Experimental assessment of the progress variable space structure of premixed flames subjected to extreme turbulence

Flamelet models of turbulent premixed combustion assume that (a) turbulent-transport and processes can be decoupled treated independently, suggesting preheat reaction zones remain layer-like do not become highly fragmented and/or distributed. By further assuming (b) the scalar-structure (e.g. distribution thermochemical quantities, like species mass fraction, vs. a control variable, such as progress variable) flame is akin to in an associated laminar flame, detailed chemical properties introduce into simulation at low computational cost via pretabulated flamelet tables derived from calculations. The authors previously quantified conditions when assumption remains valid. present work assesses for Reynolds numbers exceed those previous studies by ∼ 7 × . Namely, planar laser-induced fluorescence (PLIF) formaldehyde (CH2O), hydroxyl (OH), methylidyne (CH) acquired jointly with Rayleigh scattering are used produce joint PDFs (scatter plots) former variable (CR) latter. Regardless turbulence level piloted Bunsen flames considered here were subjected to, peak-normalized conditional mean (CM) profiles obtained agree well Additionally, within near field modestly flames, two-term β-PDFs found accurately describe CR-distributions. However, agreement between CR-distributions worsens increased axial distance burner. Small discrepancies measured CM calculations also emerged conditions. For instance, under conditions, CH over predict measurements where 0.6 < CR 0.9. Nevertheless, overall good qualitative simulated results supports use flamelet-based extreme turbulence.