1E33 Numerical simulation for pantograph aerodynamic noise reduction(Environment and Energy)

抄録

It is necessary to reduce aerodynamic noise, when increasing the maximum operation speed of Shinkansen. In particular, aerodynamic noise from pantographs is a major aerodynamic noise source. In this study, we focused on aerodynamic noise from the upper part of pantograph, which is difficult to reduce with pantograph noise insulation panels. To investigate the noise generation mechanism, we conducted numerical simulation and analyzed the contribution of each noise source. From the analysis, we found that within a frequency range of 200Hz to 700Hz noise from the pantograph head support took up a dominant share of noise within the upper part of the pantograph. In addition it was found that the strong pressure fluctuation causing the noise from the pantograph head support was generated by interference between flow around the pantograph head and flow around the pantograph head support. To reduce pressure fluctuation, we conducted numerical simulations for some shapes by changing the positional relationship of the pantograph head and pantograph head support. From the above findings, we proposed an improved shape that embeds the pantograph head into the pantograph head support. By applying the "improved shape", noise from the pantograph head support was reduced over a wide frequency range and the strong pressure fluctuation on the pantograph head support that was observed in "standard shape" was reduced. We confirmed that the improved shape reduced the noise contribution ratio of the pantograph head support below a frequency of 800 Hz, and reduced the overall noise level of the upper part of pantograph by approximately 1dB.