Technological power starts with upgrading lenses

Chapter 258 Large Ducted Turbofan Engine
Whether the performance of an aircraft engine is good or not usually depends on its thrust, and then on this basis, fuel economy is pursued.

But the problem is coming,
根据F（推力）=W*（C1出口气流速度-C0飞机速度）以及效率n=2/1+（C1/C0）两个公式可以得出的结论：

The faster the engine outlet airflow speed C1, the greater the thrust, but the corresponding efficiency is low.

In addition to this problem, the bypass ratio also has a great impact on aircraft flying at different altitudes and speeds. For example, for a fighter with a small bypass ratio, the bypass ratio exceeds 0.7, which is more suitable for low altitudes, and the bypass ratio is lower than 0.5. , more suitable for high altitudes.

Therefore, fuel economy and thrust, large bypass ratio and small bypass ratio are contradictions in themselves, and it is difficult to balance all aspects. In fact, this is just one of the contradictions between various needs and technologies when designing aerospace engines.

Behind every seemingly subtle design change is the result of trade-offs and compromises between needs and technology.

Of course, technology is constantly developing, and scientific research also requires a bold hypothesis and careful demonstration.

Take the large-ducted turbofan engines of passenger aircraft and transport aircraft as an example. They have only one inlet fan, and the diameter is usually more than three meters. Therefore, a lot of air can be sucked in, most of which enters the outer duct. Provides more than 85% of the engine's thrust.

Therefore, for large ducted engines, the effect of expanding the diameter of the outer duct and fan to increase thrust is very obvious. This is what the F35 engine on the F135 does.

But the side effects are also obvious. If the diameter of the outer duct and fan is too large, the windward resistance will be large. Therefore, it is difficult for aircraft with a large bypass ratio to fly at supersonic speeds.

For Hangfa, there are three main cores: design, materials, and technology.

Among them, the design drawings are available, and any country that wants the materials will definitely provide them. However, if Kang Chi does not go to the aerospace industry to study the craftsmanship, it will probably be difficult for Kang Chi to figure it out on his own in just a year and a half.

As for Kang Chi,

Variable loops currently have two directions,

After the end of the Cold War, the Blackbird cost as much as 20 billion U.S. dollars per aircraft and the monthly operating cost of 3700 million U.S. dollars, which made Old M complain that it was too much to bear, and finally withdrew from the stage of history in 1998.

As soon as you hear the name, you will know that the structure of this thing must be very complicated. Let’s not say whether it can be made. Just adding so many systems and parts to a high-temperature and high-speed engine, reliability and lifespan are always difficult issues.

In addition to HP's J-58, the old American GE company also successfully developed the F-120 variable cycle engine, but it was eventually eliminated due to cost and other reasons. Later, GE learned its lesson and did not blindly pursue high technology. Instead, we looked for cost-effectiveness.

It is the first practical jet aircraft to successfully break through the thermal barrier. Even missiles cannot catch up with it at a speed of Mach 3.2. It has been attacked by thousands of anti-aircraft missiles in its 24 years of service. However, except for one reconnaissance mission to Korea, it was attacked by One 5200 missile was damaged, and the others were all unscathed. Its technological content can still be used even today.

Not to mention anything else, just asking him to follow the drawings of the Turbofan 20 would take a lot of effort to reproduce a Turbofan 20, let alone a brand new black technology engine.

He is greedy. Since it is theoretically possible, he wants them all!
But when he got started, he found that things were far from simple as he imagined.

So someone raised a question. Since the aircraft needs a small bypass ratio to obtain greater thrust and speed when taking off or fighting, and pursues a large bypass ratio when cruising to save fuel and endurance,
So if we get an engine with a variable bypass ratio, wouldn't this problem be perfectly solved?
Theoretically, it is indeed feasible. To put it bluntly, a turbofan engine is just two cylinders with different diameters and sizes that are put together. As long as a retractable outer cylinder and fan are built, an engine with a variable bypass ratio will be born.

One is to activate or deactivate the afterburner according to the situation. The afterburner is actually the intersection of the hot and cold gases ejected from the inner duct and the outer duct, plus a fuel injection combustion device, using no energy consumed in the air. The lost oxygen is burned again to increase thrust. In this state, the entire engine is actually no different from a turbojet.

And this aircraft, which is equipped with a J-58 self-circulating engine and looks very sci-fi like an alien product, has indeed become a myth of an era.

