Experimental study on the basic laws of the aerodynamic effect of 350 km·h-1 high speed railway tunnel

On the high-speed railway from Wuhan to Lechang and from Zhengzhou West to the south section of Sanmenxia, field tests from 250 to 350 km·h-1 were carried out by CRH2C and CRH380A type EMUs, including EMUs passing through tunnels with the length from 287 m to 10081 m and with the effective clearance area of 100 m2, and EMUs passing by each other in 2 728 m long Jiuzixian tunnel. The basic laws of the aerodynamic effect of 350 km·h-1 high-speed railway tunnel as well as the influences of the aerodynamic effect in tunnel on the dynamic performance of EMU, the structural strength of carbody and the comfort of human ear were studied. Results show that, in the process of EMUs passing tunnels or passing by each other in the tunnel at 350 km·h-1 or below, the maximum lateral wheelset force is 41.28 kN, the maximum derailment coefficient is 0.70, the single peak value of the maximum rate of wheel load reduction is 0.79, the maximum differential pressure between inside and outside is 3 224 Pa, the maximum internal air pressure variation is 1064 Pa within 3 s. All these indexes are in their allowable ranges for EMU operation safety, carbody strength and human ear comfort. Both the inside and outside air pressures increase basically with the increase of train speed. For EMUs passing different tunnels with the length less than 3000 m at the same speed, the maximum inside and outside pressure changes increase with the increase of tunnel length. The optimization of EMU's head form and sealing can improve the aerodynamic performance for trains passing through tunnels and passing by each other in tunnels.