Chapter 1183 Extreme Heat Dissipation

Chang Haonan returned to the capital this time to participate in the membrane rupture test of the Institute of Mechanics just by the way. The main reason was to prepare for the warhead test of the superb verification projectile.

With the help of two sets of cold wind tunnels, JF8A and JF10, the Aerodynamics Group and the First Academy of Aerospace Science and Technology developed the basic configuration of the double cone relatively smoothly.

Although the lift coefficient and internal space have not been optimized to the theoretical limit, they are sufficient for the current stage.

Especially in terms of structural strength and appearance drag reduction——

The reason why the biconical rocket plan of the First Academy of Aerospace Science could not be continued was mainly because it failed to do a good job in mechanical calculations, which led to the failure of the first test.

Once bitten by a snake, you will be afraid of well ropes for ten years.

Now that they have another chance, they naturally have to be careful where they fell into a trap last time.

However, the cone shape in a broad range has a pair of contradictions that are difficult to resolve in principle.

The smaller the nose cone curvature is, the more conducive it is to reducing wave resistance.

The larger the nose cone curvature is, the more conducive it is to reducing aerodynamic heating.

Since the biconical warhead has chosen to favor drag reduction in the force and heat balance, the requirements for nose cone cooling have increased accordingly.

After the working meeting at the beginning of the year, Chang Haonan handed over the research task of a new sweating material to Li Yabo, who had already stayed at the school to teach, based on the molecular mechanics calculation results provided by the system.

Now two months have passed and it’s time to test the results.

…

The day after inspecting the Institute of Mechanics, Chang Haonan took Li Yabo with him to the Launch Vehicle Technology Research Institute.

Xing Muchun, who was in a meeting, immediately stopped the meeting and took the two of them to his laboratory.

"Academician Chang, during this period, we have conducted several rounds of different types of sweat cooling experiments on the scaled model of the conical head according to your requirements."

As he introduced, he took out his glasses from his pocket and put them on, then sat next to the computer in the laboratory:

"Judging from the laboratory results alone, after the forced sweating cooling system used on the rocket engine nozzle is moved to the warhead, no matter in terms of cooling efficiency, working time, structural strength, or the difficulty of integrated production with the load-bearing layer, All basically meet the requirements of our warhead system.”

While he was talking, a light suddenly lit up in an originally inconspicuous transparent glass cover next to him, attracting the attention of Chang Haonan and Li Yabo.

Inside the cover is a double-cone shell mounted on a bracket, but the shell, especially the first cone surface, is almost completely covered by a layer of white whisker-like solid.

Under the airflow coverage and light illumination, it is crystal clear and looks really beautiful.

"You see, this is the arc heating, sweating and cooling experiment we are conducting... Because we knew you were coming, we didn't turn off the equipment immediately after the results came out."

Xing Muchun turned around and explained to the two people behind him:

"For safety reasons, our indoor experiments used water as the coolant, which lowered the wall temperature to the freezing point when the surface evaporated. Therefore, the water would freeze on the surface, then be heated and melt, and then sweat, cool, and freeze. , this process will be repeated, and finally this layer of ice whiskers will be formed, but this is unlikely to happen in actual use. "

In fact, Chang Haonan certainly knew these details, so it was better to say that he was explaining to Li Yabo, who was here for the first time.

And the latter is also a little puzzled at the moment——

According to the other party, this cooling technology seems to be quite complete and does not leave much room for the new material he created.

“Let’s not talk about the engineering application level first.”

Chang Haonan waved his hand directly:

"The technical route of sweating and cooling itself should be certain to be feasible, right?"

"Of course."

Xing Muchun nodded:

"According to calculations, the entire system can achieve a heat dissipation efficiency of about 8 W/m^2 on the warhead surface. Although it is only about half of that on the nozzle surface, for our aerodynamic heating...or even faster, it can reach 10 It’s more than twice the speed of sound, which is enough.”

Although he said this, there was not much joy on his face.

At this time, Li Yabo, who had been bending down to look at the ice whiskers on the double cone shell, straightened up and asked Xing Muchun:

"Director Xing, I see that the ice layer on the surface of the shell is still growing slowly. I guess the consumption of coolant will not be too small. I don't know where the coolant is stored..."

"This is the problem we face now..."

