The Effect of the Nose Length on the Aerodynamics of a High-Speed Train Passing Through a Noise Barrier

The unsteady air flow around a train and a noise barrier can be intensified due to the partially enclosed space when the train passes through the barrier. This may lead to the accidents, such as noise barrier failure. Therefore, in this study, the evolution of dynamic pressure loads, transient air velocities, and wake structures were investigated using an improved delayed detached eddy simulation (IDDES) method based on the Shear Stress Transport (SST) k–ω turbulence model. An overset grid method was utilised to address the moving boundary problem. The numerical prediction results were verified by comparison with the results of the full-scale experiment. The impacts of train nose lengths of 4, 7, and 9 m on the temporal and spatial evolution of the flow field were studied. The results showed that the pressure peaks on the train surface and noise barrier and the slipstream peaks decreased as the nose length increased, especially as the nose length increased from 4 to 7 m. One of the main reasons for this improvement was the decrease in the turbulence intensity in both the flow development region and the wake propagation region caused by the weakening of dynamic flow topological structures. Therefore, to ensure the safety of trains and noise barriers, a long nose length train is recommended.