Damköhler number scaling of active cascade effects in turbulent premixed combustion
نویسندگان
چکیده
Effects of combustion heat release on turbulent velocity and scalar statistics are investigated as a function the Damköhler number using three direct numerical simulation databases spatially developing premixed jet flames. At low Karlovitz numbers, where heat-release effects dominate kinetic energy budgets, their relative significance scales with integral in priori Reynolds-Averaged Navier–Stokes (RANS) filter Large Eddy Simulation (LES). The Damköhler-number scaling counter-gradient transport this regime follows theoretical arguments underpinning linear-algebraic turbulence models, which explains efficacy at numbers. Conversely, moderate LES subfilter is more strongly influenced by than analogous large-scale RANS turbulence. This consistent notion an “active cascade,” postulates that heat-release-induced volumetric expansion competes intermediate classical forward-cascade transfer. exposes these dynamics dominant subfilter-scale physics, unlike RANS, they secondary to mean-shear production large scales. interactions promoted itself, modifies spectral basis incorporating local flame-normal averaging. highlighted comparing fields obtained 3D those modified 2D filter, excluding direction, significantly reduces apparent influence but not representative practice. modeling challenges posed distinctions numbers order-unity remain be understood.
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ژورنال
عنوان ژورنال: Physics of Fluids
سال: 2021
ISSN: ['1527-2435', '1089-7666', '1070-6631']
DOI: https://doi.org/10.1063/5.0039119