Chapter 18 The idea of ​​hypersonic speed

"Xiao Chang, Xiao...Professor Liu told me before that you had a very deep and clear understanding of this design during the defense. To be honest, I didn't believe it, but now I can see it."

Du Yishan cheerfully picked up the design plan of Chang Haonan and others on the table: "It's like the waves behind the Yangtze River push the waves ahead. I, an old man like me, can hardly keep up with the ideas of you young people."

"Academician Du is so impressed. I just used some simulation methods to make an improved model design. There are still many things I need to learn from seniors like you."

Chang Haonan was not a random compliment. In fact, Du Yishan still played a vital role in the aviation industry until the new century, and played an important role in the development of a certain type of transport aircraft.

"Ha, it sounds nice to talk." Du Yishan has obviously read this design report many times, and he immediately turned to the content about the performance test: "What do you think is the biggest advantage of the mandibular air intake designed by you? What? Or, besides being on this plane, is there any other place available?"

This question shocked Chang Haonan, and he secretly sighed that Academician Du's vision was really good. He only spent two or three hours at most reading the design instructions before discovering the greater potential of this design.

"In fact, we have discovered in simulations that the new air inlet has more obvious advantages at higher speeds than the traditional design. Although the maximum speed of the improved J-7 can only reach Mach 2.0, we still have higher speeds. Some calculations were made on the flow field distribution and performance at high speed. The results show that this inlet design can maintain a total pressure recovery coefficient of more than 3.5 up to the speed of Mach 4.0-6 and the inflow angle of attack of 0.73°. , and if the high speed is specially optimized in the design point selection, the performance can be even higher."

"Can it reach Mach 4?"

Du Yishan had made qualitative judgments based on experience before, but after all, his eyes were not in a wind tunnel, so he still couldn't see the specific data.

"Well... we have calculated up to Mach 4. If the speed is higher, the current calculation and simulation method is not suitable. The method needs to be improved, and better equipment is needed."

In other words, Chang Haonan means that this design still has potential to be tapped, but it cannot be tapped due to current conditions.

"As for the use, I think in the short term, we can consider combining it with a liquid fuel ramjet engine and using it on missiles with a speed of Mach 3-4. In the long term, if we need to develop and use scramjet engines for flight in the future, For air-breathing hypersonic aircraft with speeds above 5 times the speed of sound, this design idea should also be useful as preliminary research."

This time, Du Yishan's eyes were a little shocked.

In 1996, China had not even fully developed a subsonic cruise missile using a turbojet engine.

Under this circumstance, this junior undergraduate student has actually begun to consider making technical preparations for supersonic cruise missiles and even hypersonic cruise missiles.

Although it is not that no one is doing preliminary research in this area, they are basically still in the feasibility analysis or theoretical research.

And this air inlet design, and more importantly, this integrated design idea, can even be counted as part of engineering practice.

It's a pity that with the current strength of China's aviation industry, there is no way to carry out more in-depth system development work.

Looking at the expression of Academician Du Yishan in front of him, Chang Haonan knew that he should be stable.

Sure enough, after about a minute of ideological struggle, Du Yishan put the design instructions in his hand back on the table next to him, raised his head and asked Chang Haonan:

"Xiao Chang, I wonder what your plans are for your future?"

Not far away, Professor Liu Hongbo closed his eyes in pain - his last glimmer of hope was shattered.

As a student of Du Yishan, he knew very well that what he just said was a standard question before an academician prepares to recruit disciples.

Faced with this problem, Chang Haonan almost did not think twice: "Since I have chosen Beijing Airlines' aircraft system, it is natural to continue my studies and use scientific research results to help the development of our country's aviation industry!"

He had already walked this path without a system in his previous life, and it was even more impossible to change his mind now.

"Well... your course design can be used as a graduation project with a slight modification. I can be your graduation project tutor." Du Yishan nodded: "As for the future, I have two suggestions. , I wonder if you are interested in hearing it?"

Although this is a question, if someone is really not interested in answering, they are probably stupid.

"Of course, please give the lecture, Academician Du."

Chang Haonan took a deep breath and tried to calm down his excitement.

"First, I can make an exception for you to apply for a place to study abroad on a government-sponsored basis. It may be in the UK or the United States. If you are willing to take this path, then in your senior year, focus on overcoming the language barrier, and you will be able to pass by You can adapt to the environment as quickly as possible after that.”

Du Yishan was only halfway through his proposal when Liu Hongbo on the other side wanted to get up and seemed hesitant to speak.

Although government-sponsored students studying abroad must return to their country to work according to regulations, in this era, there are quite a few people who never return after going abroad. In fact, most people do not intend to break the contract at the beginning, but after arriving abroad. After seeing better living, working and even scientific research conditions, I finally chose to stay outside.

Although publicly-sponsored international students who refuse to return to their country need to repay all state-funded expenses in accordance with the agreement and pay an additional 30% liquidated damages, with the current income gap between domestic and foreign countries, this money is not considered at all for those who stay in European and American countries to work. What.

Therefore, Liu Hongbo's philosophy has always been that if a student has the idea of ​​going abroad, he will not object, but if the student has no intention to do so, he will not take the initiative to mention it.

He was really afraid that the good prospect he had fallen in love with would never come back.

Especially for a genius like Chang Haonan, who can be said to be one in a million. If he goes abroad, he will definitely be the target of the other country's competition. Even if he wants to come back, it may not be that easy.

"Second, this is also an exception. You can choose to join my research group and skip the master's degree and directly study for a doctorate. Compared with going abroad, you can get exposed to more practical projects here, but the conditions are indeed not the same as others. There is no comparison, it will be more difficult. If you choose this, I will let you participate in some key projects as soon as possible."

"Of course, if you have other ideas of your own, I will try my best to help. In short, the choice is yours."

"I choose the second one." Chang Haonan replied looking into Du Yishan's eyes.

This was his original idea, to prove his ability through course design and participate in specific projects as soon as possible, but the actual situation was smoother than previously expected.

"You really don't want to go abroad?" Du Yishan smiled and asked again: "If you go abroad for further study, you can still build the country when you come back."

In fact, if Chang Haonan didn't have this system, he might really choose to go abroad. After all, in this era, no matter which company is Britain, the United States, France or Russia, they are far ahead of the country in aviation. After going out, he only needs to learn something and return to the country. It’s all valuable experience and knowledge afterwards.

But with the help of the system, this gap no longer exists for Chang Haonan. If he goes abroad, he will contribute knowledge to others instead of learning knowledge.

This ran counter to his original intention.