253 トンネル内の高温度領域によるパルス音放射特性への影響(G05-4 流体騒音,G05 流体工学)  [in Japanese] 253 Effect of High Temperature Zone in Tunnel on Radiated Pulse  [in Japanese]

An impulsive pressure wave which is called a micro-pressure wave or a tunnel sonic boom radiating from a tunnel exit is one of the important environmental problems in high-speed railways. In this study, the radiation characteristics of pulse have been studied numerically to show the effect of high temperature zone in tunnel near the exit on the radiated pulse. Especially, the peak values of the radiated pulse are calculated for various thickness and distances from the tunnel end to high temperature zone. The result shows that the local high-temperature region reduces the peak values of radiated pulse by about 30 percents, and changes the direction of the radiated acoustic energy from open end.