送风井位于隧道中部的半横向分区段通风特性研究

Characteristic study of a sectionalized semi-transverse ventilation system in which inclined shaft is built at the middle of the tunnel

为了确定一种送风井位于隧道中部,隧道内需风量存在分区段变化的半横向通风方式计算方法,以厦门海沧疏港通道-芦澳路城市地下互通隧道工程为依托,采用理论分析和数值模拟研究方法对风道内的压力分布进行研究,并对比送风井位置对风机压力的影响。研究通过在风道末端与风道内任意断面建立一元伯努利方程推导风道末端风速为0和风速不为0 2种情况下风道内的压力分布求解公式,数值计算结果验证了公式的正确性。根据研究结果,送风井位于隧道中部时,两侧风道始端全压可以视为相等,送风机提供满足通风压力较大一侧所需全压即可实现整个隧道的有效通风,该通风方式在增大通风长度适应性以及减小风机功率,以及提高经济性方面具有显著的优势。

In this paper, a special form of semi-transverse ventilation applied in Xiamen Shugang-Luao underground overpass was studied. Different from ordinary ones, inclined shaft was built at the middle of the tunnel and the requirement of fresh air per meter along this tunnel is not constant in this ventilation. According to the fresh air requirement standard per meter, air duct was divided into different sections. Based on an assumption that air was evenly supplied in each section, flow rate of the air duct was obtained. With energy conservation equations built between the cross sections internal and at the end of duct sections, two formulas for calculating static pressure along the air duct were derived and the theoretical calculations was verified with numerical results. In this kind of ventilation, air flow from the inclined shaft separates into two directions and research reveals that the two sections nearly have same total pressure at the separation point, which leads to a great reduction of fan power when compared with those in which shaft built at the end of a tunnel.