Reduction of the droplet luminosity in the formaldehyde PLIF of acetone spray flame

Abstract

Formaldehyde planar laser-induced fluorescence (HCHO-PLIF) is performed in a spray flame of acetone in a canonical burner. The laser interaction with the acetone droplets results in the additional contribution that interferes with the HCHO-PLIF signal of interest and limits the applicability of the technique. The spectral analysis of the droplet interference contribution shows four intense peaks corresponding to the stimulated Raman scattering (SRS) of the vibrational stretch of C-H bond. In this paper, we show that by doping the acetone with Rhodamine 6G, the SRS contribution is greatly suppressed. Quantitative measurements of the SRS interference contribution on the HCHO-PLIF signal are presented for two different dye concentrations, over a wide range of laser pulse energies, and with different filters combinations.