Stability of large room airflow structures in a ventilated room

ABSTRACTThis paper presents a new set of experimental data for different kinds of room airflows in a ventilated room. The data are used to examine Archimedes number effects on the behaviour of large-scale flow structures and their stability versus time. All experiments are performed in a simplified room geometry, representing a small meeting room, a train or an airplane cabin. The supply air is introduced at the ceiling and the exhaust air leaves the room at the bottom zone. The heating power is realised by four controllable heat sources in the lower part of the model room. The experimental investigations apply different supply air set-ups as well as changing supply air velocities and a variation of the heating power. The data of the experiments indicate that the room geometry-based Ar number can be used to distinguish between unstable to stable room airflow structures. Low velocities and high thermal loads cause time depended, unstable room airflows. Neither the forced nor the free convection dominates t...