Study on the acoustic characteristics of low-height trackside barriers for the reduction of railway vehicle rolling noise

초록

Low height trackside barriers can be used on railway to block the noise from the rolling noise sources and the lower unit of railway vehicles as an alternative to conventional full-height barriers. In this paper, the acoustic performance was investigated by using the phased ray tracing numerical method for the sound field around the low height barrier having the angled shape absorptive panels. The noise sources were modeled as the wheel and rail vibration sources. First, the contact force was obtained by applying the rolling noise model 'PRiNT' and the wheel vibration was estimated considering the wheel modal properties from the FE analysis. The vibration response was used as the source input for the ray tracing analysis. The absorptive panel surface was characterized as the acoustic impedance which was measured by the in-situ absorptive measuring instrument using a P-U sensor. Then the directional indices of noise radiation in vertical plane was investigated around the low height barrier. For the rail vibration sources, the monopole point sources were located to the rail heads and the sound field around the low height barrier was studied using the ray tracing analysis. It was found that the amount of noise reduction is different for the two sources and the noise reduction values were estimated along the vertical angle of the source and receiver. Although the low height barrier could not provide screening for all of the aerodynamic sources or upper noise sources, it can be applied efficiently for reducing the low noise sources such as the rolling noise sources.