Investigation of soot nanoparticles during combustion of liquid hydrocarbons with injection of a superheated steam jet into the combustion region

The characteristics of soot particles formed during combustion of liquid hydrocarbons in a laboratory version of an original burner with injection of a superheated steam jet into the combustion region are experimentally studied. The concentration and particle size of soot formed in the burner plume are measured by a diffusion aerosol spectrometer. It is shown that the majority of the primary particles have sizes ranging from 20 to 60 nm. The particle concentration in the external flame rapidly decreases with distance from the burner exit from 10$^8$ to 5 $\cdot$ 10$^6$cm$^{-3}$. The images obtained by transmission electron microscopy demonstrate a chain-branching (fractal-like) structure of aggregates. The primary particles composing these aggregates have a bulbous structure with the interplane distance between the layers smaller than 1 nm. Compact aggregates with sizes up to 500 nm are observed in cooled combustion products. The content of soot in combustion products is 35 mg/m$^3$, and the mean particle mass is 7 $\cdot$ 10$^{-12}$mg. Results measured in the combustion modes with injection of a superheated steam jet and with injection of an air jet are compared.