Recently, the Indian media Eurasian Times quoted the news from the South China Morning Post to publicly announce the "good news": China's wind tunnel set a "record-breaking speed", which can simulate a flying environment up to 33 times the speed of sound, and the wind speed can r

Recently, the Indian media Eurasian Times quoted the news from the South China Morning Post to publicly report the "good news": China Wind Tunnel set a "record-breaking speed", which can simulate a flying environment up to 33 times the speed of sound, and the wind speed can be Adjust within the range of 1.5~11.5km/s!

Recently, the Eurasian Times frequently exposed China's new progress in the field of science and technology, and many technologies have reached the level of world-leading . For example: my country has developed an plasma device for H-20, which not only improves stall performance, but also improves stealth ability. For example: my country has successfully developed an optical thermal search radar, which can scan the entire sky within a few seconds, and can track and image aircraft 300km away.

And in the 33 times the speed of sonic wind tunnel project, China once again leads the world. Chinese scientists are the first to complete the peak challenge that Australian scientists imagine but failed to complete!

China's wind tunnel technology set another record: the speed can reach Mach 33

Flight speed is an important indicator to measure the performance of the aircraft. One entry threshold for fifth-generation aircraft is to have supersonic cruise capability , such as: J-20's fastest The degree can reach Mach 2 and F-22 can reach Mach 2.25, which requires the wind speed tested by the wind tunnel must reach or be higher than the supersonic speed.

How strong is the "record wind tunnel" built in my country? is divided according to speed. Mach 1.3~5 is supersonic, Mach 5~15 is hypersonic, and Mach greater than Mach 15 is supersonic . According to the Eurasian Times, the newly built wind tunnel in my country can be adjusted within the range of ~33 Mach , which is two levels higher than the speed of the fifth-generation aircraft, and is more than enough for testing the hypersonic aircraft .

This wind tunnel is not only the largest high enthalpy wind tunnel in the world, but also an expansion tube shock wind tunnel driven by an piston. Its performance is better than detonation drive, combustion drive and light gas drive.

Let's start with the piston drive pipeline, which was originally proposed and designed by Australian scientist Raymond Stalker in the 1960s, so it is also called a stalker tube. Its advantage is that it uses high-pressure nitrogen (rather than hydrogen ) to drive the piston, which is cheap and easy to maintain. China, the United States, Japan and Germany have also built such piston shock wind tunnels. The principle of the

test can be roughly divided into three parts to introduce.

1, the pipeline is divided into a drive tube and a shock tube. The former is thick and the latter is thin, and the inside is filled with driving gas and test gas respectively.

2, the high-pressure nitrogen storage chamber is connected to the left side of the piston, and the right side of the piston is low-pressure gas such as helium and . When the piston is released, there is a huge air pressure difference on the left and right sides, and the piston drives in the direction of the low-pressure gas.

3, the piston can accelerate to 500~600km/h, the test gas instantly reaches a high pressure state and generates incident shock waves. shock wave passes through a solid film and is compressed secondary in the drive section, and the gas is sprayed along the shock tube onto the aircraft under test.

In addition to being large in scale, the performance of this wind tunnel is also impeccable. The parameters for evaluating wind tunnel performance include Mach number range, Reynolds number range, nozzle diameter, total mild total pressure , etc. Judging from the current public data, the Mach number range has obviously reached the world's leading level. At present, the top wind tunnel in the United States is the LENS-X wind tunnel, with the fastest wind speed of 0 Mach ; the strongest wind tunnel in Russia is AT-303, which is officially said to reach 0 Mach , which is less than Mach 33 in my country. It is accurate To put it, it is 3.8 Mach .

Look at the nozzle diameter again, the specifications also reach the world's first. Previously, the largest piston shock wind tunnel in the world was the X3 wind tunnel in Australia, with a diameter of only 40cm, while the wind tunnel in my country was 80cm, and the specifications were doubled. In terms of design, my country's piston shock wind tunnel is also more advanced, and the accuracy of ground tests is better.

On the other hand, the record-breaking nozzle size also makes the weight of the wind tunnel piston reach 840 kg. When it accelerates to 540km/h, the gas pressure is equivalent to 1,000 times its own gravity.Some people may be worried about the service life of heavy pistons, but the experimental results show that there is no need to worry at all!

Scientific researchers adopted new materials and novel structural designs. The piston did not scratch after multiple intense and repeated tests, indicating that the piston can be reused, greatly reducing the operating cost of the wind tunnel.

China's top wind tunnel research: In fact, I have long had a clear idea, and the goal is to develop spacecraft ?

my country is a major wind tunnel research and development country, and it is not surprising that technology is leading. On the official website of China Aerodynamic R&D Center, there are more than 10 ultrasonic wind tunnels developed, with powerful performance. Taking the 2-meter shock wind tunnel FD-14A as an example, the test time can reach 14~18 milliseconds, the nozzle diameter has two specifications: 1.2m and 2m, the Mach number range is ~24, and the Reynolds number is 1.0×10^6 ~1×10^8/m, with the ability to test the detached ramjet engine.

