Reduced-order analysis of flow structures around trains passing through plateau tunnels based on HHT-POD

Abstract

Based on the typical meteorological characteristics of a railway in western China, the three-dimensional compressible SST k-ω turbulence model and overset mesh technology were adopted to investigate the pressure characteristics of a full-scale eight-carriage train passing through a single-track tunnel. The rationality of the simulation method was verified through comparison with experimental results from the reference. A method combining the improved Hilbert-Huang transform (HHT) with proper orthogonal decomposition (POD) was proposed to study the pressure field structures at the head and tail trains. Finally, the sliding window-based permutation entropy (SWPE) was introduced to quantify the degree of disorder of the flow field. The results indicate that when a train is traveling through a tunnel, for the head train, the pressure wave dominates the primary mode and stimulates a strong response in the bogie; for the tail train, it couples with and amplifies the serpentine motion of the airflow around the bogie. From a dynamic perspective, the pressure waves promote the flow transformation into a more ordered and low-entropy state.

Keywords

high-speed train / high-altitude tunnel / pressure wave / Hilbert-Huang transform / proper orthogonal decomposition

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