Non-premixed combustion in supersonic turbulent flows - A numerical study for co-flowing H2-air jets

Advanced MHD assisted mixing of reacting streams

“…In this particular but very important practical case the combustion and mixing can develop simultaneously affecting each other [4][5][6] (see also [7] with many example of particular recently performed studies in the field). The combustion as an elementary chemical reaction between fuel and oxidant molecules needs the direct contact (collision) of these molecules.…”

Stabilization of non-premixed flames in supersonic reactive flows

“…A more detailed inspection of the system of Eqs. (1) for ξ and Y leads to different responses depending on the values of the characteristic mixing time scales τ ξ and τ Y . On the IEM mixing lines, the chemical source terms can be neglected with respect to the mixing terms and the system (1) becomes:…”

“…Then, a direct comparison between this chemical time scale and an estimated convection time scale or particle age allows the identification of a self-ignition domain in the composition space. Such a convection time scale or particle age τ a is the time needed by a Lagrangian particle to reach a given value of the mixture fraction ξ from its originating stream of pure oxidizer (0) or pure fuel (1). Its value is obtained by integrating the Lagrangian trajectory along the IEM pathlines as previously proposed by Izard and Mura [11,13].…”

“…The turbulent non-premixed flame that is expected to stabilize within the mixing layers, where favorable conditions are reached, needs to be studied in detail and the phenomena that drive the associated stabilization process must be taken into account in the final modelling proposal. Lagrangian strategies have been previously retained for their robustness and affordable computational costs to describe turbulent mixing and combustion either in supersonic coflowing jets [1] or in a laboratory scramjet geometry [2]. However, these previous studies did not address the modelling of the ignition phenomena associated with the conversion of kinetic energy into thermal energy via the viscous dissipation heating, a mechanism that is likely to affect the early developments of the chemical processes in high Mach number reactive flows.…”