The push-type displacement ventilation in two series-connected chambers

摘要

This research studies buoyancy-driven flow patterns in two series-connected chambers, which have the same height and a common divider. Theoretical analysis categories the ventilation modes of two series-connected chambers as the pull and push types of displacement ventilation, according to an extra resistance force of ventilation due to the unforced chamber. For the pull-type displacement ventilation, there is only a buoyant layer in the forced chamber and the extra resistance force is due to the additional upstream opening(s). This paper focuses on the steady-state push-type naturally displacement ventilation, when the forced chamber is located upstream in two series-connected chambers. For the push-type displacement ventilation, a two-layer stratification develops in both chambers, and the extra resistance force is not only due to the additional opening(s), but also the stratification in the downstream unforced chamber. This paper presents a derived theoretical model and analogous salt-bath experimental results, and shows reasonable agreement between them. Our results show that a different opening level on the unforced side wall changes the properties of both buoyant layers in two chambers. Among the openings on the unforced side wall, only those covered by the buoyant layer of the unforced chamber play the role of the exit, and the theoretical model only takes account of their parts for the push-type displacement ventilation. The effects on the opening area ratio of the unforced chamber and the same reduced area at a different opening location are also investigated in this study.