Chapter 846: Teaching the French a Lesson
Hearing Liu Yongquan’s explanation, Chang Haonan suddenly understood.
I was scared.
However, I’m afraid it’s not exactly what the former said.
In the process of aircraft engine research and development, it is normal for accidents and even some casualties to occur.
After all, France is also a long-established aviation power, so it will not be scared out of its wits simply by blowing up an engine.
But once combined with Liu Yongquan’s pretense during the previous negotiation, the effect is very good——
My own family has developed something for more than ten years, but others came up and said something about you. A problem that I have never heard of.
I went back and tested it, and found that the situation was exactly the same as the other party's description.
At this time, the focus is no longer on whether the problem at hand can be solved.
Even if he could, he wouldn't be able to feel at ease.
The mentality at this time is definitely:
Since people can see such a big problem at a glance, then if they look carefully, why can’t they see more?
What's more, it's absolutely impossible for Snecma to find a solution so quickly.
If there is no comprehensive traceability of the aircraft engine's life cycle, who would have thought that an inconspicuous electrochemical mark during the overhaul process would directly affect flight safety?
You should know that only a very small number of the latest models of engines using CFM56 or its derivative core engines will use heat-resistant coatings that are prone to arcing.
Even General Electric itself may not have solved this problem at the moment, or even discovered it.
Not to mention the French.
So, for the Rafale fighter jet, a project they couldn't afford to lose at all, they still chose to find foreign aid.
Thinking of this, Chang Haonan asked directly:
"Then what conditions did they set for coming here this time?"
For him, anyway, it was to expand on the basis of the existing contract.
As long as the price is right.
Talk, you can talk.
And Liu Yongquan was obviously prepared.
After hearing Chang Haonan's question, he immediately took out a file bag from the briefcase at hand:
"I was planning to submit the memorandum of the meeting to the group when I went to Beijing for a meeting next week, but it happened that I caught up with you when you arrived in Shengjing today, so I brought you here directly.”
After the restructuring, not only the aviation power group itself has stronger independent management rights than in the past head office period, but also the following secondary companies. Same thing.
Although the decision-making power of the group leadership is still very important, at least it is not as demanding as in the past.
Like this time, Institute 606 can first contact Snecma representatives and then report the situation to the group for decision-making.
And if it does not involve foreign trade, it does not involve military products.
For example, Shengfa Group’s QD130 gas turbine for power generation is currently the flagship product.
Then the autonomy will be greater.
Just report the business situation on a regular basis.
Chang Haonan took the file bag and opened it.
"Advance payment of 250 million euros, joint development throughout the life cycle, sales will be divided proportionally..."
"Sincerity is okay..."
Go through the memorandum as quickly as possible After reading the content, he raised his head again and looked at Liu Yongquan:
"Old Liu, what do you... think?"
Although the turbofan 10 has not yet been officially designed, it is actually just about the same. Approval in advance has saved enough hours, so Liu Yongquan can already devote a considerable part of his energy to cooperating with the French.
In this way, no matter what decision is made, he, the specific executor, must always be consulted for his opinion.
Liu Yongquan did not answer immediately.
But as he walked forward, he lowered his head and thought.
After some careful consideration, he said:
“From the perspective of performance indicators, the calibration given by the French is quite conservative. It is obvious that the temperature in front of the turbine and the stage pressure ratio of the compressor are both Not bad, but the maximum thrust is only 7.5 tons, so there is definitely potential for upgrades.”
Chang Haonan nodded:
"Now, have you found the reason why Snecma chose to lower the boost on the M88-2?"
The first model of M88, M88- 1. Generally speaking, it is a third-generation and a half mid-thrust engine whose performance meets the technical level.
But the later M88-2 suffered a considerable decline in paper performance.
It is equivalent to using the technology of the third and a half generation, or even part of the fourth generation engine, to create a third generation mid-range version that is comparable to the F404.
While talking, the two of them walked around and came to the overhaul workshop of Liming Factory.
The M88 prototype that the French shipped over at the beginning of the year is kept here.
"Mr. Chang, go in and take a look?"
"Okay."
...A medium-sized turbofan engine is quietly placed in a On top of the special engine bracket.
Its cold end and hot end have been separated, and it has obviously gone through more than one round of disassembly and research——
This is why the French were the first to have joint research and development. Definitely worried.
After all, asking someone to dismantle their own engine like this is basically equivalent to asking the French lady to take the initiative to lift the bottom of her skirt and expose her underwear.
Chang Haonan walked forward, bent down and took a closer look.
Design, of course, can't be seen.
You have to look at the drawings.
However, it must be said that as an old industrial power, the French are still very capable in the field of production and manufacturing.
