Prediction of hydrogen flame propagation in a channel with exit contraction

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.

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

Volume 6: Fluids and Thermal Systems; Advances for Process Industries, Parts A and B ◽

10.1115/imece2011-62093 ◽

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.

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Investigations on flame dynamics of premixed H2–air mixtures in microscale tubes

RSC Advances ◽

10.1039/c6ra05539g ◽

2016 ◽

Vol 6 (55) ◽

pp. 50358-50367 ◽

Cited By ~ 16

Author(s):

Aravind B. ◽

Ratna Kishore Velamati ◽

Aditya P. Singh ◽

Y. Yoon ◽

S. Minaev ◽

...

Keyword(s):

Heat Transfer ◽

Flame Propagation ◽

Propagation Speed ◽

Wall Heat Transfer ◽

Flame Dynamics ◽

Flame Shape ◽

Flame Propagation Speed

The flame propagation is affected by flame shape angle and wall heat transfer coeff. A minimum flame propagation speed is observed for planar flames with nearly zero flame shape angle for 580 h−2 K−1 wall heat transfer coeff. range.

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Ignition Dynamics in an Annular Combustor With Gyratory Flow Motion

Volume 4B: Combustion, Fuels, and Emissions ◽

10.1115/gt2018-76624 ◽

2018 ◽

Cited By ~ 1

Author(s):

Chenran Ye ◽

Gaofeng Wang ◽

Yuanqi Fang ◽

Chengbiao Ma ◽

Liang Zhong ◽

...

Keyword(s):

Flame Propagation ◽

Velocity Component ◽

Thermal Power ◽

Propagation Speed ◽

Circumferential Velocity ◽

Bulk Velocity ◽

Ignition Process ◽

Flow Motion ◽

Annular Combustor ◽

Flame Propagation Speed

In concepts of integrated design of combustor and turbine, an annular combustor model is developed and featured with multiple oblique-injecting swirling injectors to introduce gyratory flow motion in the combustion chamber. The ignition process is experimentally investigated to study the effects of introducing circumferential velocity component Uc to the light-round sequence. Experiments are carried out with premixed propane/air mixture in ambient conditions. The light-round sequence is recorded by a high-speed camera, which provides detailed flame azimuthal positions during the sequence and gives access to the light-round time τ and the circumferential flame propagation speed Sc. The results have also been compared with that obtained from a straight-injecting annular combustor. The effects of bulk velocity Ub, thermal power P and equivalence ratio Φ are also explored. Due to the gyratory flow motion induced by oblique injection, the flame fronts only propagate along the direction of circumferential flow. Both of the circumferential flame propagation speed increase with increasing bulk velocity in two injection types. It seems mainly to depend on bulk velocity, regardless of Φ, in oblique-injecting combustor when compared with the straight one. It indicates that the circumferential velocity component would play a dominant role in light-round sequence when it is sufficient higher than the displacement flame speed.

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A Comparative Study of Methane Combustion Characteristics with Different Additions in an Optical SI Engine

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4052831 ◽

2021 ◽

Author(s):

Lin Chen ◽

Xiao Zhang ◽

Ren Zhang ◽

Wanhui Zhao

Keyword(s):

Natural Gas ◽

Flame Propagation ◽

Power Output ◽

High Speed ◽

Propagation Speed ◽

Pressure Oscillation ◽

Methane Combustion ◽

Natural Gas Engines ◽

Auto Ignition ◽

Flame Propagation Speed

Abstract Natural gas is a promising fuel for IC engines with minimal modification, whereas its low power output and slow flame propagation speed remain a challenge for automobile manufacturers. To find a method of improving the natural gas engines, methane combustion with different additions was comparatively studied. High-speed direct photography and simultaneous pressure were performed to capture detailed combustion evolutions. First, the results of pure methane combustion confirm its good anti-knock property, and no pressure oscillation occurs even there is an end-gas auto-ignition, indicating that high compression ratio and high boosting are effective ways to improve the performance of natural gas engines. Second, adding heavy hydrocarbons can greatly improve engines' power output, but engine knock should be considered if low anti-knock fuel was used. Third, as a carbon-free and gaseous fuel, hydrogen addition can not only increase methane flame propagation speed but reduce cyclic variations. However, a proper fraction is needed under different load conditions. Last, oxygen-enriched combustion is an effective way to promote methane combustion. The heat release becomes faster and more concentrated, specifically, the flame propagation speed can be increased by more than 2 times under 27% oxygen concentration condition. The current study shall give insights into improving natural gas engines' performance.

