Numerical Analysis of the Effect of Streamlined Nose Length on Slipstream of High-Speed Train Passing through a Tunnel

The improved delayed detached eddy simulation (IDDES) method was employed based on the shear–stress transport (SST) k-w two-equation turbulence model to simulate the slipstream distribution characteristics of a high-speed train traversing a tunnel. The accuracy of the numerical simulation method was verified through a full-scale test. First, the wake vortex structure and the distribution of slipstreams of the train with a streamlined nose length of 7 m running in a tunnel were analyzed. Then, the influence of the streamlined nose length on the wake dynamics and slipstream was compared and analyzed. The slipstream positive peak decreased with increasing distance from the top of the rail and center of the track. As the streamlined nose length increases, the vortex intensity in the wake area weakens; moreover, the influence ranges of the wake vortex and the slipstream positive peak value become smaller. Compared with the results of a train having a streamlined nose length of 5 m, the slipstream positive peak value at 1.4 m from the top of the rail and 100 m from the tunnel entrance decreased by 46.6% from that of a train with a streamlined nose length of 9 m.