To study the flow characteristics of three-phase foam in gob area,different perfusion experiments in coal mine gob were designed and put forward in the paper.Through the observation of flow range,flow characteristics ...To study the flow characteristics of three-phase foam in gob area,different perfusion experiments in coal mine gob were designed and put forward in the paper.Through the observation of flow range,flow characteristics of three phase foam were analyzed with different flow rates.And,unsteady seepage process of three-phase foam was simulated with CFD software.Base on experiment and numerical simulation results,flow characteristics of three-phase foam and its major influence factors are discussed,and the optimal arrangement distribution of mine fire control drills is also determined.Research results show that the flow range and stacking height of three-phase foam in gob are significantly influenced by gravity.The vertical stacking height and horizontal diffusion distance of three-phase foam are also directly related to the flow volume of foam perfusion,the larger flow single hole perfusion volume,the higher stacking height and the longer diffusion distance could be obtained.展开更多
The study adopted a 20-foot long container to simulate the situation inside a turbine cabin. Water mist sprays were installed internally and used to perform fire extinguishing tests. Under these different scenarios, s...The study adopted a 20-foot long container to simulate the situation inside a turbine cabin. Water mist sprays were installed internally and used to perform fire extinguishing tests. Under these different scenarios, several operating factors were adjusted with the results of each adjustment subsequently measured. The operating factors studied included： operating pressures, foam concentrations, cabin opening issues, and obstacles. Each of the factors was compared with the others so as to find out which combinations would be most suitable for a water mist spray system installed inside a wind turbine cabin. The presence of obstructions hinders the direct impact of the mist spray on the fire source and in average an additional 2 to 3 minutes is required to put out the fire. This study found that the effect of the foam-water ratio is linear. Regardless of the scenario, the optimum mixture ratio is 3%. The line graph shows that the most unsuitable aqueous film-forming mixture ratio is 6%. This experiment found that the main fire extinguishing mechanism of water mist spray is the cooling of a large area via water droplets. This system is very effective in bringing down the temperature. The addition of foam in water mist spray, however, impaired the effectiveness of the cooling effect although the fire control mechanism via emulsification markedly reduced the time required to put out the fire. The increase in foam magnification will considerably enhance the fire extinguishing efficiency.展开更多
基金supported by the National Natural Science Foundation of China(Nos.51104154,51134020)Central Subordinate University Basic Scientific Research Foundation of China(No.2011QNA05)CUMT Innovation and Entrepreneurship Fund for Undergraduates of China(Nos.201403,201503)
文摘To study the flow characteristics of three-phase foam in gob area,different perfusion experiments in coal mine gob were designed and put forward in the paper.Through the observation of flow range,flow characteristics of three phase foam were analyzed with different flow rates.And,unsteady seepage process of three-phase foam was simulated with CFD software.Base on experiment and numerical simulation results,flow characteristics of three-phase foam and its major influence factors are discussed,and the optimal arrangement distribution of mine fire control drills is also determined.Research results show that the flow range and stacking height of three-phase foam in gob are significantly influenced by gravity.The vertical stacking height and horizontal diffusion distance of three-phase foam are also directly related to the flow volume of foam perfusion,the larger flow single hole perfusion volume,the higher stacking height and the longer diffusion distance could be obtained.
文摘The study adopted a 20-foot long container to simulate the situation inside a turbine cabin. Water mist sprays were installed internally and used to perform fire extinguishing tests. Under these different scenarios, several operating factors were adjusted with the results of each adjustment subsequently measured. The operating factors studied included： operating pressures, foam concentrations, cabin opening issues, and obstacles. Each of the factors was compared with the others so as to find out which combinations would be most suitable for a water mist spray system installed inside a wind turbine cabin. The presence of obstructions hinders the direct impact of the mist spray on the fire source and in average an additional 2 to 3 minutes is required to put out the fire. This study found that the effect of the foam-water ratio is linear. Regardless of the scenario, the optimum mixture ratio is 3%. The line graph shows that the most unsuitable aqueous film-forming mixture ratio is 6%. This experiment found that the main fire extinguishing mechanism of water mist spray is the cooling of a large area via water droplets. This system is very effective in bringing down the temperature. The addition of foam in water mist spray, however, impaired the effectiveness of the cooling effect although the fire control mechanism via emulsification markedly reduced the time required to put out the fire. The increase in foam magnification will considerably enhance the fire extinguishing efficiency.
