Numerical Simulations on Aerodynamics of Thermally Induced Plumes

Since the physics of air entrainment is not yet clearly understood, most of the fire plume expressions reported in the literature were derived empirically. Experiments with different fire geometry, fuels, and ambient conditions would be difficult when trying to derive comprehensive plume temperature and velocity fields from existing theories. Computational fluid dynamics (CFD), a practical engineering tool in fire engineering, might give a better understanding of the plume behavior. This technique can eliminate factors which are difficult to control in experiments, but would affect the plume movement. Aerodynamics for thermally induced plumes is studied by CFD in this article. Three types of thermal plumes such as axisymmetric plume, balcony spill plume, and door plume are considered. Four axisymmetric plume equations and three balcony spill plume models are assessed by comparing with the CFD results. For door plumes, qualitative results of the mass entrainment rate are obtained. Investigations in this article are useful for fire engineers in designing smoke management systems in an affordable fashion. This is a critical point in implementing an engineering performance-based fire code.