But even though this principle seems simple, it is extremely difficult to make it happen.

Compared with variable duct technology, which sounds extremely difficult at first glance, variable circulation technology is relatively simple and easy to understand.

Therefore, so far, all countries are still in the early stages of research and development, and there is no variable bypass ratio engine that can actually be produced.

In the competition with Lao Maozi, both of them, with the efforts of the whole country, did develop a lot of black technology, and they are still enjoying the aftermath of that technology competition to this day.

However, during the competition, the lives of ordinary people were not so easy. Just like China tightening its belt and carrying out two bombs, miracles have to pay a corresponding price.

The second method was actually developed by Pratt & Whitney of M country in 1962. This self-circulation engine called J-58 is also the world's first variable-cycle engine put into use. It is equipped with the SR-71 "Black Bird strategic reconnaissance aircraft.

At present, China is also researching and overcoming technologies such as reverse thrust, variable circulation, and variable ducting. What has been developed so far is afterburner technology, but it is not the kind that can start and stop automatically.

The other is to directly control the proportion of gas entering the inner and outer ducts by adding several gas valves. When high thrust is required for takeoff or breakthrough, most of the gas will be introduced into the combustion chamber of the inner duct for combustion and ejection.

But it can be seen from the fact that the aviation industry only provides drawings but not processes that they still want to keep a hand on Kangchi. This is also understandable. If someone comes up and asks Kangchi for the drawings and technology of the lithography machine, he will definitely not willing.

Although Cai Yaobin seemed to be indifferent when he gave him these 'study materials', and he was even afraid that he would not be interested, but it must have been the military bosses who had gone to great lengths to get them for him.

Therefore, Kang Chi did not expect to learn these craftsmanship by going to Xifei, and could only do it on his own.

The only way to relieve worries is to cheat.

So Kangchi finally chose to downgrade the technology. As long as an engine with these functions could be built, even if the performance was poor, it could only ignite smoothly for one second so that the system could pop up the panel.

But even so, the entire design process was extremely difficult. Just to design a foldable and zoomable outer duct sleeve, Kangchi spent more than ten days and made dozens of attempts before finally coming up with a rough idea. It's feasible. The development of the entire prototype took more than forty days, and the performance...

[Item: Large ducted turbofan engine]

[Manufacturer: Kangchi]

[Item Level: 1]

[Experience: 0/50000]

[Item status: intact]

[Item parameters: maximum thrust 8500kgf, maximum reverse thrust 3500kgf, variable bypass ratio 6-10, manual variable cycle afterburner, service life 1000 hours]

[Analysis items: no analysis items]

[General experience: 493464]

[Mastery Points: 71 (+20)]

When Kang Chi saw the panel that the system successfully popped up, he was happy but also felt a little frustrated.

An air inlet fan has a diameter of 3 meters, and there are so many cutting-edge technology engines, but the maximum thrust is only 8.5 tons.
Moreover, the service life of tens of thousands of hours, which is an advantage of large bypass engines, is even lower than that of turbojet...

All I can say is that aviation development is really difficult.

The key is that aerospace engines are not like chips. Once the chip understands the principle, it is not difficult to make an integrated circuit with poor performance. However, no matter what the performance of aerospace engines is, it must first solve the problem of high-temperature combustion and high-speed normal operation, not to mention success. With so many functional modules added, the threshold for starting is very high.

But with the prototype, the rest is easy. Kang Chi decided to upgrade boldly until it could no longer be upgraded. How could military equipment be improved without some black technology!
Not only this engine, but also the small bypass ratio engines that will be developed in the future, as well as the rotary detonation ramjet engines used in short-range and ultra-high-speed penetration and rockets, and even the entire UAV aircraft carrier and ship-based equipment cluster plan, he is preparing for it. Full of black technology.

In fact, apart from battery technology, Kangchi has always been relatively restrained in upgrading items, because it is such a dark technology that it must upgrade the existing industrial system. Mass production is very troublesome, and the cost may not be controllable. live.

Secondly, analyzing black technology consumes too many mastery points.

Finally, I am worried that the technology that is too dark in the early stage will easily make people suspicious.

But after several recent trials, especially the sudden introduction of super-strong carbon fiber material technology, Kang Chi suddenly became more courageous without even a single question, not to mention dragging him to anatomy.

