Effective Nose Shape for Reducing Tunnel Sonic Boom


Masanobu IIDA, Senior Engineer, Aerodynamics and Noise Reduction G., Environmental Preservation and Disaster Prevention Technology Development Div., Technological Development Dept.
Tsuyoshi MATSUMURA, Engineer, Wind Tunnel Technical Center, Technical Support Div.
Koji NAKATANI, Assistant Manager, Technical Development Promotion Dept., West Japan Railway Company
Takashi FUKUDA, Engineer, Aerodynamics and Noise Reduction G., Environmental Preservation and Disaster Prevention Technology Development Div., Technological Development Dept.
Tatsuo MAEDA, Chief Engineer, Aerodynamics and Noise Reduction G., Environmental Preservation and Disaster Prevention Technology Development Div., Technological Development Dept.

When a train nose enters a tunnel at a high speed, an impulsive pressure wave ('tunnel sonic boom' or 'micro-pressure wave') radiates from the tunnel exit and it causes an explosive sound or an abrupt rattling of window frames of houses near the tunnel exit. Therefore it is necessary to make the nose shape of the high-speed train effective for reducing the tunnel sonic boom.
In this paper, the effect of the train nose shape is investigated using numerical simulation of the tunnel entry problem. The nose shapes dealt with here are (1) fundamental nose shapes, (2) optimum nose shape obtained by nonlinear optimization method, and (3) the nose shape of the 500-series Shinkansen train which runs at 300km/h for the first time in Japan.