Numerical study on aerodynamic drag and noise of high-speed pantograph by introducing spanwise waviness.

It is noteworthy to explore potential measures for further reducing the aerodynamic drag and noise of high-speed pantographs. This paper proposes a method of introducing spanwise waviness into the upper and lower arms. The improved delayed detached eddy simulation (IDDES) method and the Ffowcs Williams and Hawkings (FW-H) equation are used for flow field simulation and sound propagation calculation, respectively. The effects of wavelength, wave amplitude and inclination on the aerodynamic force and radiated noise of the wave cylinder were firstly investigated, and then the aerodynamic characteristics of the pantograph with and without spanwise waviness configurations were compared. Results show that the appropriate spanwise waviness on the cylinder can diffuse the negative pressure core area in the wake, reduce the negative pressure amplitude, suppress the vortex shedding and weaken the fluctuation amplitude of the aerodynamic force, resulting in the reduction of aerodynamic drag and noise. For the high-speed pantograph by introducing spanwise waviness, when the ratio of wavelength and wave amplitude to cylinder diameter is 1.2 and 1/8 respectively, the aerodynamic drag and noise of the pantograph by introducing spanwise waviness are reduced by 1.58% and 1.16 dBA, respectively. [ABSTRACT FROM AUTHOR]