A critical study on fire-induced aerodynamics and design on smoke management system for atria

As atrium fires are not yet well understood, it is doubtful whether the fire safety provisions would work as expected. Of all the key fire aspects, fire-induced aerodynamics and smoke management systems are very important and studying these two aspects becomes the objective of this thesis. It is still not clear about the scenarios to be considered in designing smoke management systems, leading to arguments on using an axisymmetric plume, a balcony spill plume or a window plume.; Some fire safety designs in an open atrium void are conflicting with each other. Natural smoke filling in atrium space and spreading throughout the building should be studied for solving that problem. This relies on a good understanding of fire-induced aerodynamics. A comprehensive design guide for smoke control in atrium buildings cannot be developed without in-depth investigations.; This thesis starts with a critical review on atrium smoke management systems. Design guides and practices were reviewed and the key scientific aspects were identified. In designing smoke management systems, smoke movement in the atrium under typical fire scenarios should be understood first. Scenarios involving a fire located on the atrium floor to give an axisymmetric plume; and a fire in a room adjacent to the atrium to give a balcony spill plume were then analyzed. As there are few research works on spill plumes, there are still many uncertainties regarding this kind of plume. The dynamics of axisymmetric plumes and balcony spill plumes was studied in this thesis by Computational Fluid Dynamics (CFD) with the Reynolds Averaging Navier Stokes (RANS) approach. Different empirical plume models were evaluated by the predicted results. Selection of appropriate plume models for smoke control design is outlined.; Smoke movement in an atrium was then studied by a zone modelling approach with an axisymmetric plume. Smoke filling was also studied with CFD. More practical scenarios such as balcony spill plumes were also investigated by zone models. A two-layer zone model, CL-Atrium was developed for studying the smoke filling process in an atrium due to a balcony spill plume. There, four spill plume models were compared under different fire conditions. Using this model, the smoke layer temperature and the rate of descending could be predicted to get the available evacuation time. All these four models are possible choices in CL-Atrium. (Abstract shortened by UMI.)...