Chapter 1073 The Crazy Thinking of the British
Faced with Chang Haonan's request, everyone in the venue showed some hesitation.
Although Haofa Group’s experience in aviation engine design is still a little lacking, there are still some people who have been tempered by the turbofan 10 project, just a numerical simulation of a fan, and they are mainly out of curiosity. There is no need to pursue precision too much, or it won’t stump them.
But on the other hand, after all, this is a matter of being a supplier to others, or even a second-tier supplier.
Although at this point in time, any opportunity to participate in major international aviation projects is extremely valuable to China, as a supplier, as long as it is sure that there are no loopholes in the contract level, and then based on the information provided by Party A, Just ask for something to be made and that's it.
As for whether Party A's design is reasonable, and the resulting progress of the entire project, it is actually not their turn to worry about it.
What's more, considering that the design team of SeA650, especially the permanent magnet power generation system, mainly comes from the 606 Institute, there is a high probability that this project has no direct relationship with Haofa Group.
However, the more important reason is still.
The computing resources in Haojing are indeed relatively tight——
Although the timeline has changed dramatically, it is still only 2003 after all.
In 2003, in the previous life, China's first model that fully adopted computer-aided design during the development process, the JH-7A, had not even entered service.
One of the biggest obstacles that needed to be overcome during the design process of the JH-7A was that the supercomputing performance at the time did not support high-precision meshing operations on the entire machine or even on large components.
This hardware condition even almost sent the JH-7A back to the drawing board.
In fact, when Chang Haonan first arrived at the 601 Institute in 1996, the operation of converting the quadrilateral mesh into a "pseudo-triangular" mesh and then performing calculations was first developed to solve this problem. .
Of course, with the support of a large number of industrial and scientific research needs, the performance of Sugon 3000 series has now reached the forefront of the world, which is no longer the same.
But for aircraft engine design with higher simulation precision, it is still not as abundant as it was ten or twenty years later, to the extent that it can be squandered casually.
Finally, Zhang Zhenhua, who was relatively familiar with Chang Haonan, asked cautiously:
“Mr. Chang, now the entire group is concentrating resources to prepare for the turbofan 20 project. Look...can we put this matter aside, at least until the project is approved?"
But Chang Haonan waved his hand:
"Don't think about it like that."< br>
"From a broader perspective, this can be regarded as part of the preparations for the Turbofan 20 project..."
Not only Zhang Zhenhua, but also several other people around him expressed doubts.
After all, although the design of this fan is indeed a bit strange, and the size is larger than ordinary small ducts and military engines, in any case, it is obviously not the same thing as the turbofan 20.
Faced with puzzled looks, Chang Haonan had no choice but to further explain:
“Essentially, the Turbofan 20 uses the mature core machine of the Turbofan 15. The biggest design difficulty is On top of the fan.”
"So, although the properties of the engines are not exactly the same, and we are not planning to make any imitations of the Turbofan 20, it will not hurt to learn more about other people's experiences, just like doing exam questions."
After finishing speaking, he remembered that someone had just raised the possibility of the British providing a fake design.
So he added half-jokingly:
"Even if it is a wrong experience, it will still be valuable."
Originally, this sentence was just said casually. .
Because Chang Haonan also felt that, on the one hand, the British would not fool people with such obvious fakes.
We all know that it is difficult to develop an aircraft, but most of this difficulty lies in the combination of design and production.
It’s just a simple design parameter, not even complete, and not worth so much thought.
On the other hand, according to Jin Xu’s feedback, the other party handed over the information to Ren Bingda in only two days after the two parties finalized their intentions.
This time is basically the time to delete the most sensitive information and check it again.
There was no time to make a fake one.
However, no one expected it.
His unintentional words turned out to be a prophecy...
...
After Chang Haonan briefly assigned tasks, the Haofa Group was separated. Three teams were formed to analyze and simulate this fan...or strictly speaking, this blade shape.
The reason why it is divided into three is because the British did hide a lot of information that may seem inconspicuous but is very important in operation.
For example, the number of blades of a fan.
As a result, Chang Haonan could only deploy three more likely solutions based on his own experience and the leaf design provided by the other party.
If it’s not right, adjust it slowly.
As for Ren Bingda...
According to his initial estimation, the performance test of the fan was not a particularly complicated task.
It will take a few days to get a rough preliminary result.
It is not too late to sign the contract after verification.
Therefore, for a period of time afterwards, Chang Haonan still held two positions in Haojing, and was responsible for both the turbofan 20 and the communication relay system.
