According to the field experiment in the anteroom of the emergency staircase, equipped with smoke tower, it is found that smoke and air flow separately as two layers, in which upper layer is smoke and lower layer is air, and that their boundary height is determined by the volumetric ratio of air and smoke.
But, in the field experiment, the conditions of inlet and outlet openings and the volume of air and smoke are limited, so more systematic studies are needed, and this model experiment has been carried out.
In this model experiment it is assumed that, if ratios of air and smoke volume to anteroom volume are equal, flow patterns are same in the model and the field experiment.
Scale of the model is one tenth of that of the field experiment, therefore, the volume of model experiment in l/s corresponds to the volume of field experiments in m
3/s.
Results of this model experiment are as follows.
(1) Flow patterns of smoke and air in the anteroom can be classified in O, A, B, C, D and E types, and criterion of these types depend only on supply air volume.
The types A, B, and C, have two layers flow pattern, in which lower layer is perfect or semiperfect transparent. The upper limit of air supply of this domain is 5.4 l/s.
The type B has perfect transparent lower layer, and the upper and lower limit of the domain of air supply of the type B are 1.5 and 3.5 l/s respectively.
(2) The curve of relation between boundary height and air to smoke ratio in the domain of types A, B and C, converges to two-thirds of the ceiling height with increasing air to smoke ratio.
Therefore, for emergency escape, upper limit of air supply and proper air to smoke ratio are 5.4 l/s and 2 respectively.
(3) Characteristics of vertical temperature distribution in the anteroom do not differ markedly for each type of A, B, C, D and E.
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