Even though Liming Factory has replaced a batch of new equipment, if we only look at the fineness of workmanship, there is still some gap between the Turbofan 10 and the M88-2 in front of us.
However, this seems to show the outrageousness of the French design...
It was only then that Liu Yongquan, who was standing behind Chang Haonan, answered the former's question:
"During this period, we have checked the design data of the M88 engine and this prototype. The preliminary conclusion is that the French There were some problems with the matching of the fan and the high-pressure compressor, which resulted in the effective pressure ratio of the entire engine not being as high as the stage pressure ratio alone."
"The other thing is that you were deciding on the turbofan back then. 10 Overall Plan The problem mentioned at that time is that the corner area inside the channel has low-energy fluid from the end wall driven by the pressure difference between the pressure surface and the suction surface. These low-energy fluids gather under the reverse pressure gradient and are prone to flow separation. , mixing with the mainstream will cause blockage of the compressor channel. ”
“In this case, it is possible whether the air flow through the compressor is too small, too large, or changes too fast. It induces stall in the corner area, and then surge occurs. "
"Of course, more quantitative data will not be known until we send this engine to the 624 Institute for bench testing..."
Chang Haonan already understood.
Although the appearance of this problem is different from that of the original turbojet 14, the essence is very close.
They all relied heavily on other people’s compressor designs, but they were beyond their own capabilities and I didn’t know how to modify them to suit local conditions.
In the end, basic performance can only be guaranteed by reducing thrust:
“So they directly limit the maximum speed of the engine?”
"Yes."
Liu Yongquan nodded:
"They directly cut the maximum speed by nearly 20%, avoiding the upper limit of corner stall."
"But no matter what, the lower limit of the speed is impossible to avoid, so if the M88-2 is maintained at medium and low thrust for a long time, or the throttle lever moves too violently, it is still possible to cause a rotational stall or even a surge."
Hearing this, Chang Haonan couldn't help but smile and turned around to look at Liu Yongquan:
"Then they have found the right person..."
In addition to Chang Haonan himself, Liu Yongquan should be the second most experienced person in dealing with the end zone flow problem of axial flow compressors.
The latter, who suddenly received a compliment, touched his shiny head with some embarrassment:
“Having the experience of turbofan 10, I have to solve the problem of M88 compressor. Regarding the problem, I am indeed quite confident. I can just modify the design of the high-pressure compressor. "
"Eh..."
Chang Haonan quickly waved his hand:
"This kind of problem cannot be solved too neatly."
Liu Yong was completely puzzled, but he still waited for Chang Haonan's next explanation.
“If we finish the work three times, five times, five times and two times, the French may think that the work is simple and not feel our level.”
Chang Haonan said:
< br>
"Moreover, sending the improved plan back directly is equivalent to losing our bargaining chip, and the subsequent initiative will be in the hands of the opponent."
"So, this matter can be divided into three parts. Walk."
At this time, Liu Yongquan suddenly interrupted Chang Haonan:
"Wait a minute, Mr. Chang..."
Then he took out the pen and pen from his pocket. Book:
"You said."
"The first step is to change the electrochemical marker into a fluorescent marker for the current M88-2, and then design several sets of suction holes on the end arm of the engine casing to The low-energy fluid must be disposed of. I should have mentioned this method before..."
"Open suction will cause a loss of about 8-10% of the inlet flow...Is that true, Mr. Chang?"< br>
Liu Yongquan obviously remembers the knowledge points very well.
“Yes, but after this design, the speed can be added back, so it will be better than the current disabled state. Even if it is installed on the carrier-based Rafale M, it will not have any impact on the performance. There will be no big negative impact, and there won’t be any major security issues.”
Chang Haonan continued:
“The second step, M88-3, is to modify the blade shape at the end of the high-pressure compressor blade to control the total flow loss, especially the distribution of spanwise flow loss, so that the suction surface The boundary layer is stronger than the end wall boundary layer, so that the set of open suction holes can be eliminated, the performance can be restored to the original M88-1 level, and the service life can be extended to the normal level. ”
“At this step, we can also conduct some technical verification for our country’s fourth-generation mid-range thruster.”
“The third step is to reach the final model M88-4, and then consider using the curved sweep design. And end-arm closed suction, squeeze out the hot end performance potential of this engine as much as possible, and see what level of product can be produced."
"In this way, at least 8 will be achieved later. In 2010, the power upgrade of the French's main fighter jets has been in our hands. Although it is not a final decision, it is at least a powerful bargaining chip..."
Liu Yong quickly wrote down the key points that Chang Haonan said.
When the latter saw this scene, he suddenly thought of a famous scene...
"Retell it to me."
"The first step is to change the electrochemical label Into fluorescent labels..."
(End of this chapter)