Add ‘wings’ to bullet trains to make them even faster: Chinese scientists

China wants even faster bullet trains, and a team of scientists in the southwest of the country have suggested a way to do it: add wings.

Their study found that adding five pairs of small wings on each train carriage would generate additional lift and reduce the weight of the train by nearly a third, taking the top speed to 450km/h.

The research is part of a project launched by China earlier this year named CR450. The programme is a nationwide research effort which aims to develop a new generation of high-speed trains by solving a range of technical issues related to automatic control, wheel design, the steering system, rail upgrades and safety measures.

China’s high-speed rail network is currently the fastest in the world – its existing bullet trains can run at 350km/h. The CR450 project aims to have trains that run nearly 30 per cent faster, meaning it would take only about three hours to travel from Beijing to Shanghai, or just five hours from Beijing to Guangzhou.

But “as the operating speed increases, the wear on the wheels will increase and inevitably shorten the repair cycle and service life of the wheels”, according to a paper by the team from the Chengdu Fluid Dynamics Innovation Centre, led by research engineer Zhang Jun.

“The high-speed train with lift wings is a breakthrough in the traditional concept of high-speed train aerodynamic design, to reduce overall energy consumption and operating costs,” they said in the paper published in peer-reviewed Chinese journal Acta Aerodynamica Sinica on Thursday.

Zhang and his team have proposed putting an array of small wings on top of a train could generate sufficient force to lift it without the risk of hitting anything. But they cautioned that the wings would need to be carefully designed and installed.

Travelling at 450km/h, the train’s body would produce a high-speed airstream near the surface of the roof that could cause harmful turbulence if the wings were sitting too low, according to the paper.

And if a wing was too high above the train, it could run into currents generated by the wings in front and produce more drag than lift. The researchers estimated that the optimal range was for the wings to extend between 1.5 and 2 metres over the roof.

The new type of Chinese train would work more like a cruise missile than an aircraft, according to Zhang and the team, who have also worked on the country’s development of hypersonic weapons.

The first CR450 trains will likely operate on a new 300km railway line between Chengdu and Chongqing, two big economic centres in the southwest, according to Chinese media reports. Construction on that line began in September and is expected to be finished in five years.

Proponents of the wing solution believe it would be more economical and feasible for large-scale application than a maglev train with superconducting technology that travels at 600km/h. Two new maglev lines are being planned for cities in eastern China.

SOURCE: extracts from South China Morning Post,  22 Nov, 2021.
https://www.scmp.com/news/china/science/article/3156974/chinese-scientists-want-add-wings-bullet-trains-make-them-even?