The Military-industrial Scientific Research System of the Academic Master Chapter 1074

Chapter 1074: Structural pre-deformation design of aviation engine?

Chang Haonan's bold speculation made Zhang Zhenhua stunned.

At a certain moment, the latter even felt that "the British provided false data" which was more realistic.

But if you think about it carefully, it seems that it is not impossible.

After a long time, he reluctantly spoke again:

“Then our next step should be…”

Zhang Zhenhua quickly recovered his senses, but the mental shock caused just now was obviously not easy to completely subside, so he quickly asked about the next task.

“Naturally the first step is to verify this conjecture…”

Chang Haonan replied decisively.

“But you just said...”

“Two-way fluid-structure coupling is indeed difficult, but we verified that we only need to do forward analysis.”

Chang Haonan said and turned the draft paper on the table that was already covered with drawings to the other side:

“Didn't you say that all three groups have discovered that the blades elastically deform under working conditions? This is actually half the battle.”

"During the working process, there are two main types of loads acting on the fan blades. One is the centrifugal load, and the other is the aerodynamic load generated when the airflow flows through the blades. Among them, the centrifugal load is relatively easy to study. Basically it is only related to the fan speed, but the aerodynamic load requires us to comprehensively consider the internal flow conditions, as well as the engine...that is, the external overload of the aircraft itself..."

Chang Haonan did not choose to gather all the staff for a meeting, but directly analyzed the problem for Zhang Zhenhua himself in the office.

On the one hand, this allows the other party to go through a digestion and output process after receiving knowledge input.

On the other hand, Chang Haonan himself has no further specific thoughts on this issue.

Of course, structural pre-deformation design is naturally among his long-term goals.

However, according to the plan, this should at least be considered after new theoretical breakthroughs are obtained in the N-S equation.

The reason why I keep following them is largely because I just want to see what the British have come up with...

With the previous experience and Chang Haonan's personal guidance, the preliminary calculation results after considering the blade load were presented to the latter in just three days.

As usual, Zhang Zhenhua reported with the calculation results:

“Mr. Chang, after adding the workload to the calculation conditions according to your requirements, the performance of the entire fan, especially the stage pressure ratio and working stability, has undergone fundamental changes.”

“But... after all, we only speculated on a workload and blade material, so the specific index data calculated is still not ideal.”

Chang Haonan opened the calculation results and glanced at them briefly:

“The problem is not big, at least in terms of trends, it has proven that my previous speculation was correct. The British are pre-deforming the fan blades, which is enough.”

“Unexpectedly... Comrade Bingda really gave me a surprise when he went to England this time.”

For him, the focus is on the “performance improvement after deformation caused by the application of working loads” itself.

As for the specific improvement, it is not that important when a lot of information can only be speculated or even blindly guessed.

Just tracking the research progress of foreign colleagues.

It's not really about design.

After a brief pause, Chang Haonan continued:

“I estimate that the reason why the British handed over part of the data so confidently is because they are sure that we will most likely not be able to see the secret. If some parameters are copied rashly, it will have the opposite effect.”

“And to say the least, even if this data is leaked, it will not be of direct significance…”

Having said this, he smiled and shook his head.

With the British character, he should have thought of this a long time ago.

However, Zhang Zhenhua's expression was quite serious.

In other words, he has been in a low mood since he reported the calculation results just now.

“So this is... the antithesis of the fluid-structure interaction problem?”

He asked with a rather nervous expression.

This peculiar way of expression made Chang Haonan think for a moment, but finally nodded:

“If I have to say it, it's true.”

"Because the numerical solution process is half a black box, it is a bit like the account number and password in a network database. When the algorithm is unknown, even if we have encryption in hand, that is, the data after pre-deformation design, No valuable information can be recovered. "However, this is not what Zhang Zhenhua is concerned about.

After receiving Chang Haonan's affirmative reply, he almost stood up in excitement:

“But...how could they do it?”

The internal flow design of an aircraft engine is much more complicated than that of an aircraft wing.

