Study On The External Flow Field Characteristics And Fluid-solid Coupling Of Pantograph For A 400 Km/h High-speed Train

In recent years,China’s high-speed railway has developed rapidly.the 400km/h high-speed wheel-rail passenger train system has also entered the technical reserve stage.As the speed continues to increase,the aerodynamic problems encountered by trains have become increasingly obvious.Characteristics also have practical significance and research value.At present,in the three-dimensional numerical simulation,most of the research on the stable operation of the open line of the train adopts the static bypass method,that is,the air flow at the same speed as the train is used to blow through the train,and the operation of the train at this speed is simulated.The fact that the train does not move during the simulation is the opposite of its actual operating condition,which leads to the fact that the flow field around the train must be different from the actual condition.When the simulated train is moving on the open line,the number of model grids will increase due to the movement of the train,thereby increasing the calculation time.In order to reduce the number of meshes by using the frozen rigid body movement method,the train will be increased in the open line movement.At the same time,to use this method more easily,write Java commands to modify the relevant parameters in the model to control the train at different times.State of motion.At first,the frozen rigid body motion method is applied to the rotating body train model,and the rationality and reliability of the method used are verified by comparison with Japanese test data.Then use this method to calculate the stability of the 400 km train and through the tunnel,and compare and analyze the similarities and differences between the two different methods in the pressure distribution and velocity flow field to verify the method and analyze the external flow field characteristics and power receiving Bow fluid-solid coupling characteristics.Concluded as follow:(1)By comparing with the test data of the Japanese spin-on train,the rationality and feasibility of the overlapping grid method in simulating train movement are verified.At the same time,the feasibility of the frozen rigid body movement method was verified.When comparing with the Japanese rotating body test data,the average error was controlled at about 4%,the maximum error was only 6.7%,and the calculation time was reduced by 0.3 hours,and the calculation efficiency was improved by 4.9 %.(2)When the train is running on the open line,the drag coefficient of the freezing method model is only 3% different from that of the static bypass model,but the model using the frozen rigid body movement method can save 13.3% of the number of grids compared to the non-freezing method model.Increase calculation time by 11.3%.The freezing method is basically the same as the static bypass method in pressure distribution,and the freezing method is closer to the real train operating conditions in the details and distribution of the velocity flow field.Different speeds have no significant effect on the aerodynamic drag coefficient of the whole train and the proportion of each part is basically the same.The distribution characteristics of the aerodynamic resistance of each car are basically the same.The head and tail cars account for the largest proportion,reaching about 30% of the aerodynamic resistance of the whole train In different parts,the bogie system has the largest resistance ratio,about 37%;the aerodynamic resistance of the components of the pantograph is different,big or small,the tie rod ratio is the smallest,and the bow head is the largest,so the bow head should become The main drag reduction object;resistance accounts for the second base frame,accounting for about 34.9%.The deformation of the pantograph components decreases gradually from the pantograph bow head down to the base frame.(3)When the train passes through the tunnel,the differential pressure resistance accounts for 70% and the friction resistance accounts for 30% when the train runs on the open line.After the train fully enters the tunnel,the differential pressure resistance accounts for the largest proportion,which can reach 77%.The proportion of frictional resistance increases,and the proportion of frictional resistance is the largest when compression waves pass through the train,accounting for 41.5%.The freezing method and the non-freezing method are basically the same in calculating the tunnel pressure and the surface pressure of the train body.It can be seen that the freezing method can also be used for the simulation calculation of the train passing through the tunnel.For the measurement points at the same distance and different locations in the tunnel,the maximum pressure is basically the same.At different distances,the maximum pressure value tends to increase first and then decrease as the distance from the tunnel entrance increases.The maximum pressure value of the body shows a trend that the farther away from the head car,the smaller.The measuring points around the components of the pantograph have the same pressure change trend with time,but the pressures of the measuring points are different.The farther the vertical distance of the components of the pantograph from the deflector(body),the higher the pressure value.Larger,during the passage of the tunnel,the component farther away from the bottom surface of the shroud generally has a smaller displacement value,and the component closer to the bottom surface of the shroud generally has a larger deformation value..