Siheyuan: I eat melons while doing scientific research

Chapter 1182 Noise (5k)

The shape of the propeller is very important. When confidentiality was the strictest, the appearance of the submarine was almost not obscured when it was launched. However, there was one exception, and that was the tail. The tails of most submarines were tightly covered. In order to prevent the appearance of the propeller from being leaked, a large cage would be built to enclose the propeller, and then covered with cloth, making it impossible to see what the propeller looked like.

As a veteran military fan in his previous life, Gao Zhendong happened to know a perfect ready-made answer. After all, before the pump sprayed out, this thing was a representative of advancement.

As for the pump spray thing, it's really beyond our current capabilities. If we take too big a step, it will definitely be a failure.

Gao Zhendong's words made Zhu Gong overjoyed: "Really? That's great!"

He was not worried at all that Gao Zhendong, as an "outsider", would come up with some unreliable suggestions. Judging from Gao Zhendong's performance just now, he was a real expert, and an expert who had gone a long way.

The suggestions he put forward are at least of great reference value.

Gao Zhendong took out his notebook and started drawing. This thing cannot be explained clearly just by talking.

This paddle type is the one that is familiar to military fans in later generations.

——Seven-blade large tilt propeller.

Moreover, this propeller has a hidden attribute that cannot be seen from the name - large diameter.

Zhu Gong's eyes widened as he watched a somewhat strange and completely unexpected shape being created by Gao Zhendong's pen.

You know what, this thing is really addictive and looks weird at first glance, but when you think about it carefully, based on theoretical analysis, it can really solve the problems mentioned above, or at least alleviate them to a great extent.

As for making the cavitation bubbles disappear completely, that is impossible.

How did Commissioner Gao come up with such a weird thing?
But don’t be fooled by the weird look of this thing, it’s not ugly, and if you look at it more closely you can see a different kind of beauty.

Although many details cannot be seen in this picture, at least this picture is enough for Zhu Gong and his team to figure out a suitable seven-blade large inclined propeller. Gao Zhendong cannot get the details here because they are related to the submarine itself.

Our comrades who are working on submarines have the ability to build nuclear submarines based on models. I think with this picture, it will not be a problem to build a proper seven-blade large inclined propeller.

Gao Zhendong finished drawing the picture, tore it out of the notebook and handed it to Zhu Gong.

As Zhu Gong took it, he said to Gao Zhendong, "Commissioner Gao, I'm sorry. Um, could you please tear off the papers below this one for me? I'm sorry, sorry, this is really too important. I have to be careful."

He knew that this thing might not be taken seriously by Gao Zhendong, but for him, the marks left by the pen tip on the following pieces of paper must not be at risk of leaking out.

But Zhu Gong knew that it was impossible for Gao Zhendong to give him the entire notebook. The other things in the notebook might not be much worse than the one in his arms. So he had to settle for the second best and take away the few sheets underneath.

Gao Zhendong was stunned for a moment, then laughed: "Ah, yes, yes, yes, I didn't think it through."

After saying that, he tore off a few sheets of paper from the bottom of the notebook and handed them to the other party.

Mr. Zhu carefully folded and wrapped the papers, put them in the inner pocket of his shirt, and pressed them again before he felt relieved.

"Commissioner Gao, this kind of large-diameter propeller may be difficult to manufacture in our country, right?"

This is no longer a problem of titanium alloy processing, but a lack of high-precision processing capabilities for large sizes.

The processing accuracy requirements for propellers are relatively high. If the propeller is asymmetrical, it will cause uneven flow. According to the theory just mentioned by Commissioner Gao, uneven flow field will aggravate the generation of cloud cavitation, the main source of noise.

And according to his theory and summary, the propeller must be large in size, which further exacerbates the severity of the problem.

Gao Zhendong smiled and said, "As for machine tools, we are currently working on CNC milling machines with more than three axes. The progress is quite optimistic. I think it will be beneficial for the processing of this thing. Moreover, the machine tool we are working on has the ability to directly perform CNC processing based on the three-dimensional design results of industrial auxiliary design software, which can further improve the processing accuracy."

