Numerical Simulation on Rupture Behavior and Selection of Safety Membranes

2014 ◽  
Author(s):  
Chen Sheng ◽  
Zhang Jian ◽  
Xiaodong Yu
Keyword(s):  
Present Theory ◽  
Large Fluctuation ◽  
Surge Tank ◽  
Small Hydropower ◽  
Weak Points ◽  
Maximum Water ◽  
Safety Operation ◽  
Hydropower Stations ◽  
Selection Of ◽  
Rupture Behavior

This present study deals with a new mechanical device consisting of a set of safety membranes, which has been successfully applied in several middle and small hydropower stations in China instead of a surge tank. Safety membranes are installed on the penstock near the powerhouse as controlled weak points. When the pressure caused by load rejection rises to the preset explosive value, one or more membranes rupture, protecting the penstock and the unit from damage. The device is simple, reliable and economical. The method of characteristics is employed to establish numerical model of safety membranes to simulate their rupture behavior, which is then introduced to investigate how to determine the number and diameter of membranes from two aspects, large fluctuation and hydraulic disturbance. The results show that the diameter of the membranes depends on the negative pressure along pipeline under hydraulic disturbance while the number of the membrane depends on the maximum water hammer pressure under large fluctuation during load rejection of the unit. The conclusion of membrane selection can perfect the present theory of safety membranes, and provide the theoretical guidance and practical basis for membrane device design and safety operation.

The Application of Safety Membranes in Hydropower Plant

2014 ◽  
Vol 607 ◽  
pp. 449-453
Author(s):  
Sheng Chen ◽  
Jian Zhang ◽  
Xiao Dong Yu
Keyword(s):  
Hydropower Plant ◽  
Mechanical Device ◽  
Surge Tank ◽  
Small Hydropower ◽  
Membrane Rupture ◽  
Rupture Pressure ◽  
Hydropower Stations ◽  
The Mathematical Model ◽  
Rupture Behavior

Safety membrane is a good mechanical device that can be applied in middle and small hydropower stations instead of a surge tank. This present study deals with the determination of three most important parameters of safety membrane, rupture pressure, diameter, and number. The mathematical model of transient process is established by introducing the method of characteristic, which is used for the simulation of the rupture behavior of safety membrane. Then the model is applied to a specific hydropower station that only can employ safety membrane as the regulating measurement, and it shows good performance. The achievements of the study can serve as a reference for similar projects.

Influence of Surge Tank and Relief Valve on Transient Flow Behaviour in Hydropower Stations

2011 ◽  
Author(s):  
Alireza Riasi ◽  
Ahmad Nourbakhsh
Keyword(s):  
Power Plants ◽  
Transient Flow ◽  
Flow Analysis ◽  
Internal Boundary ◽  
Transient Condition ◽  
Maximum Pressure ◽  
Surge Tank ◽  
Small Hydropower ◽  
Relief Valve ◽  
Hydropower Stations

Unsteady flow analysis in water power stations is one of the most important issues in order to predict undesirable pressure variations in waterways and also probable changes in rotor speed for the power plants safe operation. Installation of surge tank and relief valve is the two main methods for controlling of hydraulic transient. The relief valve is used in several medium and small hydropower stations instead of the surge tank and mounted on the penstock near the powerhouse. The recent generation of relief valves are reliable and beneficial and consist of fully control system that directly conducted by governor. This paper presents a numerical method for transient flow in hydropower stations using surge tank and relief valve. For this purpose the governing equations of transient flow in closed conduit are solved using the method of characteristics (MOC) using unsteady friction. Hydraulic turbine, surge tank and relief valve are considered as internal boundary conditions. The influence of surge tank and also relief valve on the maximum pressure in spiral case and turbine over speed has been studied for a real case. The results show that the transient condition is considerably improved by using a relief valve and this device can be mounted in lieu of an expensive surge tank.

Reingold, N. (2017). Literature of English Modernism. History. Problematics. Poetics. A textbook. Moscow: RGGU.

2020 ◽  
Vol 1 (1) ◽  
pp. 276-281
Author(s):  
O. Yu. Panova
Keyword(s):  
Detailed Analysis ◽  
Critical Appraisal ◽  
Academic Discourse ◽  
Literary Modernism ◽  
Reading List ◽  
Weak Points ◽  
University Curricula ◽  
Points Of View ◽  
Selection Of

The review gives a write-up of the edition, its structure, composition and its material. The guidelines for teaching British literary Modernism, methods and concepts offered in the book are subject to a detailed analysis. The critical appraisal of its innovations, its tendency to extend and revise the canonical topics and the reading list, offer new points of view and unordinary approaches (in contrast with typical university curricula) is followed by critical remarks targeted at its weak points – poor reasoning and certain groundless pronouncements one sometimes comes across, principles that underlie the selection of material in particular chapters and paragraphs, correctness of style and conformity with the conventions of academic discourse. It is also emphasized that the book in question is a fascinating and enriching reading that will be duly appreciated by the students as well as colleagues and all readers interested in the British literary Modernism.

