A Timely Multi-Point Simultaneous Manometry Used in Burst and Leakage Monitoring along the Water Transmission Pipeline

2012 ◽  
Vol 170-173 ◽  
pp. 2373-2379
Author(s):  
Shao Ming Lu ◽  
Fang Li ◽  
Shao Wen Li
Keyword(s):  
Water Supply ◽  
Large Scale ◽  
Leakage Flow ◽  
River Diversion ◽  
Xijiang River ◽  
Transmission Pipeline ◽  
Secondary Disasters ◽  
Supply Capacity ◽  
Water Transmission ◽  
Leakage Monitoring

On large-scale pipelines at a water supply capacity of 5-10 m3/s, the bursted flow can reach hundreds to thousands of cubic meters within a few minutes, which could trigger secondary disasters in the densely populated areas. But the accident is hard to be monitored and found, because the leakage flow is often only 1% to 5% of the water supply capacity. This paper presents the simultaneous manometry for the burst and leakage monitoring along the pipelines. The research found that it can alarm timely in 3min to 5min and provide key information such as detonation location and the amount of the explosion leakage. The method has been applied to Xijiang River Diversion Project in China and the water supply capacity is 3.5 million m3/d(40.5m3/s).

scholarly journals Network isolators inhibit failure spreading in complex networks

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Franz Kaiser ◽  
Vito Latora ◽  
Dirk Witthaut
Keyword(s):  
Complex Networks ◽  
Large Scale ◽  
Power Transmission ◽  
Power Grids ◽  
Cascading Failure ◽  
Critical Infrastructures ◽  
Daily Lives ◽  
Supply Networks ◽  
Water Transmission ◽  
Complete Collapse

AbstractIn our daily lives, we rely on the proper functioning of supply networks, from power grids to water transmission systems. A single failure in these critical infrastructures can lead to a complete collapse through a cascading failure mechanism. Counteracting strategies are thus heavily sought after. In this article, we introduce a general framework to analyse the spreading of failures in complex networks and demostrate that not only decreasing but also increasing the connectivity of the network can be an effective method to contain damages. We rigorously prove the existence of certain subgraphs, called network isolators, that can completely inhibit any failure spreading, and we show how to create such isolators in synthetic and real-world networks. The addition of selected links can thus prevent large scale outages as demonstrated for power transmission grids.

Study of the Standard k-ε Model for Tip Leakage Flow in an Axial Compressor Rotor

2016 ◽  
Vol 33 (4) ◽  
Author(s):  
Yanfei Gao ◽  
Yangwei Liu ◽  
Luyang Zhong ◽  
Jiexuan Hou ◽  
Lipeng Lu
Keyword(s):  
Flow Field ◽  
Large Scale ◽  
Turbulent Viscosity ◽  
Axial Compressor ◽  
Leakage Flow ◽  
Reynolds Stresses ◽  
Mean Flow ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Compressor Rotor

AbstractThe standard k-ε model (SKE) and the Reynolds stress model (RSM) are employed to predict the tip leakage flow (TLF) in a low-speed large-scale axial compressor rotor. Then, a new research method is adopted to “freeze” the turbulent kinetic energy and dissipation rate of the flow field derived from the RSM, and obtain the turbulent viscosity using the Boussinesq hypothesis. The Reynolds stresses and mean flow field computed on the basis of the frozen viscosity are compared with the results of the SKE and the RSM. The flow field in the tip region based on the frozen viscosity is more similar to the results of the RSM than those of the SKE, although certain differences can be observed. This finding indicates that the non-equilibrium turbulence transport nature plays an important role in predicting the TLF, as well as the turbulence anisotropy.

Irrigation in the Medieval Islamic Fayyum: Local Control in a Large-Scale Hydraulic System

2012 ◽  
Vol 55 (1) ◽  
pp. 1-31 ◽  
Author(s):  
Yossef Rapoport ◽  
Ido Shahar
Keyword(s):  
Water Supply ◽  
Local Control ◽  
Water Allocation ◽  
Hydraulic System ◽  
Large Scale ◽  
Close Reading ◽  
Unique Case ◽  
Islamic Period ◽  
Distinctive Aspect

Abstract Because of the unique set of sources available, the Fayyum in Middle Egypt offers a unique case study of large-scale irrigation from antiquity to the Islamic period. A close reading of a cadastral survey of the province from 641/1243-4 shows that the distinctive aspect of the Islamic period was the local control of water supply and management. Drawing on the engineering experience of the villagers, water allocation and management in the gravity-fed canals of the Fayyum were in the hands of iqṭāʿ holders and tribal groups along the main canals, a pattern similar to that which pertained in mediaeval al-Andalus.

