Riding the wind of rebirth

Chapter 1968 Request not to participate

"So when designing a ship, the cavitation effect is something that must be considered. Where do you think cavitation is most likely to occur?"

"It occurs on the side of the ship, where the horizontal plane touches the ship," Zhou Zhi said.

"No, it should be generated at the propeller." Mai Xiaomiao thought for a moment: "The propeller has the highest speed of the entire transmission, and the outer edge of the propeller has the same angular velocity as the shaft. Therefore, the farther away from the center of the circle, the higher the speed. The stirred water flow will experience drastic speed changes at various parts of the propeller. This change will lead to drastic changes in local pressure, which easily forms the conditions for cavitation."

"Well, Xiaomiao is still smarter." Qin Haifeng praised.

Zhou Zhi muttered to himself, "That's because you all study science. It's unfair to compare like this. If you have the guts, come and play the game of 'Smoke Locks the Willows in the Pond' to see who's smarter!"
Qin Haifeng ignored Zhou Zhi's thoughts and continued to explain, "Vaporization is actually produced by the boiling of water. We know that the boiling point of water is 100 degrees Celsius under a standard atmospheric pressure. On Mount Everest, due to the low air pressure, water can boil at a minimum of 69 degrees Celsius."

"If there is a low pressure of less than 20 Pa in a certain area of ​​seawater at 2338.8°C, the seawater will still boil and produce bubbles. This is the principle of cavitation."

"The place on the entire hull or submersible that is most likely to produce low pressure is naturally around the propeller."

"This is actually not difficult to understand. Due to the high-speed movement of the blade, similar to the principle of the wing, the pressure on the back of the blade must be reduced, thus forming a suction surface, and low pressure is naturally generated. When the pressure is lower than the saturated vapor pressure of seawater, low-temperature boiling will occur, and a large number of bubbles will be generated."

"For ships, these bubbles are very harmful. The difference between cavitation and high-temperature boiling is that when water boils, the bubbles generated inside will continue to grow because they can continuously obtain heat from the surrounding area."

"There is no heat input around the cavitation bubble, only the strong squeezing of the surrounding high-pressure seawater. In a few millionths of a second, the cavitation bubble generated by the propeller grows explosively. Afterwards, due to the high pressure of the surrounding seawater, the cavitation bubble is rapidly compressed until it collapses. When it collapses, it forms an explosive jet, which often has a speed of more than several thousand kilometers per hour. Even a propeller made of high-strength alloy steel cannot withstand its impact over the years."

"In addition to the jet, when the cavitation bubble bursts, an explosive shock wave is also generated. This is like when a propeller rotates at high speed, the water on the back of the blade cannot keep up with the movement of the blade. Such shock waves often cause the propeller to deform and break."

"The third aspect is the huge noise generated when a large number of cavitation bubbles burst. For the military, such noise is often used to identify the type of enemy ships or even the sonar mark of a particular ship. For example, the Typhoon nuclear submarine designed by the Rubin Design Bureau can make as much as 115 decibels. The legendary typhoon can be heard throughout the North Pacific when it leaves the port of Vladivostok. This is a joke about noise. Our navy, of course, hopes that such noise will be as small as possible, and it would be best if there is no noise at all."

"But just like Xiao Miao said, as long as the propeller propulsion principle is adopted, it will inevitably cause such a drastic change in pressure difference, and it is impossible to avoid the generation of cavitation." Qin Haifeng took off his hat again and pointed at his white hair: "The white hair of your navy uncle is the product of fighting against these bubbles."

Zhou Zhi vaguely knew that Qin Haifeng joined a naval research institute after graduating from university. Now it seems that it is most likely a research institute that studies ship propulsion systems.

"So uncle, do you have any project that needs our help?" Mai Xiaomiao asked, "Use Xiaozhi's computing power?"

"Almost." Qin Haifeng said with a smile: "Now all military units are having a hard time. All localities are carrying out military-to-civilian conversion and developing the tertiary industry. We have also undertaken the design task of a cruise ship's power system. We have designed several propeller schemes, and want to verify which one is more effective in overcoming the cavitation effect and prolonging the life of the propeller." This is a bit like sprinkling pepper on a grave - damn, why do cruise ships have such high requirements for propellers? You can just copy any article in the world, so why design a separate one?
However, these may involve more secrets. Since Qin Haifeng said so, Zhou Zhi felt that it was better to understand it this way. After all, the girl sitting next to him was of foreign nationality. The navy uncle came to him probably because he urgently needed computing power to solve the problem, and secondly, the situation had undergone some subtle changes since the disintegration of the northern superpower.

The situation can be said to be a bit urgent.

"Even if it's helping the military's tertiary industry, it's also supporting national defense construction!" Zhou Zhi said with a smile: "I know how difficult the military has been in recent years."

"Yes, Elbow, you have a bond with our army. The Red Star convenience store chain of small community supermarkets helps retired soldiers find jobs, and you have helped a lot."

"You know all about this?" Zhou Zhi's worries were put to rest. Qin Haifeng had conducted a thorough investigation on himself and Mai Xiaomiao. Since he came to him after a thorough investigation, it meant that the issue of Mai Xiaomiao's nationality was not a big problem in the eyes of the big guys: "As long as you need it, we will definitely support you."

"Our request is a bit unreasonable," said Qin Haifeng.

"Please tell us first. Shouldn't it be our own reaction to decide whether it is reasonable or not?" Zhou Zhi said.

"That's right. We do want to borrow your computing system." Qin Haifeng said, "But before we do, we need to understand the architecture and operating rules of your system, as well as the core of your computing power."

"This is actually not a big problem." Zhou Zhi said, "But according to the consistent model of Clover Group, we attach great importance to IP protection. At present, we have completed the intellectual property registration of 90% of Xiaozhi's core IP. If you do not obtain authorization from our group within 20 years and build a system with the same architecture and the same protocol, it is an illegal infringement."

"It's just like the Type-C interface you guys made, right?" Qin Haifeng said with a smile, "I heard that the protocol licensing alone has earned hundreds of millions this year?"

"It's not that exaggerated." Zhou Zhi was quite modest at the moment. In fact, the real situation was much more exaggerated than this, but it was hard to explain in detail: "The cost is still quite high, so it is still competing with USB interfaces for the market."

6◇9◇Book◇Bar

"Don't worry about the IP issue. We are not an information system company." Qin Haifeng said, "What we need is computing power to verify our design plan."

"That's no problem. It's not unkind, right?" Zhou Zhi said with a smile.

"I'm not finished yet. We want to use Xiaozhi without your participation."

"What?!"