Thermal Environment Simulation And Exhaust System Study On Long Tunnel Of City Railway

With the expansion of the city, the residents’travel range is also expanded, people need more travel modes to satisfy their needs of longer distance travels. At this time, the general metro is insufficient to meet the rapidly growing transportation demands, and city railway gets rapidly development as a traffic pattern which can meet residents’needs of periodically remote travels. In addition to some common features of the general metro, city railways also have some unique features, including faster speed of trains, longer distance between stations and fewer stations in underground runnel. Because different operating characteristics between city railway and general metro will lead to different ventilation characteristic, there is a necessity of further research.In this paper, we studied the ventilation characteristics and thermal environment in underground tunnel of an actual project of Wenzhou S1 rail line. Firstly, we established the corresponding one-dimensional model of the railway tunnel, and used the Subway Environment Simulation program (SES) to analyze the tunnel’s thermal environment in different periods, then further analyzed three kinds of thermal environmental factors’ effects, and preliminarily discussed the feasibility of no TES system in Wenzhou S1 rail line.Besides, in the simulation of three-dimensional part, this paper established a longer tunnel mode with double stations underground, and used the dynamic mesh technique to obtain the distribution of near fields caused by train moving, including the pressure, the velocity and the temperature field. Also, we analyzed the variation of the piston air and its influence on the thermal environment of station tunnel, providing datas for the usage of piston air and the optimization of ventilation equipment in after projects.This paper also discussed the thermal environment of station tunnels under different ventilation settings, obtained the temperature distributions of three different working conditions, including no UPE(Up Platform Exhaust) and OTE(Over Track Exhaust) system, UPE only system and OTE only system. According to the results, we found that the tunnel temperature under the UPE only system is less than 40℃, UPE only system can meet the requirements of the national standards. However, the other two kinds of ventilation systems will cause a high temperature in the station tunnel, and is not recommended. Considering the difficulty of construction and the project investment, this paper recommend the UPE only system in the city rail underground station construction.