This paper describes the development of a simplified model for pressure evolution inside a closed volume during a combustion process in presence of a water spray. The model is based on empirical correlations available in the literature. These ingredients allow us to estimate the values for the main factors influencing the pressure evolution. The results of this model are used as a guideline for adjusting the parameters ofa three-dimensional hydrodynamic code based on CREBCOM combustion model,developed and validated for large-scale hydrogen combustion. The methodology is successfully assessed by comparing the computed results with the experimental data.