Numerical modelling of detonation initiation via shock interaction with multiple flame kernels

In this study, the deflagration-to-detonation transition from the interaction of a shock wave with multiple laminar flame kernels is analyzed computationally. For comparison, both Euler equations and Navier-Stokes equations including the effects of viscosity, thermal conduction and molecular diffusi...

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Bibliographic Details
Main Authors: Bakalis, G., Yuk, K. C. Tang, Mi, X. C., Ng, H. D., Nikiforakis, N.
Format: Conference Proceeding
Language:English
Subjects:
Acceleration
Acetylene
Aerodynamics
Burning rate
Computational fluid dynamics
Computer simulation
Deflagration
Detonation
Diffusion rate
Euler-Lagrange equation
Finite element method
Flame propagation
Flames
Fluid flow
Fluxes
Grid refinement (mathematics)
Kernels
Mathematical models
Molecular diffusion
Navier-Stokes equations
Richtmeyer-Meshkov instability
Shock waves
Simulation
Turbulent flames
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Summary:In this study, the deflagration-to-detonation transition from the interaction of a shock wave with multiple laminar flame kernels is analyzed computationally. For comparison, both Euler equations and Navier-Stokes equations including the effects of viscosity, thermal conduction and molecular diffusion for an acetylene–air mixture model with a single-gas approximation are solved numerically to identify the dominant mechanism on the transition process. A finite-volume operating splitting scheme based on the 2nd order Godunov-type, Weighted Average Flux (WAF) method with an approximate HLLC Riemann Solver and second-order finite differences for the Navier-Stokes fluxes evaluation are used in the present computation. Adaptive mesh refinement (AMR) is employed to dynamically increase the resolution of a simulation in regions of interest around shocks, flame fronts and regions of large gradients in density using a hierarchical grid structure. The simulation results show that repeated shock–multiple flames and shock-boundary interactions lead to the acceleration of the original shock into unreacted material near the wall and subsequently the development of a hotspot explosion center. The Richtmyer-Meshkov instability caused by the interaction of the shock with subsequent flames also generates and maintains a highly turbulent flame brush. In the absence of physical diffusion in the Euler simulation, the enhanced burning rate of the turbulent flame brush is suppressed. Nevertheless, the intense flow fluctuations generated by the interactions of shocks, boundary and flames create the conditions under which deflagration-to-detonation can potentially occur at later times. A numerical study is also carried out to verify the effect of numerical grid resolution.
ISSN:0094-243X
1551-7616
DOI:10.1063/1.5114012