Aerospace, let the magic of fluid enter thousands of households

Every time a space launch, the photos and videos of the scene will arouse the audience’s great shock. In the midst of admiration, the voice is always heard: “It looks like a gas stove.”

Indeed, in terms of visual effects, the bright tail flame of a rocket engine is indeed a bit like the flame of a gas stove. After all, some rocket engines use gas (methane) and oxygen (liquid oxygen).

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But when it comes to what appliances are most like a rocket, a gas stove might not be the best choice. After all, it can’t go to heaven with a gas stove. This isn’t just a joke. With the same fuel, one can fire a squid, and the other can explore the universe. The difference is that a rocket is a complex system engineering, and there are too many devices in it that are not obvious but extremely technically difficult. This complex system engineering also brings increased uncertainty, and how to make the rocket reliable is also a big problem.

01 5, 4, 3, 2, 1, washed without

At home, there is such an electrical appliance that people often experience the mood of the aerospace commander. This appliance is also considered by many to be the most similar to a rocket among all appliances. At the same time, the process of his acceptance by family members was also the most difficult.

It is, the dishwasher.

If you can speak, I believe that many household dishwashers will tell a “history of career development” with tears in their eyes. When the addition of a dishwasher is included in the family budget declaration meeting, it is often unanimously opposed by the elders of the family. The disapproval rate is even higher than buying a game console, after all, who is not a dishwasher expert?

Dishwashers cost water, dishwashers consume electricity, and dishwashers damage tableware. Faced with the three major doubts of the “Budget Approval Committee”, it is relatively easy to defeat them one by one with data and experiments. The water and energy consumption of hand-washing dishes depends on individual craftsmanship, but a peer-reviewed scientific research paper shows that dishwashers outperform even the most budget-conscious humans when it comes to saving water.

“How could it be? You never stop listening to the sound of water in the dishwasher.” When the elders learned that the water in the dishwasher can be recycled repeatedly, they understood that the dishwasher saves water and saves water. I’m not bragging, after all, when you wash dishes by hand in the sink, no matter how small the faucet is, it will be gone when it runs off.

The only thing that is difficult to convince people with data is the cleaning effect. When the dishwasher budget is finally approved, and after installation, every time it is used, it will usher in the eyes of the elders. For the first few months, most of the time, the dishwasher was able to complete its task, and the elders nodded approvingly at the sparkling cups and saucers. Trust is accumulated little by little, but trust is lost little by little. When the lid was lifted once and an unwashed dish was lying in the dishwasher: “What did I say? I still have to wash it by hand!”

Therefore, every time you have to watch the countdown on the dishwasher like the commander-in-chief of spaceflight, you must open Schrödinger’s door before the elders.

02 You can always trust aerospace technology

Recently, Fangtai conducted a live broadcast of a factory visit, which comprehensively demonstrated the technological innovation in the research and development and production of Fangtai dishwashers, the “all-round dishwashing expert”. In this live broadcast, we saw Fangtai’s engineers introduce the high-energy bubble washing technology jointly released with the Institute of Mechanics of the Chinese Academy of Sciences, adding elements of aerospace technology to the dishwasher. Your next dishwasher, with the blessing of aerospace technology, is believed to stand up to the scrutiny of the elders, because you can always trust aerospace technology.

get?code=ZDE3OGYwNTIxZTg2ZWNiNDYwNTQ5YTU Navier-Stokes equations

Fang Tai, did you really use Aerospace Homologous Technology in the dishwasher? Before we can understand how spaceflight blesses dishes, we must first learn an unsolved mystery of mankind.

How does the dishwasher clean the dishes? Most people don’t know, because the safety design guarantees that when you open the door of the dishwasher, all cleaning will stop, as if you are afraid of prying into the secret. In fact, the working method of the dishwasher is completely different from that of hand washing dishes. There is no sponge or steel wool in the dishwasher. It completely relies on the water flow from various nozzles to “attack” the dirt. Aided, the water completes the washing of the dishes. It’s just a sentence, but to explain all this in principle, we need to go to the forefront of today’s science.

03 Everything is fluid

How does the water in the dishwasher head flow? this is a problem.

More than 2,000 years ago, the ancient Greek philosopher Heraclitus said: “τὰ πάντα ῥεῖ” is a Greek phrase that I pasted, meaning “everything is fluid”.

More than 100 years ago, French scientist Navier and British scientist Stokes wrote a set of equations, known as Navier-Stokes equations, or NS equations for short. This is a set of equations that are extremely beautiful in mathematics, and the road is simple. What do you mean? It describes how the fluid changes, whether it is air, water or any other fluid, knowing what it is now, through this equation, you can find out how it will change in the future.

