Abstract
In order to understand the mechanism by which a pantograph can generate aerodynamic noise and grasp its far-field characteristics, a simplified double-strip pantograph is analyzed numerically. Firstly, the unsteady flow field around the pantograph is simulated in the frame of a large eddy simulation (LES) technique. Then the location of the main noise source is determined using surface fluctuating pressure data and the vortex structures in the pantograph flow field are analyzed by means of the Q-criterion. Based on this, the relationship between the wake vortex and the intensity of the aerodynamic sound source on the pantograph surface is discussed. Finally, the far-field aerodynamic noise is calculated by means of the Ffowcs Williams-Hawkings (FW-H) equation, and the contribution of each component to total noise and the frequency spectrum characteristics are analyzed. The results show that on the pantograph surface where vortex shedding or interaction with the wake of upstream components occurs, the pressure fluctuation is more intense, resulting in strong dipole sources. The far-field aerodynamic noise energy of the pantograph is mainly concentrated in the frequency band below 1500 Hz. The peaks in the frequency spectrum are mainly generated by the base frame, balance arm and the rear strip, which are also the main contributors to the aerodynamic noise.
Highlights
With the continuous increase in train operation speed, train noise pollution becomes more and more serious
As the pantograph is located on the train roof, the aerodynamic noise of the pantograph will be more prominent for the lines with sound barriers [1]
It can be seen from the results that the relative difference of aerodynamic drag between medium grid and fine grid is less than 2%, and the difference of sound pressure level is less than 0.5 dB, which indicates that when the mesh reaches the medium mesh scale, the computation results are independent of the grid distribution
Summary
With the continuous increase in train operation speed, train noise pollution becomes more and more serious. In the aspect of numerical simulation, Yu et al [10] applied the non-linear acoustic solver (NLAS) combined with FW-H equation to analyze the aerodynamic noise characteristics of a simplified DSA-350 pantograph and the noise reduction effects of four different designs of pantograph fairing. They found that the aerodynamic drag of pantograph area would be increased by all four schemes, and only the scheme using side sound insulation panels could reduce the noise of pantograph.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
