A study on the reduction of the aerodynamic drag and noise generated by the roof air conditioner of high-speed trains

In order to investigate how the aerodynamic drag and noise produced by the roof air conditioner of a high-speed train can be reduced, the related unsteady flow in the near-field was computed using the method of large eddy simulation. In this way, the aerodynamic source for noise generation has initially been determined. Then, the far-field aerodynamic noise has been computed in the framework of the Lighthill's acoustics analogy theory. The propulsion height and flow-guide angle of the roof air conditioner were set as the design variables. According to the computational results, a lower propulsion height or flow-guide angle is beneficial in terms of aerodynamic drag and noise mitigation. However, compared to the design scheme with propulsion height of 0mm, the aerodynamic drag coefficient of the configuration with propulsion height of 190mm and flow-guide angle of 30° is slightly larger, while the aerodynamic noise is obviously reduced. Thus, from the viewpoint of the aerodynamic drag and noise, the design scheme with propulsion height of 190 mm and flow-guide angle of 30° is the optimal configuration in the range of conditions examined in the present work. © 2020 Tech Science Press.