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    Numerical Investigation on Aerodynamic Drag and Noise of Pantographs with Modified Structures
    (2022-01-01)
    Yao, Y.
    ;
    Sun, Z.
    ;
    Li, G.
    ;
    Prapamonthon, P.
    ;
    Cheng, G.
    It is well known that the pantograph, which works as a complex component of high-speed trains, is an important source of aerodynamic drag and aerodynamic noise of a high-speed train (HST) that can affect HST performance, comfort for passengers, and quietness of nearby communities. Thus, comprehensive studies on aerodynamic characteristics including aerodynamic drag and aerodynamic noise obtained by the pantograph need to be conducted. This work presents the aerodynamic characteristics including aerodynamic resistance and aerodynamic noise generated by the prototype pantograph of a high-speed train running at a speed of 300 km/h using numerical techniques of improved delayed detached-eddy simulation (IDDES) and acoustic finite element method (FEM). Then, the structure of the original pantograph is modified by wrapping the insulators, and the base frame, so that aerodynamic resistance and aerodynamic noise may be reduced as expected. Numerical results obtained from the pantograph without modification, with two modifications to the original design i.e. the base frame, and the insulators, are discussed. Compared to the original pantograph, the two modifications of the pantograph at the base frame and the support insulators are conducive to reducing the aerodynamic drag of the pantograph. However, the results also show that the modified insulator may not achieve considerable success in noise reduction. Only the modified base frame shows that noise is reduced significantly. Therefore, this suggests that the pantograph with base frame modification is a better choice for resistance and noise reduction.
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    Analysis of aerodynamic noise characteristics of high-speed train pantograph with different installation bases
    (2019-06-01)
    Yao, Yongfang
    ;
    Sun, Zhenxu
    ;
    Yang, Guowei
    ;
    Liu, Wen
    ;
    Prapamonthon, Prasert
    The high-speed-train pantograph is a complex structure that consists of different rod-shaped and rectangular surfaces. Flow phenomena around the pantograph are complicated and can cause a large proportion of aerodynamic noise, which is one of the main aerodynamic noise sources of a high-speed train. Therefore, better understanding of aerodynamic noise characteristics is needed. In this study, the large eddy simulation (LES) coupled with the acoustic finite element method (FEM) is applied to analyze aerodynamic noise characteristics of a high-speed train with a pantograph installed on different configurations of the roof base, i.e. flush and sunken surfaces. Numerical results are presented in terms of acoustic pressure spectra and distributions of aerodynamic noise in near-field and far-field regions under up- and down-pantograph as well as flushed and sunken pantograph base conditions. The results show that the pantograph with the sunken base configuration provides better aerodynamic noise performances when compared to that with the flush base configuration. The noise induced by the down-pantograph is higher than that by the up-pantograph under the same condition under the pantograph shape and opening direction selected in this paper. The results also indicate that, in general, the directivity of the noise induced by the down-pantograph with sunken base configuration is slighter than that with the flush configuration. However, for the up-pantograph, the directivity is close to each other in Y-Z or X-Z plane whether it is under flush or sunken roof base condition. However, the sunken installation is still conducive to the noise environment on both sides of the track.