Investigation of turbulent flame structures with advanced PLIF and detection of dark combustion intermediate species with novel IRPS/DFWM

The talk will be consisted of two parts. The first part will focused on the investigation of turbulent flame structures with advanced PLIF techniques. The technical development of the single-shot PLIF imaging of CH and HCO radicals in turbulent flame with improved signal-to-noise ratios will be presented. Application of simultaneous PLIF to a partially premixed and highly turbulent jet flame will be demonstrated as an example. In the second part, spatial resolved techniques for remote, nonintrusive detection of some non-fluorescent (dark) molecular species will be presented. These species include small hydrocarbons like methane, ethane, acetylene, radicals like OH, methyl and hazard gases like HCl. Polarization spectroscopy was utilized by probing their asymmetric H-stretching ro-vibronic transitions in the mid-infrared. IR-DFWM (forward phase-matching mid-infrared degenerate four-wave mixing spectroscopy) with a novel beam arrangement will also be discussed with the potential application to dark molecules detection in harsh environments.