<b>Evaluation Method for Aerodynamic Noise Generated from the Lower Part of Cars in Consideration of the Characteristics of Under-floor Flows on Shinkansen Trains</b>

Abstract

Kiyoshi NAGAKURA Environmental Engineering Division Makoto IWASAKI

<b>Influence of Bogie Components on Aerodynamic Bogie Noise Generated from Shinkansen Trains</b>

“…2 m away from the nearest rail and 0.4 m above the rail head (actual measurements), was estimated based on the 2-D SPL (Sound Pressure Level) distribution. Details regarding the flow adjustment and the estimation procedure can be found in Reference [2]. The flow velocity at the inlet of the nozzle was 320 km/h which corresponded to the running speed of an actual Shinkansen train.…”

“…In a previous study, it was shown that noise generated from the lower part of a Shinkansen train (hereinafter referred to as lower part noise) became especially dominant at speeds above 300 km/h [1]. A method has been proposed to quantitatively evaluate aerodynamic noise generated from the bogie section (referred to as aerodynamic bogie noise) through wind tunnel tests, in which flow distributions parallel to the sleeper direction at the inlet of the bogie section are suitably modelled [2]. By using this method, it was estimated that the aerodynamic bogie noise becomes dominant especially under 500 Hz to the total lower part noise.…”

“…Next, two countermeasures were investigated: a deflector and a cavity under cover. The noise reduction achieved by these countermeasures was estimated by using the proposed estimation method in [2].…”

<b>Recent Studies on Wayside Environmental Problems</b>

“…The experimental method was validated by estimating aerodynamic noise from the bogies based on the results obtained through the experimental method, and then used to estimate lower-body noise by aggregating the contribution of rolling noise, estimated using an existing prediction model, and the contribution of noise from devices on the vehicle, obtained through field tests, to check whether estimated results coincided with actual measured values ( Fig. 2) [2]. Development work now is focusing on the identification of the mechanisms causing aerodynamic noise from bogies, and on ways to mitigate these phenomena through the use of the developed experimental methods.…”

Scale-model tests of railway rolling noise

“…Considering research in the literature on other sources of railway noise, aerodynamic noise is usually estimated in wind tunnel tests with a scale model (Yamazaki et al, 2016) and the attenuation of noise propagation is estimated by in scale-model tests (Akutsu et al, 2016). Though numerical studies related to these noise sources are an active focus of research, scale-model tests are also quite common.…”