Research On Mixed Ventilation Performance Of Semi-open Underground Comprehensive Transportation Hub

With the acceleration of urbanization and the development of urban underground rail transit,a number of large-scale and extra-large underground traffic commercial complexes with an area of more than 20,000 m2(fire unit boundaries)have emerged.By 2020,the energy consumption used for the construction of the terminal,subway station and railway passenger station environment will account for about 2.5 ‰ of the total energy consumption of the country.Among them,the annual energy consumption of a single subway station is 1 to 3 million k Wh.The intensity is much higher than ordinary public buildings.Therefore,it is possible to propose a reasonable modeling method suitable for this kind of problems in view of the characteristics of the semi-open underground transportation hub such as the complexity of the building structure and the complexity of the indoor heat load,and to study the ventilation of the semi-open underground transportation hub through numerical simulation Performance influencing factors and the changing characteristics of ventilation performance in the lower half of the open underground comprehensive transportation hub in different climate zones.This article takes a semi-open underground comprehensive transportation hub in Shenzhen as the research object.Through numerical simulation methods,various factors that affect the mixed ventilation performance of the semi-open underground comprehensive transportation hub are carefully explored and evaluated,and different climates are studied.The characteristics of the ventilation performance change of the open underground comprehensive transportation hub in the lower half of the district provide relevant references for the design,construction and evaluation of such buildings.This paper firstly focuses on the research of mixed ventilation performance of semi-open underground comprehensive transportation hub,systematically analyzes the research status at home and abroad,and the current deficiencies,and proposes the main research content and framework: semi-open underground transportation hub model establishment,semi-open Study on the factors influencing the ventilation performance of the open underground comprehensive transportation hub and the ventilation performance in the lower half of the open underground comprehensive transportation hub in different climate zones.Secondly,this article selects an underground comprehensive transportation hub in Shenzhen as the research object,systematically studies and elaborate a reasonable CFD modeling method,including the "box method" modeling method for diffuser tuyere,and the "eight" for cyclone tuyere."Flap method" modeling method,modeling method of ground heat load zoning for heat load,setting method of boundary conditions for two different working conditions of screen door switch,setting method of partition wall,outdoor wind field and selection of parameters such as calculation model Methods and summarize the evaluation indexes of ventilation performance that are applicable to such problems,including the number of ventilation,average wind speed,average temperature,area percentage of breeze area,area percentage of design temperature area,and average indoor air age.Then,this paper conducts CFD numerical simulations on various factors that affect the ventilation performance of the semi-open underground comprehensive transportation hub,such as: the setting of the sinking square,the setting of the large atrium,the opening state of the screen door at the platform level,and the change of the outdoor wind direction.Combined with the analysis of the calculation results,the effects of various factors on the ventilation performance of the semi-open underground comprehensive transportation hub are summarized: when the outdoor wind direction is directly on the sinking square with a large opening area,the sinking square enters the wind;when the number of sinking squares is relatively large When the air conditioner adopts positive pressure air supply,only the indoor air exits through the sinking square;when the large atrium is not provided,the indoor positive pressure is reduced,and the outdoor airflow is more likely to flow into the room through the sinking square and into the sinking square.There is more wind,which also affects the ventilation performance evaluation indicators such as the wind speed field,temperature field and air age of the underground layer and interlayer;when the screen door is opened,a large amount of air flow occurs between the underground layer 2 and the tunnel.The flat wind speed field is more complicated,the average wind speed is higher than the closed condition,the four sinking squares present three inlet winds,one outlet,and the inlet wind is mainly characterized by the southeast sinking square,which also affects the underground floor Ventilation performance indicators such as wind speed field and temperature field of the mezzanine,the average wind speed and average temperature are greater than the closing condition of the screen door;the outdoor wind direction changes mainly interact with the setting of the sinking square,the opening area,and the internal structure,which affect the building ventilation performance.And the outdoor airflow is easier to enter the indoor through the sinking square that is directly opposite to it and has a larger opening area and no internal partition walls.In addition,in order to study the ventilation performance of the open underground comprehensive transportation hub in the lower half of the different climate regions,this paper selected Shenzhen,Changsha,Tianjin,Harbin and Kunming as hot summer and winter warm regions,hot summer and cold regions,cold regions,severe cold regions and Representative cities in temperate regions calculated the characteristics of the ventilation performance of semi-open underground comprehensive transportation hubs in different climatic regions through CFD numerical simulation,and adopted comparative analysis to provide a theoretical reference for creating good ventilation performance and parameter design.Studies have shown that the impact of different climate zones on ventilation performance mainly affects indoor ventilation performance by changing outdoor weather parameters,namely wind direction,wind speed and temperature,and working together with the setting of sinking squares.In summary,based on the in-depth layer-by-layer model establishment and data analysis,the model construction of the mixed ventilation performance of the semi-open underground comprehensive transportation hub was modeled,and combined with the actual case,the system deeply affected the ventilation performance of the semi-open underground comprehensive transportation hub.Various factors and the variation characteristics of mixed ventilation performance of the lower half-open underground comprehensive transportation hub in different climate areas were analyzed and elaborated,which provided theoretical basis and technical support for further optimizing and improving the mixed ventilation performance of the half-open underground comprehensive transportation hub.