Turbulent flame acceleration-mechanisms and significance for safety considerations

Beauvais, Robert; Mayinger, Franz; Strube, G.

doi:10.1016/0360-3199(94)90158-9

Cited by 10 publications

(4 citation statements)

References 4 publications

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“…Lee et al (1984), Alekseev et al (2001), Silvestrini et al (2008) and Ciccarelli & Dorofeev (2008)). Results show that increasing the BR gives rise to higher flame speeds, due to increased turbulence generation, up to an optimal point where a further increase results in (partial) flame quenching and momentum loss (Beauvais et al 1994). Due to experimental challenges, the applied diagnostics is typically confined to pressure traces and flame arrival times.…”

Section: Introductionmentioning

confidence: 95%

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Fractal Grid Generated Turbulence—A Bridge to Practical Combustion Applications

Hampp

Lindstedt

2016

Fractal Flow Design: How to Design Bespoke Turbulence and Why

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Abstract.Practical applications typically feature high turbulent Reynolds numbers and, increasingly, low Damköhler numbers leading to distributed combustion. Such conditions are difficult to achieve on a laboratory scale that permits detailed experimental investigations. The aerodynamically stabilised turbulent opposed jet flame configuration is a case point -an exceptionally flexible canonical geometry traditionally featuring low turbulence levels. Fractal grids can be used to increase the turbulent Reynolds number, without any negative impact on other parameters, and to remove the classical problem of a relatively low ratio of turbulent to bulk strain. The use of fractal grids to ameliorate such problems is exemplified for fuel lean combustion with combustion regime transitions achieved through the stabilisation of turbulent premixed flames against hot combustion products. An analysis is presented in the context of a multi-fluid formalism that extends the customary bimodal pdf approach to include multiple fluid states. The approach is quantified via simultaneous OH-PLIF and PIV, permitting the identification of five separate states (reactant, combustion product, mixing, mildly reacting and flamelet fluids). The sensitivity of the distribution between the fluid states to threshold values is also evaluated. The work suggests that a consistent treatment of the delineating thresholds is necessary when comparing different types of simulations (e.g. DNS) and experiments for reacting fluids with multiple states. The use of fractal grids in a flame driven shock tube provides a further example and is shown to generate turbulent Re numbers of the order 10 5 for flows with Mach numbers approaching unity. The conditions are of relevance to flame stabilisation in hypersonics and are analysed through OH-PLIF and high speed PIV with optimal fractal grids selected on the basis of maximum flame acceleration.

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Section: Introductionmentioning

confidence: 95%

“…mixture stoichiometry, temperature and pressure) and has been investigated for a number of fuels (Beauvais et al 1994, Ciccarelli & Dorofeev 2008. Studies concerning fuel mixtures are of increasing interest as fuel blending holds significant potential for further enhancement of combustion processes (Williams et al 2007, Lieuwen et al 2008.…”

Section: Introductionmentioning

confidence: 99%

Fractal Grid Generated Turbulence—A Bridge to Practical Combustion Applications

Hampp

Lindstedt

2016

Fractal Flow Design: How to Design Bespoke Turbulence and Why

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“…A flame arrester is usually installed on the branch pipe, exhaust pipe and main pipe in front of the gas generator set. The purpose of this device is to prevent the temper of a gas generator set, a lightning strike at the outlet of an exhaust pipe, fire source caused by friction between gas and pipe wall, and pipe static electricity and other accidents 6‐9 . By absorbing and transferring the heat of the flame, the flame arrester prevents the propagation of the flame, thus avoiding the heavy casualties and property losses caused by the flame propagation 10‐13 …”

Section: Introductionmentioning

confidence: 99%

A novel detonation arrester containing a large disk with long triangular slits: Design and numerical simulation