CNC milling machines with more than three axes? If the size is large enough, it can really solve the problem of high-precision processing of propellers.

In fact, the processing accuracy requirements for propellers are still rougher than those for small precision parts, but they have to be large and have relatively high precision, which is where the trouble comes.

当年小鬼子卖给老毛子的MBP-110S九轴五联动数控铣床，一个重要配件就是22米*10米的超大工作台。而老毛子用这个九轴五联动获得了螺旋桨加工能力的飞跃，并不意味着加工螺旋桨必须要用到9轴5联动。

In fact, if it is an ordinary turbine blade, which does not require high precision and is not complicated, a dual-axis milling machine can do it.

For Zhu Gong, Gao Zhendong's words were beyond his expectations. This surprise was so big that it might have been a shock.

CNC machine tools with more than three axes? What on earth does this Commissioner Gao do? Why is he working on everything?

Shouldn't things like milling machines be the territory of the 11th Ministry of Machine Building?

And it can also directly perform CNC machining based on the design results of industrial design software? This surprised Zhu Gong very much. They also got this latest software. It is so convenient to use it for design work. It also has certain structural and mechanical analysis capabilities. It is really a powerful tool for work.

I didn't expect that they could actually process directly based on the design results of this software? If this is true, it would be even more powerful.

"Commissioner Gao, when will this milling machine be ready?"

Gao Zhendong smiled and said, "I will ask my comrades to make you a large one. The progress may not be very fast, but I think it should not be a problem to catch up with your use."

I don’t know what type of submarines they are, but no matter what type they are, Gao Zhendong knows that it will take several years to build them.

After all, the type of submarine that imitates the R-class has been finalized, and it is still a long time to start construction of those that are now being considered or pre-researched, as long as they are truly self-developed submarines, no matter what power they use.

Mr. Zhu smiled and nodded. If he hadn’t been restricted by discipline, he would have wanted to tell Gao Zhendong clearly.

"Then let me thank you first, Commissioner Gao. Your help to us is really tremendous." Zhu Gong said with a smile.

Gao Zhendong's heart moved when he heard this. While he was here, he might as well reveal more information. Although he himself didn't know much about submarines, he did know a little bit about the basics.

"Mr. Zhu, are you bothered by the noise from the submarine?" Gao Zhendong asked with a smile.

Gao Zhendong was not interested in the differences between cross rudders, X rudders, hull rudders, bow rudders, etc. These things were closely related to the situation of the boat itself. It was meaningless to discuss them without considering the boat body, just like discussing toxicity without considering the dosage was just hooliganism.

On the contrary, he is more interested in things like noise.

That's for sure. With the popularization of sonar, quietness while meeting speed conditions is almost the most core performance of a submarine, if not the only one.

Zhu Gong nodded: "Yes, there is no doubt about it."

One of the biggest sources of noise in a submarine is the propeller, but there are other sources of noise besides the propeller.

Gao Zhendong smiled and said, "Then Mr. Zhu, have you ever thought about eliminating these noises?"

"Eliminate? Many noises cannot be eliminated. And some are actively emitted by the enemy for detection, such as active sonar."

"I know. What I mean is absorption. Using flexible materials to absorb sound. It doesn't necessarily mean noise, but even the sound waves emitted by active sonar." Gao Zhendong said with a smile.

His words set off a huge wave in Zhu Gong's heart.

How could this be possible? This is a path that has never been imagined!

"Commissioner Gao, please be more specific." Engineer Zhu picked up the pen again.

"My idea is to cover the surface of the hull with rubber sheets with appropriate parameters, and use the rubber to absorb vibrations to achieve the purpose of noise reduction. No matter whether it is emitted from the inside or the outside, it can be greatly weakened by this layer of rubber tiles to a certain extent, so I named it 'anechoic tiles'." Gao Zhendong pried off the anechoic tiles without hesitation. This thing is actually similar to the radar-absorbing paint of stealth aircraft, but the anechoic tiles absorb sound waves, while the radar-absorbing paint absorbs radar waves.

