Chapter 1340 The burning of the end
"Wait a moment..."
Faced with such a drastic situation, Lin Chenggang himself could not bear the first thing he could not bear:
" Academician Chang, please let me slow down first..."
Compared with Shen Fangzhong, who is from rocket dynamics and Li Jianqiang, a technician who specializes in rocket power and solid fuels, he is a technician in the Department of Theoretical Chemistry In a superposition state of "knowing a little, but not fully understanding".
It is precisely this state that allows him to neither ignore all intermediate links and listen to the results like a pure layman, nor can he quickly and fully understand the calculation process displayed on the computer.
After all, it involves quite complex mathematical and physics knowledge, which is indeed a bit complicated for a traditional engineer.
The result was that before he could fully digest the part of the problem pointed out earlier, he heard Chang Haonan say that three new tricks were formed based on his own system.
If the heart is broken, it is a very strong mentality.
Fortunately, Chang Haonan also knew that his progress might be a little fast, so after hearing Lin Chenggang stop, he waited patiently for a while.
However, there are some things that don’t, but they don’t.
If you don't understand it at the beginning, it will be difficult to figure it out yourself in a short period of time.
So a few minutes later, Lin Chenggang's frowning brow not only did not stretch, but instead twisted deeper.
Seeing that it was not a solution to drag on like this, Chang Haonan had to speak again and interrupt the other party's thoughts that seemed to be ineffective:
"If you have any part you don't understand very well, you can also ask me directly. …”
Hearing this sentence, a trace of entanglement flashed across Lin Chenggang's face.
Obviously, it was obviously a system that was created by oneself, but now it was not better than others. This was a big blow to a technician.
But this wasn't the first time, so he almost made excuse himself.
"After all, it's Academician Chang, there's nothing shameful..."
After silently reading it in his heart twice, he pretended to be calm and nodded:
"When I designed the propellant architecture, I considered the thermal sensitivity and hydrolysis of polyvinyl alcohol, and not only conducted separate ingredient tests under laboratory conditions, but also processed into a drug column for full-process combustion simulation. No similar problems were found..."
The results of the live-fire test are here, which can match Chang Haonan's calculations. Lin Chenggang must have understood that it was his own mistake.
But he couldn't figure out what was wrong for a while.
Due to its special composition, even different batches of products of the same brand will sometimes show certain performance fluctuations, which can be at most a few percent at the numerical level. The gap cannot fluctuate with completely opposite characteristics.
"Because this belongs to a type of reaction with very obvious individual differences..."
Chang Haonan replied: "Not to mention laboratory simulation, even if it was a previous test shot, there were no problems with 10 of the 12 rounds fired?" >He said, turning the calculation process back to the previous page and explained:
"Under normal circumstances, even if it is working in the slowest burning method, the burning time of the solid propellant will not exceed 5 minutes... In fact, let alone 5 minutes, even 50 minutes is not enough to allow the water elimination reaction to spread to the entire column. At most, it will have some adverse effects on performance, and it can be basically negligible in proportion."
"Then..."
This time, Lin Chenggang's eyes were a little confused.
"So the key to degradation of polyvinyl alcohol at high temperatures is not water."
Chang Haonan finally revealed the answer:
"The main product after water elimination is olefins, Carbon-carbon double bonds are formed in the residual structure of the polymer and migrate along the polymer chain to the next adjacent hydroxyl group, which then undergoes isomerization of ketone-enol, while some polyvinyl alcohols with relatively low alcohol resolution are relatively low , a large amount of acetate groups will be retained in the molecular chain structure, causing a large amount of gaseous acetic acid to be produced in the decomposition process, and induces violent stretching and vibrations of hydroxyl and carbonyl groups..."
"..."
After transforming mathematical language into chemical language, Lin Chenggang finally understood the idea.
"So that's it..." However, both mathematics and chemistry were no different for the other two people listening next to them.