ON DISTRTBUTION PATTERN OF AMORPHA FRUTICOSA L. IN THE REGION OF KANEVSKAYA HYDROPOWER STATION (UKRAINE) IN CONNECTION WITH HYDROCHORY

2021 ◽  
Vol 14 (1) ◽  
pp. 107-115
Author(s):  
T. V. Shevchik ◽  
T. S. Dvirna ◽  
V. L. Shevchik
Keyword(s):  
Water Surface ◽  
Water Yield ◽  
Surface Level ◽  
Amorpha Fruticosa ◽  
Active Dispersal ◽  
Active Dissemination ◽  
Maximum Water ◽  
Hydropower Stations ◽  
Determining Factor ◽  
Natural Way

Amorpha fruticosa L. is a kenophyte of North American origin, ergaziophyte. Currently, this species naturalized over large areas and became the background on the coast waters of the Dnieper reservoirs of hydropower stations. It is necessary to clarify the reasons for the distribution of A. fruticosa populations in different parts of the Middle Dnieper coast under conditions of artificial regulation of its water yield. It has been proven that the high buoyancy of A. fruticosa fruits provides the possibility of its active dispersal along river beds in a natural way under conditions of fluctuations in the level of surface water yield right in spring floods. The main and determining factor in the active dissemination of the species on the coast of the Kanev and Kremenchug reservoirs is the frequent variability of the maximum water surface level. The narrow altitudinal range of distribution of this species on the coast in the lower parts, and accordingly, wider in the upper parts of the reservoirs is determined by the corresponding indicators of water level differences. The possibility of artificial regulation of the water surface level with knowledge of the characteristics of hydrochory of this invasive species makes it possible to influence its distribution in the territory near the reservoirs.

scholarly journals FUZZY MULTI-CRITERIA DECISION MAKING MODEL FOR SUBCONTRACTOR SELECTION IN INTERNATIONAL CONSTRUCTION PROJECTS

2015 ◽  
Vol 22 (2) ◽  
pp. 210-234 ◽  
Author(s):  
Serdar ULUBEYLI ◽  
Aynur KAZAZ
Keyword(s):  
Construction Projects ◽  
Decision Criterion ◽  
Practical Application ◽  
Human Judgment ◽  
Qualitative And Quantitative ◽  
International Construction ◽  
Weak Points ◽  
Initial Idea ◽  
Decision Making Model ◽  
Selection Of

A general contractor’s ability to select proper subcontractors in foreign projects is a key competitive advantage. Toward this aim, a subcontractor selection model (CoSMo) was developed in this study. As a computational approach, the fuzzy sets method was employed because it can model human judgment by means of linguistic values, combining qualitative and quantitative decision criteria into an aggregate measure. Although the algorithm may be complex for easy acceptance by industrial practitioners, this disadvantage was minimized through a computer-supported system. In order to gain a better understanding of the current practice of CoSMo, a real world construction project was conducted. As a result, it was observed that CoSMo has high practical application and can be used as an advisory system by satisfying principal contractor’s requirements to reduce the risk involved in the selection of a subcontractor. Moreover, it gives an initial idea of how subcontractors perform on each decision criterion and allows the main contractor to understand the picture on the strong and weak points of each bidder and thereby to take conscious decisions.

scholarly journals A Review of Critical Stable Sectional Areas for the Surge Tanks of Hydropower Stations

Energies ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 6466
Author(s):  
Wencheng Guo ◽  
Yang Liu ◽  
Fangle Qu ◽  
Xinyu Xu
Keyword(s):  
Electrical Coupling ◽  
Stable State ◽  
Future Research ◽  
Regulation System ◽  
Engineering Practice ◽  
Sectional Area ◽  
Surge Tank ◽  
Power Stations ◽  
Pumped Storage ◽  
Hydropower Stations

The critical stable sectional area (CSSA) for surge tanks corresponds to the critical stable state of hydropower stations and is an important index to evaluate the stability of the turbine regulation system. The research on CSSA for surge tanks is always one of the most important topics in the area of transient processes of hydropower stations. The CSSA for surge tanks provides the value basis for the sectional area of surge tanks. In engineering practice, the CSSA for surge tanks is widely used to guide their hydraulic design. This paper provides a systematic literature review about the CSSA for surge tank of hydropower stations. Firstly, the CSSA for surge tanks based on hydraulic transients is discussed. Secondly, the CSSA for surge tanks based on hydraulic-mechanical-electrical coupling transients is presented. Thirdly, the CSSA for air cushion surge tanks is illustrated. Finally, the CSSA for combined surge tanks, i.e., upstream and downstream double surge tanks and upstream series double surge tanks, is presented. In future research, the CSSA for surge tanks of pumped storage power stations should be explored. The CSSA for surge tanks considering multi-energy complement is worth studying.

Logic Design of Improved Backup Power Automatic Switching Considering the Influence of Small Hydropower Stations

2012 ◽  
Vol 463-464 ◽  
pp. 1638-1642
Author(s):  
Chen Jie Zhou ◽  
Yi Xiong ◽  
Liang Qin ◽  
Xiao Ming Zha
Keyword(s):  
Power Supply ◽  
Power Grid ◽  
Logic Design ◽  
Small Hydropower ◽  
Distributed Power ◽  
The Stability ◽  
Reliable Power Supply ◽  
Hydropower Stations ◽  
Small Capacity ◽  
Automatic Switching

The correct and quick operation of backup power automatic switching（BPAS）devices is an effective guarantee of reliable power supply to the system. However, when transformer substations are connected to small-capacity distributed power like the local small hydropower stations, the conventional BPAS devices usually fail to get into operation, which leads to the loss of power in some parts of the system. To solve this shortage，this article comes up with an improved scheme of BPAS, which has been proved through PSCAD simulation to be effective in enhancing the stability and reliability of the power grid

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