scholarly journals Analysis of Water Hammer with Different Closing Valve Laws on Transient Flow of Hydrogen-Natural Gas Mixture

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Norazlina Subani ◽  
Norsarahaida Amin
Keyword(s):  
Natural Gas ◽  
Pressure Wave ◽  
Transient Flow ◽  
Water Hammer ◽  
Wave Profile ◽  
Maximum Pressure ◽  
Gas Mixture ◽  
Pressure Waves ◽  
Closing Time ◽  
Closure Laws

Water hammer on transient flow of hydrogen-natural gas mixture in a horizontal pipeline is analysed to determine the relationship between pressure waves and different modes of closing and opening of valves. Four types of laws applicable to closing valve, namely, instantaneous, linear, concave, and convex laws, are considered. These closure laws describe the speed variation of the hydrogen-natural gas mixture as the valve is closing. The numerical solution is obtained using the reduced order modelling technique. The results show that changes in the pressure wave profile and amplitude depend on the type of closing laws, valve closure times, and the number of polygonal segments in the closing function. The pressure wave profile varies from square to triangular and trapezoidal shape depending on the type of closing laws, while the amplitude of pressure waves reduces as the closing time is reduced and the numbers of polygonal segments are increased. The instantaneous and convex closing laws give rise to minimum and maximum pressure, respectively.

scholarly journals Water Hammer Control Using Additional Branched HDPE Pipe

Energies ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 8008
Author(s):  
Michał Kubrak ◽  
Agnieszka Malesińska ◽  
Apoloniusz Kodura ◽  
Kamil Urbanowicz ◽  
Paweł Bury ◽  
...  
Keyword(s):  
Transient Flow ◽  
Oscillation Period ◽  
Water Hammer ◽  
Pressure Increase ◽  
Maximum Pressure ◽  
Main Pipeline ◽  
Closing Time ◽  
Hydraulic Transients ◽  
Flow Equations ◽  
Hdpe Pipe

In pressurised pipeline systems, various water hammer events commonly occur. This phenomenon can cause extensive damage or even lead to a failure of the pumping system. The aim of this work is to experimentally re-examine the possibility of using an additional polymeric pipe, installed at the downstream end of the main pipeline, to control water hammer. A previous study on this topic investigated additional polymeric pipes connected to the hydraulic system with a short joint section of the same diameter as the main pipeline. In the current research, a different method of including an additional pipe was considered which involved connecting it with a pipe of a smaller diameter than the main pipeline. Three additional HDPE pipes, with different volumes, were investigated. The performance of the devices was studied for hydraulic transients induced by both rapid and slow, manual valve closures. Experimental results show that the additional polymeric pipe can provide significant pressure surge damping during rapid water hammer events. As the valve closing time lengthens, the influence of the additional pipe on the maximum pressure increase is reduced. The additional HDPE pipe does not provide notable protection against hydraulic transients induced by slow valve closure in terms of reducing the first pressure peak. No relationship between the volume of the additional pipe and the damping properties was noticed. The observed pressure oscillations were used to evaluate a one-dimensional numerical model, in which an additional pipe is described as a lumped parameter of the system. The viscoelastic properties of the device were included using the one element Kelvin–Voigt model. Transient flow equations were solved with the implicit method of characteristics. Calculation results demonstrate that this approach allows one to reasonably reproduce unsteady flow oscillations registered during experiments in terms of the maximum pressure increase and pressure wave oscillation period.

Transient Analysis on Helium Coolant Tube Break Accident of Dual-Functional Lithium Lead Test Blanket Module

2016 ◽  
Author(s):  
Qian Sun ◽  
Tianji Peng ◽  
Zhiwei Zhou ◽  
Zhibin Chen ◽  
Jieqiong Jiang
Keyword(s):  
Pressure Wave ◽  
Transient Analysis ◽  
Structural Integrity ◽  
Maximum Pressure ◽  
Pressure Waves ◽  
Operating Pressure ◽  
Pressure Shock ◽  
Dual Functional ◽  
Short Time ◽  
Helium Coolant

Dual-functional Lithium Lead Test Blanket Module (DFLL-TBM) was proposed by China for testing in the International Thermonuclear Experimental Reactor (ITER).When an in-TBM helium coolant tube breaks, high pressure helium will discharge into the Pb-Li breeding zones. The pressure shock in the TBM will threaten the structural integrity and safety of ITER. Simulation and analysis on helium coolant tube break accident of DFLL-TBM was performed, and two cases with different break sizes were considered. Computational results indicate that intense pressure waves spread quickly from the break to the surrounding structures and the variation of pressure in the TBM breeding box is drastic especially when the pressure wave propagation encounters large resistance such as at the bending corner of the flow channel, the inlet and outlet of Pb-Li, etc. The maximum pressure in the TBM breeding box which is even higher than the operating pressure of helium also occurs in these zones. Although the pressure shock lasts for a very short time, its effect on the structural integrity of DFLL-TBM needs to be paid attention to.

