Using a 2.5D BE Model to Determine the Sound Pressure on the External Train Surface

In this paper, a wavenumber-domain boundary element (2.5D BE) approach is adopted to predict the transmission of noise from the wheels, the rails and the sleepers to the train external surfaces. In the 2.5D models, only the cross-section of the vehicle is created by using boundary elements, while the third direction is taken into account in terms of wavenumbers. After the sound pressure on the train cross-section is obtained, an inverse Fourier transform is applied to obtain the spatial distribution of the sound on the train surfaces. To validate this approach, the 2.5D boundary element method was used to predict the sound distribution on the train surfaces due to a point source below the vehicle, and due to the vibration of the track. The prediction of the sound distribution from the 2.5D method shows the sound pressure levels on the train floor are 20 dB higher than the pressure on the sides, and the pressure on the train roof caused by the sources below the vehicle is negligible. The 2.5D boundary element method was also used to predict the sound pressure spectrum on the train sides when the train was in running operation. Reasonable agreement was found with measurements.