Flame Diagnostics via Acetone-OH Simultaneous PLIF

Strategy to diagnose ultra-lean (ϕ < 0.6) premixed flames by acetone-OH simultaneous PLIF with one-laser and one-detector combination

“…Under the same mixture conditions, the 266 nm excitation line gives reasonable fluorescence intensity, but only in the unburned zone and no fluorescence is observed in the burned zone. By combining excitations of both 266 nm and 283 nm lines, a clear inverse-V shape of the signal "valley" appears as seen in Fig.6 (c), similar to the flame zone described in the previous studies (Nakamura et al, 2005(Nakamura et al, , 2006(Nakamura et al, , 2008. It is confirmed that the additional 266 nm excitation can dramatically improve imaging while reducing the amount of seeded acetone to less than 5 % of total fuel volume, clarity which the previous approach using only excitations at 283 nm line could never access with such a limited amount of acetone.…”

“…In this way, this scheme has an inherent capability to examine ultra-lean (φ < 0.6) flames. Although there have been several studies that applied acetone-OH simultaneous PLIF to combustion studies (e.g., Seitzman et al, 1994, Yip et al, 1994, Tamura et al, 1998, and Sick & Wermuth, 2004; note that most past works applied to non-premixed flames), Nakamura et al, was the first to apply this concept to look for the local flame structure in laminar/turbulent premixed flames and successfully achieved clear imaging of local flamelet thickness and curvature (Nakamura et al 2005). For demonstrative purpose, local extinction occurring under an ultra-lean mixture condition (φ < 0.6) in a weakly-disturbed flow field has successfully captured by this scheme (Nakamura et al 2006).…”

“…On the other hand, authors have proposed a completely different approach to diagnose the premixed flame structure based on the "acetone-OH simultaneous PLIF concept" since 2005 (Nakamura et al, 2005, 2008, Manome et al, 2007. By this scheme, "unburned" and "burnt" zones were simultaneously visualized via acetone seeded into fuel flow and OH generated by combustion, respectively, then, the flame zone was "indirectly" tracked by being sandwiched between them (see Fig.1; referred from Nakamura et al 2008).…”