Chapter 846: Teach the French a Lesson

After hearing Liu Yongquan's explanation, Chang Haonan immediately understood.

This is frightening.

However, I'm afraid it's not exactly as the former said.

During the development of aircraft engines, accidents and even casualties are normal.

After all, France is a long-established aviation power and it won't be frightened simply because of the explosion of an engine.

But once combined with Liu Yongquan's trickery during the previous negotiations, the effect was very good -

You have been developing something for more than ten years, but someone comes up and points out a problem that you have never heard of.

After going back to test, I found that the situation was exactly the same as the other party's description.

At this point, the focus is no longer whether the problem at hand can be solved.

Even if I could, I 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, wouldn't they see more if they look closely?

What's more, there is absolutely no way that Snecma could find a solution so quickly.

If the entire life cycle of an aero-engine is not comprehensively traced, who would have thought that an inconspicuous electrochemical mark during an overhaul 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 the heat-resistant coating that is easily arced.

Even General Electric itself may not have solved or even discovered this problem at the moment.

Not to mention the French.

Therefore, in the Rafale fighter jet project, which they could not afford to lose, they chose to seek external assistance.

Thinking of this, Chang Haonan asked directly:

"So what conditions did they set this time?"

For him, it's just an expansion on the existing contract anyway.

That's as long as the price is right.

Talk, you can talk.

And Liu Yongquan was obviously well prepared.

After hearing Chang Haonan's question, he immediately took out a file bag from his briefcase:

"I was going to submit the memorandum of the meeting to the group when I went to Beijing for the meeting next week, but you happened to be in Shengjing today, so I brought it here directly."

After the restructuring, not only does the Aviation Power Group itself have stronger autonomy in management than in the past head office period, but the same is true for its subordinate secondary companies.

Although the decision-making power of the group's leadership is still important, at least it does not require 100 percent control as in the past.

For example, in this case, the 606th Institute could first contact the representatives of Snecma, and then report the situation to the group for decision.

And if it does not involve foreign trade, it does not involve military products.

For example, the QD130 gas turbine for power generation is currently the signature product of Shengfa Group.

That means more autonomy.

Just report the operating status on schedule.

Chang Haonan took the file bag and opened it.

"2.5 million euros upfront, joint development over the entire life cycle, and a proportional share of sales..."

"Sincerity is not bad..."

After reading the contents of the memo as quickly as possible, he raised his head and looked at Liu Yongquan again:

"Lao Liu, what do you think?"

Although the WS-10 has not yet been officially designed, it only needs to accumulate enough hours of early trial use, so Liu Yongquan can now focus a considerable amount of his energy on cooperation with the French.

In this way, no matter what decision is made, his opinion as the specific executor must be sought.

Liu Yongquan did not answer immediately.

Instead, he walked forward, thinking with his head down.

After some careful consideration, he spoke:

"From the performance indicators, the French calibration is quite conservative. The temperature before the turbine and the stage pressure ratio of the compressor are not bad, but the maximum thrust is only 7.5 tons. There is definitely potential for upgrade."

Chang Haonan nodded:

"Now, have you found out why Snecma chose to reduce thrust on the M88-2?"

The first model of M88, M88-1, is generally a third-generation and a half medium-thrust engine with performance that meets the technical level.

But the later M88-2 showed a significant decline in performance on paper.

It is equivalent to using the technology of the third-generation and a half, or even part of the fourth-generation engine, to build a third-generation engine that is comparable to the F404.

As they were talking, the two of them went around and around and finally arrived at the overhaul workshop of the Liming Factory.

The M88 prototype that the French brought over at the beginning of the year is stored here.

"Boss Chang, can you please go in and take a look?"

"it is good."

……

A medium-sized turbofan engine is quietly placed on a 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 also why the French initially had certain concerns about joint research and development.

After all, having your engine dismantled like this is basically the equivalent of asking a French lady to lift up her skirt and reveal her underwear.

Chang Haonan walked forward, bent down and took a closer look.

As for the design, naturally, you can’t tell anything.

That depends on the drawings.

However, it must be said that as a long-established industrial power, the French are still quite capable in the field of production and manufacturing.

Even though the Liming Factory has replaced a batch of new equipment, if we only look at the workmanship, there is still some gap between the WS-10 and the current M88-2.

