It is well known that smoothing configuration is effective to reduce aerodynamic noise from high-speed vehicles. However, in the case of components such as pantographs that are subjected to strong aerodynamic forces, smooth configurations and the stability of aerodynamic characteristics are often conflict with each other. It is a critical issue, therefore, to significantly reduce the aerodynamic noise emitted from pantographs. To address this, the RTRI has developed a technique to reduce aerodynamic noise by pasting a porous metallic material onto the surface (Fig. 1).

In wind tunnel tests, the RTRI confirmed that a Shinkansen pantograph partially covered with a porous resin material is featuring an aerodynamic noise reduction effect equivalent to that of a porous metallic material reduced aerodynamic noise by 1 to 3 dB (Fig. 2). The method of pasting porous metallic material onto pantographs through the bonding and riveting was devised, and it was confirmed as having sufficient adhesion strength for practical purposes. The RTRI implemented a running test on a Shinkansen pantograph treated with the porous metallic material (Fig. 3) to confirm its ability to reduce aerodynamic noise without adversely affecting the current-collecting performance. In the running test over a period of several months, no problems were found with the adhesion performance of the porous metallic material on the pantograph surface.

The technique’s applicability to objects whose configuration is hard to be smoothed is expected to result in its widespread use as a means to reduce aerodynamic noise.