Siheyuan: I eat melons while doing scientific research

Chapter 1188 Still Needs to Burn

With this requirement, how can you burn it?
Knowing that Gao Zhendong's intention was not to embarrass them but to inspire them, the comrades also started discussing the matter.

In fact, the pulse isolation device can be said to be the biggest trouble of double pulse, no doubt about it.

Therefore, during the discussion, comrades kept hitting walls. There were even some walls that they were not qualified to touch because they could not even get there.

"Put a gas valve in between the two? Wait until the second stage is ignited and open it?" This is the simplest way.

"No way. If we want to install this gas valve without affecting the diameter of the missile, it means that the passage will be very small. Before the gunpowder gas is ejected from the tail nozzle, it will first pass through the expansion and diffusion of the shell after the first-stage combustion. That will have a huge impact." Gao Zhendong didn't even need to speak, a comrade directly rejected it. The missile body is already thin, so how much space will be left for gas after installing this thing?
Anyone who has attended elementary school knows that if the radius is reduced by half, the cross-sectional area shrinks to 1/4. In this case, the radius may even be more than reduced by half.

"Can't the gas channel be offset and the other half of the diameter be used to arrange the valve body and the control body?" For a center channel, due to its shape, the gas channel is bound to be very small, but an offset or special-shaped channel will not have this problem, as at least half of the cross-section can be retained.

"No, don't do that. The engine hasn't even left the missile yet and you've already deviated inside the missile. That will put too much pressure on our flight control! This is a bad idea." The comrade from flight control jumped up first.

"Yes, and the gas valve has a complex structure, with large weight, volume and length. It will also bring various troubles in control. It cannot be used unless it is absolutely necessary." The comrade in charge of the rocket engine shook his head.

This is the trouble with weapons and equipment. They pursue perfection, and many methods or principles that seem suitable simply cannot be implemented.

"So we use a brittle flame retardant material in the middle? Like pyrolytic graphite?"

"Hey, this method seems to work. Although pyrolytic graphite has good mechanical properties, it is still very easy to break as long as it is thin enough. Just break it and spray it out."

"Yes, yes, yes. Pyrolytic graphite is used as pulse isolation. It can solve the problems of thermal insulation, ablation resistance and fragility."

Gao Zhendong laughed when he heard this: "Comrades, you want to explode the graphite prefabricated fragments inside the rocket engine?"

Hmm? The comrades all stopped talking at once.

When the rocket engine is ignited, in the state of the pulse isolator, it is equivalent to igniting a bomb, but the shrapnel of this bomb is only in the direction of the pulse isolator. This kind of fragments is extremely destructive to the first-stage pulse casing and tail structure of the engine.

It seems this doesn't work either.

"Then use non-flammable soft wrapping?"

Gao Zhendong shook his head: "It may block the tail nozzle."

A ball of soft "cloth" that can't be burned, there is only one pressure relief port at the tail of the engine, and you don't even need to think about what will happen. Moreover, the tail of the rocket engine is constricted, and the size of this ball of "cloth" will almost certainly block it.

At this point, Gao Zhendong added: "If it is a large diameter, then using a soft pulse isolator is indeed a good idea. The soft isolator can be directly ejected using a large diameter nozzle, but this method is not suitable for the size of air-to-air missiles."

There is indeed a soft pulse isolator solution, but it is only used for medium and large diameter rocket engines. Only a large diameter nozzle can spray out the inburnable substance. For air-to-air missiles, this method is very difficult.

"Then what plan do you think has a greater chance of success?"

Seeing that they had tried every possible solution, the comrades from the Institute of Research and Development lost their temper. Fortunately, there was a less than ideal gas valve solution as a backup. If the senior consultant did not provide a solution, they might have to try the gas valve first.

In fact, the gas valve solution was indeed the earliest pulse isolator solution for dual-pulse engines, but it was quickly eliminated later.

Hearing his words, Gao Zhendong smiled and said, "Actually, you said half of it just now, but you didn't have the confidence and swallowed it back."

Huh? Really burned it? After all, this was the only one that was swallowed up halfway and not discussed.

"Burn it?"

"Yes, burn it. Or, if you can bear it, bear it. If you can't bear it, burn it. It doesn't matter."

After Gao Zhendong finished speaking, he drew something on the blackboard, a disc, and in the middle of the disc was a regular octagon that occupied most of the disc's area. If this regular octagon was calculated as a gas channel, the size would be more than enough.

According to Gao Zhendong's marking, the thickness of this regular octagon is thinner than the disc, about 1 mm thick, and there are pre-pressed marks on each diagonal line of the regular octagon.

