01. Experimental/Computational Fluid Dynamics

In this research, an extract fan is placed at the ceiling of a room which contains a point source of buoyancy at the floor and two openings, one at the floor level and the other at the ceiling level, respectively. Depending on the imposed extraction flow rate, the ventilation patterns can be divided into two main flow modes, the forward and reverse flow modes, and they are separated by a critical flow rate as presented in a previous study of our research group. This study focuses on developing a theoretical model considering the reverse flow mode, in which three stratification layers are formed due to the strong vertical momentum of the inflowing ambient fresh fluid penetrating through the top buoyant air layer which creates a new layer inside the room. This phenomenon is different from the previous study showing a two-layer stratification flow when an imposed control on the inflow momentum was applied. A new mathematical model that shows the impact of the effective area ratio on the ventilation is presented. The research results allow for a direct comparison of the ventilation performances between the two-layer and three-layer stratification flow models for the reverse flow mode of the hybrid extraction ventilation. Moreover, the developed mathematical model is supported by the laboratory salt-bath experimental observations.