土木工程毕业设计外文翻译---cfd模拟和地铁站台的优化通风节选-建筑结构(编辑修改稿)

土木工程毕业设计外文翻译---cfd模拟和地铁站台的优化通风节选-建筑结构(编辑修改稿)内容摘要：

imulation and optimization The application of CFD simulation in the indoor environment is based on conversation equations of energy, mass and momentum of inpressible air. The study adopted a turbulence energy model that is the twoequation turbulence model advanced 外文资料翻译 第 4 页 by Launder and Spalding. And it integrated the governing equation on the capital control volumes and discretized in the definite grids, at last simulated and puted with the AIRPAK software. . Preceding simplifications and presumptions Because of mechanical ventilation and the existence of traindriven piston wind, the turbulence on platform is transient and plex. Unless some simplifications and presumptions are made, the mathematics model of threedimensional flow is not expressed and the result is divergent. While ensuring the reliability of the putation results, some preceding simplifications and presumptions have to be taken. (1) The period of maximum air velocity is paid attention to in the transient process. Apparently the maximum air velocity is reached at the period when train stops at or starts away from the station (Yau et al., 2020。 Gehrke et al., 2020), so the period the simulation concerns about the best period of time for simulation is from the point when at the section of ‘x = m’ (Fig. 1) and the air velocity begin to change under pistoneffect to the point when train totally stops at the station (defined as a ‘pullingin cycle’). (2) Though the pullingin cycle is a transient process, it is simplified to a steady process. (3) Because the process is presumed to a steady process, the transient velocity of test sections, which was tested in Southwest Station in pullingin cycle, is presumed to the timeaveraged velocity of test sections. 外文资料翻译 第 5 页 (4) The volume flow driven into the station by pullingin train is determined by such factors as BR (blocking ratio, the ratio of train crosssection area to tunnel crosssection area), the length of the train and the resistance of station etc. For existent and new stations, BRs are almost the same. Although the length of the latter train doubles that of the former which may increase the piston flow volume, the resistance of latter is greater than that of the former which may counteract this increase. So it is presumed that the piston flow volume is same for both existent and new station and that the volume flow through the passenger exits is also same. Based on this presumption, the results of the field measurements at the existent station can be used as velocity boundary conditions to predict velocity filed of new station. . Original conditions To obtain the boundary conditions for putation and simulation, such as the air velocity and temperature of enclosure, measures were done by times at Southwest Station. All data are recorded during a plete pullingin cycle. The air velocities were measured by the multichannel anemonemaster hotwire anemoscope and infrared thermometer is used。