We study the dynamics and properties of a turbulent flame , formed in the presence of subsonic , high-speed , homogeneous , isotropic Kolmogorov-type turbulence in an unconfined system .
Direct numerical simulations are performed with Athena-RFX , a massively parallel , fully compressible , high-order , dimensionally unsplit , reactive-flow code .
A simplified reaction-diffusion model represents a stoichiometric H _ { 2 } -air mixture .
The system being modeled represents turbulent combustion with the Damköhler number Da = 0.05 and with the turbulent velocity at the energy injection scale 30 times larger than the laminar flame speed .
The simulations show that flame interaction with high-speed turbulence forms a steadily propagating turbulent flame with a flame brush width approximately twice the energy injection scale and a speed four times the laminar flame speed .
A method for reconstructing the internal flame structure is described and used to show that the turbulent flame consists of tightly folded flamelets .
The reaction zone structure of these is virtually identical to that of the planar laminar flame , while the preheat zone is broadened by approximately a factor of two .
Consequently , the system evolution represents turbulent combustion in the thin-reaction zone regime .
The turbulent cascade fails to penetrate the internal flame structure , and thus the action of small-scale turbulence is suppressed throughout most of the flame .
Finally , our results suggest that for stoichiometric H _ { 2 } -air mixtures , any substantial flame broadening by the action of turbulence can not be expected in all subsonic regimes .