Beijing's Bird's Nest Stadium is about to be illuminated by the Olympic flame.
The large balcony on the 4th floor of the stadium is filled with a row of consoles, which have a wide view and can see the whole picture of the main torch. Zhang Yimou, the general director of the opening ceremony of the 2022 Beijing Winter Olympics, sat in command, and the finale of the opening ceremony carefully designed by the director team was coming. At this time, Wang Yafei next to the operating platform heard instructions coming from the walkie-talkie, "The core device is activated." ”
Wang Yafei is responsible for operating and commanding the main torch, and their entire team comes from the Beijing 11 Institute of the Sixth Academy of China Aerospace Science and Technology Group Co., Ltd., a professional research institute for the development of rocket engines. Aerospace Science and Technology Group is also the implementation unit of technical support guarantee for the opening and closing ceremonies of the 2022 Beijing Winter Olympic and Paralympic Winter Games.
The Winter Olympic flag entered, the follow-up light followed the 6 flag bearers, and in the air 45 meters above the ground of the Bird's Nest Stadium, the main torch executor began to operate, and the 6 pipelines slowly drooped. The lid of the ground center platform slid open, revealing a "snowflake" hidden underground.
How the Olympic flame will be lit is a curiosity on the part of the world.
In the darkness, the technicians dressed in black moved quickly, quickly connecting the 6 pipelines hanging from the sky to the "snowflakes". The first two wires to be connected are cables and network cables, the circuit supply of "snowflakes" switches from the ground to the sky, real-time status feedback to the control room and receive commands, and the main torch has a "nerve". Then the two hydrogen tubes were successfully inserted, the hydrogen fuel supply was normal, and the main torch had a "major artery". Two WIA steel cables will pull up this "snowflake" and make it dance in the air.
The director's team issued instructions, and hundreds of special-shaped screens inlaid in "Snowflakes" lit up. In the live broadcast footage, a snowflake drifted to the center of the Bird's Nest Gymnasium, and the large "snowflakes" on the ground flipped 54 degrees from the plane to officially debut on the stage.
Subsequently, torchbearers Zhao Jiawen and Dinigal Yilamujiang climbed the steps and inserted the "flying" torch in their hands into the center of this "snowflake", so that the hydrogen supply system in the air was connected with the main torch of "snowflake", and the hydrogen in the hydrogen storage tank swam down the flexible hose, passing through the gas pipeline built into the "snowflake". The pipe inside the holding torch shell bends and loops, and the hydrogen flows along the pipe and finally sprays out.
On the opening night of the Beijing 2022 Winter Olympics, a group of astronauts developing torches seemed to be at the launch site of the rocket 'zero window'.
Demanding "artistic pursuit"
Wang Yafei and his colleagues have an impression of Zhang Yimou: more than 70 years old, thin and busy. The ideas of the director group are always changing, the requirements put forward by the technical side are very harsh, and some "artistic pursuits" are often difficult to achieve, and such artists make them a little uncomfortable.
In previous Olympic Games, the main torch fuel has been mainly alkanes, and only hydrogen fuel has been used at the 2020 Tokyo Olympic Games in Japan. The main source of alkanes is oil and gas, which are inexpensive and have high calories burned. Hydrogen energy utilization involves multiple links of "preparation, storage, transportation and application", and puts forward requirements for the comprehensive utilization level of hydrogen energy.
Hydrogen energy is recognized as a clean energy in the world, the combustion product is only water, its energy density is 3 times that of oil and 4.5 times that of coal, and it is regarded as a subversive technical direction for the future energy revolution. Under the national carbon neutrality and carbon peaking strategic planning, hydrogen energy is the ideal choice for the "Green Winter Olympics" and "Science and Technology Olympics", and also in line with the original intention of running a "simple, safe and wonderful" Winter Olympics.
