Numerical simulations to compute the actual delivered density (ADD), water density reaching the base of a fire, were conducted for a sprinkler located directly over a fire source. Two sets of equations, gas phase and liquid phase, were solved in conjunction with the ''particle source-in-cell'' (PSI-CELL) method. The computational codes employed were PHOENICS for the gas flow, which was generated by a thermal plume, and GENTRA for the liquid particles, which were traced by the Lagrangian description. The simulation of the fire and the sprinkler spray interaction was performed by numerically superposing a steady water spray on a steady thermal plume. The penetration of the drops along the center regions of the plume was successfully predicted. Although the agreement between the simulation and the measurement was good in the center pan region, it was less satisfactory in the outer plume area, predicting higher penetration of the water droplets than the measurements indicated.