Influence of the Exhaust Volume on Boundary Layer Separation Under the Lateral Concentrated Smoke Exhaust Mode in Immersed Tunnel Fires

IF 2.3 3区工程技术 Q2 ENGINEERING, MULTIDISCIPLINARY

Fire Technology Pub Date : 2023-05-08 DOI:10.1007/s10694-023-01417-4

Pai Xu, Daiqiang Zhu, Keyu Chen, Chuanyong Wen, Tipeng Zheng, Rongjun Xing, Shuping Jiang, Linjie Li

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Abstract

The boundary layer separation occurs when a fire breaks out, affecting the smoke exhaust effect in the immersed tunnel with the lateral concentrated smoke exhaust mode. The theoretical criterion of boundary layer separation is established according to the distribution of smoke flow velocity. And three boundary layer separation regions in the exhaust vents and exhaust duct are divided. The smoke flow velocity during the exhaust process in a standard three-lane immersed tunnel is simulated by FDS, and the area of each boundary layer region and its ratio under different exhaust volumes is analyzed. Results show that the order of blocking effect of each region from large to small is the region near the left sidewall of exhaust vents, the region near the right sidewall of exhaust vents, and the region near the inner sidewall of the exhaust duct. The area ratio of the boundary layer separation region in each group of exhaust vents is higher than that in the exhaust duct by 17.2%–22.7%. The increased exhaust volume is beneficial in reducing the negative effect on smoke exhaust by the boundary layer separation. The exhaust volume is 340 m³/s when the negative effect is minimum under 50 MW, at this time, the area of non-boundary layer separation regions on average in the exhaust vents and exhaust duct is 70.7% and 91.4%, respectively.

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沉管巷道侧向集中排烟方式下排风量对边界层分离的影响

火灾发生时边界层分离，影响了采用侧向集中排烟方式的沉管隧道排烟效果。根据烟流速度分布，建立了边界层分离的理论判据。并在排风口和排风道内划分了三个边界层分离区。采用FDS模拟了标准三车道沉管隧道排烟过程中的烟流速度，分析了不同排烟量下各边界层区域面积及其比值。结果表明:各区域的阻塞效果从大到小依次为排气孔左侧壁附近区域、排气孔右侧壁附近区域、排风管内侧壁附近区域。各组排风口边界层分离区面积比高于排风道面积比17.2% ~ 22.7%。增大的排烟量有利于减少边界层分离对排烟的负面影响。在50 MW以下负效应最小时，排风量为340 m3/s，此时排风口和排风道内非边界层分离区的平均面积分别为70.7%和91.4%。

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来源期刊

Fire Technology 工程技术-材料科学：综合

CiteScore

6.60

自引率

14.70%

发文量

137

审稿时长

7.5 months

期刊介绍： Fire Technology publishes original contributions, both theoretical and empirical, that contribute to the solution of problems in fire safety science and engineering. It is the leading journal in the field, publishing applied research dealing with the full range of actual and potential fire hazards facing humans and the environment. It covers the entire domain of fire safety science and engineering problems relevant in industrial, operational, cultural, and environmental applications, including modeling, testing, detection, suppression, human behavior, wildfires, structures, and risk analysis. The aim of Fire Technology is to push forward the frontiers of knowledge and technology by encouraging interdisciplinary communication of significant technical developments in fire protection and subjects of scientific interest to the fire protection community at large. It is published in conjunction with the National Fire Protection Association (NFPA) and the Society of Fire Protection Engineers (SFPE). The mission of NFPA is to help save lives and reduce loss with information, knowledge, and passion. The mission of SFPE is advancing the science and practice of fire protection engineering internationally.