This thing has good effects on both active and passive sonar.

Zhu Gong wrote quickly and couldn't help saying, "Good! Good idea!"

His voice was a little loud, and the comrades who were discussing anti-submarine warfare nearby could not help but turn their heads over, and other voices in the meeting room suddenly disappeared.

As if sensing the silence in the venue, Zhu Gong raised his head, looked around, and then said with a smile: "Sorry, sorry, I was too happy. Comrades, please continue. Comrades, please continue."

When the leader of the Defense Work Committee saw him like this, he knew that he had gotten some good stuff from Gao Zhendong, which was why he was so happy.

The leader smiled and shook his hand: "It's okay, it's okay, we will continue, and you can continue too."

It seems that when Comrade Zhu returns, the security forces will need to be strengthened.

When Zhu Gong came back to his senses and finished writing down what Gao Zhendong had just said, Gao Zhendong continued, "A lot of the noise from submarines comes from the vibration of the power and transmission systems. In this regard, I think we can also consider thinking of a solution."

The vibration of the power system is another major source of submarine noise. If this problem can be solved to a certain extent, coupled with the weakening of propeller cavitation noise, the submarine's quietness performance will definitely be greatly improved!

"What do you have in mind?" Mr. Zhu now understood that whenever Commissioner Gao raised a problem, there would usually be a solution behind it.

Gao Zhendong smiled and said, "Float valve isolation!"

"Floating valve isolation? What kind of technology is this?"

Gao Zhendong said, "Mr. Zhu, you have seen the shock absorbers of cars, right? Floating valve isolation is actually similar. It uses elastic or flexible materials or structures to fix and connect equipment that vibrates violently, and uses its elastic damping to isolate or absorb some of the vibration."

"Ah, I see! Spring shock absorbers! The principle is simple, but it should really work! Then why mention the float valve?"

"This is what I think. If you directly connect the equipment to the base with a spring, pneumatic or other vibration isolator, the isolation effect will be there, but because the vibration source and the base are directly connected, the effect is not the best. We have tested it and it will have an effect of about 10 to 20 dB."

10~20dB? That's already very high, Zhu Gong was amazed in his heart. As for why Commissioner Gao would measure this, he really couldn't figure it out for a while.

"So, I considered using vibration isolators to connect a large platform to the base, and then use vibration isolators to connect the vibrating equipment to the platform. In this way, the inertia of the platform itself can greatly weaken the vibration of the equipment, and the vibration transmitted to the base will be very small. I call this platform a floating valve. And this method can reduce the vibration by about 40dB."

40dB? Zhu Gong almost jumped up. Everyone knows the characteristics of the decibel unit.

In fact, the principle of floating valve seismic isolation is the same as that of the wind damper hanging on the top of a high-rise building. Both use elastic or flexible connections and rely on inertia to weaken displacement.

This principle is very easy to understand once it is explained. Mr. Zhu thought about it carefully and was extremely happy.

"Well, Commissioner Gao, your plan is really great! You can even do this: for low-cost ones, use single-layer vibration reduction, and for high-cost ones, consider using floating valves for vibration isolation. I will organize my comrades to do research when I get back! It's amazing, how did you come up with this idea?"

At this point, Mr. Zhu was very curious about how he came up with this idea. What on earth was going on in the mind of this Commissioner Gao? All sorts of ideas were there, but they were all quite useful, with simple principles and significant effects.

Gao Zhendong laughed and said, "This thing is actually the seismic isolation system we use on high-precision machine tools. Now our high-precision machine tools have been used, and the effect is good. I think you should be able to use it here too. If you are interested, you can also come to our factory to have a look and inspect it."

When the comrades from the Third Factory came to Gao Zhendong to find a solution to the vibration problem of high-precision machine tools, Gao Zhendong finally taught them the principle of submarine float valve seismic isolation that he had learned when he was a military fan.

