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Influence of Air Duct Arrangement on Gas Concentration in the Large-section Gas Tunnel
(1 Safety Engineering College, Chongqing University of Science and Technology, Chongqing 401331; 2 Chongqing Energy Investment Group Science & Technology Co., Ltd., Chongqing 400060; 3 China University of Mining & Technology (Beijing), Beijing 100083)
Abstract In order to optimize the air duct arrangement for the large-section gas tunnel to improve ventilation con? dition at tunnel face, a calculation of required air volume and selection of fan type were conducted by taking the Liangfengya tunnel as an example, then a hydrodynamic analysis model was established by FLUENT software to study the variation laws of gas concentration and air velocity of the large-section tunnel and the effect of air duct arrangement on airflow field and gas distribution in condition of forced ventilation, in consequence the optimal arrangement of air duct was determined. The results show that for the large-section gas tunnel the distributions of gas concentration and air velocity are very uneven in the same section; the influence range of recirculation zone in the large-section gas tunnel is positively related to the distance between air duct and tunnel face; the distance between the place where gas concentration is stable and tunnel face increases with an increase of the distance between air duct and tunnel face; for this tunnel the optimum distance from the outlet of air duct to the tunnel face is about 2.5 S（30 m） and it is 15-20 m longer compared with that of the small-section tunnel, the place where gas concentration is the lowest is around 2 m away from the tunnel face; The gas concentration at the tunnel section shows a tendency of‘decrease-increase-balance?? with an increasing of Ly.
Abstract：
In order to optimize the air duct arrangement for the large-section gas tunnel to improve ventilation con? dition at tunnel face, a calculation of required air volume and selection of fan type were conducted by taking the Liangfengya tunnel as an example, then a hydrodynamic analysis model was established by FLUENT software to study the variation laws of gas concentration and air velocity of the large-section tunnel and the effect of air duct arrangement on airflow field and gas distribution in condition of forced ventilation, in consequence the optimal arrangement of air duct was determined. The results show that for the large-section gas tunnel the distributions of gas concentration and air velocity are very uneven in the same section; the influence range of recirculation zone in the large-section gas tunnel is positively related to the distance between air duct and tunnel face; the distance between the place where gas concentration is stable and tunnel face increases with an increase of the distance between air duct and tunnel face; for this tunnel the optimum distance from the outlet of air duct to the tunnel face is about 2.5 S（30 m） and it is 15-20 m longer compared with that of the small-section tunnel, the place where gas concentration is the lowest is around 2 m away from the tunnel face; The gas concentration at the tunnel section shows a tendency of‘decrease-increase-balance?? with an increasing of Ly.
LIU Chun1 DU Junsheng1 GUO Chenye1,
2,
3 LIU Shang1
.Influence of Air Duct Arrangement on Gas Concentration in the Large-section Gas Tunnel[J] MODERN TUNNELLING TECHNOLOGY, 2019,V56(5): 114-121
2019, Vol. 56 