in order to achieve a more efficient way to accurately detect the position of the fire source of spontaneous combustion underground mine, a simple fire source locating method, based on infrared scanning system which c...in order to achieve a more efficient way to accurately detect the position of the fire source of spontaneous combustion underground mine, a simple fire source locating method, based on infrared scanning system which can determine the point where the highest temperature on the surface of igniting ores occurs, was proposed. First, the differential equations that describe heat flow in ore body were presented and the relationship between the surface temperature distribution and the depth and intensity of inner fire source was established with a relatively simple heat transfer model. With the solution of equation, the expression of the relationship between the surface temperature distribution and the inner fire source was deduced and the mathematical-physical model of heat transfer process was set up. Then, with the model, visualization of fire source on the basis of MATLAB simulation platform was realized. The results show that： 1） within 10 m, when the detecting depth is less than 2 m, the temperature perturbation on ores surface can change rapidly, and then slowly; after 4 m, in contrast, it changes very little, and is even close to zero at 10 m; 2） When it is close to self-ignition duration and the detective depths are 2, 5 and 10 m, respectively, the maximum temperature differences are correspondingly 0.5, 0.04 and 0.005 ℃ in the scope of 1 m×1 m; under the same condition, the maximum temperature differences are 1.391, 0.136 and 0.018 ℃, respectively, in the scope of 2 m×2 m. Therefore, this system can be used to measure the temperature differences on the surface of ore body and determine the highest temperature point directly. Also, it is possible to determine the depth of fire source and its intensity by locating method of fire source indirectly.展开更多
In this study,experimental and numerical simulation methods were combined to simulate the changing course of the temperature and velocity fields in nine different fire scenes. The characteristics of smoke movement in ...In this study,experimental and numerical simulation methods were combined to simulate the changing course of the temperature and velocity fields in nine different fire scenes. The characteristics of smoke movement in shafts with different fire source position factors(h/H) were quantitatively investigated,and the non-dimensional fitting function between the fire source position factors and the maximum temperature was deduced. The results showed that the location of the neutral plane moved upward as the fire source rose,and all the generated smoke spread to the upper areas;however,there was barely any smoke in the lower areas. The maximum temperature was inversely proportional to the fire source position factor;the higher the source position is,i.e. the higher the ratio factor is,the lower the maximum temperature is in the shaft. The experimental verification of the fire dynamics simulator(FDS) showed good results.展开更多
Research on the distribution of smoke in tunnels is significant for the fire emergency rescue after an operating metro train catches fire. A dynamic grid technique was adopted to research the law of smoke flow diffusi...Research on the distribution of smoke in tunnels is significant for the fire emergency rescue after an operating metro train catches fire. A dynamic grid technique was adopted to research the law of smoke flow diffusion inside the tunnel when the bottom of a metro train was on fire and to compare the effect of longitudinal ventilation modes on the smoke motion when the burning train stopped. Research results show that the slipstream curves around the train obtained by numerical simulation are consistent with experimental data. When the train decelerates, the smoke flow first extends to the tail of the train. With the decrease of the train's speed, the smoke flow diffuses to the head of the train. After the train stops, the slipstream around the train formed in the process of train operation plays a leading role in the smoke diffusion in the tunnel. The smoke flow quickly diffuses to the domain in front of the train. After forward mechanical ventilation is provided, the smoke flow inside the tunnel continues to diffuse downstream. When reverse mechanical ventilation operates, the smoke in front of the train flows back rapidly and diffuses to the rear of the train.展开更多
Based on the distribution state of the combustibles and the scale of the fires in underground mines, mine fire sources are divided into two types in this paper,namely, fixed point fire source and movable linear fire s...Based on the distribution state of the combustibles and the scale of the fires in underground mines, mine fire sources are divided into two types in this paper,namely, fixed point fire source and movable linear fire source. By analying a lot of ex periment results of mine fires, the authors studied the combustion characteristics of the two types of fire source, and have set up their mathematical models. The models have further been applied to calculate the concrete mine instances and the obtained re sults corresponded with the reality.展开更多
Based on advantages of technology of distributive fiber-optic temperature sensing and specific to its applications in monitoring mine conflagration, the corresponding Processes such as connection arrangement, signal t...Based on advantages of technology of distributive fiber-optic temperature sensing and specific to its applications in monitoring mine conflagration, the corresponding Processes such as connection arrangement, signal transmission and monitoring were illustrated. As applied in Sitai Coal Mine of Datong Coal Mine Group Co., this method is effective and accurate and could provide reliable gist for monitoring spontaneous combustion in gob area of mines.展开更多
