Effect of the discrete nature of heat sources on flame propagation in particulate suspensions

Goroshin, Samuel; Lee, J.H.S.; Shoshin, Yuriy

doi:10.1016/s0082-0784(98)80468-2

Cited by 48 publications

(34 citation statements)

References 5 publications

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“…An analogous spectrum of propagation regimes is identified in flame propagation in reactive media with spatially discrete or point-like sources. [20][21][22][23][24][25][26] A physical parameter, τ c , which is the ratio between the heat release time of each source and the characteristic time of heat diffusion between neighboring sources, is used to characterize the corresponding flame propagation regime. Similarly, in this system of discrete source detonations, single-step Arrhenius kinetics with a finite reaction rate permit us to measure the time over which a discrete source (layer or square) releases its chemical energy, t r .…”

Section: B Evaluation Of τ Cmentioning

confidence: 99%

Propagation of gaseous detonation waves in a spatially inhomogeneous reactive medium

Higgins

et al. 2017

Phys. Rev. Fluids

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Detonation propagation in a compressible medium wherein the energy release has been made spatially inhomogeneous is examined via numerical simulation. The inhomogeneity is introduced via step functions in the reaction progress variable, with the local value of energy release correspondingly increased so as to maintain the same average energy density in the medium, and thus a constant Chapman Jouguet (CJ) detonation velocity. A one-step Arrhenius rate governs the rate of energy release in the reactive zones. The resulting dynamics of a detonation propagating in such systems with one-dimensional layers and two-dimensional squares are simulated using a Godunov-type finite-volume scheme. The resulting wave dynamics are analyzed by computing the average wave velocity and one-dimensional averaged wave structure. In the case of sufficiently inhomogeneous media wherein the spacing between reactive zones is greater than the inherent reaction zone length, average wave speeds significantly greater than the corresponding CJ speed of the homogenized medium are obtained. If the shock transit time between reactive zones is less than the reaction time scale, then the classical CJ detonation velocity is recovered. The spatio-temporal averaged structure of the waves in these systems is analyzed via a Favre averaging technique, with terms associated with the thermal and mechanical fluctuations being explicitly computed. The analysis of the averaged wave structure identifies the super-CJ detonations as weak detonations owing to the existence of mechanical non-equilibrium at the effective sonic point embedded within the wave structure. The correspondence of the super-CJ behavior identified in this study with real detonation phenomena that may be observed in experiments is discussed. * Corresponding author: andrew.higgins@mcgill.ca 2

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Section: B Evaluation Of τ Cmentioning

confidence: 99%

Propagation of gaseous detonation waves in a spatially inhomogeneous reactive medium

Higgins

et al. 2017

Phys. Rev. Fluids

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“…[8][9][10][11][12][13][14] This approach has generated a number of unique results that would not be encountered in traditional flame theory, such as a limit to flame propagation in adiabatic systems that is distinct from the classical thermodynamic limit. [12][13][14] Experimental results showing an independence of flame speed on oxygen concentration for fuel particulates in suspension in a gaseous mixture has provided experimental validation of another prediction of discrete-source flame theory.…”

Section: Introductionmentioning

confidence: 99%

Influence of discrete sources on detonation propagation in a Burgers equation analog system

Higgins

2015

Phys. Rev. E

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An analog to the equations of compressible flow that is based on the inviscid Burgers equation is utilized to investigate the effect of spatial discreteness of energy release on the propagation of a detonation wave. While the traditional Chapman-Jouguet (CJ) treatment of a detonation wave assumes that the energy release of the medium is homogeneous through space, the system examined here consists of sources represented by δ-functions embedded in an otherwise inert medium. The sources are triggered by the passage of the leading shock wave following a delay that is either of fixed period or randomly generated. The solution for wave propagation through a large array (10 3 -10 4 ) of sources in one dimension can be constructed without the use of a finite difference approximation by tracking the interaction of sawtooth-profiled waves for which an analytic solution is available. A detonation-like wave results from the interaction of the shock and rarefaction waves generated by the sources. The measurement of the average velocity of the leading shock front for systems of both regular, fixed-period and randomized sources is found to be in close agreement with the velocity of the equivalent CJ detonation in a uniform medium wherein the sources have been spatially homogenized. This result may have implications for the applicability of the CJ criterion to detonations in highly heterogeneous media (e.g., polycrystalline, solid explosives) and unstable detonations with a transient and multidimensional structure (e.g., gaseous detonation waves).

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“…T ∞ =300 K and T f = 3700 K are the considered values [15]. i, j and k denote the number of layers from the specific particle to any particle along each axis.…”

Section: Governing Equations 211 Conduction Heat Transfermentioning

confidence: 99%

“…The flame propagation speed is defined as the ratio of the space between two adjacent layers to the difference of their ignition times [26]. As mentioned earlier, since micron-sized particles are being dealt with, the formulation presented by Glassman and Yetter [27] is utilized here.…”

Section: Governing Equations 211 Conduction Heat Transfermentioning

confidence: 99%

“…Goroshin et al [15] studied the effects of the discrete nature of heat sources on flame propagation in particulate suspensions. They illustrated the effect of the discrete nature of the heat sources on flame propagation by comparing flame speeds calculated both from continuous and discrete models in lean Aluminium and Zirconium particle-gas suspensions.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Modeling Flame Propagation of Coal Char Particles in Heterogeneous Media

Bidabadi

Mohammadi

Bidokhti

et al. 2015

Period. Polytech. Chem. Eng.

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Effect of the discrete nature of heat sources on flame propagation in particulate suspensions

Cited by 48 publications

References 5 publications

Propagation of gaseous detonation waves in a spatially inhomogeneous reactive medium

Propagation of gaseous detonation waves in a spatially inhomogeneous reactive medium

Influence of discrete sources on detonation propagation in a Burgers equation analog system

Modeling Flame Propagation of Coal Char Particles in Heterogeneous Media

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