The reason why Song Wencong specifically brought up the topic of bow shock wave was mainly because he was worried that the handling of this place would affect the overall project schedule.

After determining the follow-up improvement direction of the J-10 with Chang Haonan last year, the No. 10 project team did not sit back and wait for support, but soon began to rely on the existing two prototypes to carry out some pre-research work.

Because wind tunnel testing alone cannot completely restore all the phenomena that occur on the actual machine.

Although the flight hours of Jianjiao 9 are not small, the supersonic ability of that model can basically only be used to give students flight experience, and it is difficult to find the actual problems about the DSI air inlet under high-speed flight conditions.

Moreover, it is also a two-sided air intake design, which is not very susceptible to the pre-compression of the incoming head.

In this way, this problem of bow-shaped shock wave-induced enhancement of the separation of the attached surface layer was discovered, which had not been paid attention to in the past.

Anyone who works on projects on a regular basis will know that the simple and complicated parts are not scary, and the most troublesome thing is to suddenly have a problem that has never been considered before.

It is likely to affect the whole body, and even lead to a major change or even a direct discontinuation of the entire project.

Although this trouble is not too big, as long as you give enough time (and computing power, of course), you can solve it anyway.

But what is most lacking in Project 10 at the moment is time.

Therefore, Song Wencong has even made a plan.

If it really can't be done in a short time, then let Project 10 serve with the current structure first, and solve the problem of the lack of third-generation fighters in the Air Force as soon as possible.

As for the kind of improvement ideas proposed by Chang Haonan, it can be said later.

Anyway, the size of the Huaxia Air Force is not small, and it can accommodate enough sub-models.

However, now that he heard Chang Haonan give a solution almost without thinking, the people around him were suddenly relieved.

This at least shows that the former has been mentally prepared for this for a long time.

"Original...... Comrade Haonan has already studied even such technical details? ”

Compared with others, Yang Wei, who was standing beside Chang Haonan, had a hint of disbelief in his tone:

"This forward-looking and foresight is really impressive......"

"Uh...... Actually, it's not a foresight, it's a coincidence......"

The former was touted for such a while, and quickly waved his hand.

Then, he saw a few curious glances around him.

After a pause, he had to explain:

"I posted a paper on mandibular internal transfer airway the year before last, you should know, right?"

The rest of the people naturally nodded for a while.

Although everyone is a veteran who joined the No. 10 project from the beginning (except for Chang Haonan), no one has personally participated in the development of the J-7F.

However, the article "Research on the Integrated Layout of Dual-module Mandibular Internal Rotation Inlet/Cone Precursor", as a classic document of computational fluid dynamics, plus Lu Yuying has specifically mentioned the content in many conferences for a period of time, I must have read it.

"Actually...... At that time, I found that if the position of the air inlet was further modified, when it reached the belly position, the surface layer would be very unstable after the incoming flow velocity exceeded the factor, and the surface layer would be separated with a slight disturbance. ”

"I see......"

Song Wencong also suddenly realized:

"No wonder you designed that combination of a cone precursor and an airway so ...... In particular, it turns out that the key point is in this ......"

The so-called special is naturally a euphemism for ugliness.

It must be admitted that the design of the J-7F is indeed underconsidered in terms of appearance.

"What ...... this?"

In fact, Chang Haonan just found a random reason.

In fact, he would know about the bow shock wave, naturally because he had read the relevant technical materials in his previous life.

As for the solution, I really started thinking about it after I came into contact with Project 10.

Because the J-10 solved this problem in the previous life was around 2010, with the computing power at that time, when solving the shape of the DSI inlet cocoon package, you can even directly add an extra degree of freedom to optimize it.

But at the moment, there are no such conditions, so we can only use some tricks.

Who would have thought that after a single operation, even Song Wencong had a little bit of Dihua.

But it was impossible for him to shake out the truth, so he had to skip the process in the middle and vaguely summarized:

"In short, I have been studying this problem since that time, and later when I participated in the 83 Project and improved the wing of the aircraft, I came up with the idea of using a vortex generator to delay the separation of the surface layer."

"And, in addition to this main function, a well-designed vortex generator can improve the quality of the flow field at the inlet and outlet of the inlet and reduce the total pressure distortion at the inlet of the turbofan engine."

This part of the content can be said to be leaky.

On the one hand, these Rongfei technicians around them actually didn't know what was going on in the 83 Project

On the other hand, there is indeed some principle connection between the vortex generator and the wing knife......

If you have to pull it stiffly, it makes sense.

"Shhhh

As his words fell, a uniform inhalation suddenly sounded around him.

You must know that although Chang Haonan, including the people closest to him, such as Ding Gaoheng, Du Yishan, etc., is already a little numb to these things, others have not.

In the eyes of others, doesn't that explanation just now show that others have begun to think about this level of complexity in their junior year?

Isn't that the Dou Sect powerhouse terrifying?

This joint, Chang Haonan himself is actually not easy to figure out.

However, he also felt that he should change the subject.

Fortunately, Yang Wei next to him gave an assist at this time.

After all, his evolutionary journey is also quite outrageous in a way.

The same kind looks at the same kind, and it is naturally easier to accept.

Therefore, when others were still in shock that Chang Haonan was not a person, he had already begun to follow Chang Haonan's train of thought to consider technical issues:

"From a qualitative point of view, on the one hand, the vortex generator enhances the momentum exchange between the low-energy fluid on the near-wall surface and the main stream to achieve the effect of inhibiting the separation, but on the other hand, it will also increase the loss of inlet resistance, which is a design trade-off?"

Seeing that Chang Haonan, who finally talked about the topic of technology, sighed in his heart that he deserved to be a real boss, the agility of this thinking was close to the opening of the body, and he immediately nodded:

"It is true that when the supersonic velocity is high in the incoming Mach number, the interference of the shock wave attached to the surface layer is serious, resulting in a large flow separation, and the benefit of the eddy current generator to suppress the separation is more obvious, which is reflected in the total pressure recovery coefficient is a small loss."

"Correspondingly, when the Mach number of the incoming flow is low, the separation is relatively small, and the resistance loss of the eddy current generator is more obvious, which is reflected in the total pressure recovery coefficient."

"Therefore, the design of this vortex generator and the selection of parameters are very important, fortunately, the total pressure recovery coefficient of the DSI inlet at low speed is almost at the level of excess, and I don't care about the slight loss, so the optimization window is not very strict."

"In addition, under some specific electromagnetic wave incident angles, the eddy current generator will increase the radar reflection area and destroy the stealth performance."

"Stealth isn't a big problem......"

Another deputy chief designer next to him stroked his gray hair:

"Although the DSI inlet can reduce the RCS to a certain extent, under the premise that the overall design does not systematically consider low detectability, the benefit of just a few detail corrections is not large, so I don't care about this few percent change."

"It's just...... I'm just thinking about whether I can apply a similar idea to other models, and it seems that I still want to make it simple......"

This emotion immediately attracted a burst of recognition.

However, Yang Wei's focus is obviously a level higher than others:

"Wait...... If you think about it from another angle......"

"According to our current customary method, the comprehensive distortion index only includes circumferential distortion and turbulence components, but in the design of DSI inlet channels with vortex generators, radial distortion and swirl distortion need to be systematically considered."

"Perhaps, we should take this opportunity to change our design habits......"

(End of chapter)