"Bubble bullets" that can overturn warships and rockets?

2021-04-06 | "Big Technology" Magazine Original Exclusive |

In the shallow waters of the tropical ocean, there are a group of "marksmen" whose body length is only about 5 cm, but when they "fire", they can instantly kill prey that is several times the size of them."Bullets" can even knock down warships and rockets! What kind of weapon is so powerful?

The "bubble bullet" of the pistol shrimp

"Sharpshooter" is actually a kind of shrimp, nicknamed pistol shrimp. Its "pistol" is a giant claw that is half the length of the body. The powerful "bullet" is launched from the giant claw. ResearchIt was found that this giant claw can make a sound close to 210 decibels when it is lightly combined, which is louder than the sound of a rocket when it is launched. The sound wave stirs up a high-speed water flow in the water, and a string of diameters will be attached to the place where the water flows.They are millimeter-sized air bubbles. These bubbles are the "bullets" of pistol shrimp. When the bubbles burst, they will make a deafening crackling sound and generate high temperatures as high as the surface temperature of the sun. In the end, they either "shock" the prey to death.Bake them well.

Why are such mini bubbles so powerful, and how do they form? In fact, the gas in the bubbles is not simple air, but water vapor instantly vaporized from liquid water. When the bubbles burst,The energy of these high-temperature water vapor will be concentrated in a very small point, so it will produce a great sound and extremely high temperature. But the strange thing is that the water generally only vaporizes when heated, and the pistol shrimp does notHeat the water, where does the water vapor in the bubbles come from?

Actually, in addition to temperature, pressure also affects the form of substances, such as the common liquefied gas in life. The reason why it is called liquefied gas is because the liquefied petroleum gas is compressed in the tank at high pressure. At this time, the liquefied petroleum gas is compressed into a liquid state, which is convenientStorage and transportation. When in use, when the valve is opened, the air pressure drops sharply, and the liquefied gas will become gaseous and become the gas we use. The cause of the water vapor in the pistol shrimp "bullet" is similar to this, the giant claw of the pistol shrimpIn the process of rapid closing, a high-speed water flow of more than 30 m/s will be ejected. Under the impact of the water flow, the surrounding pressure drops sharply. This low pressure will turn the liquid water into water vapor, thereby generating bubbles. After the water flows,These bubbles are easily squeezed by the surrounding high pressure, and the concentrated release of water vapor produces loud noises and high temperatures enough to defeat the opponent. The small pistol shrimp defeated many "behemoths" by virtue of this magical "marksmanship"..

Small bubbles overturn the "big guy"

Don't look at the "bubble bullet" of the pistol shrimp is very small, its power is very powerful, when many bubbles are gathered together, it can even stop the destroyer.

In 1902, the British Navy began to launch the most advanced destroyer at the time, the Cobra, but soon after the test sailed, it was found that the ship’s speed decreased, the navigation noise increased, and the destroyer’s performance decreased significantly. In subsequent inspections, the engineers found that the originalThe smooth surface of the propeller has been corroded in a large area and become uneven. Engineers are puzzled. The destroyer uses an extremely corrosion-resistant aluminum alloy, and the launch time is not long. Why is there serious corrosion?

When many engineers were helpless, the Navy finally turned to the famous mechanic Lord Rayleigh. After more than 10 years of research, Rayleigh discovered that the corrosion of the propeller surface is not the chemical action of sea water, but the physicalMechanism, the culprit is the "bubble bullet" similar to the pistol shrimp! Of course, the "bubble bullet" that corrodes the propeller is not fired by the pistol shrimp, but the two have the same cause. It turns out that when the propeller rotates rapidly, it is formed in the sea water.The pressure wave, the pressure wave reduces the pressure in the surrounding area, and the dissolved gas in the seawater is precipitated to form small bubbles. In the high pressure area, these bubbles are quickly compressed, thus forming a jet stream directly impacting the surface of the propeller. This jet streamThe speed of the propeller is extremely high, about 5 kilometers per second. Such a high-speed and dense jet stream impacts on the metal surface, generating a great pressure and impulse, and finally the surface of the propeller is corroded.

