Research On The Matching Problem Of Ventilation And Exhaust Fan In Subway Tunnel

The subway is a very important part of the modern urban traffic system,which is of great significance to alleviate traffic congestion in large cities.Subway stations and subway trains have a large crowd density.Once a train block or a fire accident occurs,the people's life and property will be greatly threatened.As a necessary part of subway ventilation and smoke control system,the rationality of the design matching not only directly affects the safety of subway operation,but also has a great impact on the initial investment of the project.Due to the complexity of the ventilation flow channel shape and the contact relationship of the subway tunnel,the current matching of the ventilation power of the system depends mainly on the experience estimation.Therefore,it is necessary to carefully study the ventilation and flow characteristics of the system in order to get more accurate design basis parameters,and establish a matching calculation method for wind power parameters according to the actual connection conditions of tunnel ventilation network under different working conditions,and develop a simple calculation software.In this paper,the fan matching is taken as the main line,and the influence of different structure and working condition on the fan matching is analyzed from the ventilation resistance characteristics of the piston air duct and the train blocking.(1)Using CFD numerical simulation as the main research means.In order to verify the accuracy of the simulation method,a 1:25 tunnel experiment model was set up.By changing the location of the train's berth,we measured the wind speed and the static pressure along the tunnel at different locations,and compared them with the simulated values.(2)On the piston air duct,and the size of the connection between the change of piston wind hole,shaft,piston fan,door,location and size of their influence on the resistance coefficient.(3)For the train blocked in the impact on the tunnel ventilation flow,flow field,pressure field and different position of train simulator and contact line crossing the shaft relative to the calculation and analysis of train at different positions of the pressure distribution,air distribution and equivalent resistance coefficient comparison.Through the numerical simulation analysis and experimental test of the tunnel ventilation flow,the main parameters of the main resistance characteristics needed to match the calculation of the subway tunnel fan are obtained.Based on the distribution of air flow,velocity variation,entrance pressure of tunnel along the analysis of pressure distribution,the macro can get all kinds of channel structure and the combination of pressure loss and the equivalent resistance coefficient,from the analysis of the flow field and pressure distribution can also understand the influence of air flow on the micro resistance coefficient.(1)The flow resistance of the piston duct is greatly influenced by the geometric structure.The data used in the current engineering are larger than the simulation value,which can be explained from the two reflux angle.(2)The relative position of the train,when the resistance in the air shaft or away from a certain distance after crossing the line contact characteristics of the train when the train gradually stabilized,close to the shaft or contact until occlusion crossover,resistance characteristics change and cause the air distribution and pressure distribution is relatively large changes.According to the typical tunnel structure can be obtained the most unfavorable conditions for blocking the train accident condition when the occlusion piston air shaft in contact;crossing the line,tunnel ventilation direction and the contact line crossing an acute angle and train unshielede blocking working condition of crossing the fork of the most unfavorable conditions.According to the calculation method of ventilation network,the matching parameters of the tunnel fan under the most unfavorable conditions are obtained.Finally,a software framework for the calculation of fan matching for the ventilation system of the subway tunnel is designed,and the corresponding calculation software is developed.