| With the rapid growth of modern economy and the acceleration of the process of urban modernization, more and more people flock to the city, especially the large city which is the resident population reached 10 million or more. Therefore, people in the search for the way to deal with this kind of problem is invariably thought of the underground transportation area with the traditional ground transportation, which is the main object of the study in recent years. However, the subway project has a common problem is that the heat produced by the control has not been better control of the subway system which has been put into operation, the phenomenon of rising temperatures, so that the internal environment continues to deteriorate. The energy consumption is an important part of the total energy consumption of the subway, and the thermal environment of the subway is studied. The operating conditions of the subway system are analyzed.There are 3 main models to deal with the above problems:1 open system, the main means of this system is to establish a ventilation shaft at the connecting point of the rail transit line, and then through a certain external force such as the piston or mechanical ventilation, to achieve the purpose of ventilation, only suitable for the people is not too concentrated, the more abundant land resources area;2 closed system, this system without the use of outside air and rail air, ventilation wells in the two sides of the station, and need to install air conditioning system on the train; 3 shielded door system, as its name implies, the use of platform mounted sliding screen door, the site area and the tunnel air contact, thereby preventing the air inside the hot air and the air conditioning cold air between the station. This system has the characteristics of safety and environmental protection, but because of the high cost of the whole system construction, it has not formed a large scale.Metro piston wind mainly refers to the train traveling at high speed in a tunnel, the train will make a enormous positive air pressure due to the small space, because of the different pressure the air moves and form the wind. Due to constraints and friction between tunnel and underground gas, an exceptional airflow is formed inside the tunnel, similar to movement of the piston in the tunnel space, which is the reason of the name piston air.In the process of train moving there are mainly three aspects of piston air pressure supercharging, because there are different flow characteristics, only using different methods to study flow movement. It is not difficult to find, train head (annulus inlet section) and tail (the annulus outlet section) and traction supercharger boost impetus are very similar in principle, but the shear force booster mode annulus uniform segment is Different. By flow analysis and mathematical deduction, we may determine the relationship between the supercharger and the corresponding boost characteristic style.In accordance with the overall urban planning and integrated transport planning, the central area of Hefei city rail transit network consists of 12 lines with a total length of 336.9 km, of which the central city line density is 0.49 km/sq km, with 21 transfer station. Expected in 2020, the city public transport proportion of motorized trips reached 66.4%, rail transport accounts for public transportation volume ratio reached 32.9%. Hefei Metro Line 1, the second phase of the project started from north of Hefei Railway Station, south Huizhou Avenue station. The project line length is 24.58km, all of which is under the earth.There are 23 stations, the largest space between which space is 2462m, the minimum distance between stations 714.5m, an average station spacing 1106m.Metro system is a complex three-dimensional network made up of stations, tunnels and the entrance. Environmental Control Simulation subway system, is used to study the problem of instability aerodynamics and thermodynamics of the subway, that is the normal condition of the subway station three-dimensional temperature field, air distribution, pollutant concentration distribution, average air age, the human body simulation of comfort as well as subway stations and tunnels accident, fire conditions in the three-dimensional temperature field, air distribution, simulation of smoke flow conditions and the like. Currently the most widely popular internationally and mature, for subway environmental control simulation software is Subway Environment Simulation, referred to SES. The program is developed by the US Department of Transportation in 1975 as the world’s first subway loop control computer simulation software. We study the winds piston in Hefei Urban Rail Transit Line 1 using the SES software.This paper analyzes the characteristics of the subway tunnel, the speed and pressure of the subway tunnel, the formation mechanism and the basic flow model, and the simulation software is used to design and analyze the ventilation mode of the metro, and provide the necessary basic data and experimental verification. |
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