scholarly journals Flow-Induced Stresses and Displacements in Jointed Concrete Pipes Installed by Pipe Jacking Method

Fluids ◽  
2019 ◽  
Vol 4 (1) ◽  
pp. 34 ◽  
Author(s):  
Moses Karakouzian ◽  
Mehrdad Karami ◽  
Mohammad Nazari-Sharabian ◽  
Sajjad Ahmad
Keyword(s):  
Transient Flow ◽  
Transient Effects ◽  
Flow Conditions ◽  
Water Leakage ◽  
Pressurized Water ◽  
Transient Flows ◽  
Concrete Pipes ◽  
Induced Stresses ◽  
Pipe Jacking ◽  
Water Transmission

Transient flows result in unbalanced forces and high pressure in pipelines. Under these conditions, the combined effects of flow-induced forces along with sudden pipe displacements can create cracks in the pipeline, especially at the junctions. This situation consequently results in water leakage and reduced operational efficiency of the pipeline. In this study, displacements and stresses in a buried pressurized water transmission pipe installed by pipe jacking method are investigated using numerical modeling and considering interactions between fluid, pipe, and soil. The analyses were performed consecutively under no-flow, steady flow, and transient flow conditions, in order to investigate the effects of flow conditions on displacements and stresses in the system. Analyses of the results show that displacements and stresses in the jointed concrete pipes are significant under transient flow conditions. Moreover, because of pressure transient effects, maximum tensile stresses exceed the tensile strength of concrete at the junctions, leading to cracks and consequent water leakage.

scholarly journals Flow-Induced Stresses and Displacements in Jointed Concrete Pipes, Installed by Pipe Jacking Method

2019 ◽  
Author(s):  
Moses Karakouzian ◽  
Mehrdad Karami ◽  
Mohammad Nazari-Sharabian ◽  
Sajjad Ahmad
Keyword(s):  
Transient Flow ◽  
Transient Effects ◽  
Flow Conditions ◽  
Water Leakage ◽  
Pressurized Water ◽  
Transient Flows ◽  
Concrete Pipes ◽  
Induced Stresses ◽  
Pipe Jacking ◽  
Water Transmission

Transient flows result in unbalanced forces and high pressure in pipelines. Under these conditions, the combined effects of flow-induced forces along with sudden pipe displacements can create cracks in the pipeline, especially at the junctions. This situation consequently results in water leakage and reduced operational efficiency of the pipeline. In this study, displacements and stresses in a buried pressurized water transmission pipe installed by pipe jacking method are investigated using numerical modeling and considering interactions between fluid, pipe, and soil. The analyses were performed consecutively under no-flow, steady flow, and transient flow conditions, in order to investigate the effects of flow conditions on displacements and stresses in the system. Analyses of the results show that displacements and stresses in the jointed concrete pipes are significant under transient flow conditions. Moreover, because of pressure transient effects, maximum tensile stresses exceed the tensile strength of concrete at the junctions, leading to cracks and consequent water leakage.

scholarly journals Flow-Induced Stresses and Displacements in Jointed Concrete Pipes, Installed by Pipe Jacking Method

2019 ◽  
Author(s):  
Moses Karakouzian ◽  
Mehrdad Karami ◽  
Mohammad Nazari-Sharabian ◽  
Sajjad Ahmad
Keyword(s):  
Transient Flow ◽  
Transient Effects ◽  
Flow Conditions ◽  
Water Leakage ◽  
Pressurized Water ◽  
Transient Flows ◽  
Concrete Pipes ◽  
Induced Stresses ◽  
Pipe Jacking ◽  
Water Transmission

Transient flows result in unbalanced forces and high pressure in pipelines. Under these conditions, the combined effects of flow-induced forces along with sudden pipe displacements can create cracks in the pipeline, especially at the junctions. This situation consequently results in water leakage and reduced operational efficiency of the pipeline. In this study, displacements and stresses in a buried pressurized water transmission pipe installed by pipe jacking method are investigated using numerical modeling and considering interactions between fluid, pipe, and soil. The analyses were performed consecutively under no-flow, steady flow, and transient flow conditions, in order to investigate the effects of flow conditions on displacements and stresses in the system. Analyses of the results show that displacements and stresses in the jointed concrete pipes are significant under transient flow conditions. Moreover, because of pressure transient effects, maximum tensile stresses exceed the tensile strength of concrete at the junctions, leading to cracks and consequent water leakage.

