The Shinkansen's Beak
Rishi Kannangara
Award: Top 100
School: american school in japan
Teacher: rigel crockett
Category: Contrived
Photo #19737
The Shinkansen's Beak
The Shinkansen is an iconic Japanese high speed train, admired by many. However, in the late 20th century, when the train entered a tunnel, it regularly caused an explosive sound (tunnel boom) at the exit, which shook windows and could be heard up to 400 meters away.
The blunt nose that the train had at the time was the cause of this tunnel boom. When a Shinkansen enters a tunnel, air is compressed, generating a compression wave that travels in front of it at the speed of sound. When the wave exits the tunnel and expands, it creates a micro-pressure wave (MPV) that makes a booming sound. The amplitude of the MPV is proportional to the maximum pressure gradient, which represents when the air is being compressed the fastest. The same concept is present when the cork of a champagne bottle is opened, hence the popping sound.
Interestingly, the breakthrough in solving this issue came because the train's lead design engineer at the time, Eiji Nakatsu, is also a passionate bird watcher. He observed kingfishers diving into the water with barely a splash, the shape of their beaks helping the water to flow around them and causing a slower build up in pressure. Because air at high speeds acts like a fluid, Eiji Nakatsu designed the Shinkansen to resemble the Kingfisher's beak as it enters water, forming the basis for a new era of aerodynamic efficiency and quieter high-speed travel.
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