Study on bogie aerodynamic noise suppression based on serrated leading-edge flow control

The bogie compartment area of high-speed trains has been identified as a major source of aerodynamic noise during high-speed operation. To effectively reduce aerodynamic noise at this area, a noise reduction method based on serrated leading-edge vortex generators is proposed. Large eddy simulation (LES) and the Ffowcs Williams-Hawkings (FW-H) acoustic equation were used to numerically simulate aerodynamic noise at the bogie area based on a 1:8-scale simplified bogie model at a train speed of 400 km/h. The analysis examined the effects of serrated vortex generator heights of 20 mm, 40 mm, and 60 mm on the flow field disturbance, vortex shedding, and sound radiation characteristics at the bogie area. Numerical simulation results indicated that the serrated structures with a height of 40 mm were most effective in noise reduction within the 500 Hz frequency band, reducing wall-mounted dipole acoustic energy by up to 36%; the 40 mm high serrated vortex generators reduced far-field radiated noise by an average of 0.5 dB, with the maximum noise reduction reaching 2 dB. These effects are mainly due to the optimization and regulation from the vortex generators' characteristics to separate the shear flow at the front edge of the bogie area and to disturb spanwise vortices, which effectively weaken low-frequency noise caused by vortex shedding and shear layer instability, and suppress the self-sustained oscillation of Rossiter modes. The study shows that serrated leading-edge vortex generators significantly improve aerodynamic noise distribution at the bogie area, with the greatest noise reduction observed for the 40 mm height. These findings offer an effective approach to aerodynamic noise control at the bogie area.