Radiative shielding by water mist : Comparisons between downward, upward and impacting injection of droplets

Abstract

Radiative shielding with water curtain has been studied numerically, investigating three different possibilities of droplet injection : downward, upward and impacting on a wall to be protected. The efficiency has been evaluated based on radiation attenuation predicted considering a given incident flux attenuated when crossing the area where water is injected. For upward and downward injection, a simple water curtain is considered. For the impacting spray case, a water film streaming on the wall is considered in addition to the spray (an idealized film with constant and fixed thickness for the moment). The dynamics has been imported from an Eulerian-Lagrangian simulation and radiative transfer has been addressed with a Monte Carlo method. Results show that the upward injection performs better than the downward injection due to a favoring dynamics that increases the residence time of droplets. The impacting spray could be even more efficient owing to the possible high attenuation efficiency of films, but present results still make use of simplifications on the water film falling on the wall and present promising observations require further verification.