High Karlovitz n-Heptane premixed flame DNS: Turbulence Transformation

摘要

The study of premixed turbulent combustion involves turbulence and chemistry independently and more importantly their effects upon one another. The transformation of the turbulence across the flame is not yet well understood and it is common to assume homogeneous, isotropic turbulence before and after the flame. To better understand this complex interaction, direct numerical simulations (DNS) are performed of incoming homogeneous isotropic turbulence interacting with a statistically-stationary, statistically-planar premixed flame. The chemistry of this n-heptane/air flame is captured with a tabulated approach and the Karlovitz number is approximately 300. The integral length scale is nearly equal to the laminar flame thickness, while the smallest turbulent scales are 50 times smaller. The transformation of these turbulent scales is investigated throughout and behind the flame. The results emphasize the strong impact of the density ratio across the flame and show the appearance of anisotropy in the turbulent flow.