Dissipation Element Analysis of Turbulent Premixed Jet Flames

Abstract

Dissipation element (DE) analysis is a method for analyzing scalar fields in turbulent flows. DEs are defined as a coherent region in which all gradient trajectories of a scalar field reach the same extremal points. Therefore, the scalar field can be compartmentalized in monotonous space-filling regions.The DE analysis is applied to a set of spatially evolving premixed jet flames at different Reynolds numbers. The simulations feature finite rate chemistry with 16 species and 73 reactions. The jet consists of a methane/air mixture with an equivalence ratio φ = 0.7.Statistics of DE parameters are shown and compared to those of a DNS of a non-reacting spatial jet, a non-reacting temporally evolving jet and isotropic homogeneous turbulence.The invariance of the normalized length distribution of the DEs toward changes in Reynolds number observed in non-reacting flows holds for the reacting cases and the characteristic scaling with Kolmogorov micro-scale is reproduced. Furthermore, the DE statistics reflect the influence of the premixed flame structure on the turbulent scalar fields. ARTICLE HISTORY

Dissipation element analysis of non-premixed jet flames

“…The DE analysis was first applied to the DNS of a non-premixed flame by Gauding et al (2017), where DEs were used to compartmentalize regions of the scalar field which are either connected by diffusive flux to the flame front, the turbulent core region or the outer regions of the flow. Additionally, DE analysis was applied to temperature fields by Denker et al (2019) to investigate the effects of the premixed flame front on turbulent scalar fields in a series of premixed jet flames (Luca et al 2019). The source term present in the temperature fields resulted in a distinct departure from the characteristic features of the DE parameters observed in non-reacting flows.…”

“…Additionally, DE analysis was applied to temperature fields by Denker et al. (2019) to investigate the effects of the premixed flame front on turbulent scalar fields in a series of premixed jet flames (Luca et al. 2019).…”