The comrades at the third factory were also very helpful. They directly skipped the single-layer seismic isolation and installed a float valve, and the effect was very good.

I didn’t expect there is a real thing!
Although the size and requirements are different, a set of physical objects that have been put into use has important reference and guiding significance for the research of new equipment.

"Okay, okay, we will organize some comrades to come and learn from you. Oh, Commissioner Gao, I don't know how to thank you. You have come up with ideas and provided practical things."

Gao Zhendong smiled and shook his head: "No need to thank me, it's what I should do."

If these measures can be implemented in advance, even if only part of them are implemented, I think the Citigroup bosses will no longer be able to taunt us that "when the black fish from Dongda goes out, you can hear it on the other side of the Pacific Ocean."

The Citigroup man's words were definitely exaggerated, but it was an indisputable fact that the first generation of black fish had a lot of noise, and Gao Zhendong admitted what should be admitted. What he wanted to do now was to prevent this fact from happening again, or to make it less serious.

As for what kind of fish Zhu Gong was dealing with, Gao Zhendong didn't care. As long as he knew it, these techniques would eventually be fed back to the black carp.

The two of them kept whispering to each other until the end of the first day of the meeting.

What’s interesting is that no one interrupted them or even asked them questions.

In the eyes of the Navy and the Defense Industry Committee, the communication between these two top technicians was very important. Anti-submarine technology was definitely not as important as what they were discussing. As for what they were discussing, no one else knew. They only knew that Zhu Gong was dancing with joy and smiling, and that was enough.

If they weren't afraid of interrupting them and affecting their train of thought, the Defense Work Committee would even want to give them a separate table.

As for the anti-submarine issue, there is no rush. The meeting will last more than one day. One of them is a top submarine expert and the other is a top comprehensive technology expert. There is still time for them to speak later.

What could be more important than what Zhu Gong had in his hands?

After the two bombs and one satellite were all produced, there were only a few brightest pearls left in the field of defense engineering, and one of them was in the hands of Zhu Gong and his team.

After the meeting ended on the first day, Gao Zhendong rushed home.

Since I'm attending a meeting in Beijing, it's better to go home if I can.

Lou Xiao'e came over, handed over the tea and took the bag, with a happy look on her face.

When Gao Zhendong saw it, he thought that their drug research had finally yielded results.

"What are you so happy about? Is the medicine ready?"

Lou Xiao'e shook her head: "No, no, clinical trials don't happen that fast. It's my brother who's coming back."

Gao Zhendong heard this and then he remembered, Oh, that's right, my brother-in-law hasn't been home for a while. He hasn't been back since he went to Aocheng during the Chinese New Year this year. I don't know if he is too busy with the charity fund, Zhenxing Electronics Group, or he is too busy dating Miss He Wu.

Her wife still has deep feelings for her brother-in-law who was sent to Hong Kong Island. She was naturally very happy to hear that he was coming back.

"Oh, that's a good thing. You're probably going to get married this time you come back, right?"

"Yes, that's what my dad meant. Their relationship is stable, and they'll get things done when they come back for the New Year. My brother is already grown up, and my mom has grandchildren, but not yet grandchildren. She's a little anxious, hahahaha." Lou Xiao'e laughed so hard that she couldn't straighten her back.

"When exactly will it arrive?"

"I don't know. This time we are here to hold a wedding. I guess Xiao Wu's family also has a lot of preparations to make. Although it is not convenient for people to come, many etiquette and rules must be taken into consideration."

Given the current communication situation, it was obviously unrealistic for the He Wu family to bring as many people as they wanted, which made it much more troublesome for Lou Shouxing and his team to return.

"But in any case, it will definitely arrive before the Spring Festival." Lou Xiao'e said firmly.

It’s not even New Year’s Day yet, so there’s still some time before the Spring Festival.

Gao Zhendong nodded: "Well, that's great, then let Yan Zhi go and blackmail my uncle."

(End of this chapter)