Vortex Development and Heat Release Enhancement in Diesel Spray Flame by Inversed-Delta Injection Rate Shaping Using TAIZAC Injector 2021-24-0037

The enhancement of vortex development, fuel-air mixing and heat release in diesel spray flame by inversed-delta injection rate shaping, having been predicted via LES simulation with detailed chemical kinetics, is experimentally confirmed for the first time. Newly developed 3-injector TAIZAC (TAndem Injector Zapping ACtivation) injector realizing aggressive inversed-delta injection rate shaping was used for single-shot combustion experiments in a constant volume combustion vessel. Simultaneous high-speed (120,000fps) and high-resolution (1,280 x 704 pixels) laser schlieren and UV OH* chemiluminescence imaging combined with subsequent Flame Imaging Velocimetry (FIV) analysis was employed to elucidate the correlation between vortex development and enhanced heat release. Compared to the conventional rectangular injection rate, the inversed-delta rate shaping case showed a significant enhancement of vortex development, turbulence intensity and heat release, especially in downstream regions of diesel spray flame beyond 30 mm from the ϕ0.133-mm nozzle orifice.