在隧道火灾研究中,将临界速度作为衡量纵向通风效率的标准已被广泛认可。然而,对于排烟口位于火源两侧,两端都是进风口的情况,临界速度并不能有效地衡量通风效率。对此,研究人员提出了“限制性速度”的概念,并将其作为标准,但到目前为止,对于限制性速度的研究依然很少。本文中的CFD模型以O.Vauquelin的实验为基础,通过CFX模拟7种不同热释放率下,纵向通风对速度场和温度场的影响。模拟结果显示,限制性速度的临界点出现在L/H=2到L/H=4之间,而不是1个固定值;在限制性速度下,根据速度场分布特点可以将烟气分布为4个部分:发展部分、稳定部分、急剧变化部分和衰减部分;烟气在离开热入口后,温度迅速降低,但是随着热释放率的增加,温度的下降速度明显减小;在稳定阶段,烟气温度保持在220～450 K。模拟中还分析了该模型在高热释放率(100 MW)下的分布规律,以期为以后的研究提供参考。 In the study of tunnel fires, the critical speed has been widely accepted as a measure of vertical ventilation efficiency. However, the exhaust port is located on both sides of the fire source, both ends of the inlet, the critical speed and can not effectively measure the ventilation efficiency. To this end, researchers have proposed and adopted the concept of “speed limit” as the standard, but so far the research on the speed limit is still rare. The CFD model in this paper is based on the experiment of O.Vauquelin and simulates the influence of longitudinal ventilation on the velocity field and the temperature field by CFX at seven different heat release rates. The simulation results show that the critical point of the restrictive velocity appears between L / H = 2 and L / H = 4 instead of a fixed value. Under the restrictive velocity, the flue gas can be distributed as Four parts: the development part, the steady part, the sharp change part and the decay part; After the flue gas leaves the hot inlet, the temperature decreases rapidly, but with the increase of the heat release rate, the rate of temperature decrease obviously; in the steady stage, Flue gas temperature maintained at 220 ~ 450 K. The distribution of the model under high heat release rate (100 MW) was also analyzed in order to provide reference for future research.