Calculation of the spray supply system characteristics for obtaining film material by spray-pyrolysis

Mathematical models of the main characteristics of a spray atomizer have been developed, namely: dispersion characteristics that define the torch (the spray flow from the nozzle) as a certain set of particles of different sizes; distribution characteristics that reflect the profile of specific liquid flows across the torch cross-section; shape characteristics that allow determining the dimensions of the torch at a given distance from the sprayer. These characteristics have been calculated for a pneumatic nozzle and the calculation results have been compared with experimental data, which confirmed the adequacy of the developed models. Based on calculations, it was found that the spray droplet diameter distribution curve obeys the log-normal distribution, the median spray droplet diameter is 754 μm, the most common diameter is 249 μm. The average droplet evaporation time is about several minutes. A system of nonlinear differential equations for the motion of aerosol particles in a spray torch was obtained, which made it possible to determine its parameters. When deriving the equations, the following assumptions were made: aerosol particles have a spherical shape, the particles move at low Reynolds numbers, and the drag force is determined by the Stokes formula. As a result of the numerical solution of the nonlinear equations system, an equation for calculating the distance of a spray droplet movement in the direction perpendicular to the torch axis, which made it possible to estimate the law of the torch spray density distribution was found. The effect of the spray torch parameters (torch height and spray angle) on the type of irrigation curves was revealed. The obtained results are in good agreement with the experimental data obtained by the authors of the article, as well as with the results given in scientific sources. A technological and functional scheme for obtaining transparent conductive thin films is proposed.