China's 400km/h Bullet Train Set to Enter Commercial Operation

With innovative braking technology and a design inspired by fast-flying birds, the CR450 bullet train maintains energy efficiency even at speeds of 400km/h.

The CR450 train was built by a subsidiary of China Railway Construction Corporation (CRRC). Photo: CRRC

China’s newest bullet train, the CR450, is undergoing final performance tests in preparation for commercial operation at 400 km/h, Science and Technology Daily reported on July 21. The team has surpassed the previous maximum speed of 350 km/h, under a situation where high aerodynamic resistance and energy consumption have been technological barriers for decades.

According to Shao Jun, a researcher at the China Academy of Railway Sciences, increasing the speed by 50 km/h will lead to a 30% increase in resistance and greater energy consumption. High-speed trains face 95% of the resistance from the air. To increase speed and save energy, scientists have to adjust the shape of the train's front end to reduce resistance, taking inspiration from nature to create a design based on fast-flying birds, which cuts about 2.6% of the resistance. They then looked at the undercarriage of the train, an area that has traditionally been overlooked but has the potential to reduce resistance.

https://www.youtube.com/watch?v=XIrroQ6Bl-U

A member of the research team proposed the idea of a shield structure to protect the exposed area of the wheel set, creating a more aerodynamic shape to reduce drag. After optimizing the shield structure several times, the drag was reduced by 22%. This means that even if the speed is increased by 50 km/h, the energy consumption of the new train is still equivalent to the CR400 Fuxing train operating at 350 km/h.

Researchers on the project are also developing new materials to handle the challenges of temperature, deformation, and fatigue, which will help them handle the braking of the hypersonic vehicle. The team aims to achieve the same braking distance on the new train as the CR400, slowing from 400 to 0 km/h over a distance of 6.5 km to bring the train to a steady stop. The energy released in this process is enough to heat 6.8 tons of water from freezing to boiling in 2 minutes. While the metals used in the new material are not being disclosed, the team has conducted hundreds of tests to perfect the formula and has spent more than a year evaluating its performance.

The CR450 train was displayed at an industry conference in Beijing in early July. China's high-speed rail network now covers 48,000 kilometers, accounting for more than 70% of the world's total, connecting 97% of cities with populations of more than 500,000.

An Khang (According to Sci Tech Daily, Interesting Engineering)