Xing Muchun smiled bitterly and pointed to the fixed rod behind the casing:

"The test case is a scale model, so the coolant is injected from the outside through the hollow pipe, but we calculated that if we want the diaphoretic cooling system to maintain operation for 150 seconds, the coolant cavity will almost fill the entire double cone... …Not to mention the warhead and seeker, even the terminal accelerating engine of the Sixth Hospital will not have room to fit in..." At this time, Li Yabo's mind flashed with lightning, and he suddenly understood, and looked at Chang Haonan next to him. :

"Teacher, so our spontaneous sweating materials are designed to solve this problem?"

"Spontaneous perspiration material..."

Upon hearing this question, Xing Muchun was stunned for a moment, and then showed a somewhat complicated expression.

It seems that there is a trace of expectation mixed with the distress:

"Although Academician Chang didn't mention it before, we have actually tested a surface process that uses sintered porous tungsten as the skeleton and then infiltrates copper into the micropores. In this way, copper with a lower melting point will melt in advance and achieve evaporation and heat absorption."

“However, tungsten and copper are two incompatible materials, so it requires a powder metallurgy process that is not yet mature to achieve a good penetration effect. Moreover, if the amount of copper penetration is small, the cooling effect will not be obvious enough, and conversely it will be too If it is too large, it will reduce the thermal shock resistance of the overall structure, making it difficult to find a specific balance..."

Looking at Xing Muchun who was retrieving experimental data from the computer, Chang Haonan's eyes were a little surprised.

He did underestimate the other party's subjective initiative and work efficiency.

"Don't worry, Lao Xing."

While speaking, Chang Haonan gestured behind him.

Soon, Li Yabo took out a sample box about ten centimeters square and carefully placed it in front of Xing Muchun.

"This is……"

The latter took a look with some confusion and found that there was a pile of black and gray powder that could not be identified.

"To be honest, I didn't expect you to move so fast, otherwise I should have told you the specific tasks of the second phase earlier..."

Chang Haonan gently patted the lid of the sample box:

"The new spontaneous sweat cooling material we developed uses titanium diboride (TiB2) as the ceramic skeleton, and then infiltrates metal nickel and silver. It is a TiB2-(Ag, Ni) composite material prepared through high-temperature pre-sintering and pressureless impregnation processes. ”

"nickel?"

Xing Muchun didn't react.

The melting point of nickel is as high as 1500°C, and the boiling point is above 2700°C, which is almost the same as the melting point of the titanium diboride matrix itself, and has no value as a perspirant.

Chang Haonan had expected this and explained with a smile:

"In addition to allowing the silver itself to melt and dissipate heat, this composite material can also absorb and store a large amount of traditional sweating agents, which will seep out through the surface when the temperature is high enough, further saving the internal space of the biconical warhead. According to my calculations through molecular mechanics methods The results show that the cooling efficiency can reach approximately 3.75*10^8 W/m^2..."

Hearing this, Xing Muchun's eyes widened slightly, and he looked at the half-box of unremarkable powdered solid in front of him with some disbelief.

If it is true as Chang Haonan said, then all the engineering problems currently faced by sweat cooling will be easily solved.

After all, for the aerodynamic heat of the warhead, the efficiency of sweating cooling itself is seriously excessive.

It’s just that the duration and system complexity are difficult to meet the requirements.

"Academician Chang, this is both titanium diboride and silver. I'm afraid the cost..."

He said this, but his hand movements were not slow at all, and he had already held the sample box firmly in his arms.

As if he was afraid of being snatched back by Li Yabo again.

In fact, the extremely complex preparation process is more expensive than the material itself.

"The cost...is indeed a bit high."

Chang Haonan said with some regret:

"But there's no other way. In hypersonic research, sometimes we can't just save money..."

"Furthermore, the matrix of this material is very strong and does not peel off like ablation cooling, so it can be used not only in this one place, but also in the gas rudder of missiles and the surface of cross-space aircraft. If there is application potential, consider it an investment in the future..."

Xing Muchun was obviously just being polite as usual.

Before Chang Haonan could finish his words, he had already grabbed the phone receiver on the table and called several technicians in blue lab coats:

"You guys, use this material and follow Academician Chang's instructions to do the sweat cooling test again!"