Analysis of Trailing Vortex Structure and Turbulent Features of High-Speed Train in Vacuum Pipeline

Abstract

Through the improved delay-detached eddy simulation (IDDES), this paper establishes a 1:1 model for a high-speed train, and simulates the transient state of the train running 600km/h in a vacuum pipeline with the pressure of 1,000Pa. The results show that, following the Ω criteria, a pair of counterrotating vortexes can be captured, which alternatively shed near the tip of the last carriage, and propagate over a long distance along the flow direction. The motion and expansion of the vortexes are clearly three-dimensional (3D). Judging by the physical meaning of vortexes, the high vorticity vortexes mainly concentrate near the tip of the last carriage, while the low vorticity vortexes scatter across the wake zone. The latter vortexes have a low dissipation rate and are dominated by rotation. The turbulent energy and Reynolds stress of the wake field are very obvious near the tip of the last carriage, and attenuate quickly along the flow direction. This means the vortexes near the tip of the last carriage face a strong shear effect, and undergo apparent dissipation. Low turbulent energy and Reynolds stress are distributed in the downstream far from the tip of the last carriage, i.e., the interaction zone between vortexes and the ground / inner pipe wall.