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

Chapter 1287 Liquid and Solid, I Want Them All

After saying this half-joking remark, Chang Haonan no longer paid attention to Jiang Zonglin who was standing there stunned. Instead, he put the report aside, walked straight past Li Yabo, and sat down in front of the computer.

As the number of projects on hand and the size of the team increased, he had to understand the progress of many work through regular reports that he had hated in his previous life.

But today's research on the reaction mechanisms of metal particles has far exceeded initial estimates.

For results like this that may have a disruptive impact on an industry or even a discipline, Chang Haonan prefers to see the results firsthand.

It’s not that I don’t trust Li Yabo, but a lot of inspiration can only be stimulated in the process of analyzing raw data. Directly looking at the conclusion is skipping the most important thinking process, and it is easy to overlook certain key points or make mistakes of assumptions.

The other three then gathered behind Chang Haonan.

Driven by the Torch Group and TORCH Multiphysics software for the entire numerical computing industry, in 2006, there were already many specialized software that could graphically render simulation calculation results to improve intuitiveness.

Even veterans like Chang Haonan or Li Yabo may not need the assistance of graphics technology during the calculation process, but in order to facilitate subsequent review, they will still set aside some time and computing power for this purpose.

Even Xing Muchun, who was completely confused just now, soon figured out some clues:

"It looks like... this part of the model ignores the rates at which chemical reactions occur, and assumes that convection and diffusion only occur in radial space?"

Of course, this question is not asked to Chang Haonan, but to Xiang Li Yabo.

So the latter nodded immediately:

"There are objective computing power limitations... In my calculations, I did not assume that particle combustion is a quasi-steady-state process. Instead, I referred to the method used by my teacher in the past to study ultrashort laser processing of metals and added a large number of partial differential equations to the description of the combustion process. I really did not have the conditions to consider the situation in a three-dimensional scenario..."

"..."

Just when Xing Muchun wanted to ask something else, Chang Haonan, who had been staring at a page on the computer for a while, suddenly spoke:

"Yabo, if you modify your calculation results...would it be more appropriate to describe a solid-liquid mixed system?"

After a brief pause, he added:

"It can even be much simpler than the current non-steady-state dynamic-diffusion-evaporation control model. In addition, for solid-liquid systems, although the two-dimensional assumption is essentially still approximated, at least the influence of particle morphology can be ignored, and the accuracy is much higher than that of describing pure solid systems."

There was a flash of lightning in Li Yabo's eyes, and his gaze quickly turned to the part of the computer screen that Chang Haonan was pointing at.

However, there was no immediate response.

Instead, he lowered his head and thought for a moment.

"From a microscopic perspective on the particle surface, this is indeed the case... But considering the actual situation, solid-liquid mixed propellant should be very inconvenient to use, right?"

Chang Haonan waved his hand:

"The traditional solid-liquid hybrid system is indeed not widely used... Mainly because in the past, although this type of propellant is called solid-liquid hybrid, its essence is to vaporize the liquid oxidizer and spray it into the combustion chamber loaded with solid fuel, and then rely on the flame temperature after ignition to decompose and vaporize the solid fuel to maintain combustion."

"Under this working mechanism, because the oxidant is introduced from outside the combustion chamber, the decomposition products of the solid fuel after gasification can only form a diffusion flame with the oxidant. The combustion surface is very close to the solid surface, and the heat feedback intensity cannot be very high. Therefore, the fuel propagation rate is essentially no different from that of traditional solid propellants. Instead, it adds a lot of unnecessary trouble to the loading of propellants and the overall structural design of the aircraft."

At this point, he felt that the following content was a little unclear if he just spoke it orally, so he pulled a piece of paper from the side.

However, considering his abstract painting skills, he quickly changed his mind and opened the professional drawing software on his computer.

"But if the surface of the solid fuel can be melted to form a thin liquid film, then under the action of the surface flow, the liquid will become unstable and then atomize to form droplets into the gas phase, thereby greatly enhancing the mass transport of the fuel, which is equivalent to increasing the fuel's retreat speed at the same time."

"And in this way, the high recession velocity becomes a natural property of the fuel itself, without the need to introduce additional additives, nor the need to adopt enhancement measures such as porous configurations or rotating nozzles, which significantly simplifies the propellant preparation process..."

"..."