Numerical Simulation of Turbulent Pipe Flow for Water Hammer

2015 ◽  
Vol 137 (11) ◽  
Author(s):  
Hamid Shamloo ◽  
Maryam Mousavifard
Keyword(s):  
Shear Wave ◽  
Pressure Wave ◽  
Transient Flow ◽  
Water Hammer ◽  
Turbulent Pipe Flow ◽  
Turbulence Structure ◽  
Governing Equations ◽  
Structure Changes ◽  
Dominant Feature ◽  
Voigt Model

A numerical model of turbulent transient flow is used to study the dynamics of turbulence during different periods of water hammer in a polymeric pipe. The governing equations of the transient flow are solved by using the finite difference (FD) method, and the effects of viscoelasticity are modeled by means of a two-dimensional (2D) Kelvin–Voigt model. The experimental data with the Ghidaoui parameter P in the order of one are chosen in which the generated shear wave propagates toward the center of the pipe, while the pressure wave passes the length of the pipe. By studying the turbulence shear force during different times, it is shown that the turbulence structure changes considerably in the first cycle of water hammer. In the accelerated phases, the dominant feature is the creation of a shear wave near the wall, and in the decelerated phases the dominant feature is the propagation of the shear wave created in the accelerated phase.

Reduced-order modellin for high-pressure transient flow of hydrogen-natural gas mixture

2017 ◽  
Vol 132 (5) ◽  
Author(s):  
Baba G. Agaie ◽  
Ilyas Khan ◽  
Ali Saleh Alshomrani ◽  
Aisha M. Alqahtani
Keyword(s):  
High Pressure ◽  
Natural Gas ◽  
Transient Flow ◽  
Gas Mixture ◽  
Pressure Transient ◽  
Reduced Order

Effects of Weakly Compressibility on Propagating Properties of Water Hammer in a Long Pipe

2013 ◽  
Vol 444-445 ◽  
pp. 490-497
Author(s):  
Kun Xiong Zhou ◽  
Li Xiang Zhang
Keyword(s):  
Pressure Wave ◽  
Pipe Wall ◽  
High Water ◽  
Water Hammer ◽  
Wave Form ◽  
Pressure Waves ◽  
Water Head ◽  
The Waves ◽  
Theoretical Analyses

This paper is concerned with propagating features of pressure waves induced by water hammer in a long liquid-conveyed pipe subjected to hyper high water head. Effects of dynamically weak compressibility of the water in pipe and pipe wall elasticity on the propagating physics were investigated by comparing in-site measurements and theoretical analyses. The pressure wave form and propagating speed were significantly effected due to weak compressibility of the water and the interactions of the waves. The wave performs a strong unsteadiness while it propagates along the pipe. This study tries to explain an event with consideration of both the dynamically weak compressibility of the water in pipe and the closing features of the valves controlled actively.

The Effect of Water Hammer on Pressure Oscillation of Hydrogen Natural Gas Transient Flow

2014 ◽  
Vol 554 ◽  
pp. 251-255 ◽  
Author(s):  
Galadima Agaie Baba ◽  
Amin Norsarahaida
Keyword(s):  
Natural Gas ◽  
Transient Flow ◽  
Splitting Method ◽  
Control Valve ◽  
Pressure Oscillation ◽  
Water Hammer ◽  
Transient Pressure ◽  
Eigenmode Analysis ◽  
Flux Vector Splitting ◽  
Convex Closure

The unexpected closing of a control valve or pumping, which can be planned or accidental could lead to pressure oscillation commonly known as water hammer. Pressure waves oscillation in the fluid flow interaction leads to unsteady state phenomenon. Numerical computation on transient flow model of hydrogen natural gas mixture (HCNG) in a pipeline where different types of valves are considered for effective delivery and safety. Reduced order modeling (ROM) technique is employed in the transient analysis of high pressured HCNG in a short pipe. The flow is governed by a system of Euler equations that are discretized using the implicit Steger-Warming flux vector splitting method (FSM). Eigenmode analysis and the subsequent construction of ROM use only a few dominant flow eigenmodes. The boundary conditions are imposed using the closure law at the upstream and downstream of the pipeline. The effect of closure function is analyzed and the results are presented on different mass ratios and HCNG flow parameters. The transient pressure oscillations of HCNG at different closure functions are compared so as to test the best type of valve for HCNG transportation. The highest and lowest value of transient pressure wave occurs when instantaneous and convex closure law is considered, respectively.

