"You invested in cooperation with Beihang Materials Institute to develop the industrial production technology of DD3 monocrystalline?"

Liu Daxiang, who was surprised, felt that the whole world had changed, and the 0011 base, which was originally inconspicuous before, suddenly rose within a few years, grabbed orders and made a lot of money, and now there is money to the research and development of basic materials for aero engines invested by Southwest Science and Industry Investment in the country.

No matter how you think about it, you think it's incredible, but the facts are in front of you, this Southwest Science and Industry is really so rich, and Liu Daxiang can't believe it.

"Well, listening to you say this, it doesn't feel like a fake, since you have invested in the industrial production of DD3 monocrystal, the high-temperature turbine of the new core engine project is completely dependent on you to support, and now we 624 Institute must concentrate on winning the high-pressure compressor."

Chief Engineer Liu will find a way, and the pre-research of the advanced project of the core machine that should have been done by 624 is now pushed to Southwest Science and Industry. Of course, Southwest Science and Industry will not shirk this kind of thing, foreign aero engine giants, which is not firmly controlled by themselves the research and development and manufacturing of high-temperature turbine technology, and the current Southwest Science and Industry is just learning from foreign advanced experience.

The problem of high-pressure compressor and high-temperature turbine is determined, and only the problem of the combustion chamber is left in the three core components.

However, compared with the combustion chamber under development in the 624 Institute, it is much more backward, and the core engine technology pre-research of the 624 Institute has chosen F404 as the technical reference, although it has been placed by the Americans on the high-pressure compressor. But it's not without gains.

The F404 is not without its advantages, and the combustion chamber technology of this engine is quite good. Derived from the GE9 core machine technology, the combustion chamber of the F404 is quite technical. Directly to the short annular combustion chamber stage, which is far away from the annular combustion chamber used by the turbofan 10.

The short annular combustion chamber is much shorter in body length than the annular combustion chamber, resulting in a reduction in engine volume and weight, which is a great improvement. Moreover, the performance of the short annular combustion chamber has not been lost, and even improved, which is a point that must be admired.

Academician Liu Daxiang is also well aware of this, and one of the three parts of the pre-research has a design problem. to be toppled again; The other is that the technology of the 624 Institute is poor, which is undertaken by Southwest Science and Industry, and the only remaining combustion chamber technology must save face.

"Then let's talk about the combustion chamber, we 624 with reference to the F404 pre-research of the advanced short ring combustion chamber technology, now the progress is very good, by us continue to develop, at most two years, we can produce results, to ensure foolproof."

About the technology of the combustion chamber where the 624 is located. Yang Hui is also more assured that the advanced mid-push project of the previous plane has tested the performance of the combustion chamber quite well, using a short annular combustion chamber with several pneumatic atomization nozzles of the sudden expansion imported diffuser. It was almost the most advanced and mainstream technology in the world at that time, and even after 2000, it would not lag behind.

Although the advanced push core machine of later generations was dismounted. However, this short annular combustion chamber technology was retained and used in the Taihang engine. This is enough to show that the combustion chamber technology that is now being developed in the hands of 624 Institute has excellent performance.

"That's fine, the short annular combustion chamber technology is very good. It is indeed more advanced than the annular combustion chamber used in our current turbofan 10 engine, and there is no problem at all with the 624 continuing to develop the combustion chamber. However, in order to prevent a break in the research and development of the combustion chamber in our Southwest Science and Industry, we hope to send our technicians to participate in the research and development of the combustion chamber, and at the same time can speed up the progress. ”

This condition is reasonable, and there is no reason for the 624 Institute to refuse, Chief Engineer Liu nodded affirmatively.

"This is no problem, we can have more people to join in the development of the combustion chamber, our progress will be faster, and then let the comrades of Southwest Science and Industry go to the 624 Institute with us, according to the business trip, secondment."

The annular combustion chamber of Southwest Science and Industry is completely developed from beginning to end in accordance with the theory, without any reference, this kind of experience 624 can not have, can take the opportunity to fill this loophole, 624 can not ask for it.

As for the other components in the core machine, these are the three most important components of the core machine, all of which are small things, and they are directly divided and cooperated by 624 and Southwest Science and Technology.

The only problem is that the 624 Institute of Southwest Science and Industry proposed that the high-pressure compressor casing is made of steel casing, and the F404 core casing obtained by 624 is a titanium alloy casing, which not only has excellent mechanical properties of the material, but also is quite lightweight.

According to the original plan of the 624 Institute, it was also to prepare to use a titanium alloy casing, but Yang Hui still felt unreliable after many considerations, and the F404 engine started with a titanium alloy casing, which has never had any problems since its first flight in 1978.

But Yang Hui knew that the F404 had a problem in 1987, and in just one year, the United States lost 4 F18 aircraft because of the fire of the F404 engine.

Even the same core aircraft, the F101, had the same problem in October 1990, when the engine caught fire twice, resulting in the absence of the B1-B bomber of the US Air Force from the Gulf War.

From the problem of the F404 in 1987 to the same fire of the F101 engine, GM has not figured out why the engine had an accident and why it caught fire? GM was puzzled.

And the real reason is why Yang Hui insists on using steel casings now. On the one hand, it is due to practical reasons, and now the domestic titanium alloy processing process is not up to standard, and on the other hand, it is because titanium alloy is unreasonable to make a high-pressure compressor casing.

The F404 core machine uses titanium alloy as the casing, which is the culprit of the engine fire, and the reason for correcting it is because titanium alloy is not omnipotent, and it also has its own defects.

High-temperature titanium alloy is generally used to make structural parts with a temperature of more than 300 degrees, and is commonly used in high-strength parts inside aero engines. Usually used as a compressor impeller is the most suitable, the first three stages of the F404's high-pressure compressor are all made of titanium alloy, which is no problem.

However, it is used to make a compressor casing, which is a typical mistake in material selection, and conventional titanium alloy has a tendency to burn under specific conditions.

The chemical activity of titanium alloy is relatively large, and it will react with oxygen, nitrogen, carbon and other elements in the atmosphere at room temperature to form a skin mixed with oxides and carbides, which is why titanium alloy welding needs to be carried out in a vacuum state.

Not only that, but titanium alloys have an even more important property: they have a very low thermal conductivity (i.e. no heat transfer). If there is no heat transfer, it is easy to accumulate local heat, and the heat will be red when it reaches a certain level.

The defects of the titanium alloy material itself are introduced, and then the case of the F404 casing and compressor are both made of titanium alloy. If the titanium alloy does not rub into fine particles, it is quite difficult to burn even if it is reddened by heat.

But there is also a problem mentioned earlier, when the F404 engine in the United States has problems in a concentrated manner, it is several years after this engine is finalized, and when the F101 engine has problems, the service life is almost five years.

Why does it only happen after a few years of good use? The reason is that after a certain number of years of use, the engine is washed and rubbed by external sand and dust, and the blade shape is partially changed.

The dust is very small, but after the compressor is pressurized, there will be a very high speed, even if it is small, it will produce a considerable impact, and the compressor is also running at high speed, so the blade shape has undergone a small change, even if it is made of titanium alloy, it must follow the law. (To be continued......)