Optical Spectroscopic Study of Diffusion Combustion of a Suspension of Boron Nanoparticles in Isopropanol in Oxygen Coflow

The stationary diffusion combustion of a boron nanoparticle suspension in isopropanol in oxygen coflow and the pulsed laser photolytic initiation of this combustion were studied. Experiments were carried out using a number of spectroscopic methods. Coherent anti-Stokes Raman scattering spectroscopy was used to determine the transverse distributions and concentrations of oxygen molecules diffusing into the fuel jet and the flame temperature variation at different distances from the edge of the burner nozzle due to the addition of boron nanoparticles into the fuel. The dimensions of the region of laser ignition of the combustible mixture were determined by laser-induced fluorescence spectroscopy of electronically excited O molecules. Chemiluminescence spectroscopy of intermediate products of gas-phase reactions (OH* and BO radicals) from the ignition region made it possible to characterize the spatio-temporal dynamics of this process. The variations in the temperature field and ignition dynamics due to the addition of boron nanoparticles are explained based on an analysis of the obtained data. In particular, it is assumed that the characteristic rise in temperature in the region of the flame front is primarily due to an increase in the burning rate of the fuel with nanoparticles.