Numerical simulation of a water spray—Radiation attenuation related to spray dynamics

Radiation attenuation by a water spray is predicted on the basis of a detailed simulation. First of all, a two-way coupling treatment of the spray dynamics is achieved through an Eulerian–Lagrangian modeling. Droplet distribution combined with water vapor and carbon dioxide volume fractions are then used to compute the radiative properties of the medium. A simulation of radiation propagation is performed, aimed at the computation of the spectral transmittance through the spray. A Monte Carlo technique is used to describe radiation absorption and scattering phenomena for a real droplet polydispersion and an equivalent monodispersion. Numerical results of spray attenuation are compared to experimental data obtained on a laboratory spray with low flow rate. Satisfying accuracy can be obtained for the numerical prediction if a realistic size distribution is used for the pulverization. The mean Sauter diameter and the volumetric fraction of droplets are found to vary with the position in the spray. Tentative predictions with a monodispersion therefore fail in predicting the attenuation ability of the spray at various vertical positions below the injection point.