Chapter 1207: Variable Cycle Engine in One Step?

Chapter 1207. Variable cycle engine... in one step?

In the past few minutes, Sun Cong had experienced what a true ups and downs were——

With the resources accumulated by 601 and Shengfei over the years, it is certainly impossible to give up the development plan of a new generation of aircraft just because of this setback in model selection.

Even if I raise my own funds after returning, I must maintain my R&D capabilities without interruption.

But without support from other fraternal units, the project’s ability to resist risks is bound to plummet.

In the end, there is a high probability that they will switch to conventional layout and develop a smaller product that may be launched into the international market.

Chang Haonan's words are equivalent to reviving the semi-tailless layout plan from the coffin.

Although there is nothing wrong with low-risk options, technically more radical solutions will always lead to broader horizons.

As for the intention...

Laughing to death, can you still refuse to agree?

If the situation were different, Sun Cong might be a little more reserved.

But now, he is afraid that if he agrees a little slower, the pie that finally fell from the sky will escape on its own...

"Academician Chang, you can rest assured that we will fully cooperate with you regardless of any requirements regarding the research and development of new thrust vector technology!"

Chang Haonan looked at Sun Cong's serious expression and was basically sure that the latter would take his proposal seriously, so he nodded and prepared to leave.

But just as he was about to stand up, he heard a hint of impatience in the other person's tone.

After hesitating for a moment, he gave Sun Cong a vaccination first:

"Mr. Sun, although this pneumatic vector nozzle sounds like an aviation engine accessory, the development process is completely different from the traditional mechanical vector nozzle. You must be mentally prepared for this in advance."

Sun Cong had already taken out his mobile phone and was about to call back his colleagues who had left first to report the good news.

After hearing Chang Haonan's words, he stopped immediately, with a bit of confusion in his eyes.

Although China has not systematically completed the research and development of a thrust vector technology before, even if it has never eaten pork, it has always seen pigs running away.

Generally speaking, this is a device that is relatively independent of the engine itself, but is more closely related to the aircraft's wing control system.

So much so that the thrust vectoring nozzles on many engines are provided as options.

Therefore, Sun Cong also subconsciously felt that Chang Haonan should just prepare to try two technical routes on the turbofan 10G at the same time, and the research and development work should be roughly synchronized with the full-blooded version of the turbofan 10G.

But now that the latter reminded me, I suddenly felt a little unsure.

"Judging from our previous research on ordinary ejection nozzles, every 1% change in throat area roughly corresponds to an additional 0.3% secondary flow consumption... Then, for those who frequently require 100% of the nozzle throat area For aircraft engines with afterburners with varying ranges, at least 25-30% of the secondary flow flow rate is sufficient.”

Chang Haonan explained:

"Although by improving the structure of the aerodynamic cavity and optimizing the secondary flow adjustment algorithm, there is definitely room for further optimization of this number... However, due to the limitations of the airflow flow rules, it is impossible to have a large change of orders of magnitude."

When he heard the number "25-30%", the corners of Sun Cong's mouth twitched visibly.

After he heard the complete conclusion, he had already put down the cell phone he took out:

"Wouldn't that have a great impact on the engine thrust?"

Although all types of thrust vectoring technology will result in a loss of engine thrust, compared to a mechanical nozzle that only causes extra work by high-temperature gas in the last section, a pneumatic nozzle directly takes away a quarter of the intake air volume.

Even if the flow of air diverted away is not a complete loss, it is basically draining fuel from the bottom of the cauldron.

You know, air film cooling only consumes about 5%, but only 10% at most.

"The impact of thrust is secondary."

Chang Haonan waved his hand:

"This part of the airflow does not matter the temperature, so there is a way to make up for part of the thrust loss through secondary work... The key is that the flow itself is too large. The current design of the small bypass ratio engine is already quite compact, and it is impossible to extract it from it. A flow path that is large enough to pass through this amount of airflow.”

"Worstfan 10G won't work either?"

Sun Cong looked a little surprised.