Tip Leakage Flow Instability in a Centrifugal Compressor

2021 ◽  
Vol 143 (4) ◽  
Author(s):  
Teng Cao ◽  
Tadashi Kanzaka ◽  
Liping Xu ◽  
Tobias Brandvik
Keyword(s):  
Shear Layer ◽  
Centrifugal Compressor ◽  
Large Scale ◽  
Flow Instability ◽  
Leading Edge ◽  
Main Stream ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Unstable Flow ◽  
Tip Leakage

Abstract In this paper, an unsteady tip leakage flow phenomenon is identified and investigated in a centrifugal compressor with a vaneless diffuser at near-stall conditions. This phenomenon is associated with the inception of a rotating instability in the compressor. The study is based on numerical simulations that are supported by experimental measurements. The study confirms that the unstable flow is governed by a Kelvin–Helmholtz type instability of the shear layer formed between the main-stream flow and the tip leakage flow. The shear layer instability induces large-scale vortex roll-up and forms vortex tubes, which propagate circumferentially, resulting in measured pressure fluctuations with short wavelength and high amplitude which rotate at about half of the blade speed. The 3D vortex tube is also found to interact with the main blade leading edge, causing the reduction of the blade loading identified in the experiment. The paper also reveals that the downstream volute imposes a once-per-rev circumferential nonuniform back pressure at the impeller exit, inducing circumferential loading variation at the impeller inducer, and causing circumferential variation in the unsteady tip leakage flow.

Heat Transfer and Aerodynamics of Over-Shroud Leakage Flows in a High-Pressure Turbine

2009 ◽  
Author(s):  
Knut Lehmann ◽  
Richard Thomas ◽  
Howard Hodson ◽  
Vassilis Stefanis
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Large Scale ◽  
Suction Side ◽  
Surface Flow ◽  
Tip Clearance ◽  
Flow Visualisation ◽  
Leakage Flow ◽  
High Pressure Turbine ◽  
High Heat Transfer

An experimental study has been conducted to investigate the distribution of the convective heat transfer on the shroud of a high pressure turbine blade in a large scale rotating rig. A continuous thin heater foil technique has been adapted and implemented on the turbine shroud. Thermochromic Liquid Crystals were employed for the surface temperature measurements to derive the experimental heat transfer data. The heat transfer is presented on the shroud top surfaces and the three fins. The experiments were conducted for a variety of Reynolds numbers and flow coefficients. The effects of different inter-shroud gap sizes and reduced fin tip clearance gaps were also investigated. Details of the shroud flow field were obtained using an advanced Ammonia-Diazo surface flow visualisation technique. CFD predictions are compared with the experimental data and used to aid interpretation. Contour maps of the Nusselt number reveal that regions of highest heat transfer are mostly confined to the suction side of the shroud. Peak values exceed the average by as much as 100 percent. It has been found that the interaction between leakage flow through the inter-shroud gaps and the fin tip leakage jets are responsible for this high heat transfer. The inter-shroud gap leakage flow causes a disruption of the boundary layer on the turbine shroud. Furthermore, the development of the large recirculating shroud cavity vortices is severely altered by this leakage flow.

Determination of design capacity for water transmission systems based on the characteristics of regional peak factors

2006 ◽  
Vol 6 (5) ◽  
pp. 85-92
Author(s):  
I.-H. Hyun ◽  
S. Dockko ◽  
C.-I. Lee
Keyword(s):  
Water Supply ◽  
Transmission Systems ◽  
Design Capacity ◽  
Small Areas ◽  
Peak Factor ◽  
Water Transmission

The design capacity of a water supply can be derived from the peak factor. In this research, four different methods were used to determine the peak factor more precisely. Applying Method 1 could result in the design capacity being underestimated, by designing the lower part of the pipeline to apply the peak factor to the whole area. Applying Method 2 could overestimate it by 10–30% in the upper part of the pipeline by dividing the sum of the regional peak factors according to the ratio of peak day demand to the region. Applying Method 3 underestimates the design capacity in small areas, while it could overestimate it in large areas. Finally, Method 4 gives optimum results for the peak factor for estimating the design capacity.

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