Chapter 53: Overtaking on the Straight [Please read it! 】

At the same time, over there at Beijing Hang University.

Since it is already the summer vacation, the master's students in the research group have returned home one after another, and only Fang Zhen, Yao Mengna and Chang Haonan are still in school.

Fang Zhen was preparing to complete the project report on wing flutter analysis in one go.

Yao Mengna is planning to stay in school to continue learning computational fluid dynamics simulation.

As for Chang Haonan...

In fact, it was because he predicted that Du Yishan would find a project for him to join, so he waited at school.

Therefore, in the past few days, he has continued to study the impact of blade shape on the airflow separation of the boundary layer inside the cascade under different conditions.

If there is any actual gain, it is a letter from the editorial board of "Journal of Aeronautics and Astronautics" stating that his paper has been directly accepted and will be officially published in September.

And Wu Yifan paid him the remaining balance of 3200 yuan.

This shows that the previous fan design should have successfully defeated Fuji Electric's competing products.

Of course, the impact of this incident was limited after all. It only increased Chang Haonan's scientific research points by 4 points.

Fortunately, whether it was designing the fan or doing the wing flutter analysis project for the 603, he relied entirely on himself and did not ask the system to help.

Therefore, he now has a total of 80 scientific research points in his hand. Even if he faces some more complex problems, it should be enough to solve them if he has an idea.

But the leisurely fishing life did not last long.

One morning four days later, Du Yishan suddenly called and asked the members of the research team who were still at the school to prepare for an expert review meeting that afternoon.

Fang Zhen and Yao Mengna were both confused when they heard the news. After all, they were completely unprepared before, and they had never seen such an urgent academic conference.

Chang Haonan, who had been mentally prepared, had roughly guessed the true situation of this so-called "review meeting".

I guess a project is coming my way.

And looking at this posture, it doesn’t look like an ordinary project.

……

Although he had been mentally prepared in advance, when Chang Haonan saw the situation inside at the door of the conference room, he subconsciously took a deep breath and his eyes widened in shock.

The room is not large, with only two tables.

There weren't many people inside, only four including Du Yishan.

But he happened to know two of the other three.

They are Liang Zhuoping, chairman of China Aviation Industry Corporation, and Yang Fenghao, deputy director of the 601 Institute and chief designer of the J-8-3.

Since Project 941 was established much earlier than Project , which clarified the chief engineer's responsibility system, the chief designer is equivalent to the person in charge of this model.

The last one is a woman. Although I have never seen her before, since she can sit with the previous ones and chat and laugh, she must be of a different status.

With this configuration, even if there are only four people, it is enough to be called a big scene!

At least Chang Haonan had never seen such a battle before his rebirth.

The first person invited in was Fang Zhen.

But he only stayed in there for less than fifteen minutes before he came out.

Chang Haonan's mentality was relatively stable, but Yao Mengna next to him quickly stepped forward:

"What did you talk about? What was the project about?"

"Hmm... not exactly." Fang Zhen's expression was still a bit confused: "In addition to questions related to our group project, I also asked a lot of textbook knowledge that I learned before. Fortunately, I still remember most of them. The other thing is I'm not familiar with some things related to computational fluid dynamics, but you two should be good at it."

After a brief chat, Yao Mengna was called in for the second time.

She stayed in there longer, probably more than twenty minutes.

When Yao Mengna was asked about the situation inside, she obviously hesitated for a moment.

"It's similar to what Senior Brother Fang said just now, but in the end the white-haired expert named Yang asked me if the flutter simulation project we did for the 603 could be used on combat aircraft."

Yang Fenghao's name was not very famous in this era, so it was normal for Yao Mengna not to know what he did.

"What did you say?"

"My junior brother told me this before. When we studied high-aspect-ratio straight wings, we regarded the research object as a beam wing and then used the dipole grid method. Generally, combat aircraft are delta wings or rear wings. Sweeping wings cannot be applied mechanically."

Yao Mengna said and cast a grateful glance at Chang Haonan. By now, anyone could see that this posture was unusual. It was said that it was a review meeting but it was actually more like an interview, so answering one more question must be beneficial.

Finally it was Chang Haonan's turn to go in.

In fact, putting him as an undergraduate at the end actually explains something.

When Chang Haonan sat down behind the table near the door, although the movements of the four people opposite him did not change much, he could clearly feel that there were some subtle changes in the atmosphere of the scene.

After a brief opening session, the exchange between the two parties quickly got to the point.

The previous questions were all raised by Liang Zhuoping, and they were no different from Yao Mengna and Fang Zhen.

But when Chang Haonan said that he was recently studying the topic of using blade sweep design to control the vortex structure in the turbine cascade, the eyes of the other two people next to him lit up almost at the same time.

Especially the woman Chang Haonan didn't recognize at first almost immediately raised her own questions.

According to the introduction at the beginning, she is the director of the System Engineering Department III of the Commission of Science, Technology and Industry for National Defense, and her surname is Zhou.

"You also have research on compressor design?"

"Yes." Chang Haonan nodded: "Although there are indeed some differences between the overall design of the aircraft and the aerodynamic design, the theoretical principles of fluid mechanics and the engineering methods of computational simulation are universal."

"In fact, I think the same is true not only for compressor design, but also for related materials and manufacturing processes. As the saying goes, nothing can change without departing from its roots. If you can master the basic theory and methodology, it is also possible to conduct cross-border research in a broader scope. Totally possible."

"Take compressor blade manufacturing as an example. One of the major difficulties is that during CNC milling processing, irrecoverable deformation will occur due to clamping force, cutting force, internal stress and other reasons, which will affect product quality. This problem is generally considered to be only Rely on processing experience and material upgrades to solve the problem.

“But in fact, it is completely possible to use the mathematical functional relationship between flow stress and deformation parameters such as strain, strain rate, and temperature to establish a constitutive model of the material, so as to numerically calculate the deformation of the blade during the processing process, thereby achieving Higher processing accuracy and more stable product quality.”

"Another example is the turbine blades of aero engines. Due to their long-term operation under strong thermal shock and complex cyclic thermal stress conditions, they have higher requirements than compressor blades and need to be manufactured by investment casting. However, through traditional The experience + trial and error method of optimizing process parameters is very inefficient. As a late-developing country with insufficient experience and funds, it is very difficult for us to rely on this method to surpass others."

“But the investment casting process can essentially be summarized as two processes: mold filling and solidification. The former is a flow process we are familiar with, while the latter is a heat transfer and phase change process, plus the process similar to the milling process. After comprehensive consideration of stress and strain issues, the entire process can still be numerically calculated, thereby achieving precise calculation and control of the casting process and greatly improving efficiency."

When Chang Haonan said this, the eyes of the four people opposite him, including Du Yishan, changed when they looked at him.

The ambition of this junior student far exceeds everyone’s imagination:

Whether it’s design or manufacturing.

Overcoming the experience accumulation and trial-and-error part that consumes the most time and money, and directly explaining everything using mathematics and physics, we can narrow the gap with developed countries in all aspects under the condition of limited resources.

Even the corners...

wrong.

Overtaking on the straight!