Analysis of mixing in high-explosive fireballs using small-scale pressurised spheres

After the detonation of an oxygen-deficient homogeneous high explosive, a phase of turbulent combustion, called afterburning, takes place at the interface between the rich detonation products and air. Its modelling is instrumental for the accurate prediction of the performance of these explosives. B...

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Bibliographic Details
Published in:Shock waves 2019-02, Vol.29 (2), p.339-353
Main Authors: Courtiaud, S., Lecysyn, N., Damamme, G., Poinsot, T., Selle, L.
Format: Article
Language:English
Subjects:
Acoustics
Aerodynamics
Afterburning
Chemical reactions
Computational fluid dynamics
Computer simulation
Condensed Matter Physics
Density ratio
Detonation
Engineering
Engineering Fluid Dynamics
Engineering Sciences
Engineering Thermodynamics
Fireballs
Fluid- and Aerodynamics
Fluids mechanics
Heat and Mass Transfer
High temperature
Mathematical models
Mechanics
Organic chemistry
Original Article
Scaling laws
Thermodynamics
Turbulent combustion
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Summary:After the detonation of an oxygen-deficient homogeneous high explosive, a phase of turbulent combustion, called afterburning, takes place at the interface between the rich detonation products and air. Its modelling is instrumental for the accurate prediction of the performance of these explosives. Because of the high temperature of detonation products, the chemical reactions are mixing-driven. Modelling afterburning thus relies on the precise description of the mixing process inside fireballs. This work presents a joint numerical and experimental study of a non-reacting reduced-scale set-up, which uses the compressed balloon analogy and does not involve the detonation of a high explosive. The set-up produces a flow similar to the one caused by a spherical detonation and allows focusing on the mixing process. The numerical work is composed of 2D and 3D LES simulations of the set-up. It is shown that grid independence can be reached by imposing perturbations at the edge of the fireball. The results compare well with the existing literature and give new insights on the mixing process inside fireballs. In particular, they highlight the fact that the mixing layer development follows an energetic scaling law but remains sensitive to the density ratio between the detonation products and air.
ISSN:0938-1287
1432-2153
DOI:10.1007/s00193-018-0814-4