Fire-induced pollutant dispersion under the influence of buoyancy in urban street canyons has attracted wide attention given its adverse impact on human health.This study analyzes the influences of fire source locatio...Fire-induced pollutant dispersion under the influence of buoyancy in urban street canyons has attracted wide attention given its adverse impact on human health.This study analyzes the influences of fire source location and crossflowing wind(perpendicular to the canyon centerline)on indoor and outdoor air pollutant dispersion in an idealized urban street canyon by employing large eddy simulation.Three fire scenarios are defined according to the transverse location of the fire source:near the windward building(scenario 1),in the middle of the canyon(scenario 2),and near the leeward building(scenario 3).Results show that a re-entrainment phenomenon appears when the wind velocity reaches a critical value in scenarios 1 and 2,but it doesn't occur in scenario 3.Fire source location significantly influences the critical re-entrainment velocity.The critical velocity in scenario 1 is approximate 1.2-1.5 m/s larger than that in scenario 2.When the heat release rate is large,the critical Fr numbers are less sensitive to changes in HRR,and remain approximately constant with values of 0.47(scenario 1)and 0.37(scenario 2).When the wind velocity is large,more compartments are expected to be affected in the upper floors in all of the three scenarios,and smoke is distributed in an inverted triangle within the buildings.The indoor/outdoor temperature and pollutant concentrations are also analyzed.Our findings can provide valuable information for both human and property safety in relation to urban street canyons and their surrounding buildings.展开更多
In recent years, especially in the summer of 2002, the most serious forest fires occurred in the Daxingan Mountain of Heilongjiang province and Inner Mongolia. There has been long time serious forest fire environment ...In recent years, especially in the summer of 2002, the most serious forest fires occurred in the Daxingan Mountain of Heilongjiang province and Inner Mongolia. There has been long time serious forest fire environment in summer in Daxingan Mountain. The grass in the forest is scorched for long time drought and the moisture content of litter and turf layer decrease rapidly. The accumulation and dryness of fuel build the summer forest fire environment, which are major caused by Meteorological environment. ...展开更多
基金Project(2006BAK04B03) supported by the National Basic Research Program of ChinaProject(CX2009B053) supported by Innovation Foundation for Postgraduate Students of Hunan Province,ChinaProject(2009ybfz08) supported by the Doctoral Dissertation of Central South University,China
文摘in order to achieve a more efficient way to accurately detect the position of the fire source of spontaneous combustion underground mine, a simple fire source locating method, based on infrared scanning system which can determine the point where the highest temperature on the surface of igniting ores occurs, was proposed. First, the differential equations that describe heat flow in ore body were presented and the relationship between the surface temperature distribution and the depth and intensity of inner fire source was established with a relatively simple heat transfer model. With the solution of equation, the expression of the relationship between the surface temperature distribution and the inner fire source was deduced and the mathematical-physical model of heat transfer process was set up. Then, with the model, visualization of fire source on the basis of MATLAB simulation platform was realized. The results show that： 1） within 10 m, when the detecting depth is less than 2 m, the temperature perturbation on ores surface can change rapidly, and then slowly; after 4 m, in contrast, it changes very little, and is even close to zero at 10 m; 2） When it is close to self-ignition duration and the detective depths are 2, 5 and 10 m, respectively, the maximum temperature differences are correspondingly 0.5, 0.04 and 0.005 ℃ in the scope of 1 m×1 m; under the same condition, the maximum temperature differences are 1.391, 0.136 and 0.018 ℃, respectively, in the scope of 2 m×2 m. Therefore, this system can be used to measure the temperature differences on the surface of ore body and determine the highest temperature point directly. Also, it is possible to determine the depth of fire source and its intensity by locating method of fire source indirectly.
文摘In this study,experimental and numerical simulation methods were combined to simulate the changing course of the temperature and velocity fields in nine different fire scenes. The characteristics of smoke movement in shafts with different fire source position factors(h/H) were quantitatively investigated,and the non-dimensional fitting function between the fire source position factors and the maximum temperature was deduced. The results showed that the location of the neutral plane moved upward as the fire source rose,and all the generated smoke spread to the upper areas;however,there was barely any smoke in the lower areas. The maximum temperature was inversely proportional to the fire source position factor;the higher the source position is,i.e. the higher the ratio factor is,the lower the maximum temperature is in the shaft. The experimental verification of the fire dynamics simulator(FDS) showed good results.
