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Author: search.filters.author.Yao, YongfangSubject: search.filters.subject.Aerodynamic noise

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    Aerodynamic optimization using passive control devices near the bogie cabin of high-speed trains
    (2022-09-01)
    Yao, Yongfang
    ;
    Sun, Zhenxu
    ;
    Li, Guibo
    ;
    Yang, Guowei
    ;
    Prapamonthon, Prasert
    Bogies are responsible for a significant amount of aerodynamic resistance and noise, both of which negatively affect high-speed train performance and passenger comfort. In the present study, the passive control method is applied in designing the bogie cabins of a high-speed train to improve its aerodynamic characteristics. Two passive control measures are introduced, namely, adding a spoiler and creating diversion grooves near the bogie cabins. Furthermore, the aerodynamic and aeroacoustic characteristics of a high-speed train operating at 350 km/h under different control strategies are numerically investigated using the improved-delayed-detached-eddy simulation (IDDES) and the acoustic finite element method (FEM). The impacts of passive control devices on drag reduction, slipstream, and aerodynamic noise are presented and discussed. Numerical results reveal that the passive control devices have a major effect on the slipstream around the train. The amplitude of the fluctuating pressure is higher in the first half of the train than in the second half. The first bogie has the maximum amplitude of the acoustic pressure for both the train with and without passive devices. In the far field, the spoiler installation and placement of the diversion grooves in the front of the bogie cabin can significantly reduce aerodynamic drag and noise. Hence, as shown in this study, using passive control methods to improve the aerodynamic and aeroacoustic properties of high-speed trains can be a viable option. [Figure not available: see fulltext.].
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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.