Numerical Simulation of the Deflagration to Detonation Transition in a Tube with Repeated Obstacles: Experimental Scale Simulation Using the Artificial Thickened Flame Method

Abstract The Artificial Thickened Flame (ATF) method, which involves artificially increasing the flame thickness so as to simulate with a coarse grid resolution, is applied to reduce the computational cost of predicting the Deflagration to Detonation Transition (DDT) in a tube with repeated obstacles. While simulation results depended on the parameter N (the number of grid points in laminar flame thickness), it was found that N values of more than 10 may be excessive. The results show that the chosen simulation method predicts the flame speed as compared to a reference experiment and captures the detail of the strong ignitions near the corner between the obstacle and the sidewall. The present simulation also captures the wrinkle flame front structure during the acceleration of flame.

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Evaluation of the Accuracy of Selected Syngas Chemical Mechanisms

Journal of Energy Resources Technology ◽

10.1115/1.4029860 ◽

2015 ◽

Vol 137 (4) ◽

Cited By ~ 10

Author(s):

Fahad M. Alzahrani ◽

Yinka S. Sanusi ◽

Konstantina Vogiatzaki ◽

Ahmed F. Ghoniem ◽

Mohamed A. Habib ◽

...

Keyword(s):

Equivalence Ratio ◽

Laminar Flame ◽

Computational Cost ◽

Operating Conditions ◽

Average Error ◽

Operating Pressure ◽

Chemical Mechanisms ◽

Flame Thickness ◽

Reduced Mechanism ◽

Significant Difference

The implementation of reduced syngas combustion mechanisms in numerical combustion studies has become inevitable in order to reduce the computational cost without compromising the predictions' accuracy. In this regard, the present study evaluates the predictive capabilities of selected detailed, reduced, and global syngas chemical mechanisms by comparing the numerical results with experimental laminar flame speed (LFS) values of lean premixed (LPM) syngas flames. The comparisons are carried out at varying equivalence ratios, syngas compositions, operating pressures, and preheat temperatures to represent a range of operating conditions of modern fuel flexible combustion systems. NOx emissions predicted by the detailed mechanism, GRI-Mech. 3.0, are also used to study the accuracy of the selected mechanisms under these operating conditions. Moreover, the selected mechanisms' accuracy in predicting the laminar flame thickness (LFT), species concentrations of the reactants, and OH profiles at different equivalence ratios and syngas compositions are investigated as well. The LFS is generally observed to increase with increasing equivalence ratio, hydrogen content in the syngas, and preheat temperature, while it is decreased with increasing operating pressure. This trend is followed by all mechanisms understudy. The global mechanisms of Watanabe–Otaka and Jones–Lindstedt for syngas are consistently observed to over-predict and under-predict the LFS up to an average of 60% and 80%, respectively. The reduced mechanism of Slavinskaya has an average error of less than 20%, which is comparable to the average error of the GRI-Mech. 3.0. It however over-predicts the flame thickness by up to 30% when compared to GRI-Mech. 3.0. The NO prediction by Li mechanism and the reduced mechanisms are observed to be within 10% prediction range of the GRI-Mech. 3.0 at intermediate equivalence ratio (φ=0.74) up to stoichiometry. Moving toward more lean conditions, there is significant difference between the GRI-Mech. 3.0 NO prediction and those of the reduced mechanisms due to relative importance of the prompt NOx at lower temperature compared to thermal NOx that is only accounted for by the GRI-Mech. 3.0.

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Computational Fluid Dynamics Simulation of Deflagration-to-Detonation Transition in a Full-Scale Konvoi-Type Pressurized Water Reactor

Journal of Nuclear Engineering and Radiation Science ◽

10.1115/1.4037094 ◽

2017 ◽

Vol 3 (4) ◽

Author(s):

Josef Hasslberger ◽

Peter Katzy ◽

Lorenz R. Boeck ◽

Thomas Sattelmayer

Keyword(s):

Initial Conditions ◽

Combustion Process ◽

Computational Cost ◽

Full Scale ◽

Dynamics Simulation ◽

Pressurized Water Reactor ◽

Pressurized Water ◽

Water Reactor ◽

Deflagration To Detonation Transition ◽

Detonation Transition

For the purpose of nuclear safety analysis, a reactive flow solver has been developed to determine the hazardous potential of large-scale hydrogen explosions. Without using empirical transition criteria, the whole combustion process including deflagration-to-detonation transition (DDT) is computed within a single solver framework. In this paper, we present massively parallelized three-dimensional explosion simulations in a full-scale pressurized water reactor (PWR) of the Konvoi type. Several generic DDT scenarios in globally lean hydrogen–air mixtures are examined to assess the importance of different input parameters. It is demonstrated that the explosion process is highly sensitive to mixture composition, ignition location, and thermodynamic initial conditions. Pressure loads on the confining structure show a profoundly dynamic behavior depending on the position in the containment. Computational cost can effectively be reduced through adaptive mesh refinement (AMR).

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RANKING OF FUEL-AIR MIXTURES IN TERMS OF THEIR PROPENSITYTO DEFLAGRATION-TO-DETONATION TRANSITION

PROGRESS IN DETONATION RESEARCH ◽

10.30826/icpcd12a05 ◽

2020 ◽

Author(s):

S. M. FROLOV ◽

◽

V. I. ZVEGINTSEV ◽

V. S. AKSENOV ◽

I. V. BILERA ◽

...

