Study On Optimization Of Air Supply Performance Of Air Supply Duct And Analysis Of Flow Field In Double-deck Passenger Train

With the rapid development of China’s railway,railway has become the first choice of means of transportation for people to travel in the middle and long distance.China has a large population,and it is particularly prominent for the problem of insufficient transportation capacity during holidays.China has a vast territory,and the train passes through many climate zones,which brings forward higher requirements for the comfort in the train.The double-deck passenger train has obvious advantages in many aspects,such as increasing passenger capacity and improving passenger comfort.Due to the wide space and complex internal structure,it is relatively difficult to study the air supply performance of air supply duct and the flow field in the double-deck passenger train.In this thesis,the double-deck passenger train is taken as the study object,and CFD numerical simulation and theoretical analysis are used to optimize the air supply performance of air supply duct of the double-deck passenger train and analyze the flow field in the optimized double-deck passenger train,and the aim is to provide beneficial references for the design optimization of air supply structures of air supply duct of the double-deck passenger train.The study contents mainly include the following four aspects:(1)Taking two kinds of typical double-deck passenger train air supply ducts(type I for unidirectional air supply and type II for bidirectional air supply)as study objects,using CFD numerical simulation,it compares the air volume distribution results of air outlets of the layers.The results show that the air volume distribution of the air ducts of type I double-deck passenger train is roughly linear(increasing or decreasing)outflow,and the air volume distribution of the air ducts of type II double-deck passenger train is roughly "n" type(large in the middle and small on both sides)outflow.(2)According to the continuity theorem of incompressible fluid and the conservation theorem of fluid flow energy,firstly,it establishes the flow velocity and static pressure models of single-floor single-side air supply ducts,and it concretely analyzes three basic kinds of outflow models(uniform outflow,linear outflow and "n" type outflow).Then,it establishes the flow velocity and static pressure models of the static pressure chamber.Finally,by coupling the inlet of single-floor single-side air supply ducts and the outlet of the static pressure chamber,it establishes the whole model of the air supply theory of the air supply duct of the double-deck passenger train.(3)It analyzes and optimizes the air supply performance of air supply duct structures of the driver’s cab,the electrical cabinet and the floors of the passenger compartment.By increasing the air resistance of the air supply duct of the driver’s cab and the air volume near the front window of the driver’s cab,it effectively solves the problems of the large wind speed near the top air outlet and the nonstandard temperature near the front window.Through the analysis and comparison of 12 kinds of air supply structures of air supply duct of the electrical cabinet,it obtains the best ventilation and heat dissipation scheme of the air supply duct of the electrical cabinet(the air inlet duct is the middle duct,and the exhaust outlet is located at the lower part,and the cooling fan direction is downward),and it summarizes the regular influence of various air supply structures of air supply duct on the ventilation and heat dissipation of the electrical cabinet.To improve distribution of flow field in the air supply duct,it proposes some measures such as adding flow plate at the front end,adding rectifier plate at the front and middle end,adding guide plate at the middle end and adding baffle plate at the middle end of the air supply duct of the floors of the passenger compartment.(4)Taking the optimized double-deck passenger train as the study object,it obtains the distribution results of wind speed and temperature in the double-deck passenger train under extreme environmental conditions in summer and winter.The study results show that the wind speed in most areas of passenger compartments does not exceed the maximum of wind speed standard and the uniformity of wind speed is good,and the temperature in most areas of passenger compartments meets the corresponding design temperature standard and the range of temperature difference is within the maximum of the required range and the uniformity of temperature is good.