In this master's thesis, a three-dimensional numerical model was developed to analyse the atomisation of an incompressible Newtonian fluid with an ideal gas propellant with the Ansys Fluent software. The numerical solution is based on the finite volume method in three dimensions with the volume of fluid method, which includes geometric reconstruction of the contact surface. Turbulence is modelled using the k-ω SST model. The primary droplet breakup is modelled using the Euler-Euler formulation. After the primary breakup, individual droplets are transferred to the Euler-Lagrange discrete particle formulation. The secondary breakup is modelled using the KHRT discrete particle breakup model. An experimental apparatus was constructed to measure the spray angle of urea solution at a liquid flow rate of 0.0463 l/s and air at an overpressure of 2 bar. The spray angle was determined from the spray image using a program code developed for this purpose. The numerical model enables the analysis of quantities that are difficult to determine experimentally due to the complex nature of the two-phase system under consideration. We calculated the flow velocity, droplet size distribution in the axial and radial directions and the urea core length. The calculated droplet size was compared with the technical documentation of the nozzle. The developed numerical model adequately describes the spray angle and droplet size, which are the technologically most important quantities for the selective non-catalytic reduction process where such systems are used.
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