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Flame Propagation and Reflections of Pressure Waves through Fixed Beds of RTO Devices: A CFD Study

Industrial & Engineering Chemistry Research ◽

10.1021/acs.iecr.9b04812 ◽

2019 ◽

Vol 58 (51) ◽

pp. 23389-23404 ◽

Cited By ~ 1

Author(s):

Zhengbiao Peng ◽

Jafar Zanganeh ◽

Elham Doroodchi ◽

Behdad Moghtaderi

Keyword(s):

Flame Propagation ◽

Pressure Waves ◽

Fixed Beds

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Investigation of Pressure Rise and Flame Acceleration Characteristics in a Single Channel of Wave Rotor Combustor with Spoilers

International Journal of Aerospace Engineering ◽

10.1155/2019/6259204 ◽

2019 ◽

Vol 2019 ◽

pp. 1-14

Author(s):

Jianzhong Li ◽

Kaichen Zhang ◽

Wei Li ◽

Li Yuan

Keyword(s):

Flame Propagation ◽

Single Channel ◽

Pressure Rise ◽

Propagation Speed ◽

Blockage Ratio ◽

Wave Rotor ◽

Flame Acceleration ◽

Channel Wave ◽

Experimental Rig ◽

Flame Propagation Speed

A simplified single channel wave rotor combustor (WRC) experimental rig was established, in which the spoilers with different blockage ratios (BR) could be conveniently installed and disassembled. The spoilers were firstly used for WRC to improve the pressure rise. The effects of different blockage ratios on the pressure rise and flame acceleration characteristics in a single channel of the WRC were investigated. The addition of spoilers could remarkably improve the pressure rise and flame propagation speed in a single channel of the WRC. While the blockage ratio of the spoiler increases, both pressure rise and mean flame propagation speed are improved. When the spoilers with a blockage ratio of 38.91% are used, the peak pressure increases by 200% compared to that of WRC without the spoilers. When the spoilers of different blockage ratios (23.35%, 31.13%, and 38.91%) are used, it is found that the flame propagation speed is significantly improved with the increasing of the blockage ratio. Specifically, the maximum flame propagation speed reaches 55 m/s, and the maximum mean flame propagation speed is 36.95 m/s. Furthermore, combustion becomes more intense, and the flame is brighter around the spoiler.

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Methane Diffusion in a Porous Environment

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.353.50 ◽

2014 ◽

Vol 353 ◽

pp. 50-55 ◽

Cited By ~ 1

Author(s):

Pavel Staša ◽

Vladimír Kohut ◽

Oldřich Kodym ◽

Zora Jančíková

Keyword(s):

Fluid Dynamics ◽

Geometric Model ◽

Water Layer ◽

Mining Activities ◽

Natural Processes ◽

First Case ◽

Flow Through ◽

Methane Diffusion ◽

The Given ◽

Methane Flow

The paper deals with modeling and simulation of methane flow through the porous environment using the CFD (Computational Fluid Dynamics) software Fluent. We compare three situations, which can occur in areas, where mining activities were closed few years ago, in this article. First case is modeling of methane flow through the rocks. Second event is situation where the thin water layer is situated at the surface. The last one is occurrence of groundwater. The article responds to the need for knowledge of natural processes in the given area and it follows our previous papers [1], [2]. Software Gambit was used for creating a geometric model of the working area, for modeling the flow of gas it was used CFD software, Fluent from ANSYS, Inc..

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