The use of hydrogen energy is the strength of aerospace. At present, the hydrogen-oxygen engine of the first stage and the second stage of the core of the largest rocket in the mainland, the "Long March 5", is developed by the Beijing 11 institute of the Sixth Academy, and the liquid hydrogen propellant used in the engine reaches minus 253 degrees Celsius. In this way, the 11 Beijing institutes are fully qualified for the Winter Olympics project, and the core backbone of the main torch development team has experience in the construction of industrial torches, and the confidence is relatively sufficient.
"Reality and anticipation are not the same thing at all." Liu Yue, the technical leader of the team, talked about the development process of the torch. Initially, everyone referred to the design of the main torch of the previous Olympic Games, believing that the main torch size should be larger and the flame should be high, so in the pre-research stage of the key technology in the early stage, the minimum hydrogen fuel consumption should also be considered to be 2000 cubic meters / hour.
Director Zhang Yimou's final idea surprised them. The main torch is a snowflake containing the Olympic flame, composed of snowflakes and handheld torches, snowflakes echo the ice and snow sports and the Olympic spirit, the snowflakes install a display screen with live sound and photoelectric performances, holding the torch in the center of the snowflakes is not extinguished, hydrogen fuel flow is about 1.2 cubic meters / hour.
Your fire needs a little sense of fire
In Zhang Yimou's mind, whether there can be a perfect opening ceremony of the Winter Olympics depends on the performance of the main torch.
"Your fire needs a little sense of fire." After watching the first test of the main torch, Cai Guoqiang, who was the director of fireworks performance at the 2008 Beijing Olympic Games, made an evaluation, and he was the old partner of the general director Zhang Yimou.
Han Zongjie, who is in charge of the main torch burning system, was troubled by this sentence, and director Zhang Yimou also made the same request for the main torch - "good looking". Under normal circumstances, hydrogen combustion is light blue, and heat waves can only be seen in daylight, and the "flame color reaction" should be used to color the flames, and there is visual recognition.
When I received the task of the Winter Olympics, it was the Spring Festival of 2020, and the sudden outbreak of new crown pneumonia trapped everyone at home. Han Zongjie took local materials and tested them on the gas stove at home with microplates purchased online. After the orderly resumption of work, colleagues set up a professional test bench and tried all kinds of flame color reactants.
Red, yellow, blue, the team ended up making fires of all colors. "And the green, pure green fire looks particularly maddening." Han Zongjie said.
The flame is dyed and then shaped. The combustion tube is bent into a "mountain" arc at the top of the torch, and along the arc, the nozzles with different spacing and pore sizes are designed, and the hydrogen gas spills out of the hole and ignites, combined with the curved diversion of the shell of the torch holding the torch to form a specific flame shape.
The last "flying" torch is very different from other handheld torches. It has two combustion systems: one is a torch-holding hydrogen combustion system, supplied by an internal hydrogen cylinder that is responsible for completing the torch relay action; the other system is connected to the actuator above the Bird's Nest Stadium for the main torch show at the opening ceremony.
The combustion system is the core technology of the torch, in accordance with the idea of first breaking through the local key technology and then promoting the research and development of the subsystem, the development team will divide the combustion system into two parts: the combustion device is responsible for forming a stable flame, and the fuel supply system is responsible for storing and supplying hydrogen.
Fuel supply systems are another difficulty. The hydrogen fuel of the main torch is stored in a 35 MPa hydrogen storage tank, and the hydrogen gas flows out of the hydrogen storage tank and is converted from high pressure to near atmospheric pressure by a pressure reducing valve, which can be burned by the main torch for at least 8 hours. The pressure of the main torch hydrogen storage tank is 350 times that of the atmosphere, and the same difficulty of decompression technology is very rare in rocket engines.
At the opening ceremony, the main torch rises from the ground into the air, requiring the coordination of the executors. Therefore, the development team chose to supply gas from "heaven", fixed the hydrogen storage tank in the actuator, and hung it in the 45-meter-high darkness of the bird's nest site through the VIA system.
