, and station should be operated on high water level as much as possible.

Wicket Gate Closure Control Law to Improve the Transient of a Water Turbine

2013 ◽  
Vol 732-733 ◽  
pp. 451-456 ◽  
Author(s):  
Xiao Qin Li ◽  
Jin Shi Chang ◽  
Peng Chen
Keyword(s):  
Calculated Data ◽  
High Water ◽  
Water Diversion ◽  
Control Law ◽  
Hydraulic Pressure ◽  
Surge Tank ◽  
Hydropower Plants ◽  
Water Head ◽  
Water Turbine

The increase in speed and system hydraulic pressure may cause major accidents during the transient of load rejection, especially in high-water head hydropower plants. The current study presents a wicket gate step-by-step closure control law, where two guide vanes will be closed asynchronously to reduce the increase in pressure and improve the transient quality of a waterturbine. Compared with the calculated data in the routine closure law, the control law obviously improved the dynamic qualities of the transient in load rejection and decreased the rising hydraulic pressure from the water diversion system of the plant. The proposed control law can replace the role of a surge tank under certain conditions.

Research on Mechanical Deformation of Thrust Bearing

2014 ◽  
Vol 494-495 ◽  
pp. 550-553
Author(s):  
Yong Hai Li ◽  
Jian Wang ◽  
Rong Kui Yao ◽  
Shi Bo Liu ◽  
Jia Yang ◽  
...  
Keyword(s):  
Working Conditions ◽  
Thrust Bearing ◽  
Mechanical Deformation ◽  
Width Ratio ◽  
Bending Deformation ◽  
Length Width ◽  
Left And Right ◽  
Simulation Results ◽  
Supporting Condition ◽  
Torsion Deformation

Finite Element Method numerical simulation has been carried out to analyze mechanical deformation of thrust bearing under the point and line supporting condition. The simulation results indicate that the torsion deformation of the point supporting is the larger, torsion deformation is mainly radial bending deformation, and circumferential bending deformation is small, it becomes more and more obvious with the decrease of bearing pad length-width ratio under the same working conditions for the same pad. Line supporting torsion deformation is mainly the circumferential bending deformation, and the left and right sides are symmetrical along the circumferential, the radial bending deformation is small, torsion deformation related to the length and width of supporting, with their size increasing the torsion deformation decreased.

scholarly journals Simulation of multiple water source ecological replenishment for Chagan Lake based on coupled hydrodynamic and water quality models

2017 ◽  
Vol 17 (6) ◽  
pp. 1774-1784 ◽  
Author(s):  
L. Zhang ◽  
M. R. Hipsey ◽  
G. X. Zhang ◽  
B. Busch ◽  
H. Y. Li
Keyword(s):  
Water Quality ◽  
Water Level ◽  
Water Source ◽  
Scientific Basis ◽  
Water Diversion ◽  
Chagan Lake ◽  
Simulation Results ◽  
Ecological Water Level ◽  
Western Jilin ◽  
Grade Iii

Abstract Chagan Lake serves as an irrigation storage reservoir for the Qianguo Irrigation Area and an important ecological barrier in western Jilin. The coupled TUFLOW-FV and Aquatic Ecodynamic (AED2) models were used to simulate the hydrodynamic and water quality of Chagan Lake, and propose the water diversion scheme that could improve the water quality to reach Grade III and maintain the ecological water level. The simulation results showed a satisfactory agreement with observations. The total carrying loads of NH3-N, total nitrogen (TN) and total phosphorus (TP) for Chagan Lake were 1,147.6, 3,686.2 and 100.8 t from May to October. The range of the minimum amounts of water diversion to keep the water quality as Grade III and maintain the maximum ecological water level of 131.5 m for TN, TP were separately [32.60, 49.84, 57.19, 63.70, 70.91], [117.25, 135.26, 168.17, 190.65, 218.32] million m3 and the corresponding reduction amounts of farmland drainage for TN, TP were separately [4.03, 0, 0, 0, 0], [73.08, 61.88, 50.23, 40.94, 31.98] million m3 under the rainfall guarantee rates of 10%, 20%, 50%, 75%, 90%, respectively. The simulation results provide a scientific basis for the water quality improvement and ecological water supplement required for the interconnected river–lake system network (IRLSN) in Western Jilin Province.

