Test And Simulation Of Pressure Fluctuation In High-speed Train Under Vehicle-tunnel Coupling

Since the reform and opening,China’s high-speed railway tunnel project has entered a period of rapid development,and the speed of high-speed trains has been increasing.When the train goes through the tunnels at high speed,the intense transient pressure fluctuation is transmitted to the carriage and affect the ride comfort of passengers.Many studies have shown that the sealing gaps of train body and the air-conditioning ventilation system are the main ways that connect the interior and exterior spaces of the vehicle and transmit the pressure fluctuations outside the vehicle to the inside of the vehicle.Therefore,at home and abroad,the interior pressure is mainly maintained at a comfortable level by adopting an airtight design for the cabin and adding a pressure protection system in the air-conditioning ventilation system.At present,the dynamic leakage characteristic of the sealing gaps is not considered enough in the static air tightness test,the passive pressure protection method is difficult to consider the comfort of internal pressure and air quality both and the accuracy and breadth of the existing internal pressure calculation model need to be deepened.In this paper,the influence of the sealing gaps and the air-conditioning ventilation system on the pressure fluctuation in the train during passing through the tunnel is studied with the combined method of real vehicle test and numerical simulation.The results can provide guidance for the sealing technology of high-speed trains and provide theoretical support for the control of pressure fluctuations in the vehicle.The main research contents and conclusions of this paper include:1.An interior and external pressure fluctuation online test system of high-speed train is designed,including the overall scheme design,hardware equipment selection and test software design.The internal and external pressure fluctuation line test under vehicle-tunnel coupling is carried out.The internal pressure comfort when train operates is evaluated.The relationship between rate of pressure change in the vehicle pressure and tunnel length and the opening and closing state of air duct valve is summarized.2.The static air tightness test is carried out to explore the main leaking components and their static leakage characteristics of a certain CRH high-speed train.Considering the dynamic characteristics of the equivalent leakage area of sealing gaps changing with the pressure difference inside and outside the train,a three-dimensional model of the dynamic equivalent leakage hole is established.The air leakage process of car body gaps excited by pressure wave in tunnel is numerically simulated using CFD method.The leakage law of sealing gaps and the interior pressure comfort when the train operates under the influence of this factor are analyzed.3.The three-dimensional model of carriage and air-conditioning ventilation system are established.The air supply and exhaust process of ventilation system is simulated numerically.Furthermore,the internal pressure comfort under the influence of air conditioning and ventilation system during dynamic train operation is analyzed.And the influence of changing the opening degree of the air duct valve and closing the valve at fixed time on the pressure and CO₂ concentration in the train is studied.4.Finally,a two-factor calculation model of pressure fluctuation in the vehicle is established based on the single-factor model,and the correctness and validity of the two-factor model are verified.The pressure in the vehicle under the sealing gaps and the air-conditioning ventilation system is simulated and verified by comparison with the measured data.The simulation results are compared with the single factor model,and the actual influence of the two factors on the pressure fluctuation in the vehicle is obtained.