There may be people who may have suspicions behind the scenes, but they will definitely not delve into it. In other words, when others find it difficult to understand the technology Kang Chi presents, the final power of explanation is already in his hands.

If you can't find the problem with just a few random words, how can you dig deeper?

upgrade!

[General experience-50000]

[General experience-150000]

[Insufficient experience and upgrade failed, and the civilization has not unlocked the pre-requisite metal element No. 376]

Unlocked the front metal element No. 376?
Kang Chi was stunned when he saw the panel that popped up for the third system upgrade.

The general lack of experience is nothing. It took 20 experience for two upgrades. The remaining 29 experience cannot be upgraded, but the front metal element No. 376 is a bit interesting...

Civilization has not been unlocked, which should mean that humans have not yet discovered things that are not on the periodic table of elements. There are only two ways to discover new elements.
One is artificial synthesis.

One is that nature itself exists, but it has not been found, or it does not exist on the earth at all, lying on other planets waiting for human discovery.

But just a numerical number contained too little information. Kangchi could only put this matter aside for the time being and carefully looked at the upgraded engine parameters.

[Item: Large ducted turbofan engine]

[Manufacturer: Kangchi]

[Item Level: 3]

[Experience: 0/450000]

[Item status: intact]

[Item parameters: maximum thrust 50000kgf, maximum reverse thrust 30000kgf, variable bypass ratio 6-10, adaptive variable cycle afterburner, service life 20000 hours]

[Analysis item: parsable]

[General experience: 293464]

[Mastery Points: 71]

After seeing the system parameters, Kang Chi couldn't help shouting: The system is awesome!
Although the upgraded engine is larger in size, with a maximum thrust of 50 tons, one engine is worth three turbofan 3s and 20 F2.56s...

The most important thing is that its current volume is at a bypass ratio of 10. If the bypass ratio is reduced, its volume can be reduced by 40%. At the same time, the power is maximum in this state.

If the fuselage material will not be torn by wind resistance and thrust, just replace four of these things on the Yun-20, and supersonic flight will definitely not be a problem.

And a large transport plane that can fly at supersonic speeds?
Just thinking about it makes me excited!

Of course, large supersonic transport aircraft have no practical use other than showing off.

The real significance of this engine is to be able to build a larger transport aircraft.

Or the four turbofans 20 on the Yun-20 can be directly replaced with two turbofans 30, which can greatly reduce the dead weight and improve the thrust-to-weight ratio.

The result is that the top speed, acceleration capability and load-carrying capacity can all achieve a qualitative leap.

After getting excited, Kang Chi opened the analysis panel again.

Design analysis requires 10 mastery points.

Material analysis requires 15 mastery points.

Process analysis requires 20 mastery points.

Because engine technology is too core, Kangchi analyzed all three projects without hesitation, and the entire knowledge infusion process lasted two minutes.

Because he basically designed the engine himself, and with the experience accumulated in advance, the process of obtaining information was relatively easy. It only took Kangchi an hour to absorb and organize all the knowledge, and turned it into his own knowledge. .

This wave of analysis has allowed him to significantly improve his design capabilities in engine design. Although this Class III large-bypass turbofan engine is somewhat similar to his previous design, a large number of design optimizations and adjustments have been made. Behind every little detail is something worth pondering and learning.

For example, when changing the fan diameter at the air inlet, Kangchi originally achieved this by reducing the number of blades and changing the angle.

But after the system was upgraded, the design was directly changed to fold the blades backwards, and at the same time change the inclination angle of the blades, making it look like a badminton. Although it looks very aerodynamic, it does not reduce the number of blades and the air intake. It's generous, but the design difficulty is several levels higher.

In terms of material analysis, he also obtained a new structural ceramic material that is high temperature resistant, high strength, and corrosion resistant. It is mainly composed of Al203, ZrO3, C-BN, Si3N4, Sic and other materials, and the production process is also very complex.

The next step is to seize the time and mass-produce this engine as soon as possible.

The main idea is the same as before, we can still find OEMs and try our best to take advantage of China's industrial system.

The second is to improve the efficiency of Pangu Base and maximize the utilization rate of Pangu Base.

But before that, Kangchi plans to complete the redesign of the Y-20 and then find a way to ask XAC to help him build an fuselage.

When the time comes, the Turbofan 30 will be installed for direct test flight, which will give them a big surprise. In the future, it will be easier to get support for the UAV aircraft carrier and ship-based equipment cluster research and development plan.

(End of this chapter)