scholarly journals Numerical modeling of water hammer in long water transmission pipeline

2021 ◽  
Vol 11 (8) ◽  
Author(s):  
Mohammad Hossein Arefi ◽  
Mahnaz Ghaeini-Hessaroeyeh ◽  
Rasoul Memarzadeh
Keyword(s):  
Negative Pressure ◽  
Transient Flow ◽  
Pump Failure ◽  
Transient Flows ◽  
Software Analysis ◽  
Transmission Pipeline ◽  
Water Transmission ◽  
The Right ◽  
Pressure Phase ◽  
Transmission Pipelines

AbstractIn the present study, a water transmission pipeline under steady conditions is modeled followed by examining the transient flow created by the failure of pumps in the pipeline. This pipeline is 31 km from the water transmission pipeline of Kerman, Iran. The software analysis results were compared with those of a numerical model for a laboratory test to validate transient flow modeling. While transient flows are created by pump failure, various areas of the water transmission pipelines will be affected by the transient waves produced. Long water transmission pipelines, usually large in diameter and flow rate, will pose problems in the negative pressure phase. The negative pressure causes threatening problems like water column separation and cavitation. The results indicated that using equipment like air valves when the pumps fail alone does not have the appropriate efficiency in eliminating the hazards in the water transmission pipelines. More examination showed that installing equipment like water flow feed and hydropneumatic tanks along the pipeline length in the right places prevents the negative pressure created and the pipeline risk significantly reduces.

An Experimental Investigation Into Potential Nuclear Reactor Vessel Flow Instabilities

2010 ◽  
Author(s):  
Jeffrey A. Brown ◽  
James W. Rowland ◽  
H. Joseph Fernando
Keyword(s):  
Physical Model ◽  
Transient Flow ◽  
Plant Protection ◽  
Reactor Vessel ◽  
Flow Instabilities ◽  
Engineering System ◽  
Flow Conditions ◽  
Steam Generators ◽  
Pressurized Water ◽  
Flow Measurements

An investigation into the increase in Plant Protection System (PPS) alarms at a three-unit US Pressurized Water Reactor (PWR) plant has determined that the alarms are the result, in part, of a hydraulic instability that has developed within the Reactor Coolant System (RCS) following the replacement of the steam generators in all three units of the Palo Verde Nuclear Generating Station (PVNGS). An experimental effort has been established by Arizona Public Service Company and Arizona State University in an attempt to determine the cause of these instabilities. Preliminary investigations have determined that the time scale of these instabilities is consistent with larger scale transient flow processes of the reactor vessel. Accordingly, the flow characteristics were assessed and localized flow measurements made using a one-fifth scale physical model of the upper plenum region of the reactor core of the Combustion Engineering System 80 reactor vessel to verify the postulation that large vortex structures referred to as “precessing” vortices [Ref. 1] affect the core exit flow conditions resulting in the noted flow instabilities. The physical model investigation was complemented by numerical analysis based on a Computational Fluid Dynamics (CFD) code performed for the same geometry. Benchmarking of the CFD model by the scaled physical model is intended to provide increased confidence in the CFD code. If verified, the CFD code may be modified so as to establish corrective actions for this condition, where physical modeling would probably be time consuming and cost prohibitive. The initial results for the physical and computational models demonstrate very good agreement between the measured and calculated flows in the upper-plenum region. The results of the complementary experimental and analytic evaluations do not support the presence of any large scale vortices of appropriate space scales that could affect flow conditions within the upper-plenum region. The elimination of the reactor vessel as the source of the instabilities suggests that the replacement steam generators may be the root cause of the flow instabilities. There is a possibility, however, that frequencies pertinent to vortices may be triggering mechanisms for flow instabilities in the entire system.

