Numerical Simulation And Flow Analysis Of Ventilation Environment In Public Area Of Subway Platform

Due to the special construction environment of the subway station,the air renewal and circulation of the internal subway station need to be completed by the subway station ventilation system.Through the analysis of the ventilation environment of the internal subway station and the optimization of the design and use strategy of the subway station ventilation system,on the basis of achieving the efficient operation of the ventilation system and meeting the needs of passengers and staffs,it can reduce work noise,save energy and easy maintenance.Therefore,it is of great guiding significance to study and discuss the characteristics of airflow in subway stations,optimize the layout of ventilation equipment and ventilation strategies.The three-dimensional building model used in this article was based on the architectural design of a subway station.And the numerical simulation method is used to obtain the air flow field in the ventilation environment of the public area of the subway platform.By studying the flow characteristics and distribution characteristics of the airflow in the platform,the existing problems in the flow field and the causes of the problems are obtained.results,The main research contents of this thesis include the following four parts:In the first part,numerical simulation of the airflow characteristics in the common area of the platform using only the air supply system was carried out.The flow characteristics and distribution characteristics of the airflow flowing into the platform from different air outlets were analyzed.It was found that the airflow mainly affects the air flow near the air supply outlet,in the central part of the platform,the air flow is slow and the convection is weak.In the narrow space area,the airflow in the platform would interfere with each other,and formed a large area of vortex flow in the area,affecting the passenger waiting area.In the second part,numerical simulation was carried out for the airflow characteristics in the common area of the platform with using the return air system.It is found that turning on the return air system could effectively reduce the airflow velocity at the platform exit and enhance the air flow effect in the non-supply air port area.Under the current arrangement of return duct,increasing the total return air flow would make the return air port which far away from the total return air port failed and could not improve the air flow effect in this area.In the third part,the possible failure of ventilation pipeline on subway platform is hypothesized.Two response conditions were designed for the fault,and numerical simulation was carried out for the response conditions.Analysis of the air flow characteristics and distribution characteristics under the response conditions,the results show that only increase the flow of non-faulted supply ducts in the faulted area and increase the flow of all non-faulted supply ducts could both maintain the operation of the station with the guarantee of fresh air supply,but the local high velocity zone and the area where the airflow cannot be renewed will be formed at different levels,which will causing adverse effects on passengers..Finally,based on the study of the previous three parts and and the problems found in the second part,the layout of return duct in the public area of subway platform was optimized.Through the analysis of numerical simulation results,it was shown that the modified return duct arrangement could produce better return air effect under high return air flow than the old one.Under the condition that the total return air flow is unchanged,the ventilation effect of the public area on the platform could be improved by increasing the return air flow in the central part of the platform.