Científicos chinos proponen poner alas a trenes bala para acelerarlos 30 % /Chinese scientists want to add wings to bullet trains to make them even faster

PEKÍN.- Un estudio científico chino ha propuesto añadir cinco pares de alas a cada vagón de los trenes de alta velocidad del país para reducir su peso y así aumentar su rapidez en un 28,6 %, recoge el diario hongkonés South China Morning Post.

El estudio, parte del proyecto oficial CR450, que tiene como objetivo incrementar la velocidad de los actuales trenes, halló que la adición de unas pequeñas alas podría generar suficiente sustentación como para reducir su peso en un tercio, lo que aumentaría la velocidad hasta los 450 kilómetros por hora.

En la actualidad, los trenes de alta velocidad chinos tradicionales alcanzan hasta 350 kilómetros por hora, excluyendo el tren de levitación magnética de Shanghái, que, por su tecnología, consigue llegar a los 431 kilómetros por hora.
Ingenieros japoneses ya tuvieron una idea similar en los años 80, pero se desechó porque las alas eran demasiado grandes y hacían imposible que los trenes pudiesen circular por las vías y túneles existentes.

Sin embargo, los científicos chinos han optado por colocar unas alas más pequeñas en el techo de los trenes en lugar de en los lados, apuntó anoche South China Morning Post.

Según los científicos, que publicaron su estudio en la revista científica Acta Aerodynamica Sinica, la idea es un «avance en el campo de la aerodinámica de trenes de alta velocidad que permitirá reducir costes y energía», aunque advirtieron de que una mayor velocidad podría reducir «la vida útil de las ruedas» y de que las alas habrían de ser «instaladas y diseñadas cuidadosamente».

Con 37.900 kilómetros, China cuenta con la red de trenes de alta velocidad -definidos en el país como aquellos que pueden funcionar a más de 200 kilómetros por hora- más extensa del mundo.

EFE

Chinese scientists want to add wings to bullet trains to make them even faster

• Study finds that five pairs of wings on each carriage would generate lift, reducing the weight and taking the top speed to 450km/h (280mph)
• Research is part of CR450, a project launched by Beijing that aims to develop a new generation of high-speed trains

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 (280mph).

The research is part of a project launched by Beijing earlier this year named CR450, which aims to develop a new generation of high-speed trains that can travel at that speed.

China’s high-speed rail network is currently the fastest in the world – its existing bullet trains can run at 350km/h (217mph). 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.

The idea of putting wings on high-speed trains is not new – Japanese engineers came up with a proposal in the 1980s for a train with plane-like wings extending from the sides, eventually building a prototype two decades later.

While this early attempt proved that the wings gave aerodynamic efficiency, it failed in practical applications because the wings were too big and too wide for the train to run safely within the limited space of existing rail infrastructure like security fences and tunnels.

Zhang and his team have proposed something a little different. Instead of putting a pair of giant wings on the sides, they say an array of smaller 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 (4.9 to 6.5 feet) over the roof.

The biggest difference between their proposal and the Japanese one is that the Chinese train would work more like a cruise missile than an aircraft, according to Zhang and the team, who also work on the country’s military research programme, including the development of hypersonic weapons.

Chen Yu, a research engineer with Tongji University in Shanghai who was not involved in the study, said there were some extremely challenging engineering issues to overcome to put wings on trains.
“For a train designer, the smoother the surface the better – every additional component is an additional issue,” said Chen, who has studied the aerodynamic behaviours of high-speed trains in wind tunnels.

Wings would, for instance, inevitably increase noise in the cabin and reduce passenger comfort, he said. That would mean scientists and engineers would have to come up with ways to control the complex airstreams over the roof and absorb the increased noise with soundproofing materials or structures.

“But this will then increase the total weight of the train,” Chen said.
High-speed trains draw electricity from overhead power lines via a pantograph that sits on top of the train, and he said additional measures would be needed to keep the pantograph in constant contact with the power lines given the disturbance generated by the wings. Stephen Chen