Chapter 32 Your Level

On the other side, Chen Nian and Chen Guo rushed to the airport in a special car, and they were silent all the way.

In fact, the two of them were not high enough to arrange a special plane, but there happened to be a plane that was about to go to Chang'an to perform a mission, so the two of them got a ride.

This flight would last more than four hours. Chen Nian didn't want to waste time, so he took out the aerodynamics notebook he had prepared on the plane and started studying.

It is said to be learning, but in fact, at this stage, it is mainly based on calculations, and the targets are also many difficult problems left in Chen Guo's notebook.

Chen Guo, who was sitting aside, looked at his hands curiously and asked:

"Isn't this my notebook? Have you read it all?"

"Yes, you can read whatever I saw on the table in your study, so I won't ask you to pick it up."

Chen Nian replied with a smile.

"No, my point is, have you finished reading it? How long has it been?"

"I've finished reading it, but I only have a preliminary understanding. For most of the questions you left in your notebook, I don't even have any ideas. Those who do have ideas don't know what method to use to solve them. Isn't this just research?"

Hearing his words, Chen Guo nodded slightly.

"These problems lead to the fact that when we solve the Navier-Stokes equation, the larger the angle of attack, the worse the linearity, and finally it becomes almost random."

If these problems can be solved at Chen Nian's current level, then there really is something going on.

Thinking of this, he said:

"You don't need to invest too much energy in these questions for the time being, because every question I listed later is actually a complete research topic."

"But what if we find a complementary mechanism that can reduce the randomness of the Navier-Stokes equation? Or, what if we can reduce the probability of asymmetric vortex fields through some shape design?"

"However, when I was looking at your notebook, I also had some insights that I wanted to share with you."

And that notebook was filled with his own calculation processes.

I didn’t write this in my notebook!

You must know that I have been specializing in the direction of high-angle-of-attack mechanics in aerodynamics since I was a graduate student, and the aerodynamic uncertainty of high-angle-of-attack is the most difficult part.

In fact, most of the dozen questions at the end of the notebook were the most cutting-edge topics at the time, including the problem of flow around large angles of attack, the problem of pulsating crosswinds, the measurement method of hypersonic boundary layer instability, etc.

"The first one is the asymmetric separation of the front vortex when the angle of attack is above 30 degrees; the second one is the lateral aerodynamic force that reaches the normal force; the third one is the randomness of the front vortex body."

"The difficulty lies in the fact that the flow and aerodynamic characteristics of a slender aircraft at transonic speeds and large angles of attack are too complex."

For a long time, the domestic aviation research field has not had a stable solution to this problem.

It was not until recent years that this issue made breakthrough progress due to the increase in wind tunnel simulation time and the more accurate simulation results of some problems.

"I think the first thing to solve is the problem of cross-symmetrical airfoils. Waveriders can completely solve this problem, or use spiral asymmetrical airfoils - of course, this is only for missiles."

But how to deduce the problem from the problem to the conclusion is a bit beyond his ability.

——

However, even if it was just like this, Chen Guo, who was listening on the side, was so shocked that her eyes almost popped out.

"You see, the essence of this problem is actually to solve the asymmetric problem of flow around slender aircraft such as missiles and fighter jets when they perform large-angle maneuvers."

In fact, his notebook was not left over from his university days, but after he graduated with a Ph.D. and started teaching, one day he suddenly felt that he had never sorted out his knowledge system, so he started from the most basic textbooks and reorganized aerodynamics.

"Learned" it again.

Naturally, the issues he is concerned about are not issues that concern undergraduates.

"For example, I feel that there is a way to solve the problem of aerodynamic uncertainty at large angles of attack - especially when analyzing using a slender body as a template."

Therefore, this notebook does not represent the knowledge level of a genius undergraduate, but the review and organization of a doctoral student.

And the solution

"Do you know how to solve this problem?"

After a long time, he asked intermittently:

Chen Guo asked.

Chen Nian hesitated for a few seconds and replied:

"If you want to solve it, you have to invest a lot of time and manpower and go through a lot of experiments to complete it."

What was the solution then?

Not flying at high angle of attack!

Or, if you must fly at a large angle of attack, you can achieve this by widening the wing surface.

"You should focus on laying the foundation now and read more exercises in the textbook. If necessary, I will also find some other exercises for you to do."

"Professor Chen, I understand what you are saying."

All that remains is this notebook.

The cup in Chen Guo's hand hit the small table hard. He looked at Chen Nian in disbelief, as if he was looking at a shining treasure.

"Bang!"

"However, no matter how complicated it is, it can actually be broken down into several problems in the end."

"Did you come up with this conclusion yourself?"

He could actually think of using the Navier-Stokes equation to solve the flow problem around a slender body?

No, he can actually explain clearly the basic reasons for aerodynamic uncertainty at large angles of attack?

The symmetrical + word layout will induce the generation of asymmetric front vortex field and amplify aerodynamic uncertainty. To solve this problem, the best solution is either a flat front wing layout, similar to a waverider, or an asymmetric front wing, similar to

Certain surface-to-air missiles that can turn at right angles.

"Whenever I feel that your level is good enough, I will add you to the group and learn with other graduate students."

Chen Nian finished his reasoning in one breath. In fact, he already knew the answer to this question.

"For aircraft, it has to be a polygonal wing auxiliary lift layout like the F-22. We have also discussed this before. The wing surface vortex will offset part of the asymmetrically separated front vortex."

Chen Nian nodded. He had already realized this situation, but...

Not all of these dozen problems must be solved through experiments!

For example, regarding the aerodynamic uncertainty mechanism at large angles of attack, sufficient data was already obtained when analyzing the F-22 airframe. Now he just lacks a simple method to organize it.

——

Or to put it more clearly, he already has the answer, but doesn't know how to write it out.

Chen Nian nodded and took out another notebook from his backpack.

"I haven't finished the calculation, but based on the current direction, I can roughly guess the result."

This is obviously a compromise made to achieve stability.

"It's not a push, it can only be a half-guess. My current foundation is still too weak."

"Are you still weak?"

Chen Guo's eyes widened.

"Your level is better than when I was in the second year of junior high school!"
Chapter completed!