Using helium smoke as a surrogate of fire smoke for the study of atrium smoke filling

This study developed a method of using pure helium to generate a cold buoyant plume as the surrogate of a fire smoke for the study of the smoke-filling process in an atrium. Aided by the numerical simulations, a series of experiments in a 1:26.5 scale model of the full-size atrium with the fires up to 1.6 MW from the literature were conducted to investigate the similarity between a helium smoke and a hot fire smoke. Helium concentrations, smoke layer heights, and smoke optical densities were compared well between the current experiment and the simulations. The experimental study thus verified the capability of a helium smoke test to reproduce the smoke-filling process of the corresponding hot smoke test in the atrium studied. This study also showed how to model a hot smoke test with a t-squared fire by the corresponding helium smoke test by pre-mixing helium and artificial smoke in a mixing box.