Aerodynamic noise in the near and far fields beneath the leading car of high-speed trains

Research on train radiated noise typically focuses on turbulent pressure fluctuations and far-field predictions, neglecting the spatial sound field and bogie noise contributions. This study employs a subdomain approach to simulate noise from the head car and leading bogie of a high-speed train, utilizing the improved delay detached eddy simulation method for turbulent field analysis and the acoustic perturbation equation alongside the Ffowcs Williams–Hawkings equation for noise prediction. Results indicate that airflow adheres to the head car surface, while the bogie bottom displays complex streamlines with turbulence and vortices, particularly around the wheelsets. The irregular airflow and high-pressure fluctuations within the bogie cavity make it a significant source of aerodynamic noise, with elevated total and sound pressure levels in the rear structure and downstream areas. Noise primarily originates from the front and rear wheelsets, peaking at 110 and 245 Hz. Sound pressure waves propagate spherically, with strong disturbances at the bogie's rear and downstream cavity. The train structure diminishes sound pressure waves upstream and downstream, with greater strength on the sides. The leading bogie is the main source of far-field radiation noise, with substantial contributions from the car body. Most noise energy is concentrated below 800 Hz. The results highlight the importance of modeling and predicting aerodynamic noise in the underneath region of high-speed trains to facilitate a more comprehensive identification of noise sources.