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

Chapter 1458 Virtuous Circle

Compared with the X51A project which has almost become a mess, China's hypersonic weapons research and development has entered a new stage after the Dongfeng 17 successfully completed its test launch and review missions.

The development work on the gliding hypersonic missile has come to an end, and subsequent improvements can be completely completed by the technical team of the Aerospace Science and Industry Corporation.

The only thing left for Chang Haonan's R&D team was the one at the top of the entire technology tree -

Air-breathing hypersonic vehicle.

Moreover, unlike the rocket-propelled X51A, it can only fly within a specific narrow speed range.

China's ambitions are even greater...

In the control room of the JF14 wind tunnel in Huairou Science City, Xing Muchun was facing the computer screen, reporting to Chang Haonan on the recent work progress.

"Boss Chang, during your absence, we worked with several project teams of the China Aerospace Science and Industry Corporation and obtained a lot of working parameters of sub-combustion ramjet-powered missiles from them."

Xing Muchun moved the mouse pointer for a long time, and finally found the one he needed from the dozens of PDF files covering his computer desktop:

"Combined with the wind tunnel data from our previous tests and the retrospective analysis of the X51A flight test parameters, we can basically determine that the design weakness of the entire system lies in the matching between the inlet duct and the combustion chamber, especially during the switching process between the subsonic mode and the scramjet mode."

Chang Haonan stared at the work cycle curve on the screen for a while, and then made a judgment before the other party finished speaking:
"The parameters of the shock wave system...especially the location, are difficult to define?"

Xing Muchun was choked back as he was about to say something.

Although he has been working with Chang Haonan for several years, it seems that every time he can bring him a new and surprising experience.

After a few seconds, he nodded awkwardly:
"There are many appearances, but it is true in the end..."

He dragged the scroll bar on the far right of the screen downwards and came to the middle of the file:
"During the dual-mode conversion process, the lower the Mach number at the inlet entrance and the higher the total pressure recovery coefficient of the inlet, the lower the required combustion-induced shock wave train compression ratio, thereby achieving higher performance. In other words, the difficulty of inlet design can be reduced. On the other hand, too low an intake speed is not conducive to the normal start-up of the scramjet mode. It is very likely that, like the X51A back then, it will stay in the transition mode for a long time and cannot enter the real scramjet working cycle..."

Although both tests of X51A ended in failure, it brought a lot of inspiration to China's scramjet technology.

In particular, the first test of the Long March 9 nuclear submarine, which was monitored throughout the entire process, can almost be regarded as an encyclopedia of failed lessons in the engineering world.

After a pause, Xing Muchun sat back in the chair behind him and pointed at Jiang Zonglin on the other side:
"Lao Jiang has proposed a new idea before, which is to reduce the specific impulse at the cost of expanding the upper limit of the subsonic ramjet section and the lower limit of the scramjet section."

Then he pointed to the curve on the screen that represented the transition mode:
"At low flight Mach numbers, a larger combustion chamber can be used with an intake duct with a smaller compression ratio. In the process of flying to a higher Mach number, the combustion chamber expansion ratio can be continuously reduced, and the compression ratio of the intake duct can be increased. While reducing the fuel equivalence ratio, the combustion chamber size can be adjusted to maintain the optimal modal operating conditions, thereby reducing the duration of the modal conversion process."

Although Jiang Zonglin is also an engineer by background, because he has spent most of his life studying hypersonic wind tunnels, his understanding of hypersonic flight dynamics is mainly at the theoretical level.

Judging from the data listed in the figure alone, his proposal is very reasonable, but it is very difficult to implement.

“The wider the operating range, the larger the size range that needs to be adjusted, and the worse the feasibility of the adjustment mechanism.”

Chang Haonan shook his head.

"Taking into account the fuel supply system, the active cooling system of the combustion chamber, and the impact of external airflow under ultra-high-speed flight conditions... With the current material properties, it is extremely difficult to realize a geometrically adjustable combustion chamber. Even if it is achieved, the reliability will be affected due to the extreme working conditions and the overly complex structure."

Since he began studying computational materials science, he has gained a very deep understanding of the ultimate performance of materials, especially metal materials.