基金Project(U1134203)supported by the Major Program of the National Natural Science Foundation of ChinaProject(51105384)supported by the National Natural Science Foundation of China
文摘Research on the distribution of smoke in tunnels is significant for the fire emergency rescue after an operating metro train catches fire. A dynamic grid technique was adopted to research the law of smoke flow diffusion inside the tunnel when the bottom of a metro train was on fire and to compare the effect of longitudinal ventilation modes on the smoke motion when the burning train stopped. Research results show that the slipstream curves around the train obtained by numerical simulation are consistent with experimental data. When the train decelerates, the smoke flow first extends to the tail of the train. With the decrease of the train's speed, the smoke flow diffuses to the head of the train. After the train stops, the slipstream around the train formed in the process of train operation plays a leading role in the smoke diffusion in the tunnel. The smoke flow quickly diffuses to the domain in front of the train. After forward mechanical ventilation is provided, the smoke flow inside the tunnel continues to diffuse downstream. When reverse mechanical ventilation operates, the smoke in front of the train flows back rapidly and diffuses to the rear of the train.
文摘Based on the distribution state of the combustibles and the scale of the fires in underground mines, mine fire sources are divided into two types in this paper,namely, fixed point fire source and movable linear fire source. By analying a lot of ex periment results of mine fires, the authors studied the combustion characteristics of the two types of fire source, and have set up their mathematical models. The models have further been applied to calculate the concrete mine instances and the obtained re sults corresponded with the reality.
基金Supported by the National Natural Science Foundation of China （50375026,50375028）
文摘Based on advantages of technology of distributive fiber-optic temperature sensing and specific to its applications in monitoring mine conflagration, the corresponding Processes such as connection arrangement, signal transmission and monitoring were illustrated. As applied in Sitai Coal Mine of Datong Coal Mine Group Co., this method is effective and accurate and could provide reliable gist for monitoring spontaneous combustion in gob area of mines.
基金This work was sponsored by the National Natural Science Foundation of Shandong Province(No.ZR2020QE279)Shandong Jianzhu University Doctoral Fund(No.X19055Z)Plan of Guidance and Cultivation for Young Innovative Talents of Shandong Province.
文摘Fire-induced pollutant dispersion under the influence of buoyancy in urban street canyons has attracted wide attention given its adverse impact on human health.This study analyzes the influences of fire source location and crossflowing wind(perpendicular to the canyon centerline)on indoor and outdoor air pollutant dispersion in an idealized urban street canyon by employing large eddy simulation.Three fire scenarios are defined according to the transverse location of the fire source:near the windward building(scenario 1),in the middle of the canyon(scenario 2),and near the leeward building(scenario 3).Results show that a re-entrainment phenomenon appears when the wind velocity reaches a critical value in scenarios 1 and 2,but it doesn't occur in scenario 3.Fire source location significantly influences the critical re-entrainment velocity.The critical velocity in scenario 1 is approximate 1.2-1.5 m/s larger than that in scenario 2.When the heat release rate is large,the critical Fr numbers are less sensitive to changes in HRR,and remain approximately constant with values of 0.47(scenario 1)and 0.37(scenario 2).When the wind velocity is large,more compartments are expected to be affected in the upper floors in all of the three scenarios,and smoke is distributed in an inverted triangle within the buildings.The indoor/outdoor temperature and pollutant concentrations are also analyzed.Our findings can provide valuable information for both human and property safety in relation to urban street canyons and their surrounding buildings.
基金China NKBRSF Project (No. 2001CB409600)Key Technologies R&D Programme (No. 2001BA510B09)Social Public Fund Proiect (Lightning Fire)
文摘In recent years, especially in the summer of 2002, the most serious forest fires occurred in the Daxingan Mountain of Heilongjiang province and Inner Mongolia. There has been long time serious forest fire environment in summer in Daxingan Mountain. The grass in the forest is scorched for long time drought and the moisture content of litter and turf layer decrease rapidly. The accumulation and dryness of fuel build the summer forest fire environment, which are major caused by Meteorological environment. ...
