| With the gradual acceleration of China’s urbanization process and the increasing number of people traveling,high-speed rail has become the main trans-regional transportation mode.With the increasing requirements of passengers for the comfort of vehicles,improving the comfort of trains when they are fully loaded has become a top priority.In this paper,a highspeed train is taken as the research object,and Computational Fluid Dynamics software FLUENT is applied to carry out numerical research on the air conditioning and ventilation system and air distribution in the carriage in detail.The specific research content that has been completed is as follows:(1)The model of second-class seat car and air channel of a certain high-speed train was established,and the highquality unstructured tetrahedral mesh was divided by using local encryption method.The temperature of each inner wall surface in the presence of solar radiation was determined,and the boundary conditions of other numerical calculations were determined;(2)A single air material in FLUENT software was selected as the flow medium to conduct simulation analysis on the internal flow field of the original design scheme of train full load in summer and winter.The deficiencies of the internal flow field were judged according to the set human comfort standard and the causes were analyzed;(3)After enabling the component transportation function of FLUENT software,the flowing medium in the train was set as a mixture of oxygen,carbon dioxide,water vapor and nitrogen,and passenger respiration was taken as the boundary condition to calculate the non-breathing condition and the breathing condition when the mixed material was the flowing medium.At the same time,the comfort of flow field in breathing condition of mixed material was evaluated.A typical cross section was selected to compare with a single air material condition to summarize the influence of mixed materials and respiration on the internal flow field;(4)Relative humidity and carbon dioxide mass concentration were added into the passenger comfort evaluation standard,and the airconditioning system,air duct structure and heating system with full load in summer and winter were improved in view of the shortage of flow field in the breathing condition of mixed materials,and the rationality of the improvement scheme was judged.The results show that: the temperature field and velocity field are affected by different materials.Compared with the single air material condition,the temperature field at full load in summer increased by 0.4℃ to 1.3℃,and the velocity field increased by 0.04m/s to 0.13m/s.In winter,the full-load temperature field decreases about 0.5℃～4℃,and the speed increases between 0.05m/s and 0.1m/s.In the improved scheme,for summer full load,the height of the two-position end baffle plate is increased to improve the air supply uniformity.Finally,the vertical temperature difference decreases from 3.5℃ to 2.5℃,and the flow rate of the front and middle feet decreases from 0.25m/s～0.34m/s to 0.25m/s～0.31m/s.The flow rate of the rear head increases from 0.25m/s～0.31m/s to about 0.32m/s;In winter,full load reduces the inlet air temperature and aisle heater temperature,and increases the inlet water vapor content,so that the temperature distribution in the room decreases from 23℃～26℃ to 18℃～22℃,the horizontal and vertical temperature difference decreases from 2.5℃ to about 1.5℃,and the relative humidity increases from 3%～8% to 35%～43%.The improved method of increasing the pressure difference by reducing the size of the waste outlet of the electrical cabinet makes the waste outlet of the toilet work normally in summer and winter. |