They were confused and finally waited for this part to end. Shen Fangzhong quickly got to the topic so that Lin Chenggang would continue: "Academician Chang, I don't understand very much. Chemistry… But from the perspective of combustion dynamics, since the workflow can be completely controlled, can we abandon the traditional core combustion mode and directly use end-face combustion? ”
"This way, the charge cross-section can be made into a porous honeycomb shape, or it is simply solid... or even if the hollow charge remains unchanged, the burning of the end face can increase the overall strength of the medicine column during the work process and reduce the potential for failure. . ”
In order to ensure the uniformity of combustion, traditional solid propellants are made into cylindrical shapes, and then burn from the top of the column hole in layers from the inside to the outside.
The problem this brings is that the entire medicine column will become thinner and thinner, and the intensity will become worse and worse.
In the past, solid propellants were all a one-time trading method. They ended quickly after a wave of explosions. The impact of this combustion method may not be great.
But the combustion of the electronically controlled propellant almost runs through the entire flight. Even if the initial strength of the medicine column is improved, it is easy to cause problems due to the huge lateral overload at the middle end.
The burning of the end face means that the medicine column is burning from bottom to top is getting shorter and shorter, and the ability to withstand overload is getting stronger and stronger, so there will be no concerns in this regard.
Chang Haonan was only interested in the propellant system developed by Lin Chenggang, so he took advantage of the moment before the gliding superb entered the critical stage of R&D to see the situation, and did not consider it in advance that it was closer to the application level. So when I heard this, I didn’t answer immediately, I just lowered my head and thought for a moment.
"There is no problem with the burning of the end surface. At most, a special expansion chamber can be set up between the charge and the nozzle. The key is the ignition method..."
No mistakes, one song, one stroke, one inner one Rong Yi reads the book 6-9!
He said as he looked at Lin Chenggang who was taking out a book and writing quickly.
As the designer of the CTK series propellant, the other party must have considered this issue.
The latter happened to finish his notes at this time, raised his head and replied: "Unlike conventional propellants, the ignition of the electronically controlled propellants depends on the contact between the electrode and the medicine column. Also, because multiple ignitions are required, the electrode must overcome the morphological changes caused by the combustion of the medicine column and always maintain contact with the combustion surface..."
"In this case, the core electrode is obviously the most intuitive. In this way, the outer electrode can be directly fused with the rocket shell, while the inner electrode can directly replace the original position of the igniter. If the end surface is made to burn, there will be problems with the electrode arrangement. At least one end needs to be moved with the medicine column before Realize continuous work."
Perhaps because he felt that simple oral words were a bit abstract, so he looked around for a few times, and then pulled a whiteboard from the other end of the computer room.
"I have also considered the design of the ring-end electrode, and both electrodes are fixed... This allows the heat generated by the thermal effect of the electrical energy to be mainly concentrated in the combustion end surface area, effectively reducing the melting of the medicine column, and the structure is relatively simple. The problem is The contact performance between the drug column and the annular electrode is unreliable. If an interference combination is used, there will be problems with the movement of the drug column..."
"..."
For a moment, Several people fell silent around the whiteboard.
"Maybe...what should I use a coplanar electrode?"
Chang Haonan has not studied this aspect specifically, so he is not very sure:
"Two exactly the same electrodes are arranged on the same surface, and the column is moved downward with the combustion by air pressure or hydraulic pressure to maintain contact. The column current density is concentrated on the combustion surface of the column, and the advancement of the surfaces of the two electrodes The agents are burned, and at the same time they can overcome the defect of the overall superheating and melting of the drug column under the influence of current and thermal effects..."
He took the marker and made a little modification on Lin Chenggang's picture.
Designing something like this is sometimes like this.
The essence may not be complicated, but if the inspiration is not in place, it may be stuck for a long time.
So, Lin Chenggang understood almost instantly:
"And it is easier to arrange mesh electrodes to ensure that there is no excessive additional resistance during the gas emission process..."
Seeing that his idea is feasible, Chang Haonan threw the marker aside and continued :
"The only problem is that because the external balance force needs to be continuously moved to the column to achieve continuous contact between the electrode and the column, the external balance force of the column should be able to change with the load change, and the mobile drug The speed of the column should be matched with the combustion speed of the medicine column, which may be difficult for solid propellants. "
"This is not a problem. I have enough combustion speed-voltage matching data over there. , it is easy to develop a new control logic..."
(The end of this chapter)