| Speed-up of train system is the common trend of railway technology development all over the world, and one of an inevitable result of social and economic development as well.Rapidness, safety and comfortability is the main development goal of high-speed railway in China and other countries. Compared to the lower-speed trains, high-speed trains passing through the tunnels and passing by each other in the tunnels can cause significant aerodynamic phenomena which will lead to drastic pressure fluctuation outside of coaches.As the train can not be completely sealed and leakage through gaps or air conditioning system,such as air inlets and waster air outlets, the pressure fluctuation outside can propogates into coaches and cause pressure fluctuation inside. This in turn can cause ear discomfort phenomenon of drivers and passengers, such as ear swelling, eardrum pain, which seriously affects individuals' physical and mental health and deteriorates riding comfortability. How to reduce or slow down the influence of external pressure wave on that inside coaches has become a stringent problem and needs to be solved in the high-speed development of railway in the world. Nowadays, passive ventilation with cut-off valves, active ventilation of continuous pressure protection devices and mixed mode of active and passive combination are widely used three ways in pressure protection to reduce the pressure changes inside coaches.Each of them works in deferent principles. Therefore, it is necessary to carry out the research on the adaptability of internal pressure protection devices. This paper based on the passive and active pressure protection methods to study the characteristics of the inner pressure change in high speed trains.Under reasonable assumptions, this paper uses one-dimensional, unsteady, compressible and nonisentropic flow model and the method of characteristic to calculate the train external pressure fluctuation. Comparing to the foreign literature test and calculation results, it shows that the results are in good agreement, which shows the correctness of the present calculation method. From then on, under using the pressure protection of the high-speed trains, the decoupling algorithm was established and the Fortran program was developed to calculate the pressure change inside trains. Comparing the results with the foreign literature test and calculation results, it shows that the calculation method and procedure of this paper are reasonable and feasible.In this paper, based on the internal pressure decoupling algorithm calculating the internal pressure, characteristics of the internal pressure change was analyzed, and pressure riding comfortability was explored according to the domestic pressure comfort standard. Exploration of train was obtained under the two kinds of pressure protection, through a typical railway designed running speed of 350 km, tunnel fault area of 100m2 of typical curve in China, trainsgo through or rendezvous at the same speed different length tunnels at different speeds, As results, under the air tightness index 12 s and the high static pressure fan, the maximum rate of pressure change inside cars every 3s meets domestic pressure comfort standards. This shows that the train under the two kinds of pressure protections can be well to suppress the impact of external pressure fluctuations on that inside the cars, thus ensure the theriding comfortability.In all, the research on the problem of the discomfort and ride comfort caused by the internal pressure of the vehicle is carried out with a known external pressure fluctuation, and the decouping algorism was established to calculate the internal pressure inside the vehicles.This method can be used to predict the pressure of high speed train using pressure protection valves or high static pressure fan technology, which provides a feasible method to study the characteristics of internal pressure change of the vehicles. |
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