SENARIET, A Water Hammer Software for Analyzing Hydraulic Transients in Complex Circuits

2011 ◽  
Author(s):  
Marta Vargas-Mun˜oz ◽  
Manuel Rodri´guez-Ferna´ndez ◽  
A´ngel Peren˜a-Tapiador
Keyword(s):  
Safety Issue ◽  
Propagation Speed ◽  
Water Hammer ◽  
Pressure Waves ◽  
Pipeline Systems ◽  
Travelling Time ◽  
Fluid Transients ◽  
Complex Circuits ◽  
Compressibility Effects ◽  
Circuit Length

Water hammer transients are a danger for piping integrity and represent an important safety issue. In the design of pipeline systems it is necessary to take into account the magnitudes of pressure waves associated with water hammer phenomena and, therefore, it is important that these water hammer effects are calculated with the appropriate accuracy. SENARIET is a programme to study fluid transients in pipeline systems to obtain pressure and velocity distributions along a circuit. When a transient process occurs in periods of the same order of the pressure waves’ travelling time along a circuit (the order of the circuit length divided by the effective propagation speed), the compressibility effects in liquids have to be considered. Taking this effect into account, the appropriate equations of continuity and momentum are solved by the method of characteristics, to obtain pressure and velocity along pipes as a function of time. The programme considers different devices that usually take part in complex circuits, such as pumps, motorized valves, check valves, elbows, change of sections, bifurcations, vacuum valves, damping devices, reservoirs, etc. The simulated results have been compared to theoretical and experimental ones to validate and evaluate the precision of the software. The results help to perform efficient and accurate predictions in order to define the pipelines.

scholarly journals Prediction of hydrogen flame propagation in a channel with exit contraction

2019 ◽  
Vol 128 ◽  
pp. 01013
Author(s):  
Ali Cemal Benim ◽  
Björn Pfeiffelmann
Keyword(s):  
Fluid Dynamics ◽  
Flame Propagation ◽  
Propagation Speed ◽  
Pressure Waves ◽  
Average Pressure ◽  
Hydrogen Flame ◽  
Flame Shape ◽  
Combustion Turbulence ◽  
The Given ◽  
Compressibility Effects

The propagation of a flame front in a homogeneous and initially quiescent hydrogen-air mixture in a channel with exit contraction is numerically analyzed by means of Computational Fluid Dynamics. For the given configuration, the compressibility effects are important, the average pressure increases in time due to the exit contraction, and pressure waves occur, which affect the flame propagation. Flowturbulence is modelled by the Realizable k-e model. In modelling combustion, turbulence-chemistry interactions are neglected. Predictions are compared with the measurements for evolution of the flame shape, propagation speed and pressure. It is observed that the flame propagation speed, and, thus, the rate of pressure increase are over-predicted by the present approach. Still, a fair qualitative agreementto measurements is observed.

Development of a New Simulation Technique Based on the Modal Approximation for Fluid Transients in Complex Pipeline Systems With Time-Variant Nonlinear Boundary Conditions

2006 ◽  
Vol 129 (6) ◽  
pp. 791-798 ◽  
Author(s):  
E. Kojima ◽  
T. Yamazaki ◽  
M. Shinada
Keyword(s):  
Boundary Conditions ◽  
Nonlinear Boundary ◽  
Safety Valve ◽  
Nonlinear Boundary Conditions ◽  
Simulation Technique ◽  
Nonlinear Relationship ◽  
Calculation Methods ◽  
Pipeline Systems ◽  
Fluid Transients ◽  
Modal Approximation

A new simulation technique called the system modal approximation method (SMA) for fluid transients in complex pipeline systems has been proposed. The superiority of this technique compared to other existing methods has been verified. Thus far, however, detailed considerations have been limited to pipelines having elementary boundary conditions. In the present paper, for the generalization of the SMA method, calculation methods are newly proposed for the case in which the boundary conditions are given by the time-variant nonlinear relationship between pressure and flow rate, such as the conditions in a safety valve, and its usefulness is verified by comparison to experimental measurements.

scholarly journals Pressure generated at the instant of impact between a liquid droplet and solid surface

2018 ◽  
Vol 5 (12) ◽  
pp. 181101 ◽  
Author(s):  
Y. Tatekura ◽  
M. Watanabe ◽  
K. Kobayashi ◽  
T. Sanada
Keyword(s):  
Solid Surface ◽  
Shape Factor ◽  
Liquid Droplet ◽  
Pressure Rise ◽  
Propagation Speed ◽  
Spherical Shape ◽  
Water Hammer ◽  
Droplet Impact ◽  
Maximum Pressure ◽  
The Impact