"Well... the upgrade potential of the turbofan 10 is indeed greater than other types of engines, but it cannot be so much greater."

Chang Haonan replied helplessly:

"In order to meet the requirements of the aerodynamic vector nozzle, it is necessary to consider leaving a margin in the outer duct from the beginning of the design, and adjust it according to the working conditions, so it must be matched with a technology that is more advanced than the turbofan 10G in terms of technical principles. Advanced aviation engines, that is..."

"Variable cycle engine?"

Sun Cong and Chang Haonan almost said the final answer in unison.

"That's right."

The latter nodded, obviously very satisfied that Sun Cong could keep up with his thoughts:

“In order to change the cycle parameters during engine operation, the variable cycle engine itself needs to be equipped with ring features such as front and rear duct injectors and adjustable low-pressure turbine guides to offset changes in external and internal flow caused by changes in cycle parameters. Effects on the static pressure balance of the mixer cross-section..."

"Of course, the design of these components themselves and how to integrate them with the main structure of the engine would require several major subjects... But to sum it up simply, when the engine is working in dual connotation mode, it is necessary to add appropriate The large opening of the rear duct ejector ensures low duct pressure demand under the small opening of the front duct ejector; when the mode selection valve is fully opened, the opening of the rear duct ejector increases appropriately, thereby reducing Effect of small back pressure on fans.”

"In addition, if the variable cycle engine afterburner is put into operation, the opening of the rear duct ejector should also be appropriately increased to ensure that the airflow speed within the afterburner meets the normal requirements for afterburner ignition and flame stabilization..."

"And very coincidentally, due to the structural limitations of materials and the physiological limitations of the pilot, when we need a larger thrust vector amplitude, the aircraft will be at a relatively low speed, which corresponds to a turbofan engine with a larger bypass ratio. configuration, and the afterburner is most likely being used. At this time, the opening of the ejector is at its maximum, which can just meet the demand for secondary flow flow..."

"..."

Sun Cong was not familiar with the specific technical route of variable cycle engines, but fortunately Chang Haonan did not focus too much on this part.

The basic principles are not that difficult to understand after all.

"So our semi-tailless solution...needs to wait until the fifth-generation engine comes out and then test it simultaneously?"

He really believes in Chang Haonan's ability, but now that the plan for the fourth-generation fighter jet and its supporting power has just been finalized, he has already reached the fifth-generation...

The equipment generation, development generation, and pre-development generation were the methods used in the past when we were lagging behind. They correspond to the second, third, and fourth generations of main battle equipment respectively.

But now that we are about to catch up with the international advanced level, can we continue to do this?

Chang Haonan quickly saw the uncertainty in the other person's eyes:

"Whether it is a fourth-generation and a half engine or a fifth-generation engine... In short, the foundation for the turbofan 10 has been laid. The development of the turbofan 10G is basically step-by-step. We only need to wait for the ten or so engines that are currently lacking. If all the key technologies are in place, I may not be personally responsible for managing them.”

“Also, don’t think that variable cycle technology is so insurmountable. Beijing Hangzhou University, the Chinese Academy of Sciences, and of course our Aerospace Power Group are all studying the flow and combustion characteristics of the rear duct ejector, as well as the actuating mechanism. We have carried out preliminary research on key technologies such as structural strength optimization. In addition, I submitted a list of 80 key technologies to Director Li of the Industrial and Construction Committee a few days ago, of which the last 40 are related to the newer generation of aero engines..."

When he directly mentioned the term "newer generation engine", the expression on Sun Cong's face finally showed a slight fluctuation——

If my semi-tailless solution uses a variable-cycle engine, would that be equivalent to directly developing a fifth-generation fighter jet in one step?

Furthermore, there is currently no news about fifth-generation or fourth-and-a-half-generation fighter jets, whether in the United States, Russia or Europe.

And if this model can really be implemented, even if it is only implemented as a technology verification machine...

It all seems to mean that for the first time, China has the right to define the most advanced fighter jets!

Thinking of this, Sun Cong, who was still a little confused at first, gritted his teeth and closed his eyes.

"Done!"