Laser induced fluorescence spectroscopy of aromatic species produced in atmospheric sooting flames using UV and visible excitation wavelengths

Soot modeling of counterflow diffusion flames of ethylene-based binary mixture fuels

“…Note, however, that since the particle sizes are comparable in the four tested flames, a relative comparison among the cases with ethylene fuel and binary fuel mixtures may not be influenced by the choice of constantm. Recent studies [84][85][86] have indicated that large PAH species could also absorb light in the visible range and thus may interfere with light extinction caused by soot particles. According to [84], the level of extinction may differ by about 20% between the wavelengths of light of 532 nm and 1064 nm in a premixed flame where soot (SVF around 0.7 ppm) coexisted with large PAHs in the post-flame zone.…”

Influence of soot aggregate size and internal multiple scattering on LII signal and the absorption function variation with wavelength determined by the TEW-LII method

“…The other is that the two investigated flames (premixed in the present 1 3 study and diffusion in the study of López-Yglesias et al) are likely to present different spatial structuration in terms of chemical structures mapping (localization of PAH's, soot precursors, and soot). This kind of differences has been put in evidence by using laser-induced fluorescence excited from UV to visible [35].…”

“…A stabilization steel plate was placed at 20 mm above the burner exit surface, and a nitrogen flow through a co-annular porous sintered matrix was used to help stabilization of the sooting flame and prevent the formation of an outer diffusion flame. Further details of the experimental conditions to generate the flame were described in [35]. …”

“…In order to measure the ratios of laser pulse energy leading to E(m, λ)/E(m, 1064 nm), temporally and spectrally resolved LII signals were acquired for each laser excitation configuration using the same LII detection arrangement [1]. Briefly, the time-resolved LII (TiRe-LII) measurements were taken with a photomultiplier tube (500 LII time decays averaged with a detection bandpass filter centered at 720 nm to avoid any laser-induced fluorescence, LIF, signal coming from PAH and/or soot precursors in the flame at λ laser = 266 nm [35]). LII spectra were obtained by means of imaging spectrograph coupled to an ICCD camera (60 ns delayed after the peak of the laser pulse with a gate width set to 50 ns to avoid LIF or any other laser-induced nonincandescence signals), with the photomultiplier tube and the camera being connected simultaneously to the two exit ports of the spectrograph.…”

Time-resolved spatial patterns and interactions of soot, PAH and OH in a turbulent diffusion flame

“…3 example from [13] (although for a different pumping scheme) and as can be verified by operating in an off-resonance mode. When the laser does not match an OH absorption line, there is essentially no signal.…”