Flow structures and Reynolds number effects in a simplified ventilated room experiment

Abstract

Despite a variety of investigations, precise calculations of room airflows are still only possible to a limited extent. However, since the airflow in a room is decisive for the thermal comfort within that room, it is of particular interest to acquire comprehensive knowledge of the room airflow structures for different boundary conditions. In the model room shown here, extensive experiments were carried out in order to draw conclusions about the flow structures. By varying the supply air velocity and the thermal loads, different two- and three-dimensional flow structures can be observed. In case of isothermal boundary conditions and low supply air velocities, the flow field is partly depending on Reynolds number effects. There are regions within the flow field whose mean velocities do not scale linearly with the supply air velocity. The experiments indicate that the minimum supply flow rate for a Reynolds number independent flow field can be estimated by a Reynolds number based on the cross-sectional surface of the supply jet. Depending on the heat flux emitted by the heat sources in the room, large-scale eddies dominate the overall flow structures at higher supply air velocities. Lower flow velocities leads to undefined flow pattern.