If you are interested, you can try to solve this partial differential equation. If you solve it, you can get at least a million bonus. In 2000, a mathematics institute offered a million-dollar bounty for seven math problems, known as the Millennium Million Math Problem. One of them is finding “smooth solutions” to the Navier-Stokes equations. Twenty-two years later, no one can take the money from the old gentlemen of Navier and Stokes.

Therefore, everything flows and everything is mysterious, from the magma flow that shapes the mountains and valleys of the earth, to how mosquitoes travel through raindrops. When it comes to fluid mechanics, there are problems everywhere. Even if you turn on a tap at home, you can observe several global problems. For example, turn on a large water tap and then turn it off quickly. If you live in some old residential areas, you may feel the huge vibration of the water pipe when you hear a series of thumping sounds, just like someone hit it with a hammer. It is the water hammer effect, which is difficult to calculate accurately. If the faucet is turned on a little smaller, the water flows smoothly and steadily to the surface of the sink, creating a small circular “pond” in the sink, where the water level rises suddenly, this is called a “hydraulic jump” , is also extremely difficult to calculate.

get?code=MTAwOTNlNzk4MDayYzNiNTA0MTg4MjU hydraulic jump

You can’t even figure it out, so what kind of fluid mechanics are you still playing? Do you still have the confidence to take a boat or a plane? Engineers never wait until science is perfect, they have a solution. In engineering practice, although there is no absolute perfect solution for fluid mechanics, simulation and experiment can be used to approach the perfect solution as much as possible, thus turning it into experience.

04 Aerospace, turning the magic of fluids into reality

The best use of fluid mechanics is aerospace.

Everyone will be amazed at how rockets fly at extremely high speeds and how fast objects in the atmosphere are subjected to forces. This is a complex fluid mechanics problem. Equally complex fluid mechanics problems occur inside rockets. The different propellants are squeezed into the combustion chamber at extremely high pressures, mix, and burn, creating a tail flame that propels the rocket forward.

get?code=NWQ3MTEzNmYxNTFjODY2Y2Q2MjcyM2E Laval nozzle of the Apollo spacecraft engine

The part of the rocket that emits the tail flame is called the nozzle, and it has a lot of mystery. Many aerospace enthusiasts think that the nozzle is the most beautiful part of the rocket, because it has an enchanting curve. The term is called “Laval nozzle”, which was invented by Swedish inventor Gustav de Laval. Goddard, the father of rockets, applied it to rockets for the first time. This nozzle is unusual. When the tail flame of the rocket passes through the thin and thick pipes in the middle, the speed will exceed the speed of sound, releasing great power.

If the fluid velocity is not so fast, such a tube is called a “Venturi tube”, which was invented by Italian scientist Giovanni Venturi. He found that a thick and thin pipe, the fluid flows faster in thin places ,low pressure. In the hot summer, certain corridors or corners are particularly popular, because the wind is always stronger there than elsewhere, these draughts are actually the actual application of Venturi. Such effects can also be described by the Navier-Stokes equations.

If you have watered flowers and plants with a transparent hose in the garden, you may find a phenomenon. If the hose is bent or pressed, there are often some air bubbles where the diameter of the hose narrows, accompanied by a buzzing Voice. In fact, what you see here is also a Venturi tube. The narrow place has a fast flow rate and low pressure. If the pressure is small enough to make the water boil, the water turns into water vapor. Doesn’t it take very high temperatures for water to boil? Not necessarily, the lower the pressure, the lower the boiling point, and the higher the pressure, the higher the boiling point. This is also the reason why the plateau does not cook rice without a pressure cooker. In the narrow part of the tube, the pressure can be so small that the water boils at room temperature. The term is called cavitation effect.

05 Don’t underestimate the bubbles

You might say there’s nothing wrong with that, just bubbles. Then you underestimated this little bubble. In a rocket engine, there is one place where cavitation occurs, where? in the engine pump. A pump is a machine that compresses fluid. The fuel pump uses high-speed rotating blades to compress liquids such as liquid oxygen or kerosene to a great pressure. Spinning at high speed, remember the Venturi? The faster the speed, the less pressure. The liquid propellant then becomes cavitation bubbles on the vanes of the pump.

This phenomenon was first detected on the propellers of ships. A good propeller, so strong, after driving for a while, it is full of small pits. The research found that it is the ghosts of those cavitation bubbles. When these inconspicuous cavitation bubbles burst, they can actually generate high temperatures of tens of thousands of degrees Celsius and strong shock waves. Granted, the range is all small, but it’s enough to gnaw holes in solid metal. This is the cavitation corrosion effect.

get?code=ZjgyZGNhNTUxN2U3ZTg3OGIwMDIwYmJ Pump corroded by cavitation

On ships’ propellers and pumps in rocket engines, scientists are trying to reduce this phenomenon of cavitation corrosion, such as changing the shape of the blades. In other places, cavitation corrosion does not necessarily mean destruction, but may still be a kind of construction. For example, cleaning your teeth.