The spacecraft recovery landing ground integrated test site, 50 kilometers from the Bird's Nest, holds a 1:1 sample of the main torch. The test site belongs to the 508th Institute of the Fifth Academy of the Aerospace Science and Technology Group, where the tower once hoisted the Chang'e probe, and also participated in the verification of key technologies in manned space engineering, and now it has become the "birthplace" of the main torch of the Beijing Winter Olympics.
The tower can hang the "snowflake" nearly 30 meters high, and the height is basically the same as that in the bird's nest. In the early stage of the test, various leaders, experts and staff walked into the wall of the test site, and the main torch plan was also iteratively refined.
After the rehearsal of the first opening ceremony, Zhang Yimou said to the main torch team: "Once you get things done." ”
Hidden under the torch stand outside the stadium
In addition to the main torch in the stadium at the opening ceremony, three off-site torch platforms were installed in the Olympic Sports Square outside the Bird's Nest, Yanqing District in Beijing and Zhangjiakou City in Hebei Province, which were jointly unveiled on the evening of February 4.
In Yanqing, Beijing Badaling International Convention and Exhibition Center Square built a blue fence of more than ten meters high, which is very mysterious. As soon as they saw the situation, the old man and the old lady in the vicinity all came to inquire.
A 10.6-meter-high "snowflake" was erected in the enclosure, 96 small snowflakes formed a ring, the stars held the moon around the center of the "flying" torch, 6 olive branches stretched out along the ring, forming 6 petals of large snowflakes, metal streamers in the air to draw a smooth arc, surrounding the "snowflakes", the ground is an oval mirror with a diameter of 22 meters.
After the main torch inside the nest was lit, the three off-site torch stations also removed the fence and met with the people.
The ground is full of light, and there is a hidden dry under the ground.
The flare stand can be divided into three parts: a mirrored snowflake table on the ground, a rotating actuator underground, a control room 100 meters away and a hydrogen supply system. Under the mirror disc, the underground rotating mechanism is hidden in the pit, and the central motor drives the "snowflakes" to rotate clockwise. The outer ring gears drive the metal streamer to rotate counterclockwise, accentuating the main torch in the center. A hundred meters away, a wrist-thick hydrogen gas pipe protrudes from the hydrogen supply room and is connected to the underground rotating mechanism. Zhang Fan, who is in charge of the off-site torch stand project, explained that the thick pipe outside is a "protective tube", and the real hydrogen pipe inside is only a thumb thin.
Hydrogen is only one-14th the density of air, it is easy to "escape", if the hydrogen exceeds a certain concentration in the air, it may cause an explosion. Before the torch left the factory, it experienced reliability experiments such as the rainstorm test of 50 mm of precipitation, the low temperature test of minus 40 degrees Celsius, and the high altitude test of 4000 meters above sea level, and multiple guarantees were designed on the spot to ensure that "everything is foolproof".
One afternoon before the acceptance of the project, the sculpture factory notified that the "snowflakes" were ready, and Zhang Fan turned on the lights and saw the problem at a glance: "No, there are several light leakage points." The others ran over, blinked their eyes, and fixed their eyes before slowly counting: "There is a place below this, and there is also a place above." "There is a gap the size of a green bean in the weld of the sculpture, which faintly reveals the light point inside.
The "snowflakes" in Zhang Fan's eyes are 3D models in the computer, metal fragments deconstructed in pieces on transport vehicles, sculptures with rough welds tied to scaffolding, and torch platforms 10.6 meters high in front of us today.
"Snowflake" is made of metal shaping, inlaid with hundreds of special-shaped screens in the middle, each weld has to be polished by 8 times, and the last one is mirror polished with wool felt. Wang Gong, who is in charge of the sculpture, said that the 88-meter-high Yang Asha sculpture in Guizhou was completed in half a year, and the construction period of the 10.8-meter-high Winter Olympic Torch Platform was also half a year, but there was more trouble.