The prime objective of this study is to answer the question: How large is the pressure developed at the instant of a spherical liquid droplet impact on a solid surface? Engel first proposed that the maximum pressure rise generated by a spherical liquid droplet impact on a solid surface is different from the one-dimensional water-hammer pressure by a spherical shape factor (Engel 1955 J. Res. Natl Bur. Stand. 55 (5), 281–298). Many researchers have since proposed various factors to accurately predict the maximum pressure rise. We numerically found that the maximum pressure rise can be predicted by the combination of water-hammer theory and the shock relation; then, we analytically extended Engel’s elastic impact model, by realizing that the progression speed of the contact between the gas–liquid interface and the solid surface is much faster than the compression wavefront propagation speed at the instant of the impact. We successfully correct Engel’s theory so that it can accurately provide the maximum pressure rise at the instant of impact between a spherical liquid droplet and solid surface, that is, no shape factor appears in the theory.

scholarly journals Investigation on Water Hammer Control of Centrifugal Pumps in Water Supply Pipeline Systems

Energies ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 108 ◽  
Author(s):  
Wuyi Wan ◽  
Boran Zhang ◽  
Xiaoyi Chen
Keyword(s):  
Water Supply ◽  
Method Of Characteristics ◽  
Water Hammer ◽  
Moment Of Inertia ◽  
Evaluation Methodology ◽  
Centrifugal Pumps ◽  
Positive Effects ◽  
Pipeline Systems ◽  
The Moment ◽  
Water Supply Pipeline

Water hammer control in water supply pipeline systems is significant for protecting pipelines from damage. The goal of this research is to investigate the effects of pumps moment of inertia design on pipeline water hammer control. Based on the method of characteristics (MOC), a numerical model is established and plenty of simulations are conducted. Through numerical analysis, it is found that increasing the pumps moment of inertia has positive effects both on water hammer control as well as preventing pumps rapid runaway speed. Considering the extra cost of space, starting energy, and materials, an evaluation methodology of efficiency on the increasing moment of inertia is proposed. It can be regarded as a reference for engineers to design the moment of inertia of pumps in water supply pipeline systems. Combined with the optimized operations of the valve behind the pumps, the pipeline systems can be better protected from accident events.

Fluid Transients in a Pipeline With One Open End

2008 ◽  
Author(s):  
Robert A. Leishear
Keyword(s):  
Water Hammer ◽  
Atmospheric Conditions ◽  
Air Entrapment ◽  
Complex Interactions ◽  
Fluid Transients ◽  
Pipe Line ◽  
Multi Phase Flow ◽  
Time Required ◽  
Multi Phase ◽  
Transparent Tube

Water hammer during multi-phase flow is rather complex, but in some cases an upper limit to the pressure surge magnitude during water hammer can be estimated. In the case considered here, a two mile long pipeline with a single high point was permitted to partially drain. Due to gravitational effects, air bubbles up through the pipe line to its highest point, but the time required for air to reach the top of the pipe is rather long. Consequently, some transients caused by valve operations are affected by air entrapment and some are not. The intent of this research was to investigate the complex interactions between air, water vapor, and liquid during water hammer in a long pipe with one end of the pipe open to atmospheric conditions. To understand the system dynamics, experimental data was obtained from a long pipeline with an open end and also from a short, transparent tube. Transient calculations were performed for valve closures and pump operations as applicable. The limitations of available calculation techniques were considered in detail.

Numerical Simulation of Condensation Induced Water Hammer

2004 ◽  
Author(s):  
Sanja Prica ◽  
Vladimir Stevanovic ◽  
Blazenka Maslovaric
Keyword(s):  
Heat Conduction ◽  
Time Integration ◽  
Water Hammer ◽  
Phase Region ◽  
Fluid Particle ◽  
Pressure Waves ◽  
Two Phase ◽  
Water Steam ◽  
Pipe System ◽  
Waves Propagation

A numerical model for the simulation and analyses of condensation induced water hammer is presented and applied to the prediction of intensive pressure waves propagation in a two-phase pipe system. The modelling approach is based on the one-dimensional homogeneous two-phase flow model, tracking of the water column–steam bubble interface and modelling of the direct steam condensation on the subcooled liquid. The mass, momentum and enthalpy conservation equations are solved with the method of characteristics. The explicit time integration is performed along the three characteristic paths, where two of them are determined with the pressure waves propagation and third by the fluid particle flow. Fluid particle and water-steam interface tracking is achieved through the third-order accurate solving of the energy equation in space, where the thermodynamic quality determines the presence of water, two-phase mixture or steam. The heat conduction term is included into the enthalpy equation with the appropriate effective heat conduction coefficient in the two-phase region. The model is applied to the simulation and analyses of condensation induced water hammer in laboratory test case.

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