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. ...
