The fifth-generation engine, of course, is not possible at the moment.

The third generation is F110 and AL31F, which have a push ratio of about 8.

The fourth generation is the F119, F135, and AL51F, which have a push ratio of 10 or more.

If the turbofan 10 is built according to Chang Haonan's idea, it will probably skip the third generation of fundamentalism and directly enter the category of three and a half generations.

Of course, there are actually many differences between the third and fourth generation engines, which can be said to be different from the original design ideas, manufacturing processes, and material selection.

The thrust-to-weight ratio is just one of the most intuitive data that is reflected in the performance.

Of course, there is also a three-and-a-half-generation engine sandwiched in the middle, that is, the foundation of the late-stage F110, F414, and AL41F is still a third-generation engine, but the technology of some fourth-generation engines is applied, resulting in a performance that is significantly higher than the upgraded version of their predecessors.

It is worth mentioning that the fourth-generation engine is no different from the third-generation engine in the most basic principle, so there is still a performance trade-off that cannot be avoided physically - the fuel consumption of the high-speed oriented model is generally amazing, while the low-speed oriented model will be extremely strained in supersonic performance (see chapter 415 for a detailed explanation).

It is precisely in order to solve this contradiction that the adaptive variable cycle mode has been widely introduced in the conceptual design of the fifth-generation engine in various countries.

At low speeds, it can be a fuel-efficient, medium-bypass ratio turbofan engine, and at high speeds, it can even be transformed into a high-performance turbojet engine.

Therefore, although the fifth-generation engine may not be able to achieve such a terrifying leap from 8 to 10 on paper data, it may even be due to an additional set of variable cycle devices, resulting in a decrease in the thrust-to-weight ratio at sea level (the dead weight has become larger, and the thrust has not become so large), but the actual performance installed on the aircraft will far exceed that of the fourth generation.

It's just that although the idea of variable loops is simple, there are still too many details to perfect if you really want to implement it.

Even before Chang Haonan's rebirth, everyone had not yet decided which variable-cycle technology path was more feasible.

Not to mention, the specific design concept of the compressor is about to undergo an almost earth-shaking change.

So after a brief chat about the future planning of the domestic engine spectrum, Chang Haonan and Liu Yongquan still returned to the current research.

"Multi-row superimposed full-coverage air film cooling ......"

Liu Yongquan repeated this somewhat awkward term.

"That's right."

Chang Haonan took Liu Yongquan to the experimental table next to him, a laptop was placed on it, and an isothermal curve was displayed on the screen:

"I thought that the air-heat coupling simulation could be done directly with the current TORCH Multiphysics software, but when it comes to actually operating it, I found that the situation is still too simple."

As he spoke, he circled a part of the graph with the Brush tool:

"You see, after the main stream comes into contact with the high-momentum cooling jet, a pair of vortex structures with opposite rotational directions will be generated in the downstream areas of the jet, which plays a role in concentrating the wall cooling gas to inhibit lateral diffusion in the rotation direction of the vortex structure, and at the same time, it also has a tendency to lift away from the wall cooling gas."

"So ......"

Liu Yongquan still understands this picture:

"So the greater the blowing ratio (the momentum of the cooling airflow), the more difficult it is for the main stream to suppress the cooling jet, and the sooner the cooling gas will leave the solid wall surface, resulting in a worse cooling effect downstream?"

Chang Haonan nodded, and said in his heart that he was worthy of really bringing the turbofan 10 into a mature person on the original timeline, although he was still slightly inexperienced in addition to the hairstyle of the big guy, but the basic skills were indeed okay, and he quickly grasped the key conclusion after just a few glances:

"That's right, so if you consider the air-heat coupling effect of the entire engine, you will find that if you blindly increase the amount of cooling gas, then the further you go, the less obvious the improvement of the cooling effect will be, and you will soon hit an upper limit, and because the airflow loss is too large, it will also affect the performance of the engine itself, and even the working stability."

"This is impossible to find out if we only study the effect of the air film cooling on the blades without considering the engineering as a whole, and I speculate that this should be one of the reasons why the Americans are currently taking a detour."

After his judgment was affirmed by Chang Haonan, Liu Yongquan almost subconsciously thought of the most direct way:

"If we enlarge the pore size of the air film hole, we can reduce the air flow rate and improve the ...... while the amount of cooling gas is the same."

But he quickly denied himself:

"No, simply increasing the pore size of the air film will lead to greater pressure loss, and the gain will outweigh the loss......"

