隧道侧部集中排烟模式下排烟速率对烟气层吸穿的影响研究

排烟速率是公路隧道侧部集中排烟模式下烟气层发生吸穿现象最为直接的影响因素。为研究隧道侧部集中排烟模式下烟气层发生吸穿现象的临界条件,分析了隧道侧部集中排烟过程中排烟口处烟气层的受力情况以及不同排烟速率对烟气层吸穿的影响,并结合前人相关的研究成果,进一步分析得到隧道侧部集中排烟模式下排烟口下方烟气层发生吸穿时的临界弗洛德数。结果表明:隧道侧部集中排烟模式下排烟口下方烟气层发生的吸穿现象不同于隧道顶部集中排烟模式,隧道侧部集中排烟模式下烟气层的吸穿区域发生在排烟口下方近火源侧角落,且烟气进入排烟口时与排烟口截面存在一定的角度,由靠近火源来烟一侧倾斜通过排烟口流向排烟道出口方向,当弗洛德数小于1.28时,烟气层吸穿未发生,当弗洛德数大于1.28时,烟气层吸穿已经发生。

Influence of the Concentrated Smoke Exhaust Rate on the Side of the Tunnel on the Smoke Layer Plugholing

The smoke exhaust rate is the most direct influence factor of the smoke layer plugholing under the concentrated smoke exhaust mode on the tunnel side.In order to study the critical conditions for the smoke layer plugholing under the concentrated smoke exhaust mode on the tunnel side,this paper analyzes the stress of the smoke layer at the smoke vent and the effect of different smoke exhaust rates on the smoke layer plugholing during the tunnel side concentrated smoke exhaust process,and further obtains the critical Froude number when the smoke layer plugholing occurs at the side concentrated smoke exhaust vent.The results show that the smoke layer plugholing at the smoke vent under the side concentrated smoke exhaust mode is different from that under the top concentrated smoke exhaust mode,as the former occurs at the corner of the lower part of the smoke vent near the fire source and forms an angle to cross-section of the smoke vent,and the side of the smoke coming from the fire source is inclined to flow into the exhaust duct through the exhaust port.When the Froude number is less than 1.28,the smoke layer plug-holing will not occur;when the Floude number is greater than 1.28,the smoke layer plugholing will occur.