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, the progress to this point 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. This is not research."
Hearing his words, Chen Guo nodded slightly.
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 organized his knowledge system, so he started from the most basic textbooks and reorganized aerodynamics. "Learned" it again.
All that remains is this notebook.
Therefore, this notebook does not represent the knowledge level of a genius undergraduate, but the review and organization of a doctoral student.
Naturally, the issues he is concerned about are not issues that concern undergraduates.
Most of the dozen questions at the end of the notebook were the most cutting-edge topics at the time, including flow around large angles of attack, pulsating crosswind problems, hypersonic boundary layer instability measurement methods, etc.
If these problems can be solved at Chen Nian's current level, then there is really something wrong...
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."
"If we want to solve it, it will take a lot of time and manpower and a lot of experiments to complete."
"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."
"Whenever I think your level is good enough, I will add you to the group and learn with other graduate students."
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 he doesn't know how to write it out.
"Professor Chen, I understand what you are saying."
"However, when I was looking at your notebook before, I also had some insights that I wanted to talk to you about."
"For example, the problem of aerodynamic uncertainty at large angles of attack, I feel that there is actually a way to solve it - especially when analyzing using a slender body as a template."
"You see, the essence of this problem is actually to solve the problem of asymmetric flow around slender aircraft such as missiles and fighter jets when they perform large-angle maneuvers."
"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."
"But no matter how complex it is, it can ultimately be broken down into several questions."
"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."
"These problems cause us to solve the Navier-Stokes equation. The larger the angle of attack, the worse the linearity, and finally it becomes almost random."
"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?"
Chen Nian finished his reasoning in one breath. In fact, he already knew the answer to this question.
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.
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 sidelines, was so shocked that her eyes almost popped out.
He could actually think of using the Navier-Stokes equation to solve the flow problem around a slender body?
No, he can actually explain the basic reasons for aerodynamic uncertainty at large angles of attack?
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.
For a long time, the domestic aviation research field has not had a stable solution to this problem.
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 it by widening the wing surface.
This is obviously a compromise for stability.
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.
And the solution...
"Do you know how to solve this problem?"
Chen Guo asked.
Chen Nian hesitated for a few seconds and replied:
"I haven't finished pushing it, but based on the current direction, I can roughly guess the result."
"I think the first thing to solve is the problem of cross-symmetrical airfoils. The waverider can completely solve this problem, or use spiral asymmetrical airfoils - of course, this is only for missiles."
"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 asymmetric separation of the front vortex."
"boom!"
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.
After a long time, he asked intermittently:
"This conclusion... is it you who came up with it yourself?"
Chen Nian nodded and took out another notebook from his backpack.
And that notebook was filled with his own calculations.
"It's not a push, it can only be a half-guess and 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!"
