1、PDF外文：http:/ 第 1 页 CFD simulation and optimization of the ventila
2、tion for subway side-platform Feng-Dong Yuan *, Shi-Jun You Abstract To obtain the velocity and temperature field of subway station and the optimized ventilation mode of subway side-platform station, this paper takes the
3、 evaluation and optimization of the ventilation for subway side-platform station as main line, builds three dimensional models of original and optimization design of the existed and rebuilt station. And using the two-equation turbulence model as its physics model, the thesis makes computational flui
4、d dynamics (CFD) simulation to subway side-platform station with the boundary conditions collected for simulation computation through field measurement. It is found that the two-equation turbulence model can be used to predict velocity field and temperature field at the station under some reasonable
5、 presumptions in the investigation and study. At last, an optimization ventilation mode of subway side-platform station was put forward. 1. Introduction Computational fluid dynamics (CFD) software is commonly used to simulate fluid flows, particularly in complex environments (Chow and L
6、i, 1999； Zhang et al., 2006； Moureh and Flick, 2003). CFD is capable of simulating a wide variety of fluid problems (Gan and Riffat, 2004； Somarathne et al., 2005； Papakonstantinou et al., 2000； Karimipanah and Awbi, 2002). CFD models can be realistically modeled without investing in more costly exp
7、erimental method (Betta et al., 2004； Allocca et al., 2003； Moureh and Flick, 2003). So CFD is now a popular design tool for engineers from different disciplines for pursuing an optimum design due to the high cost, complexity, and limited information obtained from experimental methods (Li and Chow,
8、2003； Vardy et al., 2003； Katolidoy and Jicha, 2003). Tunnel ventilation system design can be developed in depth from the predictions of various parameters, such as vehicle emission dispersion, visibility, air velocity, etc. (Li and Chow, 2003； Yau et al., 2003； Gehrke et al., 2003). &
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10、 第 2 页 Earlier CFD simulations of tunnel ventilation system mainly focus on emergency situation as fire co
11、ndition (Modic, 2003； Carvel et al., 2001； Casale, 2003). Many scientists and research workers (Waterson and Lavedrine, 2003； Sigl and Rieker, 2000； Gao et al., 2004； Tajadura et al., 2006) have done much work on this. This paper studied the performance of CFD simulation on subway environment contro
12、l system which has not been studied by other paper or research report. It is essential to calculate and simulate the different designs before the construction begins, since the investment in subways construction is huge and the subway should run up for a few decade years. The ventilation of subway i
13、s crucial that the passengers should have fresh and high quality air (Lowndes et al., 2004； Luo and Roux, 2004). Then if emergency occurred that the well-designed ventilation system can save many peoples life and belongings (Chow and Li, 1999； Modic, 2003； Carvel et al., 2001). The characteristics o
14、f emergency situation have been well investigated, but there have been few studies in air distribution of side-platform in normal conditions. The development of large capacity and high speed computer and computational fluid dynamics technology makes it possible to use CFD technology to
15、predict the air distribution and optimize the design project of subway ventilation system. Based on the human-oriented design intention in subway ventilation system, this study simulated and analyzed the ventilation system of existent station and original design of rebuilt stations of Tianjin subway
16、 in China with the professional software AIRPAK, and then found the optimum ventilation project for the ventilation and structure of rebuilt stations. 2. Ventilation system Tianjin Metro, the secondly-built subway in China, will be rebuilt to meet the demand of urban development and expected to be a
17、vailable for Beijing 2008 Olympic Games. The existent subway has eight stations, with a total length of 7.335 km and a 0.972 km average interval. For sake of saving the cost of engineering, the existent subway will continue to run and the stations will be rebuilt in the rebuilding Line 1 of Tianjin
18、subway. Although different existent stations of Tianjin Metro have different structures and geometries, the Southwest Station is the most typical one. So the Southwest Station
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20、 model was used to simulate and analyze in the study. Its geometry model is shown in Fig. 1. 2.1. The structure and original ventilation mode of existent station The subway has two run-lines. The structur
21、e of Southwest Station is, length width height = 74.4 m(L) 18.7 m(W) 4.4 m(H), which is a typical side-platform station. Each side has only one passageway (length height = 6.4 m(L) 2.9 m(H). The middle of station is the space for passengers to wait for the vehicle. The platform mechanica
22、l ventilation is realized with two jet openings located at each end of station and the supply air jets towards train and track. There is no mechanical exhaust system at the station and air is removed mechanically by tunnel fans and naturally by the exits of the station. 2.2. The design structure and
23、 ventilation of rebuilt station The predicted passenger flow volume increase greatly and the dimension of the original station is too small, so in the rebuilding design, the structure of subway station is changed to, (length width height = 132 m(L) 17.438 m(W) 4.65 m(H
24、), and each side has two passageways. The design volume flow of Southwest Station is 400000 m3/h. For most existent stations, the platform height is only 2.9 m, which is too low to set ceiling ducts. So in the original design, there are two grille vents at each end of the platform to supply fresh ai
25、r along the platform length direction and two grille vents to jet air breadthways towards trains. The design velocity of each lengthways grille vent is 5.54 m/s. For each breadthways vent, it is 5.28 m/s. Under the platform, 80 grille vents of the same velocity (4.62 m/s, 40 for each platform of the
26、 station) are responsible for exhaust. 3. CFD simulation and optimization The application of CFD simulation in the indoor environment is based on conversation equations of energy, mass and momentum of incompressible air. The study adopted a turbulence energy model that is the two-equation turbulence model advanced