When Chang Haonan was in charge of the space fishing boat project, he heard Yin Liangxing say that because the movement rate of solid fuel is relatively low, in order to maintain a sufficiently high combustion chamber pressure and generate a large enough thrust, a porous configuration is generally used to increase the combustion surface area.

Taking the more typical HTPB as an example, small charges require 4 holes, while large charges even require 32 holes.

On the one hand, this increases the size of the engine with the same propellant capacity and makes processing more difficult. On the other hand, it also reduces the structural strength of the charge, making it easy to cause internal fractures and accidents such as the fall-out of the charge.

Especially in high-acceleration flights such as hypersonic aircraft, the hidden dangers will be more obvious.

Although liquid fuel does not have such concerns, its flexibility of use and storage safety are not satisfactory. Perhaps it has little impact on launch vehicles, but as can be seen from the complicated preparation process before the previous verification missile test launch, it does not quite meet the requirements of missiles, especially tactical missiles.

In contrast, this new solid-liquid mixed system exists in solid or semi-solid form during storage, and its combustion characteristics after entering the working state are close to those of liquid fuel, which is equivalent to having the advantages of both.

Of course, for such a good thing, the cost is definitely not easy to reduce.

But for a national weapon like hypersonic weapons, effectiveness is definitely more important than price.

Moreover, the application of this type of mixed propellant is not limited to the project that Chang Haonan is working on.

In the long run, most missile types that are not particularly sensitive to size can be converted from traditional solid propellants to the new system.

From the perspective of industrial laws, production costs will also be reduced accordingly after the application is rolled out.

Li Yabo, who was standing behind Chang Haonan, had obviously thought of this at this moment, and his eyes gradually changed from doubt at the beginning to understanding.

Then he frowned again and fell into thought:

"If this is the case, then not just any liquid film will form atomized droplets under flow. It also depends on the tension and viscosity of the liquid under working conditions... So the HTPB fuel we are currently studying will definitely not meet the requirements, and we must develop a completely new type of propellant."

Although Chang Haonan studies computational materials science, it is not database after all, and he has not come into contact with too many types of solid propellants in the past.

Therefore, professional matters must be left to professionals:

"Old Xing, please contact Comrade Lin Chenggang immediately and ask him to come over here..."

……

Upon receiving the news, Lin Chenggang thought that a breakthrough had been made in the research on the AP/HTPB/AI system. After hanging up the phone, he rushed to Huairou Science City without even having time to eat lunch.

However, after seeing Li Yabo's calculation results and hearing Chang Haonan's new ideas, his first reaction was -

This work is organized and uploaded by Liujiu Book Bar~~

The sky is falling.

Originally, he just wanted to make some improvements based on the existing research.

but now……

Bad news: The shabby house was leaking everywhere, and the paperhanger we hired didn’t do a good job.

Good news: the paperhanger is actually a civil engineer. He has built a new one right next to it for you, and you can move in right away.

The only problem is that all the experience of the past ten years or so may need to be updated...

Lin Chenggang took a lot of effort to suppress his curiosity. He didn't ask how the two of them could have done such a cruel thing in just one month. Then he quickly focused his attention on the report in front of him.

I have to say that although this new idea is essentially just a pipe dream, it is indeed very attractive.

While waiting for him to come over, Chang Haonan and Li Yabo had already roughly calculated a range of physical properties that met the requirements.

All Lin Chenggang needs to do is come up with a propellant or a class of propellants that are feasible as the matrix.

“表面张力6.5-8.0mN/m、粘性0.59-0.73mPa·s、熔点不低于323K，沸点不高于720K，熔化热小于185kJ/kg……”

There are hundreds of types of solid propellants, but after screening based on these ten or so conditions, there are not many left.

“It shouldn’t be the case, right?”

Looking at Lin Chenggang whose expression was erratic, Li Yabo became a little impatient.

Fortunately, as soon as he finished asking the question, he heard the former mutter an answer:

"paraffin……"

"paraffin?"

This somewhat ordinary result surprised Li Yabo.

"Of course it's not ordinary paraffin. It has to be modified and blended... But as a base fuel, alkanes with an average carbon number of about 30, which we often call paraffin, do meet all the requirements in this table..."

Chang Haonan didn't show much surprise, but just nodded calmly:

"Then I'll make a copy of these results for you. When you go back, please verify whether the use of paraffin-based fuel can meet the performance requirements of the booster stage of an air-breathing hypersonic rocket!"