On the characterization of sprays produced by water-mist injectors

The present work is aimed at providing a thorough characterization of the spray produced by a water-mist injector. An experimental investigation on drop-size and flux distribution, initial velocity and spray-cone angle is proposed. These parameters appear to be the most suitable to provide a quantification of atomization and dispersion phenomena in any generic spray. In addition, some numerical simulations of the sprayed flow have been run employing FDS (Fire Dynamics Simulator): its capability of predicting the fluid-dynamics behavior of the spray has been challenged through a comparison with experimental outcomes. An experimental facility has been built to serve as the set for the entire experimental campaign. A typical water-mist nozzle has been inserted and the activity has been focused on one of the available injectors. Laser-based diagnostics has been employed to measure drop size and initial velocity. Most notably, a Fraunhofer-diffraction-based device (Malvern Spraytec) has been used to investigate the former, while the latter has been evaluated through PIV (Particle Image Velocimetry) technique. FDS code has been employed to carry out some simulations of the behavior of the water-mist spray. The implemented settings and initial conditions resulted from the experimental study, while the computational domain has been set to reproduce the test room. Then, numerical predictions have been validated through a comparison with experimental outcomes. In addition, a classic correlation to predict characteristic drop size has been proposed for the present case and validated