Keyword(s):

Detonation Wave ◽

The Other ◽

Practical Application ◽

Deflagration To Detonation Transition ◽

Other Hand ◽

Pressure Gain Combustion ◽

Reactive Mixture ◽

Detonation Transition ◽

The One ◽

Energy Converting

The term "detonability" with respect to fuel-air mixtures (FAMs) implies the ability of a reactive mixture of a given composition to support the propagation of a stationary detonation wave in various thermodynamic and gasdynamic conditions. The detonability of FAMs, on the one hand, determines their explosion hazards during storage, transportation, and use in various sectors of the economy and, on the other hand, the possibility of their practical application in advanced energy-converting devices operating on detonative pressure gain combustion.

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DEFLAGRATION-TO-DETONATION TRANSITION IN A STRATIFIED SYSTEM “GASEOUS OXYGEN-LIQUID FILM OF N-DECANE”

NONEQUILIBRIUM PROCESSES. Vol. 2. Fundamentals of combustion ◽

10.30826/nepcap2018-2-30 ◽

2020 ◽

Author(s):

S. M. FROLOV ◽

◽

V. S. AKSENOV ◽

I. O. SHAMSHIN ◽

◽

...

Keyword(s):

Liquid Film ◽

Ignition Source ◽

Gaseous Oxygen ◽

Deflagration To Detonation Transition ◽

Operation Process ◽

Continuous Detonation ◽

Smooth Channel ◽

Detonation Transition ◽

Run Up ◽

X 24

Deflagration-to-detonation transition (DDT) in the system “gaseous oxygen- liquid film of n-decane” ' with a weak ignition source was obtained experimentally. In a series of experiments with ignition by an exploding wire that generates a weak primary shock wave (SW) with a Mach number ranging from 1.03 to 1.4, the DDT with the detonation run-up distances 1 to 4 m from the ignition source and run-up time 3 ms to 1.7 s after ignition was observed in a straight smooth channel of rectangular 54 x 24-millimeter cross section, 3 and 6 m in length with one open end. The DDT is obtained for relatively thick films with a thickness of 0. 3-0.5 mm, which corresponds to very high values of the overall fuel-to-oxygen equivalence ratios of 20-40. The registered velocity of the detonation wave (DW) was 1400-1700 m/s. In a number of experiments, a high-velocity quasi-stationary detonation-like combustion front was recorded running at an average velocity of 700-1100 m/s. Its structure includes the leading SW followed by the reaction zone with a time delay of 90 to 190 s. The obtained results are important for the organization of the operation process in advanced continuous-detonation and pulsed-detonation combustors of rocket and air-breathing engines with the supply of liquid fuel in the form of a wall film.

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Flame Speed and Deflagration-Detonation Analysis in Flare Stack and Header

Volume 2: Development and Applications in Computational Fluid Dynamics; Industrial and Environmental Applications of Fluid Mechanics; Fluid Measurement and Instrumentation; Cavitation and Phase Change ◽

10.1115/fedsm2018-83445 ◽

2018 ◽

Author(s):

Philip Diwakar ◽

Jaleel Valappil

Keyword(s):

Ambient Air ◽

Flame Speed ◽

Safety Concerns ◽

Deflagration To Detonation Transition ◽

Detonation Transition

This paper examines safety concerns related to flame speeds when warm relief gas snuffs out the pilot at the flare stack and pulls in ambient air and a spark ignites the vapor in the header. The flame speed essentially determines if the propagating flame speed is a deflagration or a detonation based on whether its subsonic or supersonic. While pipes are sized for deflagrations, they need to be analyzed and tested for detonation pressures and temperatures. Transient CFD calculations help determine the flame speeds, deflagration to detonation transition, pressures and temperatures are compared to pipe specifications and help determine if a detonation leads to a Loss of Containment and suggests mitigations.

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Efficient simulation of flame acceleration and deflagration-to-detonation transition in smooth pipes

Journal of Loss Prevention in the Process Industries ◽

10.1016/j.jlp.2021.104504 ◽

2021 ◽

pp. 104504

Author(s):

C. Wieland ◽

F. Scharf ◽

H.-P. Schildberg ◽

V. Hoferichter ◽

J. Eble ◽

...

Keyword(s):

Flame Acceleration ◽

Efficient Simulation ◽

Deflagration To Detonation Transition ◽

Detonation Transition

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A geostatistical extreme-value framework for fast simulation of natural hazard events

Proceedings of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rspa.2015.0855 ◽

2016 ◽

Vol 472 (2189) ◽

pp. 20150855 ◽

Cited By ~ 6

Author(s):

Benjamin D. Youngman ◽

David B. Stephenson

Keyword(s):

Natural Hazard ◽

Computational Cost ◽

Additive Model ◽

Simulation Method ◽

Value Theory ◽

Extreme Value ◽

Wind Gust ◽

Continuous Space ◽

Statistical Framework ◽

Distribution Parameters

We develop a statistical framework for simulating natural hazard events that combines extreme value theory and geostatistics. Robust generalized additive model forms represent generalized Pareto marginal distribution parameters while a Student’s t -process captures spatial dependence and gives a continuous-space framework for natural hazard event simulations. Efficiency of the simulation method allows many years of data (typically over 10 000) to be obtained at relatively little computational cost. This makes the model viable for forming the hazard module of a catastrophe model. We illustrate the framework by simulating maximum wind gusts for European windstorms, which are found to have realistic marginal and spatial properties, and validate well against wind gust measurements.

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