Chapter 1074: Structural Pre-Deformation Design of Aircraft Engines?

Chang Haonan's bold speculation made Zhang Zhenhua stunned.

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

But if you think about it carefully, it seems feasible.

After a long time, he reluctantly spoke again:

"Then our next step should be..."

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

"Of course, we should first verify this speculation..."

Chang Haonan answered decisively.

"But you just said..."

"Bidirectional fluid-solid coupling is indeed very difficult, but we only need to do forward analysis for verification."

Chang Haonan turned the draft paper on the table that was already full of drawings to the other side:

"Didn't you say that all three groups found that the blades undergo elastic deformation when they are working? This is actually half the success."

"During the working process, there are two main 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 and is basically only related to the fan speed, but the aerodynamic load requires us to comprehensively consider the internal flow, as well as the engine...that is, the external overload of the aircraft itself..."

"..."

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

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

On the other hand, Chang Haonan himself did not have any further specific ideas about this problem.

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

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

The reason for tracking it down is largely 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 as you requested, the performance of the entire fan, especially the stage pressure ratio and working stability, has undergone fundamental changes."

"However... after all, we have only speculated a workload and blade material, so the specific index data calculated is still not ideal."

Chang Haonan flipped through the calculation results and took a quick look:

"It's not a big problem. At least in terms of the trend, it can be proved that my previous speculation is correct. The British are pre-deformed the fan blades, which is enough."

"I didn't expect... Comrade Bingda really gave me a surprise when he went to the UK this time."

For him, the focus is on the fact that "performance is improved after deformation caused by the application of workload".

As for how much it has improved, it is not so important when a lot of information can only be speculated or even guessed.

It's just tracking the research progress of foreign counterparts.

It's not really designing.

After a short pause, Chang Haonan continued:

"I guess the reason why the British handed over some of the data so confidently is that we are sure that we will not be able to see the mystery in it. If we rashly copy some parameters, it will have the opposite effect."

"And even if we take a step back, even if these data are leaked, they don't have much direct significance..."

He smiled and shook his head when he said this.

With the British character, he should have thought of this level earlier.

However, Zhang Zhenhua's expression was quite serious.

Or, since he reported the calculation results just now, his mood has been a little low.

"So this is...the inverse proposition of the fluid-solid coupling problem?"

He asked with a rather twisted expression.

This peculiar way of expression made Chang Haonan think for a while, but he nodded in the end:

"If you must say it, it is true."

"Because the process of numerical solution is considered a half black box, this thing is a bit like the account and password in the network database. In the case of unknown algorithm, even if we have encryption, that is, the data after pre-deformation design, we can't restore valuable information."

However, Zhang Zhenhua is not concerned about this.

After getting Chang Haonan's affirmative answer, he almost stood up excitedly:

"But...how can they do it?"

The internal flow design of the aeroengine is much more complicated than the wing.

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

In a field like this, let alone the inverse proposition, even fluid-solid coupling 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 fluid-solid coupling equations.

As for using the time-discontinuously stabilized spatial finite element method to discretize the fluid-solid coupling model equation to solve the flow problem of two-dimensional structural viscous fluid, it was finally realized after Chang Haonan was reborn, combining the experience of his two predecessors and the help of the system.

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

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

As a result, in just 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 was one type that took a lot of effort and finally went from being out of reach to being out of reach, and it seemed that it was possible to keep up with them.

As a result, the other party 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, obviously thinking:

"I can only say that this may be the British idea, but ideas may not necessarily 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 the need 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, it is not just about selecting a few working points to optimize. Instead, we need to 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 have been developed by me, so I can make bold judgments , 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."

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

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

This 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 there are still 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 make its first flight 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 tasks 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 just 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..."