Influence of Flow Disturbing Grooves Underneath the Cowcatcher on Aerodynamic Noise Generated Around a High-Speed Train Bogie

The influence of the flow disturbing grooves underneath a cowcatcher on the flow and aerodynamic noise performance around a high-speed train bogie is investigated based on acoustic analogy method. Results show that the parallel grooves set on the rear end of cowcatcher bottom surface, interfere with the forming and shedding of the large-scale vortices generated at the rear rim of cowcatcher as well as the leading edge of the bogie cavity where the flow separation and flow interaction between the wake and the geometries are mitigated. Thus, the wall pressure fluctuations on the solid surfaces of cowcatcher and bogie areas are decreased and the flow-induced noise is reduced. Based on the semi-anechoic wind tunnel experimental measurements on the scaled high-speed train nose car model with the flow disturbing method applied underneath the cowcatcher, it is found that the far-field noise at the location opposite to the bogie region is reduced around 0.5 dB(A) and the noise source area around the bogie cavity is decreased with the sound amplitude level reduced up to 1 dB(A) under 20 kHz. This demonstrates that the aerodynamic noise is reduced effectively and verifies the noise reduction effect calculated from the numerical simulation.