The military-industrial scientific research system of the academic master.

The design review will officially begin soon.

Although the entire meeting will last two full days, everything is difficult at the beginning. The most important moment is actually the few hours in the morning of the first day.

Not only because the big leaders are there, but also because the most important design ideas and basic technical routes are usually concentrated in the first half of the day.

If there is no problem with this part, the entire project will be basically stable.

"This is a component-level analysis model of the turbofan 10 engine, which is a zero-dimensional analysis model."

"During the overall design stage of the aircraft, a large number of design options need to be evaluated. Considering the limited actual performance of my country's supercomputers, this requires the calculation speed of the engine analysis model to be fast enough."

"At the same time, taking into account the accuracy requirements and the need for thermodynamic parameters of engine components for engine noise and emission calculations, component-level performance models are used to calculate the thrust and fuel consumption characteristics of the engine..."

“Therefore, we regard each component of the engine as a whole, and only calculate the thermodynamic characteristics of the inlet and outlet of each component. Based on the common working relationship of each component of the engine, we determine the common operating point of the engine, and finally obtain the thrust, fuel consumption and The status of each component..."

"At this step, we will not consider the casing and other auxiliary accessories for the time being, and simply calculate the design point and non-design point performance of the engine..."

“When calculating the design point performance, based on the input design point altitude and flight Mach number, as well as the engine bypass ratio, fan boost ratio, compressor boost ratio, turbine front temperature and other thermodynamic cycle parameters, the efficiency of each component or the total Pressure loss and engine air flow.”

“Based on the order in which the airflow flows through the various components of the engine, the thermodynamic parameters of the airflow at the inlet and outlet of each component of the engine, the unit thrust and fuel consumption rate of the engine, etc. are calculated. Finally, the net thrust of the engine and the main cross-sections of each component of the engine are calculated based on the air flow of the engine. Size parameters……"

These contents will be basic knowledge for aerospace designers twenty years from now, or even graduate students in related majors, and can be conveyed directly in two sentences.

But in the 90s, apart from Chang Haonan himself, there were few people in the country who had seriously engaged in aviation engine design from scratch. Everyone was groping in the dark, so I still need to introduce it in detail.

On the other hand, these workflow-level things are also very important for technical staff who sit further back and only attend meetings.

Due to the different division of labor, most of the members involved in the research and development of the Turbofan 10 did not actually have the opportunity to truly touch the entire project. They only completed a certain small direction and even small details in accordance with the requirements of Chang Haonan or their immediate superiors. It’s just a task.

For the turbofan 10 itself, this division of labor is certainly reasonable.

But after all, Chang Haonan is planning to use these people as seed personnel in China's aviation power field.

Specific technology development is of course important, but for them, they still need to be exposed to the relevant ideas of overall design as early as possible.

The best opportunity is, of course, the two-day technical review meeting.

From Chang Haonan's perspective on the stage, many people can already be seen writing furiously with their heads down.

He even slowed down a bit specifically for this purpose.

After all, I have been a student. The teacher talked endlessly on the stage, and I wrote down the notes below. Who hasn’t experienced the feeling of taking off?

Therefore, Chang Haonan added two more sentences here:

"However, compared with other common zero-dimensional models, thanks to our company's newly developed multi-physics coupling algorithm, we can relatively accurately establish mathematical models describing these aerothermodynamic processes in this step, so there is no need to Too many simplifying assumptions.”

"First of all, the airflow in the engine still needs to be treated as a one-dimensional flow. This is the core of establishing a zero-dimensional model."

“However, thanks to new technologies, it is possible to take into account the impact of turbine cooling bleed air, external bleed air and power extraction on engine performance, combustion chamber combustion and heat transfer models, and the impact of Reynolds number on the characteristics of each component... …”

Now, it's not just the melon-eaters sitting behind who are taking notes.

Even Jiang Fuhe and others on the podium pressed the ballpoint pens one after another, making an almost uniform "click" sound.

"Next, I will introduce the aerodynamic and thermodynamic characteristics of each component in the order of atmospheric environment, inlet, compressor, combustion chamber, turbine, nozzle, manifold, and joint working model..."

