Numerical Simulation And Analysis On Aerodynamic Effects Of High-Speed Train Passing Through Tunnels With 400km/h

The rapid development of modern high-speed railways has pushed trains to move faster.Although the increase speed of train will bring great convenience to people’s travel,the higher the speed,the more aerodynamic effects will be produced.When the train passes through the tunnel at a high speed,the air in the tunnel is squeezed,which will cause a lot of aerodynamic effects,which will greatly reduce the safety and comfort of the train during operation,and the environment around the tunnel will also be damaged.Specific manifestations are:passengers in the train will experience symptoms such as tinnitus and vomiting due to alternating air pressure in the tunnel,and ride comfort will be greatly reduced;the tunnel lining and train body structure will be damaged due to aerodynamic loads,and the staff’s safety in the tunnel cannot be guaranteed;micro-pressure waves generated at the tunnel entrance will emit a large number of low-frequency infrasound waves,which will adversely affect surrounding residents and buildings.In recent years,China has begun to pay attention to high-speed trains with speeds of 400 km/h and above.Most previous studies on the aerodynamic effects of tunnels have focused on speeds below 300 km/h.Based on the three-dimensional transient compressible Reynolds time-averaged N-S equation and the k-εtwo-equation turbulence model,this paper numerically studies the working conditions of EMUs passing through a single-line tunnel and a two-line tunnel at the same speed.According to the calculation results,the air pressure changes at different measurement points on the surface of the train body and the tunnel wall are analyzed.The obtained research results provide a reference for analyzing the impact of the aerodynamics of the tunnel on the train body,the tunnel lining and the auxiliary facilities in the tunnel.The main work of the paper is as follows:(1)Numerical simulation of the working conditions of an EMU with a length of 8 sections passing through a 70m~2 single-track tunnel at 200km/h.Based on the comparison of the calculation results of the pressure on the EMU surface and the tunnel wall with the actual train test results,the numerical simulation was verified.The correctness of the method also provides a basis for the accuracy of the results of subsequent working conditions.(2)Numerical simulation of pressure changes generated by an 8-section marshalling length and a 3-section marshalling unit EMU through a 70m~2 single track tunnel at 300km/h and 400km/h,respectively.The research results in four operating conditions show that the maximum value of positive peak,negative peak,and peak-to-peak pressure of the tunnel wall appear in the middle of the tunnel;the three-dimensional effect of the single-line tunnel is not obvious;The maximum value of positive peak pressures on the surface of the EMU appears at the tip of the nose;the maximum value of the negative peak and peak-to-peak pressures on the surface of the EMU appears in the tail car;there is little difference in pressure between the measuring points in the middle of the EMU;When an EMU passes a single-track tunnel at the same speed,the aerodynamic effect of an EMU with a length of 8 sections is stronger than that of an EMU with a length of3 sections;when the EMU of 8 sections length passes through a single-line tunnel at 400km/h,the maximum value of positive peak pressure of the EMU surface and the tunnel wall can reach 10.733k Pa and 4.676k Pa,respectively.(3)Numerical simulation of the pressure change of the 8-segment marshalling length and the 3-segment marshalling EMU at 300km/h and 400km/h in a 100m~2 double-line tunnel at the same speed.The results in the four operating conditions show that the maximum value of positive peak,negative peak and peak-to-peak pressure of the tunnel wall appear in the middle of the tunnel;due to the influence of the intersection,there is no obvious three-dimensional effect in the double-line tunnel;The maximum value of the positive peak and peak-to-peak pressure on the surface of the EMU appear at the tip of the nose;the maximum value of the negative peak pressure at the surface of the EMU appears in the middle car;When the EMU meets in the double-track tunnel at the same speed,the aerodynamic effect of the 8-section marquee length is stronger than that of the 3-section marquee length;when the EMU with a length of 8 sections meets in the 100m~2 double-line tunnel at the same speed of 400km/h,the maximum value of positive peak pressure on the EMU surface and the tunnel wall can reach14.405k Pa and 7.158k Pa,respectively.