20 kHz CH2O and OH PLIF with stereo PIV

Planar laser-induced fluorescence (PLIF) of hydroxyl ( OH) and formaldehyde (CH2O) radicals was performed alongside stereo particle image velocimetry (PIV) at a 20 kHz repetition rate in a highly turbulent Bunsen flame. A dual-pulse burst-mode laser generated envelopes of 532 nm pulse pairs for PIV as well as a pair of 355 nm pulses, the first of which was used for CH2O PLIF. A diode-pumped solid- state Nd:YAG/ dye laser system produced the excitation beam for the OH PLIF. The combined diagnostics produced simultaneous, temporally resolved two-dimensional fields of OH and CH2O and two-dimensional, three-component velocity fields, facilitating the observation of the interaction of fluid dynamics with flame fronts and preheat layers. The high-fidelity data acquired surpass the previous state of the art and demonstrate dual-pulse burst-mode laser technology with the ability to provide pulse pairs at both 532 and 355 nm with sufficient energy for scattering and fluorescence measurement at 20 kHz. (C) 2018 Optical Society of America