中文摘要：

通过数值模拟，分析了长通道内机械排烟时排烟口下方的流场结构、烟气层温度和厚度，定量描述了烟气层厚度、温度与排烟速率之间的关系．结果表明，排烟速率大到一定程度时会导致烟气层吸穿，使得机械排烟效率降低．

英文摘要：

In a long model channel under mechanical extraction, the flow pattern, vertical temperature distribution and depth of the smoke layer below the extraction vent were analyzed by numerical modeling. The variations of the depth and temperature under different mechanical extraction rates were quantitatively described. The results show that plugholing occurs in the long channel when smoke extraction rate increases to some relative high levels, causing the efficiency of the mechanical extraction system to be reduced.