However, Xing Muchun obviously still did not give up on this idea:
"Can we make the low-temperature components adjustable in the low Mach number range where the heat load is low, and keep the high-temperature components fixed, and simply increase the physical size to achieve heat distribution and thermal throat adjustment? Anyway, our thrust is already in excess, so even if the weight increases a little, it won't affect the maximum speed..."

If Mr. Collinger on the other side of the ocean heard this extremely Versailles statement, he would probably be so angry that he would vomit blood on the spot.

But the three people at the scene seemed to have no emotional fluctuations at all, as if "excess thrust" was already a common sense accepted by everyone... "From the perspective of technical verification model, it is possible."

Chang Haonan stood up, walked back and forth in front of the console twice, and then turned and said:

"But when I talked to several military leaders a few days ago, they said they were planning to expand hypersonic weapons to multiple platforms..."

According to the leaders, since the two bombs and one satellite project, no other weapon equipment has been able to improve China's international discourse power as immediately as the Dongfeng 17.

In just one week after the military parade, many cooperation projects or multilateral agreements that were still in a stalemate were concluded with unprecedented efficiency. The many external obstacles that were originally faced disappeared without a trace. Several leaders attended dozens of international conferences almost non-stop, and their hands were sore from signing so many documents...

However, because of the requirements for the initial velocity and altitude of the launch, gliding hypersonic missiles can basically only use ballistic missiles as launch vehicles. Excluding intercontinental missiles that are almost impossible to use, tactical models like the Dongfeng 17 can only deter areas around the mainland, and their deterrent capabilities for targets farther away are insufficient.

Therefore, military users who have tasted the sweetness of hypersonic weapons urgently need to expand the flexibility of using subsequent air-breathing hypersonic weapons so that they can go further away to reason with others.

To be frank, there are only three types of platforms for long-range delivery of tactical weapons:

Destroyers, submarines and aircraft carriers.

"In this case, it is necessary not only to allow bombers to carry it, but also to consider the vertical launch systems of large surface ships, the torpedo tubes of submarines, and even the belly heavy-load hanging points of tactical aircraft such as the J-11."

Chang Haonan concluded:
"The only feasible solution for high-efficiency wide-range operation may be a multi-design point combustion chamber, combined with precise fuel injection and mixing design, to control the movement of the heat release area, the heat distribution ratio, and the tail nozzle expansion ratio, to come up with a solution that compromises wide-range efficiency and physical size."

Xing Muchun also understood the implicit meaning, but he was not very confident about such a one-step plan:

"This is an unprecedented challenge for the detection and control accuracy of the shock wave system...at least it is much more stringent than the requirements of the gliding system."

Completely unaware of each other, hypersonic developers on both sides of the Pacific were focusing on the same specific problem.

The difference is that China has entered a virtuous circle through the success of the Dongfeng 17 project.

"My opinion is."

Chang Haonan grabbed a piece of paper from the table next to him and casually drew a schematic diagram of the ramjet intake duct and combustion chamber:
"An array of static pressure sensors is set at a certain interval in the isolation section. The pressure detected each time is compared with the reference level of the supercritical low support pressure of each sensor. If the reading of a sensor is higher than the reference value of the sensor, it means that the shock wave system is in front of the sensor occupying the same position."

"Of course, since it is impossible to arrange an infinite number of sensors, we still need to conduct a lot of wind tunnel tests and use interpolation methods to increase the fidelity of this shock wave positioning system."

Jiang Zonglin, who had been silent the whole time, rubbed his hands together, revealing an expression that was hard to tell whether it was excitement or worry:
"The number of tests required for this process is probably about an order of magnitude more than the previous stage. Moreover, because air-breathing hypersonic aircraft mainly fly in the atmosphere below 40km, the requirements for the total temperature of the wind tunnel are also higher than those for gliding aircraft..."

Simply put, it means spending money.

Burning much more money than in previous years.

“Don’t worry about research resources.”

However, Chang Haonan assured almost without hesitation:
"Because of the positive impact of the DF-17, our superiors have agreed to give us an additional special grant starting next year, which will be enough to support a higher frequency of wind tunnel tests than now, as well as..."

He deliberately dragged out the sound, which made Jiang Zonglin feel a little itchy:

“And a brand new, ultra-high-speed wind tunnel with a higher total temperature rating!”

(End of this chapter)