Time-resolved conditional flow field statistics in extinguishing turbulent opposed jet flames using simultaneous highspeed PIV/OH-PLIF

Time-resolved particle image velocimetry (PIV) and planar laser-induced fluorescence (PLIF), both at 5 kHz, were applied simultaneously on extinguishing turbulent opposed jet flames. This repetition rate allowed tracking of transient extinction events in turbulent combustion. The additional information acquired about time history enabled a study of the evolution of vortex-flame interactions leading to extinction from individual events. A newly introduced multidimensional conditioning technique to avoid spatial- and temporal-smearing of important flow field information was developed in order to compare individual extinction events in a meaningful, statistical manner. The conditional statistics show that vortices tend to align around the flame and generate regions of high strain in the region where the flame is about to extinguish.