The world's most powerful wind tunnels.

Wind tunnels have become a cornerstone of the aerospace industry, helping to test the aerodynamics of countless aircraft and missiles.

A wind tunnel is a machine that simulates the flow of air through objects. The system always includes a long, narrow tube where airflow is introduced using various methods, such as powerful fans. The model or object to be examined is placed inside the tube. The airflow is controlled to study its effect on the object under different conditions, such as varying wind speeds. First developed in the late 19th century, wind tunnels are now widely used in many industries. For example, wind tunnels used in the automotive industry test the aerodynamics of cars, race cars, trucks, and other vehicles.

In civil engineering, wind tunnels test the structural integrity of buildings and infrastructure projects. They also help optimize aircraft and missile designs for safer and more efficient flight. Below are some of the world's most powerful wind tunnels today, according to Interesting Engineering .

1. JF-22

The JF-22 wind tunnel can simulate the environment during spacecraft re-entry. Photo: CCTV

The JF-22 is the world's most powerful supersonic wind tunnel. Built at the Institute of Mechanical Engineering of the Chinese Academy of Sciences (IMCAS) north of Beijing, the JF-22 can reach speeds of up to Mach 30 (37,044 km/h or 10.3 km/s).

The JF-22 does not use fans because fans cannot generate such high-speed airflow. Instead, this wind tunnel uses timed explosions to produce shock waves that reflect off each other and converge at a single point inside the 4-meter-diameter, 167-meter-long tube. The JF-22 can deliver 15 gigawatts (GW) of power, equivalent to 70% of the power of the Three Gorges Dam, the world's largest hydroelectric dam in Yichang, China.

2. JF-12

The JF-12 is often considered the predecessor of the JF-22, being an open-circuit wind tunnel. Like the latest JF-22 wind tunnel, the JF-12 uses shock waves to create flight conditions ranging from Mach 5 (6,174 km/h) to Mach 9 (11,174 km/h), at altitudes from 25,000 m to 50,000 m.

Built by the Institute of Mechanical Engineering under IMCAS between 2008 and 2012, the JF-12 is crucial in the development of China's DF-ZF hypersonic glide vehicle (HGV), according to a report from the China Aerospace Research Institute. The JF-12 remains in active service alongside the JF-22.

3. T-117 TsAGI Supersonic Wind Tunnel

T-117 TsAGI Wind Tunnel. Photo: TsAGI

The T-117 TsAGI is a large supersonic wind tunnel built at the Central Hydrodynamics Institute in Moscow, Russia, in the 1970s. The system operates on a bottom-out principle, in which high-pressure air is rapidly released into the remaining area of ​​the wind tunnel to create an airflow. Two separate, detachable electric furnaces, depending on the experiment, heat the airflow.

One furnace uses two electric arcs to deliver a maximum power of 25 megawatts, while the other uses a single electric arc for a maximum power of 2.5 megawatts. The air in the furnaces is heated between two electrodes aligned along the same axis, generating an electric arc. The arc then rotates due to a magnetic field, warming the air passing between the electrodes.

In this way, the T-117 TsAGI can simulate the high temperatures encountered by hypersonic vehicles during flight, while simultaneously generating test speeds ranging from Mach 5 (6,174 km/h) to Mach 10 (12,348 km/h). In 2018, the T-117 TsAGI was used to test the hypersonic flight mode of the Federation spacecraft, a project of the Russian space agency Roscosmos aimed at replacing the Soyuz spacecraft in various missions in low Earth and Moon orbits.

4. High-Speed ​​Tunneling Facility (HTF)

The Hypersonic Tunneling Facility (HTF) is located at NASA's Neil Armstrong Test Site, within the Glenn Research Center in Sandusky, Ohio. Originally built to test nuclear-heated rocket nozzles in the Nuclear-Driven Vehicle (NERVA) program, the facility now specializes in testing large-scale hypersonic propulsion systems at speeds from Mach 5 (6,174 km/h) to Mach 7 (8,644 km/h), simulating real-world altitudes (36,500 m).

The test area in the HTF can be adjusted from 3.05 m to 4.27 m. There, a graphite-cored electric heating furnace heats nitrogen gas, which is then mixed with oxygen and room-temperature nitrogen to create artificial, unpolluted air at the correct ratio. The temperature of the artificial air is controlled to meet the specific requirements of the test. The HTF can operate for 5 minutes at a time, depending on operating conditions.

5. Unitary Wind Tunnel Plan (UPWT)

A model of the UPWT (Ultrasonic Wind Tunnel) space launch system being tested in a subsonic wind tunnel. Photo: NASA

The Unitary Plan (UPWT) wind tunnel is one of the largest operational wind tunnels in the world. The facility is located at NASA's Ames Research Center in Moffet Field, California. Since its completion in 1955, the Unitary Plan (UPWT) wind tunnel has been used to test both conventional aircraft (commercial and military ) and spacecraft (such as NASA's now-defunct Space Shuttle). The tunnel played a key role in the development of Boeing's aircraft fleet, as well as the F-111 fighter jet and the B-1 Lancer bomber.

UPWT comprises three closed-circuit wind tunnels: a 3.4 x 3.4 m subsonic wind tunnel (TWT), a 2.7 x 2.1 m supersonic wind tunnel, and a 2.4 x 2.1 m supersonic wind tunnel. The final wind tunnel can reach speeds of up to Mach 3.5 (4,321 m). All are powered by four 65,000 hp wound-rotor electromagnetic motors operating at 7,200 volts.

An Khang (According to Interesting Engineering )

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