Effects of small-scale heat release on turbulence scaling in premixed and nonpremixed flames

MacArt, Jonathan F., Grenga, Temistocle and Mueller, Michael E. (2016) Effects of small-scale heat release on turbulence scaling in premixed and nonpremixed flames. 2016 Spring Technical Meeting of the Eastern States Section of the Combustion Institute, ESSCI 2016, , Princeton, United States. 13 - 16 Mar 2016.

Abstract

The effect of combustion heat release on small scales of turbulence is studied using static statistical analysis of low Mach number Direct Numerical Simulations (DNS) of hydrogen turbulent planar jet flames, both premixed and nonpremixed. For the premixed flames, the central fuel/air jet is surrounded by turbulent co-flows of equilibrium combustion products to ensure a constant mixture fraction and high turbulence intensity. For the nonpremixed flames, the central fuel jet is surrounded by turbulent co-flows of air in order to ensure high turbulence intensity. The calculations are performed with detailed chemistry and detailed transport, and grid convergence tests verify that the calculations are fully resolved. Previous scaling studies have suggested that the dilatation from small-scale heat release has a much more significant effect on the turbulence dynamics in premixed flames than in nonpremixed flames, with the turbulence in nonpremixed flames being scaled with Kolmogorov/Batchelor scales but in premixed flames being scaled with flame scales. The validity and applicability of this hypothesis is verified against the DNS data using density-weighted energy spectra in both reacting and nonreacting portions of the flame domains.

This record has no associated files available for download.

Contributors

Author: Temistocle Grenga

Download statistics