Experimental Study on Single-sided Ventilation Characteristics in Rectangular Spaces with Various Shapes

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  • 多様な形状を有する空間の片側換気特性に関する実験的研究
  • タヨウ ナ ケイジョウ オ ユウスル クウカン ノ カタガワ カンキ トクセイ

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Abstract

This paper describes the single-sided ventilation characteristics in rectangular spaces which are constructed aside an airway. The experiments were carried out using small models of rectangular spaces. The methane was flowed out from the center at the end surface of each space using a gas flow system controlled by a computer. The distributions of the gas concentration and the ventilation characteristics, such as age-of-air, amount of ventilation air and air-exchange rate of the spaces, were measured for the spaces with various aspect-ratios, D/W, where D is depth and W is inlet width along the airway. The summary of the present experiments is as follows: 1) The ventilated space of each shape is roughly classified into three regions based on the results of the observations using tuft, the distributions of averaged and r.m.s. values of gas concentration that are affected by the ventilation flow with three dimensional structure (see Figs. 5 and 7). 2) The amount of ventilation air or ventilation efficiency, Q_v, is roughly proportional to the inlet width W of the spaces. Its relationship between Q_v and W is expressed as Eq. (4). However, the amount of ventilation air of the square shape is considerably large compared with that of other shapes. 3) The air-exchange rate, N, is roughly inverse proportion to the depth D under a constant inlet width W. Its relationship between N and D is expressed as Eq. (6). 4) For the spaces with square shape, ventilation flow from the airway is circulated within the whole of the space. The gas is well diffused by this recirculated ventilation flow. 5) For the spaces with shallow shapes (D<0.7W), the ventilation flow is circulated mainly within the downstream region of the space, then the gas is convective-diffused within the upper stream region. 6) For the spaces with deep shapes (D>1.5W), the gas concentration keeps relatively high level in the interior region near the end-surface except the inlet region of the space in which the ventilation flow is circulated.

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