Yue

Long

Liu

et al. 2020

Process Safety Progress

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Aiming at the problem that common flame arresters can only extinguish deflagration flame, but cannot effectively extinguish detonation flame in large pipelines, this paper proposes a novel structure of detonation arrester based on heat transfer theory to improve the detonation flame extinguishing efficiency. The flame arresting element is composed of a large disk with long triangular slits and is used as the quenching part of detonation arrester in a monolithic structure. Compared with common flame arrester consists of several small fires retarding elements, the proposed monolithic structure is safer due to its integrity. In addition, this paper explores the relationship between flame extinguishing ability, detonation pressure, and temperature change. This investigation determined that the diameter of the quenching part and the parameters(length and height) of the long triangular slits were the key factors affecting the quenching characteristics, and as the diameter and porosity increase, the detonation pressure at the front of the flame arrester will decrease. Finally, the rationality and applicability of the structure are verified by simulation experiments. These preliminary conclusions are helpful to reveal the nature of the proposed structure and solve the technical problem of preventing detonation flame propagation of coal mine gas in large pipelines.

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“…In many industrial applications, contaminant in fuel storage tanks, chemical and radiolytic generation of gases can create sensitive combustibles; under certain conditions the deflagration to detonation transition (DDT) or direct initiation of detonation could occur in these mixtures. Due to the high reaction sensitivity or hazardous properties of hydrogen, these issues are of particular concerns in term of safety [1][2][3][4] and had long been main focus in the field of hydrogen energy research [5][6][7][8][9][10][11][12][13]. In particular, several studies have indeed been performed to understand the combustion and explosion characteristics of the hydrogen-nitrous oxide mixtures, notably at CalTech [14][15][16][17][18], US Bureau of Mines [19] and ICARE [20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Critical energy for direct initiation of spherical detonations in H2/N2O/Ar mixtures

Zhang

Mével

et al. 2011

International Journal of Hydrogen Energy

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Although the detonation phenomenon in hydrogen-nitrous oxide mixtures is a significant issue for nuclear waste storage facilities and development of propulsion materials, very limited amount of critical energy data for direct initiation  which provides a direct measure of detonability or sensitivity of an explosive mixture  is available in literature. In this study, the critical energies for direct blast initiation of spherical detonations in hydrogen-nitrous oxide-Ar mixtures obtained from laboratory experiments and theoretical predictions at different initial conditions (i.e., different initial pressure, equivalence ratio and amount of argon dilution) are reported. In the experiments, direct initiation is achieved via a spark discharge from a high voltage and low inductance capacitor and the initiation energy is estimated accordingly from the current output. Characteristic detonation cell sizes of hydrogen-nitrous oxide-Ar mixtures are estimated from chemical kinetics using a recently updated reaction mechanism. A correlation expression is developed as a function of initial pressure, argon dilution and equivalence ratio, which is fitted to provide good estimation of the experimental measured data. The direct link between cell size and critical energy for direct blast initiation is then analyzed. Good agreement is found between experimental results and theoretical predictions, which make use of the cell size estimation correlation and the semi-empirical surface energy model. The effects of the initial pressure, equivalence ratio and the amount of Ar dilution on the critical initiation energy H 2 -N 2 O-Ar mixtures are investigated. By comparing the critical energies with those of H 2 -O 2 -Ar mixtures, it is shown that H 2 -N 2 O mixtures are more detonation sensitive with smaller initiation energies than H 2 -O 2 mixtures at the same initial pressure, equivalence ratio and amount of argon dilution, except for higher diluted condition with amount of argon in the mixture above 20%. Attempt is made to explain the critical energy variation and comparison between the two H 2 -N 2 O-Ar and H 2 -O 2 -Ar mixtures from the induction length analysis and detonation instability consideration.

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Turbulent flame acceleration-mechanisms and significance for safety considerations

Cited by 10 publications

References 4 publications

Fractal Grid Generated Turbulence—A Bridge to Practical Combustion Applications

Fractal Grid Generated Turbulence—A Bridge to Practical Combustion Applications

A novel detonation arrester containing a large disk with long triangular slits: Design and numerical simulation

Critical energy for direct initiation of spherical detonations in H2/N2O/Ar mixtures

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