Deflagration-to-detonation transition in an unconfined space

Koksharov, Andrey; Bykov, Viatcheslav; Kagan, Leonid; Sivashinsky, G. I.

doi:10.1016/j.combustflame.2018.03.006

Cited by 28 publications

(10 citation statements)

References 14 publications

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“…Here n s -number of species, ρ -density of the mixture, T -temperature, P -thermodynamic pressure, R 0 -ideal gas constant, c i -concentration of species i, X i -molar fraction, h i -specific molar enthalpy, j d i -molar diffusion flux, µ -shear viscosity of the mixture, λ -thermal conductivity of the mixture,ω i -chemical source of species i, W i -molar mass, Σ -flame folding factor. The thickness of the temperature profile l is chosen such that a minimal ignition energy is provided [24]. Note that equations (2.3) and (2.5) imply the conventional continuity equation, ∂ρ/∂t + ∂ρu/∂x = 0.…”

Section: Mathematical Modelmentioning

confidence: 99%

“…In computations it is implemented by detailed study of the hot spot width l for different values of Σ such that minimising the chosen value of width of the hot spot by 5% leads to an ignition failure. The system is then integrated for different constant values of Σ and internal structure of the accelerating flame front is investigated (for details see [24]). As it was predicted and was shown in a number of works [16,24] there is a critical value of Σ leading to very strong DDT, when an over-driven detonation is formed.…”

Section: Numerical Implementationmentioning

confidence: 99%

“…The system is then integrated for different constant values of Σ and internal structure of the accelerating flame front is investigated (for details see [24]). As it was predicted and was shown in a number of works [16,24] there is a critical value of Σ leading to very strong DDT, when an over-driven detonation is formed. Until this critical value is reached, flames with deflagration flame structure are observed with only a moderate pressure increase between the precursor shock and the flame front.…”

Section: Numerical Implementationmentioning

confidence: 99%

“…In this work, in contrary to our prevision study [24], where the transition to the detonation is reported and investigated in detail, the focus is made on the properties of the transition relevant to the chemical kinetics and to internal structure of the accelerating flame. The method used to integrate system in time is outlined first.…”

Section: Introductionmentioning

confidence: 97%

See 3 more Smart Citations

Study of internal flame front structure of accelerating hydrogen/oxygen flames with detailed chemical kinetics and diffusion models

Bykov

Koksharov

2018

Math. Model. Nat. Phenom.

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The problem of Detonation to Deflagration (DDT) is revisited. A stoichiometric hydrogen/oxygen combustion system is considered. The study focuses on the investigation of the system solution in the thermo-chemical state space of the system. The Σ model is implemented to study the flame acceleration and DDT in 1D formulation. The model was suggested to take into account wrinkling of the flame surface. In this way, the problem becomes treatable numerically even with the detailed mechanism of chemical kinetics and with detailed models for molecular diffusion. In order to treat and integrate the model a recently developed numerical scheme to deal with very stiff systems both in time and in space is introduced and applied. Typical system solution profiles of the ignition, quasi-deflagration, flame acceleration, DDT and detonation stages are considered to study the structure of the flame front in the system thermo-chemical state space. The results of computations show that at the stages of the ignition, deflagration and acceleration the flame structure in the state/composition space moderately depends on Σ, however, significant influence shows up during later stages of the flame acceleration and DDT. Moreover, the path of the solution in the detonation regime significantly deviates from that of deflagration. This means that accurate and quantitative study of the DDT is not possible without reliable mechanisms of chemical kinetics able to describe the system state space during the transient.

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Section: Mathematical Modelmentioning

confidence: 99%

Section: Numerical Implementationmentioning

confidence: 99%

Section: Numerical Implementationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

See 2 more Smart Citations

Study of internal flame front structure of accelerating hydrogen/oxygen flames with detailed chemical kinetics and diffusion models

Bykov

Koksharov

2018

Math. Model. Nat. Phenom.

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“…This is primarily due to the practical importance of studies of the stability for flames subjected to small perturbations: it is instability that is the main cause of flame autoturbulization [2,3] and acceleration [4,5]. In turn, acceleration of the flame can cause its transition to detonation [6][7][8] or to deflagration explosion [9]. Thus, the problem of hydrodynamic flame stability is closely related to the general problem of explosion safety [9][10][11].…”

Section: Introductionmentioning

confidence: 99%

A theoretical study of stability of solid fuel burning with a twophase gasification area

Волков

Makoyed

Loboda

et al. 2020

EEJET

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Theoretically, the combustion stability of solid fuel, which during the combustion process is decomposed according to the "solid phase-liquid phase-gas" scheme, is investigated. The physical and mathematical models for the propagation of small perturbations of combustion are constructed. The medium in all areas of combustion and in combustion products is assumed to be incompressible, and the viscosity of the fuel in the liquid phase is taken into account. Thus, perturbations of hydrodynamic parameters are considered not only in the two-phase gasification zone, but also in the combustion products area and the geometric perturbation of the instantaneous combustion front (flame), distorting the shape of its surface, is also specified. That is the characteristic feature of the presented physical model. The mathematical eigenvalue problem is set and solved. This problem is reduced to an algebraic characteristic equation for a dimensionless complex eigenvalue, which positivity determines the instability. It is proved that in the limiting case of the absence of a liquid phase, absolute instability takes place. At the other limiting case-for perturbations with infinite wavelength-a transition to stability takes place. The latter fact indicates that the presence of a viscous liquid film and changes in the length of the gasification zone under the influence of perturbations have a significant stabilizing effect on solid fuel combustion. In the general case, a sufficient condition for the instability of the roots of the characteristic equation is analytically determined. The physical interpretation of the mathematical results explains the processes of autoturbulization of solid fuel combustion and the possible transition of combustion to deflagration explosion or detonation. The results of the study are in qualitative agreement with experimental data and can additionally be used for theoretical analysis of the stability of the liquid fuel combustion process in the combustion chamber

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Transition of Combustion to Explosion and Decision Support Systems for Explosion Protection

Волков

Kryvchenko

2020

Advances in Intelligent Systems and Computing

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Deflagration-to-detonation transition in an unconfined space

Cited by 28 publications

References 14 publications

Study of internal flame front structure of accelerating hydrogen/oxygen flames with detailed chemical kinetics and diffusion models

Study of internal flame front structure of accelerating hydrogen/oxygen flames with detailed chemical kinetics and diffusion models

A theoretical study of stability of solid fuel burning with a twophase gasification area

Transition of Combustion to Explosion and Decision Support Systems for Explosion Protection

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Deflagration-to-detonation transition in an unconfined space

Cited by 28 publications

References 14 publications

Study of internal flame front structure of accelerating hydrogen/oxygen flames with detailed chemical kinetics and diffusion models

Study of internal flame front structure of accelerating hydrogen/oxygen flames with detailed chemical kinetics and diffusion models

A theoretical study of stability of solid fuel burning with a two­phase gasification area

Transition of Combustion to Explosion and Decision Support Systems for Explosion Protection

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Product

Resources

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A theoretical study of stability of solid fuel burning with a twophase gasification area