Characterization of spray parameters and flame stability in two modified nozzle configurations of the SpraySyn burner

One of the key parameters for spray-flame synthesis of nanoparticles with defined properties is the temporal flame stability. Flame pulsation and consequently flame stability strongly depend on spray characteristics (e.g., droplet sizes and velocities), which are directly influenced by the nozzle geometry. This influence is analyzed in this work. For this purpose, the flame stability of the SpraySyn burner (Schneider et al., Rev. Sci. Instr. 2019) with different nozzle geometries is investigated experimentally. Phase-Doppler measurements and high-repetition-rate chemiluminescence imaging are used to investigate spray formation and flame stability at several heights above the burner for two different liquids and two dispersion-gas flows. The converging geometry of the modified nozzle leads to overall smaller droplets and a narrower droplet-size distribution, presumably increasing the flame stability by enhanced evaporation and less interaction between the pilot flame and remaining large liquid lumps. The flame active time and the coefficient-of-variation are considered as two parameters to evaluate flame stability. Compared to the previous SpraySyn configuration, higher flame active time and lower values for the coefficient-of-variation are observed, indicating a more stable flame in this nozzle configuration.& COPY; 2022 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

Automated summary

The temporal flame stability is an important parameter for spray-flame synthesis of nanoparticles. This study investigates the influence of different nozzle geometries on the flame stability of the SpraySyn burner. The converging geometry of the modified nozzle leads to smaller droplets and enhanced evaporation, resulting in a more stable flame.