Study on the Influence of Tailrace Tunnel Outlet Bottom Slope on Water Level Fluctuation in the Tailrace Surge Tank

2014 ◽  
Vol 1065-1069 ◽  
pp. 644-649
Author(s):  
Zong Pu Zhang ◽  
Fu Lin Cai ◽  
Yu Long Hua ◽  
Huan Cheng
Keyword(s):  
Water Level ◽  
Water Level Fluctuation ◽  
Water Diversion ◽  
Level Fluctuation ◽  
Surge Tank ◽  
River Bed ◽  
Connection Pattern ◽  
Ceiling Height ◽  
Power Generation System ◽  
Tailrace Tunnel

Combining with hydraulic model experiment of water diversion and power generation system of one hydropower station, the effects of different connection patterns between the tailrace tunnel outlet and downstream river bed and flow states in the transient process on the water level fluctuation in tailrace surge tank have been investigated. The results show that: there is not remarkable influence on water level fluctuation when tailrace water level in downstream river is higher or close to the ceiling height. On the opposite side , it has notable influence on water level fluctuation in the tailrace surge tank when tailrace water level in downstream is lower than the ceiling height, and the water level fluctuation in tailrace surge tank presents some regularity under the same connection pattern when the tailrace water level in downstream river is lower than the ceiling height.

scholarly journals Diversity of Pod Shape in Pisum

Diversity ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 203
Author(s):  
Thomas Henry Noel Ellis ◽  
Julie M. I. Hofer ◽  
Eleni Vikeli ◽  
Michael J. Ambrose ◽  
Paola Higuera-Poveda ◽  
...  
Keyword(s):  
Allelic Variation ◽  
Size Variation ◽  
Width Ratio ◽  
Negative Regulators ◽  
Wide Range ◽  
Yield Determination ◽  
Organ Specific ◽  
Length Width ◽  
End Use ◽  
Pod Length

The seed-containing pod is the defining structure of plants in the legume family, yet pods exhibit a wide range of morphological variation. Within a species pod characters are likely to be correlated with reproductive strategy, and within cultivated forms will correspond to aspects of yield determination and/or end use. Here variation in pod size, described as pod length: pod width ratio, has been analyzed in pea germplasm represented by 597 accessions. This pod size variation is discussed with respect to population structure and to known classical pod morphology mutants. Variability of the pod length: width ratio can be explained by allelic variation at two genetic loci that may correspond to organ-specific negative regulators of growth.

Lake and inland dunes as interconnected Systems: The story of Lake Tresssee and an adjacent dune field (Schleswig-Holstein, North Germany)

The Holocene ◽  
2020 ◽  
pp. 095968362098168
Author(s):  
Christian Stolz ◽  
Magdalena Suchora ◽  
Irena A Pidek ◽  
Alexander Fülling
Keyword(s):  
Water Level ◽  
Bronze Age ◽  
Environmental Changes ◽  
High Water ◽  
Alluvial Fan ◽  
Water Levels ◽  
Lake Area ◽  
Dune Field ◽  
The North ◽  
Sand Drift

The specific aim of the study was to investigate how four adjacent geomorphological systems – a lake, a dune field, a small alluvial fan and a slope system – responded to the same impacts. Lake Tresssee is a shallow lake in the North of Germany (Schleswig-Holstein). During the Holocene, the lake’s water surface declined drastically, predominately as a consequence of human impact. The adjacent inland dune field shows several traces of former sand drift events. Using 30 new radiocarbon ages and the results of 16 OSL samples, this study aims to create a new timeline tracing the interaction between lake and dunes, as well, as how both the lake and the dunes reacted to environmental changes. The water level of the lake is presumed to have peaked during the period before the Younger Dryas (YD; start at 10.73 ka BC). After the Boreal period (OSL age 8050 ± 690 BC) the level must have undergone fluctuations triggered by climatic events and the first human influences. The last demonstrable high water level was during the Late Bronze Age (1003–844 cal. BC). The first to the 9th century AD saw slightly shrinking water levels, and more significant ones thereafter. In the 19th century, the lake area was artificially reduced to a minimum by the human population. In the dunes, a total of seven different phases of sand drift were demonstrated for the last 13,000 years. It is one of the most precisely dated inland-dune chronologies of Central Europe. The small alluvial fan took shape mainly between the 13th and 17th centuries AD. After 1700 cal. BC (Middle Bronze Age), and again during the sixth and seventh centuries AD, we find enhanced slope activity with the formation of Holocene colluvia.

Meshing Method of High Precision FEM in Large Complex Structural Simulations

2012 ◽  
Vol 195-196 ◽  
pp. 701-704
Author(s):  
Yan Hua Xue ◽  
Zhi Guang Wang ◽  
Xiao Hong Li ◽  
Xin Jiang
Keyword(s):  
Finite Element ◽  
Complex Structure ◽  
Width Ratio ◽  
Two Dimensional ◽  
Element Analysis ◽  
Large Complex ◽  
Mesh Density ◽  
Length Width ◽  
Complex Structural ◽  
Dimensional Element

Shing is playing an important role in the large complex structural FEM simulations; it has a direct effect on calculating precision of structural simulations. For increasing the calculation accuracy and analysis accuracy of complex structure, the finite element meshing problems is proposed on the finite element analysis of large complicated structures. The effects caused by element type, mesh density and intergradations on calculating precision are studied and discussed. A research argues that with length-width ratio of 1~2 and length-thickness ration of 1.5~4.5 of two-dimensional rectangular element, the quality of meshing method of two-dimensional element is above normal. As the height of one-dimensional element is equal to the sum of reinforcing rib height of outer panel and half the thickness of panel, more accurate results can be obtained.

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