Effect of geometry simplification and boundary condition specification on flow field and aerodynamic noise in the train head and bogie region of high-speed trains

Shi, Jiawei, He, Yuan, Zhang, Jiye and li, Tian (2024) Effect of geometry simplification and boundary condition specification on flow field and aerodynamic noise in the train head and bogie region of high-speed trains. Journal of Zhejiang University - Science A (Applied Physics & Engineering), 25, [716–731]. (doi:10.1631/jzus.A2300307).

Abstract

The purpose of this study is to determine a suitable modeling method to make computational fluid dynamics (CFD) simulation more efficient for aeroacoustics optimization of the bogie region of high-speed trains. To this end, four modeling methods are considered, which involve different geometry simplifications and boundary condition specifications. The corresponding models are named the three-car marshalling model, computational domain shortening model, carbody shortening model, and sub-domain model. Combining the detached eddy simulation (DES) model and Ffowcs Williams-Hawkings (FW-H) equation, the unsteady flow field and far-field noise of the four models are predicted. To evaluate the effect of the different modeling methods, the time-averaged flow field, fluctuating flow field, and far-field noise results of the four models are compared and analyzed in detail with the results of the three-car marshalling model used as basis for comparison. The results show that the flow field results of the bogie region predicted by the four models have relatively high consistency. However, the usage of the non-time varying outlet boundary conditions in the computational domain shortening model and sub-domain model could affect the pressure fluctuation on the upstream carbody surface. When only the bogie region is used as the source surface, the differences between the far-field noise results of the three simplified models and the three-car marshalling model are all within 1 dB; when the train head is used as the source surface, the results of the carbody shortening model and the three-car marshalling model are more consistent.

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