The hose reel gun irrigation system is the most popular in Europe. To improve its performance, a good knowledge of the size and spatial distributions of the generated droplets is necessary. The objective of this paper is to investigate the water jet issuing from an irrigation nozzle. In order to model the atomization process close to the nozzle, we used an Eulerian approach of a single turbulent flow representing the liquid-gas mixture. As for a single-phase flow, a mean approach combined with the k-epsilon turbulence model is used and only one system of transport equations for the mixture is solved. The model considers two transport equations, namely, the mean liquid mass fraction equation that controls the liquid dispersion and the mean liquid-gas interface density equation that allows the calculation of the drops size. This equation includes production and destruction terms that represent physical phenomena contributing to the interface stretching and collapse. Optical probes were used to have an experimental description of the phase distribution in the two-phase flow and a database to validate numerical calculations.