Not only the giant ship in the water, but also rockets on land are also affected by "bubble bullets." Liquid rockets are rockets that use liquid chemicals as energy sources. Before launching, the engine pump will rotate at high speed to suck fuel.At this time, the pressure at the entrance of the engine pump is lower than that in other places, and it is easy to produce "bubble bullets", which will corrode the engine pump. The rockets of Japan and the United States have corroded the engine pump due to the "bubble bullets", and finally failed to launch..

Big use of small bubbles

Although we have suffered a lot of losses due to the destruction of the "bubble bullet", as we learn more about it, we have also found some countermeasures, such as predicting the location of bubbles that may be generated through the model, and using strengthBetter materials or install multiple valves in series to reduce the generation of turbulence, etc. Moreover, now we have also begun to learn to use "bubble bullets".

According to research findings, the resistance to sailing in sea water is 900 times greater than the resistance in air. Affected by this, the speed of underwater navigation will be greatly slowed down. And if the entire underwater vehicle can be wrapped with bubblesUp, let the underwater vehicle move like it is in the air, which can greatly reduce the resistance of the object and realize high-speed navigation. The "Storm" torpedo developed by Russian researchers is just such a "scud".

The "Storm" torpedo is first launched by a rocket into the sea, accelerating the torpedo to a supercavitation speed. After entering the sea, the cavitation generator located on the head of the torpedo will depressurize to produce small bubbles.The air pipe injects gas into the bubbles to make the small bubbles expand larger, forming a supercavitation covering most or all of the surface of the torpedo, so that the torpedo is equivalent to traveling in the "air". The speed of the torpedo running in the supercavitation can beIncreased to 100 meters per second, which is about 4 to 5 times the speed of ordinary torpedoes.

"Bubble bullets" can also be used in medicine. Since "bubble bullets" can destroy propellers and pumps made of extremely strong metals, they can also destroy some "bad things" inside the human body, such as fat tissues of obese people, Thrombus blocking blood vessels and various types of stones in cavitary organs, etc. Ultrasound is a high-frequency, high-energy sound wave. When it travels in the blood, it will form a "polarization" of pressure where it passes, and the central pressure is high., The pressure at both ends is low, and there will be many small bubbles at the low pressure. Now the hospital can use ultrasonic equipment to create a large number of small bubbles in the human body, so as to "bomb" these bad things to achieve the purpose of treatment.

The small bubbles produced by ultrasound can not only be used as "bombs", but also as "couriers" to deliver drugs to the lesion. For example, some anti-cancer drugs that are highly harmful to human cells can be "packaged" and delivered directly toTumor Center, reduce damage to normal cells. Biomedical scientist Zhou Qifa and his team at the University of Southern California tested this usage for the first time.

In the artificial blood vessel made of silica gel, the sudden drop in pressure caused by ultrasound causes the gas originally dissolved in the "blood" to separate out and become small bubbles. The chemotherapy drugs in the artificial blood vessel are wrapped in bubbles, and the researchers use a "Acoustic tweezers"-focus the ultrasound to control the movement of the bubbles. These bubbles can reflect the ultrasound very well, and the doctor can track the reflected ultrasound to determine the location of the bubbles. In this way, when the drug-laden bubbles run to the tumorAt this time, the researchers can increase the intensity of the ultrasound, break the bubbles, and release the drug at the desired location.

Researchers said that this method can kill two birds with one stone. It can not only control the movement of the drug and administer the drug deeply into the lesion, but also monitor the progress of the drug during the drug delivery process, which greatly improves the accuracy of drug release. Moreover, tumor drugs are onlyOne of the test drugs, other drugs can also be delivered by this method. For example, some super-powerful antibiotics against drug-resistant bacteria can directly guide the antibiotics to the infection site through ultrasound to avoid harming other beneficial bacteria in the human body.

From the "troublemaker" to the "little assistant", with the help of humans, the "bubble bullet" successfully "transformed" in this way.

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