Numerical Simulation Study On The Aerodynamic Characteristics Of Subway Train

The transient pressure and a strong piston action produced by the subway train during its fast operation in the interval tunnel will not only affect the surfaces of the train and tunnel,auxiliary facilities inside,but also affect the safe operation of metro trains in tunnels.In this paper,the real change of piston wind speed in the tunnel around the 2nd Workers' Cultural Palace Station of Guangzhou Metro Line 2 is tested,and the numerical simulation method is used to analyze the aerodynamic characteristics of the subway train in the tunnel when the subway train in the tunnel experiences the whole process of accelerating departure,driving at a constant speed until slowing down and entering the station.When solving the calculation,the dynamic grid technology provided by ANSYS fluent is adopted when the metro train runs in the short tunnel.In the aspect of piston wind and annulus flow field inside a tunnel,the paper mainly discusses the wind speed distribution in the annulus space composed of train and tunnel,shows the details of air flow between train and tunnel under the condition of fully developed turbulence in tunnel,and makes up for the defect that only the general law of wind speed change can be shown in the measured data.By comparing the wind speed values of different train running speed,two kinds of head shape and different vertical height of the ring gap,it can be found that in the target short tunnel,the change of train running speed,head shape and vertical height of the ring gap space have almost no effect on the flow field type of the ring gap between the train and the tunnel,no matter what train running speed and vertical height,whether the headstock is streamlined or not,the type of flow field in the annular space always presents the Poiseuille type.In the aspect of the pressure,this paper analyzes in detail the law of pressure fluctuation in the tunnel and the causes of the wave peak and wave trough during the operation of the train under the condition of variable driving.According to the occurrence time of pressure peaks and troughs in the tunnel and the running state of the train,the positive pressure peaks of the measuring points in the tunnel are not always caused by the arrival of the train head at the measuring point,but also may be affected by the superposition of the positive pressure in front of the train and the pressure waves reflected which encountering the train head;the negative pressure wave peak of the measuring point in the tunnel is not always caused by the negative pressure at the rear of the train.With the decrease of the running speed of the train,the influence of the negative pressure of the vehicle body on the pressure at the measuring point is gradually greater than that at the rear of the train.When the subway train accelerates to the maximum speed in the tunnel,the maximum pressure wave intensity is about 410 pa and the maximum negative pressure is-810 pa.In order to consider the influence of the pressure superposition caused by the operation of multiple trains in the tunnel on the pressure bearing and smooth opening and closing of the PSD,it is necessary to reasonably set up air shaft in the platform tunnel area at the entrance end of the train.In this paper,the research on the aerodynamic characteristics of metro train can provide a theoretical basis for the safe operation of metro in short tunnels.