CFD-modeling of flow in confluence nodes of ventilation units of multi-storey buildings

Abstract

Abstract This paper considers the flow characteristics in ventilation units, which are used in natural ventilation systems of multi-storey residential buildings. Three configurations of ventilation units were considered: standard with straight walls, with a beveled wall and with a guide insert. For each configuration, three sizes of bypass hole at the confluence of flows from the satellite channel and the collection channel were considered. The problem was solved numerically using the CFD Flow3d software package. It was established that for a ventilation unit with a straight wall in the satellite channel, the formation of separation zones that are significant in width and length at the confluence node is typical. The length and width of separation zones affecting the resistance of ventilation unit as a whole increases with the enlarging of the bypass hole size in the collection channel and decreases when using a beveled end wall, that directs the flow upstream of the exhaust air. For the considered geometries of confluence nodes of ventilation units, the relationships between local resistance coefficients and velocity (Reynolds number) in the collection channel are obtained.