Hybrid Large-Eddy Simulation of Detonations in Reactive Mixtures (original) (raw)
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Development and validation of the hybrid code for numerical simulation of detonations
Journal of Physics: Conference Series, 2018
The present paper describes a numerical code for simulation of detonation flows on hybrid computational clusters (CPU/GPU). The code can solve 1D, 2D and 3D unsteady Euler equations for multispecies chemically reacting flows using high-order shock-capturing TVD schemes and a finite-rate chemistry solver. The implementation is based on the OpenMP, MPI and CUDA technologies allowing for both flexibility and computational efficiency of the code. The program is verified on the analytical Zeldovich-von Neumann-Doering solution for the 1D detonation wave in H 2 /O 2 mixture. Some examples of 2D computations are also given.
Numerical Simulations of Mildly Unstable Gaseous Detonations in Small Channels
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Detonation is a complex phenomenon that consists of a shock w ave coupled to reaction zone moving at a high-speed velocity. It has issues in many engineering scie nces such as safety and explosion, aerospace propulsion systems (pulse-, rotatingand oblique-detona ti engines). Detonation wave propagating in a narrow channel filled with a reactive mixture exhibits di fferent flow features and hydrodynamics instabilities with boundary layers effects. The flow resist ance can lead to a detonation velocity deficit compared to the ideal Chapman-Jouguet detonation velocity and can eventually cause the failure of the detonation. Detonation are unstable for most known gaseous c mbustible mixtures. These multidimensional instabilities provide an essential mechanism for de tonation propagation. Different mechanisms were proposed to explain the velocity deficit. Zel’dovich [1 ] proposed an analytical model based on a one-dimensional formalism in which drag forces and heat los ses are considered ...
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Numerical simulations can be the key to the thorough understanding of the multi-dimensional nature of transient detonation waves. But the accurate approximation of realistic detonations is extremely demanding, because a wide range of different scales need to be resolved. This paper describes an entire solution strategy for the Euler equations of thermally perfect gas-mixtures with detailed chemical kinetics that is based on a highly adaptive finite volume method for blockstructured Cartesian meshes. Large-scale simulations of unstable detonation structures of hydrogen-oxygen detonations demonstrate the efficiency of the approach in practice.
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The essentially nonoscillatory (ENO) shock-capturing scheme for the solution of hyperbolic equations is extended to solve a system of coupled conservation equations governing two-dimensional, time-dependent, compressible chemically reacing flow with full chemistry. The thermodynamic properties of the mixture are modeled accurately, and stiff kinetic terms are separated from the fluid motion by a fractional step algorithm. The methodology is used to study the concept of shock-induced mixing and combustion, a process by which the interaction of a shock wave with a jet of low-density hydrogen fuel enhances mixing through streamwise vorticity generation. Test cases with and without chemical reaction are explored here. Our results indicate that, in the temperature range examined, vorticity generation as well as the distribution of atomic species do not change significantly with the introduction of a chemical reaction and subsequent heat release. The actual diffusion of hydrogen is also relatively unaffected by the reaction process. This suggests that the fluid mechanics of this problem may be successfully decoupled from the combustion processes, and that computation of the mixing problem (without combustion chemistry) can elucidate much of the important physical features of the flow.
Computer Physics Communications, 2017
A new solver developed within the framework of OpenFOAM 2.3.0, called rhoCentralRfFoam which can be interpreted like an evolution of rhoCentralFoam, is presented. Its use, performing numerical simulations on initiation and propagation of planar detonation waves in combustible mixtures H 2-Air and H 2-O 2-Ar, is described. Unsteady one dimensional (1D) Euler equations coupled with sources to take into account chemical activity, are numerically solved using the Kurganov, Noelle and Petrova second order scheme in a domain discretized with finite volumes. The computational code can work with any number of species and its corresponding reactions, but here it was tested with 13 chemically active species (one species inert), and 33 elementary reactions. A gaseous igniter which acts like a shock-tube driver, and powerful enough to generate a strong shock capable of triggering exothermic chemical reactions in fuel mixtures, is used to start planar detonations. The following main aspects of planar detonations are here, treated: induction time of combustible mixtures cited above and required mesh resolutions; convergence of overdriven detonations to Chapman-Jouguet states; detonation structure (ZND model); and the use of reflected shocks to determine induction times experimentally. The rhoCentralRfFoam code was verified comparing numerical results and it was validated, through analytical results and experimental data.
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Journal of Hazardous Materials, 1993
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Journal of Hazardous Materials, 1996
The code REACFLOW developed at the JRC Ispra combines advanced numerical techniques for the simulation of transient, multi-dimensional, multi-component gas flows undergoing chemical reactions to a unique tool. It uses a true 2-D discretisation with an unstructured triangular grid to ensure a maximum of flexibility for the representation of complex geometries. The numerical discretisation uses a finite volume scheme based on an approximate Riemann solver. Explicit, implicit and semi-implicit methods cover the whole range of time scales. Compressible and incompressible flow is treated with an arbitrary number of components. Chemical reactions are calculated fully implicitly. Diffusion processes are also modelled using a finite volume equivalence to the finite element Galerkin method. A k-e turbulence model is currently being implemented. A system for dynamic grid adaptation automatically detects locations of refinement and coarsement based on local gradients of flow variables. The code capability will be demonstrated by various applications, including a hydrogen/air explosion in a containment and a 'tulip' flame calculation.