Just as Chang Haonan expected, after he released more detailed design data on the projection screen, whispers came from the entire judging panel.

After all, the structure of Turbofan 10 is considered unique even in the field of turbofan engines in the world.

哪怕是9级压气机，也一般会选择3+6，很少出现2+7的情况。

What's more, the pressure ratio of his high-pressure compressor is very high, and the subtracted first-stage fan even seems to be deliberately lowering the first-stage pressure ratio...

The estimated thrust-to-weight ratio of 8.5-9.0 made everyone's first reaction unbelievable.

Because this is already the technical indicator that third-generation major modification engines such as AL41F or F110-GE-132 have been pushed to the limit.

These two models are actually still in the process of flight testing...

好家伙，涡喷13还是60年代水平，涡喷14已经能跟80年代早期的F404打个有来有回，这到了涡扇10……

Directly catch up with the most advanced level in the 21st century?

Is it really just the same model for twenty years?

……

Until Chang Haonan's mouth went dry while talking, he finally came to an end on the overall design and component-level analysis model, and entered the morning question session.

Even if the leaders sitting at the leadership table know a little bit about technology, they cannot be experts in the field of aviation development, so the first person to ask questions was Jiang Fuhe, who had already been impatient.

The question is naturally about the core machine structure that he has been itching about for a long time.

"Comrade Chang Haonan, I noticed that you used a structure like a 10-stage high-pressure compressor on the turbofan 7. Of course it is very advanced, but I want to confirm that the current compressor design level in our country can guarantee that it will pass 2+ Can the total boost ratio of 7-25 be achieved in the form of 26?"

"In addition, it is also a 9-stage compressor. Why choose 2+7 instead of the more common 3+6 form?"

Chang Haonan's answer was even more direct:

"These two questions are actually the same thing."

"Because the core engine of the Turbofan 10 is actually the core engine of a fourth-generation engine."

"what?"

"woc..."

"Really...really the fourth generation?"

"..."

It almost exploded down below, but fortunately there was a big leader sitting next to it, so order was quickly restored.

Chang Haonan continued to explain:

"Regarding the issue of single-stage pressure ratio, we have made a huge breakthrough in the active control technology of blade separation flow. The single-stage pressure ratio is significantly improved compared to traditional compressor blades. With a total of 9 stages of compressor, it can be achieved The total boost ratio required in the design specifications."

"As for the specific technical details, according to the plan, they should be discussed this afternoon."

After finishing speaking, Chang Haonan added another important statement:

“Actually, if we don’t take into account that the inlet structure of this engine has a very good boost capability, this 2-7-1-1 structure can even reach a pressure ratio of around 28. But in that case, the supersonic performance of the J-10 and J-11 will definitely not be optimistic."

"That's why you specifically reduced the number of fans?"

Liu Zhenxiang seemed to understand something.

"Yes, but not entirely."

Chang Haonan said and turned the PPT back to the page where the overall structure of the turbofan 10 was drawn:

"Generally we think that third-generation engines such as AL41F and F110GE132, which use part of the fourth-generation engine technology and have been enhanced, are called 3.5 generations."

"As for our Turbofan 10, it is essentially a fourth-generation engine, but because our country does still have huge shortcomings in materials and processes, it is unable to meet some of the requirements of a true fourth-generation engine, so , we had to lower some performance requirements.”

"If I have to say it, it is probably forced to use some fourth-generation engines that have been weakened by the third-generation engine technology. Therefore, we are accustomed to calling it...the 3.75th-generation engine."

This statement is concise and concise enough that even leaders, let alone experts, understand it completely.

Does it mean that you are ready to enter the international leading level?

Looking at the speechless audience, Chang Haonan left behind the desk and walked to the middle of the podium:

"That's why I designed the seven-stage high-pressure turbine required for a one-stage engine with a thrust-to-weight ratio of 10. After all, the core engine structure cannot be changed, and the fan can be added later."

"In the future, we only need to make in-depth improvements based on this core aircraft to develop a true fourth-generation aviation engine!"