Numerical Investigation on Aerodynamic Noise Source Identification and Far-Field Noise Characteristics of the High-Speed Train Bogie Region

The bogie region is one of the most important aerodynamic noise sources of high-speed trains. A thorough understanding of the generation mechanism and characteristics of bogie aerodynamic noise is the prerequisite for effective implementation of noise control measures. In this study, a delayed detached eddy simulation (DDES) is performed to solve the unsteady flow field around the bogie region, and an aerodynamic noise source identification method based on the integral solution of the Ffowcs Williams-Hawkings (FW-H) equation is adopted to determine the dipole and quadrupole sources distribution in the bogie region. The identification results of the two types of sources provide different understandings of the noise generation mechanism of the bogie region but determine the same flow structures closely associated with the bogie aerodynamic noise, which are the shear vortex structures formed at the rear edge of the cowcatcher and the front side edges of the bogie cavity. The flow field data obtained by DDES simulation is also used as input for the FW-H solver to calculate far-field noise, and the source contribution, spectrum characteristics and directivity of the far-field noise are analyzed. The results show that at a speed of 350 km/h, the aerodynamic noise in the bogie region is still dominated by dipole sources, and the contributions of the bogie itself and the bogie cavity to far-field noise are equally important despite the significant differences in their radiation characteristics.