However, this seems to show how outrageous the French design is...

It was not until this time 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 have made some problems in matching the fan and the high-pressure compressor, resulting in the effective pressure ratio of the entire engine not being as high as the stage pressure ratio alone."

"Another issue is what you mentioned when you decided on the overall plan for WS-10. There is low-energy fluid from the end wall in the corner area inside the channel, driven by the pressure difference between the pressure surface and the suction surface. These low-energy fluids gather under the adverse pressure gradient and are prone to flow separation. After mixing with the mainstream, they will cause blockage of the compressor channel."

"In this case, whether the air flow through the compressor is too small, too large, or changes too quickly, it may induce corner stall and then surge."

"Of course, we will have to wait until we send this engine to the 624th Institute for bench testing to get more quantitative data..."

Chang Haonan already understood.

Although the problem with the first edition of WP-14 is different in appearance, the essence is very similar.

We have referred extensively to other people's compressor designs, but these designs are beyond our own capabilities and we don't know how to modify them according to local conditions.

Finally, the only way to ensure basic performance is by reducing thrust:

"So they just limit the maximum engine speed?"

"Correct."

Liu Yongquan nodded:

"They cut the maximum speed by nearly 20%, avoiding the upper limit of corner stall."

"But no matter what, it is impossible to avoid the lower limit of the speed. Therefore, if the M88-2 is maintained at medium-low thrust for a long time, or the throttle lever is moved too violently, it is still possible to suffer from rotational stall or even surge."

Hearing this, Chang Haonan couldn't help but smile and turned to look at Liu Yongquan:

"Then they have found the right person..."

When it comes to dealing with flow problems in the end area of ​​axial flow compressors, apart from Chang Haonan himself, the second most experienced person should be Liu Yongquan.

The latter, who suddenly received a compliment, touched his shiny head a little embarrassedly:

"With the experience of WS-10 as a foundation, I am quite confident in solving the problems of M88 compressor. I can simply modify the design of the high-pressure compressor."

"Eh……"

Chang Haonan quickly waved his hand:

"This kind of problem can't be solved too neatly."

Liu Yong was confused, but still waited for Chang Haonan's further explanation.

"We finished the work in no time, so the French might think it was a simple job and not feel our level."

Chang Haonan said:

"Moreover, if we send the revised plan back directly, it would be equivalent to throwing away our bargaining chips, and the initiative will be in the hands of the opponent."

“So, this matter can be divided into three steps.”

At this time, Liu Yongquan suddenly interrupted Chang Haonan:

"Wait, Mr. Chang..."

Then he took out a pen and a notebook from his pocket:

"You say."

"The first step is to change the electrochemical mark to a fluorescent mark on the current M88-2. Then, design a few sets of suction holes on the end arm of the engine casing to remove the low-energy fluid. I should have mentioned this method before..."

"Open suction will cause a loss of about 8-10% in inlet flow... Is that right, Mr. Chang?"

Liu Yongquan obviously remembered the knowledge points very well.

"Yes, but with this design, the rotation speed can be increased, so it will be better than the current disabled state. Even if it is installed on the ship-borne Rafale M, it will not have a big negative impact on performance, and there will be no major problems with safety."

Chang Haonan continued:

"The second step, M88-3, is to modify the blade profile of the high-pressure compressor blade tip to control the total flow loss, especially the distribution of spanwise flow loss, so that the suction surface boundary layer is stronger than the end wall boundary layer. In this way, the set of open suction holes can be cancelled, and the performance can be restored to the level of the original M88-1, while the service life can also be brought back to normal levels."

"At this point, we can also conduct some technical verification for our country's fourth-generation mid-range thrusters."

"The third step is to adopt the swept design and end-arm closed suction for the final model M88-4, so as to squeeze out the hot end performance potential of this engine as much as possible and see what level of product we can produce."

"In this way, the power upgrade of the French main fighter jets will be in our hands for at least the next 8 to 10 years. Although it is not a trump card that can make the final decision, it is at least a powerful bargaining chip..."

Liu Yongquan wrote quickly and wrote down the key points that Chang Haonan said.

When the latter saw this scene, he suddenly thought of a famous scene...

"Repeat it for me."

"The first step is to change the electrochemical labeling to fluorescent labeling..."