Study On Thermal Comfort Of Subway Platform And Subway Carriage Based On CFD

With the rapid development of urban rail transit in our country,as a kind of green energy-saving,safe and fast means of transportation,subway plays an important role in solving the problem of traffic congestion.At the same time,more and more attention has been paid to the thermal environment of the subway platform and train carriage,and the thermal comfort has become one of the most important research subjects.In this paper,the CFD(Computational Fluid Dynamics)numerical simulation method was used to research the thermal comfort of the platform and the carriage,and the influence of the piston wind on the platform environment was analyzed.Main works are as follows:(1)This paper introduced the ventilation and air conditioning design standards for the subway station and train carriage in China.On this basis,the evaluation indexes of thermal comfort of subway were established,namely,air temperature,velocity,non-uniform coefficient,air diffusion performance index and energy utilization coefficient.(2)This paper expounded the basic governing equations of fluid mechanics,the k-εturbulence model,discrete method of governing equations and mesh generation method.The standard k-ε turbulence model was used to describe three-dimensional turbulent flow of air in platform and carriage.Finite volume method was used to discrete the governing equations.And the mesh was divided by the combination of structural mesh and unstructured mesh.(3)The thermal comfort of the island-platform with platform screen door system was analyzed.Taking Nanjing Metro in the morning peak in summer and winter as an example,the three-dimension models of platform were established.The cooling load of platform was calculated to provide data for the boundary conditions in the numerical simulation.Under different working conditions of air supply quantity and air supply angle,FLUENT software was used for numerical simulation of air flow field.Based on the evaluation indexes,the thermal comfort under different working conditions was analyzed and the optimal air supply parameters were put forward.(4)The thermal comfort of train carriage was analyzed.Taking Nanjing Metro in the summer morning peak as an example,the research process was similar to the thermal comfort analysis of platform.The fully-loaded carriage model was established,and the thermal comfort under different conditions of air supply quantity and air supply angle was analyzed,and the optimal air supply parameters were put forward.(5)The influence of tunnel piston wind on thermal environment of the platform with screen door with vents in winter was researched.The hot air in the tunnel was leaded into the platform by the train-induced piston effect,and the variation law of temperature field and velocity field of platform and the influence on thermal comfort were analyzed based on the transient simulation of the train arrival and stop process.The result showed that vents on screen door was helpful to improve the thermal environment of the platform.In this paper,the CFD numerical simulation technology was applied to research the thermal comfort of subway system,which can provide the theoretical basis for thermal comfort optimization of domestic subway platform and train carriage,and also has practical value for improving subway service level.