Investigation on aerodynamic noise generated from the simplified high-speed train leading cars

The aerodynamic noise behavior of flow passing the simplified leading car and nose car scale models of a high-speed train is investigated through the vortex sound theory and acoustic analogy approach. The unsteady flow developed around the geometries is solved numerically and the data are applied to study the near-field quadrupole sound source and calculate the far-field noise radiated. It is found that the turbulent flow developed around the leading car is characterized by multi-scale vortices separated from the geometries. The intensity of volume dipole source is much larger than that of volume quadrupole source and the volume dipole source becomes the predominate source of the near-field quadrupole noise. The flow is separated noticeably in the regions of the nose, bogies, bogie cavities, and train tail of the leading car where the pressure fluctuations are generated largely upon the solid surfaces and correspondingly a dipole noise of high level is produced. By comparison, the noise contribution from the leading bogie and bogie cavity is larger than that from the other components. Moreover, the numerical and experimental results of train nose car model demonstrate that the flow around the bogie region is the dominant aerodynamic sound source. Therefore, the flow-induced noise generated from the leading cars may be reduced efficiently within a certain frequency range and specific direction by mitigating the flow interactions around the areas of leading bogie and bogie cavity.