After finishing the painting, Gao Zhendong patted the chalk dust off his hands.

"We use a metal disc with pre-pressed notches. In this way, when the pulse works at the first level, the disc can effectively isolate the first and second levels. When the second level works, the gas can easily break through the barrier along the notches. As for the depth of the notches, you can conduct experiments and choose a suitable one. Please note that in addition to the surrounding structure, the most important part of this isolator is a consumable isolation structure in the middle, which is what we just said, it is used for burning." As long as it can be burned and sprayed out with the gas, there will be no problem.

This plan sounds simple, but the comrades are skeptical about it.

"Advisor Gao, ordinary metals can't withstand this temperature, right?"

Gao Zhendong nodded. "If the design is not appropriate, it will not be able to withstand the impact. However, we can consider the combustion mode of the first-stage charge appropriately. That is, the metal disc should not be exposed to the gas for a long time. It will only withstand the impact for a short while at the end of the first-stage engine operation. In this way, the requirements for the metal disc will be much lower."

"But common high-temperature-resistant metals are generally harder, right?"

"Your idea is exactly the opposite. We don't want high-temperature-resistant metals, nor do we need hard metals. What we want is metals with a low melting point, good ductility, and low hardness. In this way, after the gas channel is opened, the isolator can be taken away with the gas when necessary. Even if it cannot be taken away, the high ductility will not cause it to break into fragments. And even if fragments are produced, the hardness will not cause damage to the rear part of the engine."

When the comrades heard it, they thought it sounded very familiar.

"This metal seems to be very common."

"Nonsense, it must be common, aluminum, copper, both."

"Can these two really withstand high temperatures?"

"According to what the senior consultant just thought, there shouldn't be any major problems."

"..."

Seeing that his comrades were thinking quickly, Gao Zhendong smiled and said, "I suggest that you consider copper first. Although it is a little heavier, this little amount will not have much impact. Moreover, copper has better ductility than aluminum. When it first expands, it is not easy to break into pieces. Moreover, it is softer than aluminum alloy, has a larger turning angle, and is easier to open the channel."

This is the result of finite element analysis, and Gao Zhendong said it with great confidence.

In fact, foreign reports showed that aluminum isolators were used, but in this matter, Gao Zhendong chose to believe domestic papers.

“But even with this method, it is still difficult to guarantee that the copper insulator will not be burned through by the first stage, or that no fragments will be produced, right?” said the comrade in charge of the rocket engine.

After all, the combustion gas of the rocket engine is really too violent, and the pre-engraved indentation part of the isolator is relatively weak and can be easily burned through.

Gao Zhendong laughed: "Yes, that's right, but we can add something on the side facing the pulse level one."

"Add something?" Could it be pyrolytic graphite?

"Yes, add something. Actually, it's not some high-end stuff. Just put some flame-retardant rubber of appropriate thickness on it. After all, it only needs to resist for a short time. This rubber can not only enhance the strength of the copper isolator and greatly reduce the probability of generating fragments, but also protect the isolator to a certain extent when working at level one. With all these measures, the isolator should work normally. The rest depends on your experiments. How thick the copper isolator is, how deep the pre-compression notch is, and how thick the flame-retardant rubber is, these are your jobs."

The comrades then remembered that this isolator was a one-time deal. They used soft rubber and notches to ensure the reliability of opening during secondary operation. At the same time, they used flame-retardant rubber to protect the isolator to ensure that it worked normally before being opened.

As for being broken through by the gas, it wouldn't be a big deal even if this thing was burned.

"Okay, okay, we understand. We'll organize the experiment when we get back."

You only need to get a small portion of the charge to make a two-stage simulated igniter. It is very easy to use this igniter to test the isolator.

Commissioner Gao has already done a lot of simulation analysis work. What comes next is the time for our Research Institute to put his simulation analysis into practice!

The comrades who were originally a little bit nervous about the dual-pulse engine are now completely relieved. This thing should not be a big problem, it is just a matter of time.

"Advisor Gao, can the soft isolator we just mentioned also be used for large-diameter rocket engines?"

"Yes, it can. As long as it can be ejected, a soft isolator is also very useful. Under the same conditions, its total specific impulse is better than the rigid isolator just discussed. It is also suitable for fiber-wound casings, especially for large-diameter engines."

Large diameter? We have it... The comrades in the Institute of Research and Development were very happy.

"However, this thing is not without its shortcomings. First, it has chemical compatibility issues. Second, it is difficult to integrate into the engine. Third, the design is complex and has a low degree of freedom. It cannot be used for overly complex charge interfaces."

(End of this chapter)