Numerical investigation on aerodynamic noise sources identification and noise radiation characteristics of the bogie region of high speed train

Abstract

The bogie region is one of the most important aerodynamic noise sources of high-speed trains. In order to deepen the understanding of the generation mechanism and noise radiation characteristics of the aerodynamic noise in the bogie region, the unsteady flow field around the bogie region is simulated by using the DDES (Delayed Detached Eddy Simulation) model. An aerodynamic noise source identification method based on the integral solution of the FW-H (Ffowcs Williams-Hawkings) equation is performed to determine distribution of dipole and quadrupole sources in the bogie region. Combining the noise source identification results and flow field analysis, the key flow structures related to the generation of aerodynamic noise are determined and the formation mechanism of aerodynamic noise sources in the bogie region is explained from two different perspectives. 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 far field noise are analyzed in detail. The results show that the jet shear layer formed at the rear edge of the cowcatcher and the front side edge of the bogie cavity are closely related to the formation of dipole and quadrupole sources in the bogie region, especially the shear vortex structures formed at the rear edge of the cowcatcher. At the speed of 350 km/h, the aerodynamic noise in the bogie region is still dominated by dipole noise, the contribution of the dipole noise generated by the bogie itself and the bogie cavity to far field noise is equally important despite the significant differences in their radiation characteristics.