"Then Mr. Chang, if the cooling hole is changed from cylindrical to conical, the inlet area is small, and the outlet area is large, won't the coverage of the airflow on the blade surface be improved?"

At this moment, Chang Haonan was indeed a little impressed by him.

The cooling effect of special-shaped holes is better than that of round holes, which is something that any undergraduate student of related majors will know in 20 years, but at present, the research on this aspect in China is still in a blank.

In my previous life, it was not until about a year later, when Rolls-Royce sponsored a research project related to active cooling at Northwest University of Technology, that Huaxia realized this.

Engineering stuff is sometimes like a layer of window paper, pierced, and it looks like that, but if there is no one to guide you, it will take a lot of time just to find where the window is.

And Liu Yongquan found the right direction at least in a short time.

"The idea is right, but it can go further."

Chang Haonan took a pen and paper from the side and drew a schematic diagram on the paper:

"In fact, there is no need to make major changes to the cooling hole itself, as long as an expansion section is connected to the outlet part, that is, the end of the hole, so that the pressure loss is smaller, and the flow rate at the outlet of the air film hole can be greatly reduced."

"A decrease in flow velocity means a decrease in momentum, and the cooling gas is almost non-blowing, and the wall attachment effect is better."

"Moreover, the interaction between the main stream and the cooling gas is weak, the strength of the kidney-shaped vortex on both sides of the jet is weak, and the meridian region will form a structure with the anti-kidney-shaped vortex, which can also enhance the lateral diffusion effect of the cooling gas, which can make the cooling gas film more uniform!"

"That ......"

Liu Yongquan only had a feeling of enlightenment at this time, and the solution to the whole problem seemed to be as simple as 1+1:

"Then let's just change the hole to something like this...... This kind of special-shaped hole is enough? ”

"Of course, it can't be that simple, what I just said is just the basic principle."

Chang Haonan put the pen aside, waved his hand and replied:

"The gas film formed by the special-shaped hole will not only improve the effectiveness of the downstream of the hole, but also improve the heat transfer coefficient of this part, so the cooling effect of the solid wall area with low heat transfer coefficient is relatively poor."

"Moreover, this awkward opening method must affect the structural strength of the workpiece, we are building an aero engine, there are requirements for overload, and the environment of high temperature, high centrifugal force, and strong air flow impact itself is also a test of structural reliability."

"Therefore, what kind of hole type to use, how to design the distribution of air film holes on the surface of the workpiece, and the angle of the hole - not only the pitch angle, but also how to design the transverse angle, these are all questions, and they must be trade-offs."

"That's why I have to order a special equipment, on the one hand, to study the specific air film cooling scheme, on the other hand, to accumulate some data for the next major version of the TORCH Multiphysics software, the gas-thermal coupling, and the simple mechanical-thermal coupling is still quite different, I am afraid that a new functional module is needed to do a good job."

Even Chang Haonan is not really omniscient, he has tried it with his own software before, but there are too few theories and data in this area, what are the simulated results......

It can only be said that it has a certain reference value.

"Then Mr. Chang, I'll design the experimental plan?"

Liu Yongquan behind him was already eager to try.

"Actually, I've already designed ......"

Chang Haonan glanced at the brand-new experimental equipment not far away.

"Ah......h

Liu Yongquan scratched the top of his head, which was already hairless, with some embarrassment.

But Chang Haonan changed his words again:

"But you can also try it first, and then match the plan I gave you later."

Liu Yongquan's eyes lit up, and he suddenly felt that he could:

"That'...... Regarding the sample of turbine parts for testing, or do you want to do it directly with the turbofan 9? ”

"That's right, if you don't have the design data of turbofan 9, you can directly ask for it from Factory 430."

Under the operation of Chang Haonan, the turbofan 9 has now basically become the technical verification model of the turbofan 10.

Although the temperature before the turbine of the former cannot reach the level of 1200-1250°C, the cooling effect is certainly not too high.

Especially if there is no need to change the blade material.

Of course, it's not the 430 factory of the prostitute family.

Spey MK202 is actually just a thrust-to-weight ratio of 5 level engine, except for fuel consumption, which is even inferior to many of the last generation turbojets.

Some of these technologies tested by the turbofan 9 can always be used back to the production model, and the performance will definitely be improved under the premise that the cost and overall structure are basically the same.

(End of chapter)