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Explore the numerical simulation of detonation failure and re-initiation in bifurcated tubes using Monotone Integrated Large Eddy Simulation (MILES) methodology. The study involves deflagration, detonation, and DDT, along with equations, reactions, and modeling approach. The code development, testing, detonation simulation, and results in various speed and pressure conditions are detailed, showcasing good agreement with experiments. Learn about the structures of detonation fronts and the intricacies of boundary and initial conditions for accurate simulations.
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Numerical simulation of detonation failure and re-initiation in bifurcated tubes Centre for Fire and Explosion Studies School of Mechanical and Automotive Engineering, Kingston University London A. Heidari and J.X. Wen Centre for Fire and Explosion Studies
Outline • Introduction • Deflagration, Detonation and DDT • Equations, Reaction and Modelling approach • Code development and testing • Detonation simulation • Summery
Combustion waves low speed High speed Deflagrations Detonations Laminar flames Turbulent flames DDT Detonations U 3 m/s 800 m/s 2000 m/s P 0.1 atm 5 atm 20 atm Diffusion of mass and energy Auto-ignition due to shock heating
Governing equations & Numerical modelling Multidimensional, time-dependent, compressible reactive Navier–Stokes equations Modelled: • chemical reactions • molecular diffusion • thermal conduction • viscosity
Turbulence & Numerical modelling • Monotone Integrated Large Eddy Simulation (MILES) “monotone schemes have an inherent truncation error that acts as a numerical diffusion, which can emulate the effects of physical viscosity” • Discretization: Gaussian finite volume integration • Time derivatives: Crank-Nicholson • Van Leer (TVD) scheme for shock capturing
Boundary and initial conditions • Smallest grid size: 10 micron, structured (AMR) • 20 grid points across the detonation half reaction length • Boundary conditions: no-slip reflecting boundaries • Fuel: Hydrogen-Oxygen-diluent mixture • Ignition: a region of high temperature and pressure (T= 2500 K, p= 15 atm) • Single step reactions, 16 kPa, 300 K initial
Detonation propagation in a bifurcated tube C. J. WANG, S. L. XU AND C. M. GUO, “Study on gaseous detonation propagation in a bifurcated tube”, Journal of Fluid Mechanics (2008), 599: 81-110
Summery A solver for simulation deflagration, flame acceleration and detonation is developed and validated. Monotone Integrated Large Eddy Simulation (MILES) is used Structured mesh and Adaptive Mesh Refinement is used to increase the efficiency and reduce the computational cost. Good agreement with experiments and other numerical works is achieved. Detonation failure due to wave diffraction and subsequent detonation re-initiation is simulated and compared against the experimental observation of Wang et. al.