Due to the complex geometry of a railway wheel, the shape of its modes may have to be properly considered to understand and predict the sound radiation directivity around it. A straight-web metro wheel is studied in this paper with a radial excitation. First, the near-field sound radiation at the natural frequencies is measured in experiments performed in a semi-anechoic room. The natural frequencies here were determined by modal test. The corresponding mode shape is calculated from a finite element (FE) model. A good agreement is found between measurements and simulations in terms of natural frequencies. Further, the relationship between mode shape and sound field near the wheel is determined. Second, a rotating semi-circular frame of radius 2 m centered at the center of the wheel is employed to measure the directivity pattern. The directivities of A-weighted total level, one-third octave bands and modes are recorded at a total of 667 measuring points. A radial mode (r, 2) and an axial mode (1, 2) are taken as examples to derive empirical equations of directivity pattern. A model developed by the boundary element (BE) method is found to simulate the directivity pattern more precisely than the derived equations.
Study on the Sound Radiation Directivity of a Railway Wheel and the Relationship between Directivity and Mode Shape
Notes Numerical Fluid Mech.
Noise and Vibration Mitigation for Rail Transportation Systems ; Kapitel : 16 ; 117-124
2015-01-01
8 pages
Aufsatz/Kapitel (Buch)
Elektronische Ressource
Englisch
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