Study On Air Distribution Characteristics And Ventilation Effect Of Circular Column Attached Ventilation

Now the large span space,such as the supermarket,subway station,exhibition center and train waiting room,is using the traditional mixing ventilation mode.There are some problems in practical application,such as low ventilation efficiency,poor human thermal comfort and air quality.In this paper,a new type of air supply mode known as Column Attached Ventilation(CAV)is proposed,which is based on the numerous and uniformly distributed column in the large span building.This paper focuses on the circular cylinder with the column attached ventilation model.Based on the theories of various attached jet,the theoretical model of circular cylinder attached jet is presented,which divide the flow field of this jet into vertical column-attached area,jet impinging deflection area and horizontal air lake area.In order to study the flow characteristics of the jet,the full-scale experiment was carried out firstly.According to the flow visualization experiment,the effectiveness of the air supply model was validated;By utilizing the three-dimensional velocity field test,based on the experimental data,this paper definite the areacoverage of the jet,analyze the velocity characteristics of the jet,present the main section jet velocity distribution,the axis jet velocity,the downstream jet thickness expansion formula of different flow area.Also the calculation formula of the axis jet velocity distribution of the whole flow field is obtained.Based on the full-scale experimental model,the numerical simulation model of the new air supply mode is established.The experimental results show that the Reynolds stress turbulence model based on linear pressure strain(RSM)is valid in the prediction of air distribution.By numerical simulation of the extended working condition,analyze the influence on the axis jet velocity of different diameter cylindrical column and the temperature characteristics of the jet,the formula of jet axis temperature and the temperature distribution along the height of the room is obtained under non-isothermal air supply.At the same time,the ventilation effect of the new air supply mode is studied,comparing and analyzing the influence of air supply velocity,air supply temperature,indoor load,cylinder column diameter,air diffuser width and column type.The results show that the new air supply mode has good ventilation effect and can meet the requirements of human thermal comfort.Based on the study of jet characteristics and ventilation effect,the engineering design method and calculation procedure of the air supply mode are put forward.According to a actual engineering case,the design scheme is given.Finally,the comparison with the mixed ventilation,displacement ventilation,air curtain ventilation and the new air supply mode of airdistribution characteristics and ventilation effects is given,to facilitate the reference of engineer.