Modelling solid transport in building drainage systems

1996 ◽  
Vol 33 (9) ◽  
pp. 9-16 ◽  
Author(s):  
John A. Swaffield ◽  
John A. McDougall
Keyword(s):  
Decision Making ◽  
Boundary Conditions ◽  
Numerical Solution ◽  
Water Conservation ◽  
Transient Flow ◽  
Drainage System ◽  
System Model ◽  
Flow Depth ◽  
Flow Conditions ◽  
Solid Transport

The transient flow conditions within a building drainage system may be simulated by the numerical solution of the defining equations of momentum and continuity, coupled to a knowledge of the boundary conditions representing either appliances discharging to the network or particular network terminations. While the fundamental mathematics has long been available, it is the availability of fast, affordable and accessible computing that has allowed the development of the simulations presented in this paper. A drainage system model for unsteady partially filled pipeflow will be presented in this paper. The model is capable of predicting flow depth and rate, and solid velocity, throughout a complex network. The ability of such models to assist in the decision making and design processes will be shown, particularly in such areas as appliance design and water conservation.

Local characteristic of horizontal air–water two-phase flow by wire-mesh sensor

2016 ◽  
Vol 40 (3) ◽  
pp. 746-761 ◽  
Author(s):  
Weiling Liu ◽  
Chao Tan ◽  
Feng Dong
Keyword(s):  
Void Fraction ◽  
Transient Flow ◽  
Two Phase Flow ◽  
Wire Mesh ◽  
Local Characteristic ◽  
Phase Flow ◽  
Flow Conditions ◽  
Two Phase ◽  
Horizontal Pipe ◽  
Local Flow

Two-phase flow widely exists in many industries. Understanding local characteristics of two-phase flow under different flow conditions in piping systems is important to design and optimize the industrial process for higher productivity and lower cost. Air–water two-phase flow experiments were conducted with a 16×16 conductivity wire-mesh sensor (WMS) in a horizontal pipe of a multiphase flow facility. The cross-sectional void fraction time series was analysed by the probability density function (PDF), which described the void fraction fluctuation at different flow conditions. The changes and causes of PDFs during a flow regime transition were analysed. The local structure and flow behaviour were characterized by the local flow spectrum energy analysis and the local void fraction distribution (horizontal, vertical and radial direction) analysis. Finally, three-dimensional transient flow fluctuation energy evolution and characteristic scale distribution based on wavelet analysis of air–water two-phase flow were presented, which revealed the structural features of each phase in two-phase flow.

EXPERIMENTAL INVESTIGATION OF DEBRIS DAMMING IN TRANSIENT FLOW CONDITIONS

2019 ◽  
Author(s):  
GABRIELLA MAUTI ◽  
JACOB STOLLE ◽  
IOAN NISTOR ◽  
MAJID MOHAMMADIAN
Keyword(s):  
Experimental Investigation ◽  
Transient Flow ◽  
Flow Conditions

Modeling of Fluid Interaction Produced by Water Hammer

2011 ◽  
Vol 1 (1) ◽  
pp. 29-41 ◽  
Author(s):  
Kaveh Hariri Asli ◽  
Faig Bakhman Ogli Naghiyev ◽  
Soltan Ali Ogli Aliyev ◽  
Hoosein Hariri Asli
Keyword(s):  
Method Of Characteristics ◽  
Transient Flow ◽  
Practical Investigations ◽  
Computationally Efficient ◽  
Hydraulic Simulation ◽  
Computational Performance ◽  
Difference Form ◽  
Large Water ◽  
Water Transmission ◽  
Fluid Interaction

This paper compares the computational performance of two numerical methods for two models of Transient Flow. One model was defined by method of the Eulerian based expressed in a method of characteristics “MOC”, finite difference form. The other model was defined by method of Regression. Each method was encoded into an existing hydraulic simulation model. Results indicated that the accuracy of the methods was comparable but that the “MOC” was more computationally efficient for analysis of large water transmission line. Practical investigations in this article have shown mainly this tendency.

scholarly journals Evaluation of the Aerodynamic and Aeroacoustic Response of a Vehicle to Transient Flow Conditions

2013 ◽  
Vol 6 (1) ◽  
pp. 389-402 ◽  
Author(s):  
Nicholas Oettle ◽  
Oliver Mankowski ◽  
David Sims-Williams ◽  
Robert Dominy ◽  
Claire Freeman
Keyword(s):  
Transient Flow ◽  
Flow Conditions
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