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

Chapter 1207 Variable cycle engine...all in one go?

In the few minutes that just passed, Sun Cong experienced what it means to have a real ups and downs.

With the resources accumulated by 601 and Shengfei over the years, it is certainly impossible for them to abandon the research and development plan of the new generation of aircraft just because of this selection setback.

Even if I raise funds on my own after returning, I must maintain my research and development capabilities without any interruption.

However, without support from other sister units, the project's ability to resist risks will inevitably plummet.

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

Chang Haonan's words were equivalent to resurrecting the semi-tailless layout plan that was already half buried in the ground.

Although there is nothing wrong with low-risk options, technically more radical solutions always have more potential.

As for the intention...

It's so funny, how can I not agree?

If it were a different occasion, Sun Cong might have been a little more reserved.

But now, he was afraid that if he was a little slower in agreeing, the pie that had finally fallen from the sky would slip away...

"Don't worry, Academician Chang, we will fully cooperate with you in the research and development of the new thrust vectoring technology, no matter what your requirements are!"

Chang Haonan looked at Sun Cong's serious expression and was basically certain 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 shot of prevention:

"Mr. Sun, although this aerodynamic vector nozzle sounds like an aircraft engine accessory, its research and development process is completely different from that of the traditional mechanical vector nozzle. You must be mentally prepared for this in advance."

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

After hearing Chang Haonan's words, he stopped what he was doing, and there was a hint of doubt in his eyes.

Although China has not systematically completed the research and development of thrust vectoring technology before, even if you have never eaten pork, you have always seen pigs run.

In general, 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 thrust vector nozzles on many engines are provided as optional parts.

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

But now that he was reminded by the latter, he suddenly felt a little unsure.

"Based on our previous research on ordinary ejector nozzles, every 1% change in throat area corresponds to an additional 0.3% of secondary flow consumption... So, for aircraft engines with afterburners that require a 100% change in nozzle throat area, at least 25-30% of secondary flow is needed to be sufficient."

Chang Haonan explained:

"Although this number can certainly be further improved by improving the structure of the aerodynamic cavity and optimizing the secondary flow regulation algorithm... However, due to the limitations of the airflow momentum rules, it is impossible for a large change of orders of magnitude to occur."

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

After hearing the full conclusion, he put down his cell phone:

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

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

Even if the air volume that is diverted away is not completely lost, it is basically cutting off the fuel from the bottom of the pot.

You should know that film cooling only consumes about 5%, at most 10%.

"The thrust effect is secondary."

Chang Haonan waved his hand:

"It doesn't matter if the airflow is hot or cold, so there is a way to compensate for some of the thrust loss through secondary work... The key is that the flow rate itself is too large. The current design of small bypass ratio engines is already quite compact, and it is impossible to carve out a flow path that can pass such a large amount of airflow."

"Not even 10G turbofan?"

Sun Cong seemed a little surprised.

"Well... the upgrade potential of the WS-10 is indeed greater than that of other engine models, but it cannot be that 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. Therefore, it must be equipped with an aero-engine that is more advanced than the WS-10G in terms of technical principles, that is..."

"Variable cycle engine?"

Sun Cong and Chang Haonan gave the final answer almost at the same time.

"Yes."

The latter nodded, obviously very satisfied that Sun Cong could follow his thoughts:

"In order to change the cycle parameters during the operation of the engine, the variable cycle engine itself needs to be equipped with front and rear duct ejectors and adjustable low-pressure turbine guide vanes and other annular characteristic components to offset the impact of changes in external and internal flow caused by changes in cycle parameters on the static pressure balance of the mixer section..."

"Of course, the design of these components and how they are integrated with the main structure of the engine require several major subjects to be discussed in detail... But to sum it up simply, when the engine is operating in dual duct mode, the opening of the rear duct ejector is appropriately increased to ensure the low duct pressure requirement under the condition of a small opening of the front duct ejector; when the mode selection valve is fully opened, the opening of the rear duct ejector is appropriately increased to reduce the impact of back pressure on the fan."

"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 afterburner internal airflow velocity meets the normal requirements of afterburner ignition and flame stabilization..."

"And what is very coincidental is that due to the structural limitations of the materials and the physiological limitations of the pilots, when we need a larger thrust vector amplitude, the aircraft will be at a relatively low speed, corresponding to the engine configuration of a large bypass ratio turbofan, and it is likely that the afterburner is being used. At this time, the ejector opening is the largest, which can just meet the secondary flow rate requirements..."

"..."

Sun Cong was not familiar with the specific technical route of the variable cycle engine, 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 plan... needs to wait until the fifth-generation engine comes out before we can test it simultaneously?"

He really believed in Chang Haonan's ability, but now that the fourth-generation fighter and its supporting power plan had just been finalized, he had already drawn the pie for the fifth generation...

Equip one generation, develop one generation, and pre-research one generation. That was the method used in the past when we were lagging behind, and 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 like this?

Chang Haonan quickly noticed the hesitation in the other person's eyes:

"You can call it a fourth-generation and a half engine or a fifth-generation engine... Anyway, the foundation of the WS-10 has been laid, and the research and development of the WS-10G is basically proceeding step by step. We just need to wait for the dozen or so key technologies that are currently lacking to be in place. In fact, it is not necessary for me to be in charge of the overall work personally."

"Also, don't think that variable cycle technology is so insurmountable. Beijing University of Aeronautics and Astronautics, Huaxia Academy of Sciences, and of course our Aviation Power Group, are all conducting preliminary research on key technologies such as the flow and combustion characteristics of the rear duct ejector and the optimization of the structural strength of the actuator. In addition, I submitted a list of 80 key technologies to Director Li of the Construction Commission a few days ago, and the last 40 of them are related to the newer generation of aircraft engines..."

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

If this semi-tailless plan of mine uses a variable cycle engine, wouldn't it be equivalent to developing a fifth-generation fighter jet in one step?

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

And if this model can really be put into use, even if it is only used as a technology verification machine...

All of this 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 originally a little conflicted, gritted his teeth and closed his eyes.

"Done!"