The biggest pressure came from the requirements of the director group, especially the general director Zhang Yimou, who in addition to watching on the spot, also let the team shoot with various camera equipment during the day and night, and repeatedly confirmed the effect of the torch stand in the shot.
The above-ground construction area of the Torch Stand of the Olympic Sports Plaza is close to the Bird's Nest, and the security and fire departments go to the scene every day to inspect, and the vehicle transportation routes, times, and berthing points are strictly regulated; there are countless pipelines buried under the floor tiles, and the Deeper Beijing Metro Line 8 whistles through. Power supply, fire protection, environmental protection, epidemic prevention and control, special fuels, transportation... A project has to deal with more than a dozen departments, Zhang Fan's mobile phone rings every ten minutes on average, and from noon onwards, he relies on the charging treasure to "survive".
Every two days, Zhang Fan must take time to go to The Olsen long-distance run, while exercising, while relieving the pressure of work. New Year's Day 2022 is a critical period for the construction of the torch platform, and Zhang Fan is staring at the progress of the site, anxious to make a fire bubble in the corner of his mouth. He had planned to run 20.22 kilometers to welcome the New Year, but accidentally took a few more steps, jumping to 20.23 kilometers. He said that a 10-meter error would not work either, and that he would have to run another perfect 2022.
Once in a lifetime
With a round trip of 40 kilometers, Han Zongjie often shuttled between the unit and the 101 houses of the sixth hospital. Step into the gate of 101, all the way up the mountain, the terrain is getting higher and higher. The torch test plant on the hillside was converted from an idle laboratory, and mosquitoes are particularly fierce in the summer.
101 institute is the earliest institution in China to conduct research on aerospace hydrogen energy utilization technology, and the engine of the mainland Long March rocket must undergo a high-intensity assessment here before launch. Under the traction of aerospace engineering, 101 has become the largest liquid hydrogen production unit in mainland China.
"Thanks to the help of the brothers of 101 institutes." Han Zongjie said that outside the torch test plant, 101 institutes have set up a special hydrogen refueling platform for the Winter Olympics, and 100 meters away is a hydrogen production plant, and the hydrogen energy supply is continuous.
In Beijing, the winter night was freezing, and Han Zongjie wrapped a down jacket in the factory. He randomly selected 5 of the 30 hydrogen cylinders for combustion verification and screened the "core" of the last torch of the opening ceremony of the Winter Olympics.
Staying up until 9 o'clock at night, several brothers who worked overtime together froze and stomped their feet. Xing Ke is Han Zongjie's preparation post, the key work and important place of the Winter Olympics project, and they will both appear together. The Winter Olympics are like a marathon. Han Zongjie said that in case something happened to him, someone must be able to top it.
Sometimes, Han Zongjie also misses some important occasions. On the last day of 2021, after a morning review by the expert group, the main torch project of the Winter Olympics was successfully accepted, and the cake was ordered and sent to the Bird's Nest Gymnasium to celebrate this moment, but Han Zongjie and several backbones of the project team were absent because of their work.
Li Xiaofeng, secretary of the Party Committee of the 11 Institutes in Beijing, feels that the main torch development team is particularly difficult, there have been no holidays in the past two years, and everyone has relied on a kind of responsibility and responsibility until now.
"Once in a lifetime." Han Zongjie said that this is also the common belief of the main torch development team, and this time it must be the best.
At the opening ceremony, the music sounded, and everyone returned to the first throbbing, "snowflakes" and "flying", exquisite appearance, fiery inside, this is the moment that belongs to the ice crystal snowflakes and the Olympic torch, and is the romantic "song of ice and fire" of the Beijing Winter Olympics.
Image source: CCTV News, Aerospace Science and Technology Group Sixth Academy Beijing 11
Article/Reporter Hu Lanyue
Video/Reporter Zhang Xiaoning
Voiced by/ Pang Zeyu
Editor/He Ximei
Audit/Yang Cheng
Producer/Soadi