1993 Fiscal Year Final Research Report Summary
Convective Diffusion of Harmful Gas in Underground Spaces
| Project/Area Number |
04832005
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
社会システム工学
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| Research Institution | Mining College, Akita University |
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Principal Investigator |
MIYAKOSHI Hiroshi Mining College, Akita Univ, Professor, 鉱山学部, 教授 (10006653)
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| Co-Investigator(Kenkyū-buntansha) |
IMAI Tadao Mining College, Akita Univ, Assistant, 鉱山学部, 助手 (00250895)
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| Project Period (FY) |
1992 – 1993
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| Keywords | Harmful Gas / Gas Concentration / Convective Diffusion / Underground Space / Ventilation |
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| Research Abstract |
The purpose of this study is to investigate the characteristics of convenctive diffusions of leak gas in underground rectangular spaces(cavities) which are aside a main airway and ventilated from a single side. Experiments were carried out with the small-scale model leaking the gas(methane) from the center of the end surface of the cavity. The numerical analysis using two-dimensional finite different method has been applied to predict flow pattern and gas concentration in the spaces. The aspect ratio of the cavity D/W(W : cavity width, D : cavity depth) was widely changed in a ranged D/W=0.25-3.
The summary of this study in as follows :
1) For D/W=1, the ventilation flow from the main way was circulated strongly within the whole of the space. The leak gas was also convective diffused by the recirculation flow. The ventilation flow into the space related to this aspect ratio was comparably strong than that of the other aspect ratios.
2) In a ranged 0.25< D/W <0.7, the ventilation flow was circulated within the down stream region of the space, while the leakage was convective diffused within the upper stream region with weak secondary recirculation flow. So the concentration of the leak gas within the upper stream region is comparably high.
3) For D/W >1.25, the leak gas forms the layr by the ceiling within the interior region of the space exept the inlet region in which the strong ventilation flow is circulated.
4) For D/W=1, the calculation results are similar to that of experiments. However, the numerical results are much different from experimental ones for the cases of other aspects. The reason is the effects of 3-dimensional convective flow.
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Research Products
(6 results)
