Swirling turbulent non-premixed flames of methane: Flow field and compositional structure

A priori investigation of PDF-modeling assumptions for a turbulent swirling bluff body flame (‘SM1’)

“…The present study deals with a direct statistical analysis of experimental scatter data for the swirling non-premixed methane/air bluff-body flame 'SM1' [1][2][3][4][5][6], in the context of the popular non-premixed combustion modeling concept of mixture fraction and progress variable. For the flame studied, the scatter data in composition space, taken at fixed locations in physical space, is similar to what is observed in jet type flames with a substantial amount of local exinction, such as Sandia Flames E and F [7][8][9] in that there is strong deviation from steady-flamelet type lines in composition space (corresponding to little or no local extinction).…”

Effects of Swirl on Intermittency Characteristics in Non-Premixed Flames

“…A schematic diagram of the experimental burner is given in Figure 1 (Kalt et al 2002, AlAbdeli and Masri, 2003, Masri et al 2004. The burner has a fuel jet of diameter 3.6mm surrounded by a bluff body of D=50mm diameter.…”

“…In our computations we assumed x mm as axial distance and r mm as radial distance. In the present study only the pure methane SM1 flame from the experimental data base (Kalt et al 2002, Al-Abdeli and Masri, 2003, Masri et al 2004) is considered, which has a fuel jet velocity of 32.7m/s with a swirl number S=0.5. The flame contains two recirculation zones, the first closer to the bluff body which stagnates at about 43mm and the second further downstream which stagnates at 70mm on the centreline.…”

“…Therefore selecting a stoichimetric mixture fraction value as a threshold could help to determine the similarities and differences between the mixture 23 fraction and temperature intermittency. Here we used a threshold value of 0.054 th f  which is a stoichiometric mixture fraction for pure methane SM1 swirling flame (Kalt et al 2002, Al-Abdeli andMasri, 2003). As seen in Figure 18 the radial variation of the mixture fraction intermittency follows a Gaussian shape at all axial locations for all three cases.…”

“…The swirl burner used in this work is the Sydney burner (Al-Abdeli and Masri, 2003, Kalt et al 2002, Masri et al 2004, which is frequently used in modelling unconfined swirling flames. Our previous LES investigations targeted some of the Sydney flames for LES validation (Malalasekera et al 2007(Malalasekera et al , 2008 and instability analysis of swirling flames (RangaDinesh et al 2009).…”