Turbulent flame speed based on the mass flow rate: Theory and DNS

Starting with an integral formulation of average mass flow rate through an ensemble of isotherms constituting a statistically planar, turbulent premixed flame, a scaling for the corresponding turbulent flame speed is derived without invoking Damkiihler's hypotheses. Major approximations and interim results are validated using a large Karlovitz number, unity Lewis number, Direct Numerical Simulation (DNS) dataset of n-heptane/air mixture, computed with reduced chemistry. A length scale quantifying the fluctuation distance of the isotherms within the premixed flame structure is analysed. (c) 2023 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

Automated summary

Starting from an integral formulation of the average mass flow rate through a statistically planar, turbulent premixed flame consisting of isotherms, this study derives a scaling for the corresponding turbulent flame speed without invoking Damkiihler's hypotheses. Major approximations and interim results are validated using a Direct Numerical Simulation (DNS) dataset of n-heptane/air mixture with a large Karlovitz number and unity Lewis number, computed with reduced chemistry. A length scale quantifying the fluctuation distance of the isotherms within the premixed flame structure is analyzed.