Simulation of Piston Effect and Temperature-rise Problem for Subway Tunnel

• Main Authors: Chih-Sheng Chen, 陳誌生
• Other Authors: Yang-Chang Shih
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/5m4g62

碩士 === 國立臺北科技大學 === 冷凍空調工程系所 === 93 === The follow-up construction of Taipei Metro system at underground station will establish a Platform Screen Door (PSD) system at platform. The platform screen door system can assure the safety of passengers within the platform and reduce the demands of environmental control as well as decrease the operational costs. However, owing to the influence of piston effect, the pressure can only be released through draught relief shaft. This is a challenge towards the PSD pressure resistance. The metro frequent round trips in the underground tunnels result in the effects of heat sink and the nearly saturation of soil heat retention ability, which make the temperature within tunnels to increase gradually. Thus, this thesis used the CFD (Computational Fluid Dynamics) method to analyze the effects of various designing parameters on PSD pressure for the G19 station of Songshan line. In addition, the effect of different air temperature within the tunnel on the problem of heat sink was addressed in this study. This thesis adopted the CFD software FLUENT6.1 to analyze the pressure variation resulting from the moving metro on the PSD. The dynamic mesh was employed to investigate the metro motion. The influence of metro speed, draught relief bypass shaft height, draught relief bypass shaft area, and two-way train to enter the station etc. on PSD pressure is considered in this study. The numerical results indicate that faster metro results in the larger pressure on the PSD. The higher the draught relief bypass shaft is, the worse the pressure-relieving ability is. The increase of draught relief bypass shaft area does not have significant change on pressure variation. The two-way metro entering the station at the same time is not good for the pressure depression because of the air drawing each other. In this study, the CFD software-AIRPAK2.1 is employed to simulate the heat sink effect of the tunnel. According to the numerical results, it is known that when the higher the designing air temperature is, the faster the hot saturation of soil occurs. For example, when the air temperature within the tunnel is maintained below 46℃, the soil can absorb about 200W for per meter long of tunnel, which can be regarded as the designing reference of heat rejection.