The specific simulation tasks were handed over to Zhang Zhenhua.
Then...
The preliminary results were indeed taken out on the fifth day. But the result itself was quite different from Chang Haonan's previous estimate.
No matter which blade number and layout plan it corresponds to, the blade design provided by the British cannot be said to be exquisite in every way, or at least it can be said to be useless.
Even Zhang Zhenhua couldn’t help but complain:
"Mr. Chang... If you really want to design a fan with such a low pressure ratio and air intake efficiency, very difficult to process, and a small surge margin... or a low-pressure compressor, to be honest ...It’s quite difficult.”
Looking at the calculation results, Chang Haonan also had some doubts about the software and algorithms he developed for the first time...
However, Zhang Zhenhua was very He quickly saw what Chang Haonan was thinking, and quickly added:
"Mr. Chang, I supervised the entire work. The three calculation groups completed the calculation tasks independently, and there was no communication in between."
“In addition, we actually got the calculation results yesterday afternoon, but because it was so... incredible, I asked them to verify the calculation method using the Rotor67 standard blade type, and found no significant differences. Obvious problem..."
The meaning of these words is obvious.
Unlikely a human calculation error.
It is also unlikely that there is a problem with the algorithm or program.
It’s just that the design provided by the British is wrong.
But the problem is...
Forget about Rolls-Royce.
Even China a few years ago would not have designed a fan of this level.
“Is it possible that the data is true or false?”
Zhang Zhenhua originally didn’t agree with this guess.
But now there seems to be no other more reasonable possibility.
Chang Haonan did not answer immediately. He just turned over the short report and read it twice.
My mind is a bit confused:
“But wide chords, sweeps, and air structures...this is indeed the current mainstream development direction.”
“And you Look, Ye Shan still has some design space left for boundary layer active control technology... It shows that the British have actually started to pay attention to our research results a few years ago. If they want to provide false data, they can delete it. Get rid of these details..."
Boundary layer active control is a technology used by Chang Haonan in the design of turbofan 10.
Of course, the turbofan 10 itself has no export record, but it was also used in the development process of M88 and SeA650.
It is also normal for the British to discover and follow the application.
The two people were puzzled and fell into entanglement again.
After a period of silence, Zhang Zhenhua broke the silence again:
“Actually, there are more problems with this blade than just that…”
"Oh?"
Chang Haonan also became interested at this time.
He really wanted to know what new tricks an engine fan could create.
“All three groups reported to me that in the process of preparing for fluid-structure interaction calculations, they found that the rigidity of these blades is very low, and it will inevitably occur if the properties of any common material are substituted. Elastic deformation... So in the end, I had no choice but to give up on the structural issues and produce pure CFD results..."
For Zhang Zhenhua, he just complained about his experiences at work.
But Chang Haonan was suddenly awakened by his words:
"Elastic deformation?"
He quickly picked up the report that had been placed on the table:
“What if we consider aerodynamic loads under operating conditions?”
“Huh?”
Zhang Zhenhua also raised his head, but he still didn't realize the meaning of Chang Haonan's question.
The latter had no choice but to explain further. At the same time, he took out a pen and paper from the side and drew a simple diagram:
“Look, these leaves are in a static state, that is, the leaf shape in a cold state. It is indeed very strange, but in the working state, that is, after the hot state, the blade shape will change accordingly..."
"And this deformation, in turn, will change the aerodynamic force, which will lead to further The elastic deformation...This constitutes an interaction between structural deformation and aerodynamics..."
Zhang Zhenhua is also an old engineer after all, he just didn't keep up with the leaps in thinking just now.
Now that I have been sorted out like this, how can I not understand the meaning:
“It’s like the wings in aircraft design?”
Although my major is aviation design, However, aviation technology does not belong to separate families, and Haofa Group has always had a variety of businesses in the past, so he will not turn a blind eye to the outflow issue.
“That’s right!”
Chang Haonan nodded:
"I suspect that the British idea is to completely abandon the blade stiffness in order to reduce the weight of the fan as much as possible. Instead, use structural analysis to determine the optimal aerodynamic geometry of the blade under design conditions, that is, the original thermal blade profile. Carry out reverse inference to obtain the cold-processed airfoil, which is the pre-deformed airfoil."
"The data we obtained is this cold-processed airfoil, and we can directly use this airfoil. Analyzing aerodynamic performance will naturally lead to a very bad result!”
(End of this chapter)