Whether it is CFD or CSM, in fact, humans have not fully studied the theory... or even to exaggerate, at the theoretical level, it is just an entry-level problem.

In a field like this, not to mention the inverse proposition, even fluid-structure interaction itself was proposed as early as 1933. As a result, it was not until 1991 that someone used semi-implicit and semi-explicit methods to solve the problem. A system of fluid-structure coupling equations.

As for using the space finite element method to discrete fluid-solid coupling model equations with time discontinuous stabilization to solve the flow problem of viscous fluid around a two-dimensional structure, it was after Chang Haonan was reborn that he combined the experience of two generations of predecessors and systematic With help, it finally came true.

The systematic use of fluid-structure coupling ideas to solve buckling and large deformation problems of three-dimensional structures is a new function that has only been available since version TORCH Multiphysics 2.0.

Of course, the earlier NUMECA can also perform calculations under some special circumstances.

As a result, only a year ago, the British began to reverse the operation and use the working blade shape to reversely process the blade shape?

This situation really hit Zhang Zhenhua hard.

There is a kind of thing that took a lot of effort, and finally changed from being unreachable to being far behind, and it seems that it is possible to keep pace with it.

As a result, the opponent suddenly accelerated and no one could be seen again.

This kind of blow is indeed serious.

However, Chang Haonan is still relatively calm:

“Actually… they may not have done it.”

As he answered, he tapped his pen on the table unconsciously, apparently thinking:

“I can only say that this may be the British idea, but the idea may not be realized.”

"Um?"

The shock in Zhang Zhenhua's eyes gradually turned into confusion.

“You know, aviation engines do not only have a few typical working conditions, and the biggest difficulty in structural pre-deformation design is that it needs to provide at least an acceptable degree of deformation for each working condition...”

Chang Haonan worked hard to organize the language and try to make his description as simple as possible:

“In other words, if we really want to achieve a thorough and successful structural pre-deformation design, we will not just select a few working points to optimize them, but we must interact with the flow field change information in the fluid domain and the structural deformation information in the solid domain. Exchange transfer, calculate the structural dynamics equation under the action of generalized force, and obtain the deformation caused by unsteady aerodynamic force through the nonlinear transient response analysis of the structure through modal superposition, thereby predicting the anti-torsion blade shape..."

"Even if you only consider centrifugal force, this process is quite complicated in theory, not to mention aerodynamics and temperature. Frankly speaking, almost all existing engineering methods were developed by me, so I can make a bold judgment. It would be almost impossible to accomplish without completely new theoretical tools…”

“So I estimate that Rolls-Royce will eventually return to the traditional rigid blade design.”

Chang Haonan, as a professional engineer, naturally has to dare to make judgments.

Besides, whether it was the F135 or F136 of the previous generation, they finally switched back to the traditional rigid design.

It shows that at least at this point in time, Luo Luo does not have the ability to solve the problem.

After listening to Chang Haonan's analysis, Zhang Zhenhua recovered a lot from the shock he had just received.

But I still have some doubts:

“But Mr. Chang, if this is really a fan developed for F135 or F136, then according to the plan, the JSF project will first fly in 2005 and enter service in 2008. How can the British have time to go back and forth like this?”

Hearing this question, Chang Haonan almost laughed out loud.

He knows very well that there are countless abstract activities in the entire JSF project.

Until his rebirth, the latest news from Lockheed Martin is that they have abandoned the complete technical state, which is the block 4 batch of F35.

In other words -

There are some problems that we cannot change no matter what, so you can make do with it...

“Don't worry, I can make a bet with you.”

Chang Haonan held back his smile and said to Zhang Zhenhua:

“Let alone 2008, the JSF project will not be able to form complete mission capabilities in another ten years by 2018.”

“As for this structural pre-deformation design…”

He thought for a moment, then continued:

“On the British side, I'm afraid they will only be able to stay on PPT for a long time…”

(End of this chapter)

Chapter end

Report