Effect of dynamic flexible biomimetic fishtail on the wake characteristics and aerodynamic drag of high-speed trains

Abstract

The increase in aerodynamic drag brings high energy consumption, which is a critical issue in the development of high-speed trains. Inspired by the excellent hydrodynamic characteristics of fish movement in nature, a two-dimensional numerical simulation method based on spring-smoothing model and adaptive mesh technology was utilized to explore the effects of different fishtail structures and two flexible motion modes (Eel mode and Lunate-tail mode) on the wake of high-speed trains, and to assess their potential for aerodynamic drag reduction. Results indicate that the biomimetic fishtail successfully suppresses the alternating shedding of vortices in the wake, and induces the aerodynamic drag fluctuation period to align with the fishtail oscillation period. The fishtail length, oscillation mode, and frequency have a significant impact on the wake flow and aerodynamic drag of the train. Among these, a 1850 mm Eel fishtail with parameters of λ = 1 and T = 8 s achieves the optimal drag reduction effect, with drag reduction rates of 39.12% and 26.00% for the tail car and the entire train, respectively. These findings provide a theoretical basis for the design of new low-resistance railway trains, promoting the sustainable development of rail transit towards goals of high-speed and energy-efficient.

Keywords

high-speed train / aerodynamic drag reduction / wake characteristics / bionics / flexible fishtail

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Central South University