Optical spectroscopic study of diffusive combustion of a suspension of boron nanoparticles in isopropanol in cocurrent oxygen flow

The stationary diffusion combustion of a suspension of boron nanoparticles in isopropanol in cocurrent oxygen flow and the pulsed laser photolytic initiation of this combustion were studied. The experiments were carried out using a number of spectroscopic methods. Coherent anti-Stokes light scattering spectroscopy was used to determine the transverse distributions and concentrations of oxygen molecules diffusing into the fuel jet and the flame temperature change at different distances from the edge of the burner nozzle due to the addition of boron nanoparticles into the fuel. The dimensions zones of laser ignition initiation of the combustible mixture were determined by laser-induced fluorescence spectroscopy of electronically excited $\mathrm{O}_2^*$ molecules. Chemiluminescence spectroscopy of intermediate products of gas-phase reactions ($\mathrm{OH}^*$ and $\mathrm{BO}_2^*$ radicals) from the ignition region made it possible to characterize the spatio-temporal dynamics of this process. The changes 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.