| With the continuous improvement of our country’s urbanization rate,more and more urban agglomerations have emerged in China,and the status of urban trains in people’s daily travel has become increasingly apparent.Since urban trains have a passenger flow similar to that of subways,but their ride time is longer,in order to improve the comfort of passengers in the train,it is necessary to optimize the air supply uniformity of the air supply system and the pressure field and temperature field in the train.First of all,in terms of air supply system,this thesis studies the air supply system of a certain type of urban train,and uses numerical simulation as the object to conduct simulation analysis,analyzes the causes of uneven air supply in the initial plan,and conducts targeted optimization,to improve the overall air supply uniformity and reduce the resistance loss of the air supply system.Secondly,in the passenger compartment,a coupled simulation model of the passenger compartment,the return air system,the waste exhaust system and the air-conditioning unit was established to simulate the calculation and analysis of the passenger compartment flow field,temperature field and resistance loss,and to evaluate the pressure and resistance loss in the passenger compartment and the air duct.The final optimized structure of the return air duct and the waste exhaust air duct is determined.The main research results of this thesis are:(1)Through the structural optimization of the air supply system,the air supply uniformity of urban trains is greatly improved,the backflow problem at the outlet of the static pressure box is solved,the air volume balance of the air ducts on both sides is strengthened,and the deviation between the air outlets is greatly improved.(2)The establishment of the coupled model and the simulation analysis help to find out two main problems of the non-uniform return air volume of the return air system and the excessive resistance loss of the waste and exhaust air system.By changing the structure of the waste outlet,the flow cross-sectional area of the waste outlet is increased,and the flow resistance from the passenger compartment to the waste outlet is reduced from 600 Pa under the initial scheme to 146 Pa.By changing the connection method of the vertical return air duct and the horizontal return air duct,the return air volume of the 4 air-conditioning units can be balanced,which is of great help for the operation and maintenance of the air conditioner.(3)After optimization,the average temperature of the passenger room under no-load conditions in summer is about 19°C.Due to the lack of air supply ports at both ends of the middle train,the temperature still has a certain deviation from the overall average temperature of the passenger room.The temperature under no-load conditions in summer is about 20°C-22°C,which is also within the acceptable range of the standard.Due to the high heat transfer coefficient at the top of the train,it is not possible to go up to a certain distance from the air outlet,and the temperature deviates from the overall average temperature of the passenger room.However,due to the high position here,it has little effect on human comfort.Due to the lack of air supply outlets on both sides of the train,there is a certain deviation from the average temperature in the passenger compartment,but these areas are not the main areas for personnel activities,so the impact is not large.93 figures,13 tables,and 59 references... |