Paper 22: Transient Flows in Short Curved Diffusers

1969 ◽  
Vol 184 (7) ◽  
pp. 45-56
Author(s):  
B. E. L. Deckker ◽  
T. K. Ramakrishnan ◽  
D. H. Male
Keyword(s):  
Pressure Wave ◽  
Transient Flow ◽  
Pressure Waves ◽  
Steady Regime ◽  
Circular Arc ◽  
Transient Flows ◽  
Area Distribution ◽  
Flow Through ◽  
Total Divergence ◽  
Curved Walls

The work reported is the first stage of an investigation into the effect of pressure waves of varying amplitude on the flow through the blade passages of turbomachines. Attention is confined to the interaction between the pressure wave and the geometry of four curved diffusers with the same area distribution about a circular- arc centre-line. The geometry of these diffusers is based on a straight diffuser with a total divergence angle equal to 12° and a length of 5 in. The nominal turning angles are 30°, 45°, 60°, and 90°. The transient flow through the five diffusers has been compared on the basis of sequences of Schlieren photographs taken at 50 μs intervals. The attenuation of the wave at the curved walls has also been measured. Systematic measurements have been made of the net and transmitted pressures, and also the pressures on the curved walls, during the quasi-steady régime. An attempt has been made to predict the net and transmitted pressures by means of two simple analyses, one of which is moderately successful. Diffuser effectiveness has been compared under conditions of steady and quasi-steady flow.

Leak detection of non-isothermal transient flow of hydrogen-natural gas mixture

2017 ◽  
Vol 48 ◽  
pp. 244-253 ◽  
Author(s):  
Norazlina Subani ◽  
Norsarahaida Amin ◽  
Baba Galadima Agaie
Keyword(s):  
Natural Gas ◽  
Transient Flow ◽  
Leak Detection ◽  
Gas Mixture

Effect of Chemical Hythane Composition on Pressure in Combustion Chamber of Engine

2019 ◽  
pp. 36-42
Author(s):  
A. P. Shaikin ◽  
I. R. Galiev
Keyword(s):  
Natural Gas ◽  
Combustion Chamber ◽  
Power Plants ◽  
Engine Speed ◽  
Combustion Engine ◽  
Fuel Mixture ◽  
Maximum Pressure ◽  
Chamber Volume ◽  
Excess Air ◽  
Scientific Papers

The article analyzes the influence of chemical composition of hythane (a mixture of natural gas with hydrogen) on pressure in an engine combustion chamber. A review of the literature has showed the relevance of using hythane in transport energy industry, and also revealed a number of scientific papers devoted to studying the effect of hythane on environmental and traction-dynamic characteristics of the engine. We have studied a single-cylinder spark-ignited internal combustion engine. In the experiments, the varying factors are: engine speed (600 and 900 min-1), excess air ratio and hydrogen concentration in natural gas which are 29, 47 and 58% (volume).The article shows that at idling engine speed maximum pressure in combustion chamber depends on excess air ratio and proportion hydrogen in the air-fuel mixture – the poorer air-fuel mixture and greater addition of hydrogen is, the more intense pressure increases. The positive effect of hydrogen on pressure is explained by the fact that addition of hydrogen contributes to increase in heat of combustion fuel and rate propagation of the flame. As a result, during combustion, more heat is released, and the fuel itself burns in a smaller volume. Thus, the addition of hydrogen can ensure stable combustion of a lean air-fuel mixture without loss of engine power. Moreover, the article shows that, despite the change in engine speed, addition of hydrogen, excess air ratio, type of fuel (natural gas and gasoline), there is a power-law dependence of the maximum pressure in engine cylinder on combustion chamber volume. Processing and analysis of the results of the foreign and domestic researchers have showed that patterns we discovered are applicable to engines of different designs, operating at different speeds and using different hydrocarbon fuels. The results research presented allow us to reduce the time and material costs when creating new power plants using hythane and meeting modern requirements for power, economy and toxicity.

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