Ah, open your mouth, the irrigator flushes out the sour water, and the tartar and calculus that are firmly adhered to the teeth are washed away. No, they are not washed off, but by cavitation erosion. The dental irrigator uses ultrasonic waves to generate cavitation to clean the teeth.

If the dishwasher also uses this cavitation bubble to impact oil stains, wouldn’t it be invincible? Fang Tai engineers tamed these bubbles using aerospace technology.

They improved the internal structure of the dishwasher spray head using the structural design of the Laval tube, which increased the range of the water flow by 20%. This time, the water flow is not only a water flow, but a gas-liquid two-phase flow, that is, it contains a large number of cavitation bubbles. In the past, similar cavitation jets have been used industrially to clean “harder dishes” such as boat bottoms overgrown with barnacles and mussels. If you have intensive phobia, it is strongly recommended not to search for photos of the bottom of the boat. The bio-glue secreted by these sea creatures is comparable to the strongest glue, and is much harder to clean than dry rice grains stuck to a plate. Under the impact of cavitation jets, even these thorny sea creatures can be easily cleaned up.

In the Fangtai dishwasher, engineers precisely control the energy of the cavitation jet, combined with a high-speed stable water flow of 30 meters per second and a high temperature of 75 degrees Celsius, which has greatly improved the cleaning power of similar products. Especially those small cavities, when they burst, they produced an impact comparable to the speed of a bullet. This process is not only a physical process, the rupture of vacuoles will also produce free radicals with oxidative effect on the water, which has a good removal effect on pesticide residues and germs. This water is mixed with a lot of cavitation bubbles, which is cleaner and saves more water.

06 Dishwashing is a systematic project

Once, 5, 4, 3, 2, 1, open the lid, you never know if there are still leaves hanging on the plate in Schrödinger’s dishwasher. Now, 5, 4, 3, 2, 1, a dishwasher full of shiny kitchen utensils is waiting for you. After you press the start button, Fangtai dishwasher is also doing a countdown of 5, 4, 3, 2, 1. 5. Washing, cavitation bubble water column rinses every corner. 4. Disinfection. The vacuoles themselves have a significant killing effect on microorganisms. With the continuous high temperature of 75 degrees Celsius, the tableware is pasteurized while washing dishes. 3.Drying, the ceramic heater cooperates with hot air to fully remove the moisture in the dishwasher and make the tableware dry quickly. 2. Slag removal. In the past, after washing dishes, the accumulation of residue in the dishwasher will not only easily block the sewer pipe, but also cause odor and secondary pollution. Fangtai is the first in the industry. 1. Storage. In the past, how many dishwashers have been reduced to cupboards. Today, Fang Tai has made dishwashers a better storage space. If you don’t use it frequently, you can turn on the storage mode, and the dishwasher will dry it with hot air at regular intervals to prevent the tableware and the dishwasher itself from getting damp, moldy, and smelly.

These are actually the specific technologies used in Fangtai dishwashers. In fact, similar to aerospace, dishwashers are also a complex system engineering, and even face more difficult tests than rockets. Because after all, the mission of the rocket is clear. It is clear which load island and orbit to be launched at a certain time, and in what launch window. If the designed parameters are exceeded, the launch can be aborted, delayed or even cancelled. However, before you press the start button, the dishwasher will never know whether you are eating a porridge and side dishes for one person or a sumptuous feast for the family. Faced with such a complex and changeable task, Fangtai’s engineers need to rely on another aerospace technology – twin digital simulation. Before actually starting to build, first use digital modeling to build a virtual dishwasher, give it various virtual tasks, see its completion, and improve the design on this basis.

Of course, virtual simulation does not completely replace testing in a real environment.

After all, the Navier-Stokes equations have not been fully solved, so we have not been able to use the formulas and equations to accurately determine the changes in all states of the fluid. Therefore, whether it is aviation or aerospace, engineers must constantly explore the operation conditions under various working conditions, from digital simulation models to scaled wind tunnel models to prototype flight test experiments. The current manned carrier rocket in my country’s aerospace industry is the Long March 2 F type, which is a member of the distinguished Long March 2 family. The Long March No. 2 was born in the mid-1970s and is nearly half a century old. The reason why such an aging rocket is used is that it has been tested for a long time, and the engineers who have launched more than 100 times have made engineers know it very well, so they can fully trust it. Although the dishwasher is not an important national weapon, it also needs the spirit of craftsmanship. As a leader in the field of kitchen appliances, Fangtai has proved that it is worth entrusting by every family with its impressive historical sales and exploration of cutting-edge technology.

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