城市特长隧道带散排口的分段纵向排烟模式排烟性能研究OA

To investigate the smoke exhaust performance of the dispersed exhaust mode in urban extra-long tunnels,longitudinal temperature decay patterns,the flow and temperature field characteristics at the dispersed ex-haust outlets,and the heat exhaust efficiency under varying heat release rates,longitudinal velocities,and exhaust volumes are analyzed in this study.The results show that as the heat release rate increases,the amount of high-temperature smoke generated within the tunnel grows,leading to greater heat exhaust through the outlets;howev-er,this results in poorer smoke control and higher overall temperatures inside the tunnel.As the longitudinal ve-locity increases,smoke spread accelerates,and the maximum temperature rise beneath the ceiling decreases,but excessively high longitudinal velocities impair smoke control via the dispersed exhaust outlets.Increasing the ex-haust volume raises the heat exhaust through the outlets and lowers the downstream temperatures.Although larg-er exhaust volumes improve smoke control,they reduce the utilization rate of the downstream outlets,causing wasted exhaust capacity.The heat exhaust efficiency of the dispersed exhaust outlets is nearly independent of the heat release rate and the longitudinal velocity,but increases with the exhaust volume.Based on this finding,a prediction model for the exhaust efficiency of the dispersed exhaust outlets,correlated with the dimensionless ex-haust volume,is proposed.In practical engineering,the heat exhaust efficiency exhibits a marginal effect as the exhaust volume varies;therefore,a reasonable exhaust volume should be selected in design.