Study On Interior Pressure Fluctuation Factors And Dynamic Air Tightness Under The Excitation Of Tunnel Pressure Wave

In recent years,high-speed trains have developed rapidly.While people enjoy the convenience brought by high-speed trains,their demands for safety and comfort increase.However,with the increasing speed of high-speed trains,the fluctuation of pressure increases during the condition operating inside a tunnel,which seriously affects the riding comfort of drivers and passengers.Researches show that the three major factors of interior pressure change induced by external pressure wave are the body structure,the airtightness of the train and the ventilation system of the train,while dynamic air tightness can reflect the demand of seal performance of operation train under the action of three factors.Therefore,numerical simulation and test methods are used to study pressur change inside the train caused by pressure outside the train under the factors such as the train body structure,the air tightness of the compartment and the ventilation fan system of the train,and the internal pressure fluctuation under the action of single factor and multi-factor is analyzed and compared.Meanwhile the dynamic air tightness of high-speed trains passing through a tunnel is studied based on the measured data.The main research contents and conclusions of this article include:1.The simulation model of the 3-units train passing through the 500 m tunnel and the coupling simulation model of the carriage structure-flow field are established.The train body surface pressure and the pressur inside train caused by pressure outside train under the factor of the train body structure is analyzed.The simulation results show that with the increase of the speed,the maximum pressure outside the vehicle is linear with the speed to the power of2.15.In the range of pressure difference between inside and outside of the train in structure-flow field coupling simulation,the volume change of the train is approximately linear with the pressure difference between inside and outside of the train.The pressure fluctuation inside train meets the riding comfort requirements of the driver and passenger.2.The air tightness test scheme of the components is designed,based on the existing air tightness test of the whole train.The variation law of the sealing gap of the compartment and the air tightness gap of the components is analyzed,and the pressur inside train caused by pressure outside the train under the factor of the airtightness of carriage is calculated.The research shows that the equivalent leakage area of the train and the leakage area of the components have a strong nonlinear relationship with the pressure difference between inside and outside the train.When considering only the airtightness of the carriage,the pressure fluctuation inside train caused by the pressure outside the train also meets the riding comfort requirements of the driver and passenger.3.The internal and external pressure transfer model is established by considering the factors of train body structure,the air tightness of carriage and ventilation fan system.By modifying the parameters of the model,the pressure change in the vehicle is simulated only the ventilation fan system is considered,and the relationship between inside pressure and valve switch position in ventilation fan system is studied.The pressure inside the car caused by the pressure outside the train under three major factors is analyzed and compared.The research shows that the pressure change caused by the ventilation system of the train is the largest,and the waveform is similar to the interior pressure obtained by coupling three factors.The maximum pressure obtained by normalization processing in the compartment is a quadric polynomial function of valve opening.4.A convenient test system is built to measure the pressure of inside and outside the train in the tunnel,and the law of the dynamic air tightness variation of the train is studied based on the test data.The test results show that with the increase of tunnel length,the maximum negative pressure on high-speed trains increases first and then decreases,while the maximum negative pressure inside trains increases with the increase of tunnel length.The "dynamic" tightness of the same car decreases with the increase of the tunnel length.The tail car has the best "dynamic" seal by comparing the dynamic air tightness index of the head car,middle car and tail car.