Whenever domestic wind tunnel technology makes a breakthrough, it can always arouse the strong interest of foreign media. As early as November 16, 2017, the British " Daily Mail " published a related article: China is preparing to test a hypersonic aircraft with a speed of 43,200km/h per hour in 2020, which can fly to the United States within 14 minutes.

This article mentioned that "the test wind tunnel is expected to be completed in 2020", which obviously does not refer to the JF-12 wind tunnel, because the wind tunnel was completed in 2012 and its simulated wind speed can reach Mach 9. It is speculated that the more likely wind tunnel should be the long-awaited JF-22. The wind tunnel is expected to be completed in 2022. The upper limit of Mach number is greater than 30, which roughly meets the setting of "flying to the United States in 14 minutes".

0 June 8, 2021, the Eurasian Times published another article pointing out that the super-large shock wind tunnel and JF-22, which can simulate flight at 30 times the speed of sound, will be put into use soon, and its ability is about 20 to 30 years ahead of the West .

Whether it is a JF-22 wind tunnel or a piston shock wind tunnel, it will push the test wind speed of China's wind tunnel to the level of Mach 30. Every major breakthrough in wind tunnel technology will promote the upgrade of aircraft, and a large number of advanced new generation aircraft may enter the fast lane.

It is worth noting that the speed of Mach 30 is quite special. If it is not counted as the reentry process of the aircraft, it is difficult for the aircraft in the atmosphere to exceed Mach 10. The speed of Mach 5 to 10 is already exaggerated, and it is enough to reach any place in the world within 1 to 2 hours!

From the application direction, the Mach 30 super wind tunnel is likely to be no longer limited to the test of scramjet engine . The subject being tested will most likely expand to interstellar detection aircraft, return capsule of lunar landing project . space shuttle and other spacecraft.

free piston shock wind tunnel: Australia's earliest research and development, why can my country lead?

According to the test wind speed, wind tunnels can be divided into low-speed wind tunnels, high-speed wind tunnels, and ultra-high-speed wind tunnels. Among them, ultra-high-speed wind tunnels are divided into different types such as low-density wind tunnels, hot-rush wind tunnels, pulse wind tunnels, etc.

hypersonic high-enthalpy wind tunnel

The free piston shock wind tunnel mentioned at the beginning is actually a type of pulsed wind tunnel. In 1959, Australian scientist Stalker built the first free piston shock tube in history. The compression tube (drive tube) has a diameter of 0.073m, a length of 1.61m, a shock tube has a diameter of 0.025m, a length of 1.70m, and an incident shock wave of 25. Mach, effective test time is 0.05ms.

For a long time, Australia has been in the leading position in the field of shock wave wind tunnels. In 1984, the T4 wind tunnel was built, with more than 10,000 tests, and the wind speed range was ~10 Mach . In 1987, University of Queensland built high-performance X1 expansion The X2 and X3 expansion tubes were built in 1995 and 2001 respectively, but the maximum Mach number is not higher than 15.

In comparison, although my country's wind tunnel research and development started late, its achievements attracted worldwide attention. Mainstream wind tunnels can simulate wind speeds of Mach 10~24, and wind tunnels of Mach 30~33 are about to be put into operation. Western countries are shocked. It's not unreasonable. Behind the "Chinese Wind Cave Miracle", the meritorious figures that must be mentioned are Qian Xuesen and Guo Yonghuai .

Qian Xuesen and Guo Yonghuai

In 1968, two scientists proposed to establish a pneumatic center in Sichuan, which was soon approved by the state and began construction in February of that year. Qian Xuesen was the first person to propose "hypersonic". Guo Yonghuai accurately predicted the direction of China's development of hypersonic aircraft in the 1950s. Their vision was world-class. In the early stages of completion, the pneumatic center targeted the most cutting-edge technologies of wind tunnels in the world, gaining an advantage in the advance layout of domestic wind tunnel technology.

After more than half a century of development, the aerodynamic R&D center has become the largest and most comprehensive wind tunnel experimental base in China, achieving the connection between low-speed, high-speed and ultra-high-speed. Wind tunnel testing, numerical calculation and simulated flight have all been obtained A major breakthrough.

Thanks to the comprehensive and reliable wind tunnel device, the aerodynamic experiments of many aircraft and high-speed trains were successfully completed, such as: my country's J-10, FC-1 JF-1 Fighter, C919 large passenger aircraft and Shenzhou series spacecraft, magnetic levitation, high-speed trains, After multiple rounds of wind tunnel tests at the aerodynamic base, the overall launch costs of satellite and spacecraft have been reduced by 90%.

With the hard work of the older generation and the new generation of scientists, there are miracles of China's wind tunnel technology again and again. Technically surpassing the United States and Australia and other countries is not our ultimate goal. China will move towards the vast universe and the sea of ​​stars in the future.