Chapter 1329 Seeking Inspiration From Others’ Mistakes

Although it suffered a huge impact during the process of disintegration and subsequent fall into the water, perhaps due to its location, the portion of the air inlet fragments made of lightweight alloy did not appear to be too irreparable. bizarre deformations.

After scanning its appearance into the database, the technicians basically restored its original appearance without much "rationalization".

This is undoubtedly a huge benefit for subsequent analysis work——

The rationalized deduction certainly has sufficient theoretical basis to support it, but the problem is that the American design may not be as reasonable as imagined.

"Academician Chang, further analysis has proven that the reason why this thing can float on the sea for a long time, in addition to its suitable appearance, is that the inside of its wall is also designed as a hollow structure."

Xing Muchun pointed to the 3D model of most of the air intake on the screen and introduced to Chang Haonan:

"However, because there is no further specific information, it is impossible to judge whether these spaces are used for coolant flow channels or whether they are designed purely for weight reduction."

The latter moved closer to the monitor and stared at the series of triangular cross-sectional shapes on the cross-section diagram for a while:

"It's unlikely to be coolant..."

Chang Haonan shook his head:

"If the aircraft adopts liquid cooling, it will basically use fuel directly as the heat exchange medium. However, some water samples collected on the sea surface have been analyzed before. It is based on JP7 aviation fuel and mixed with some flammable metals. The...mixture made with metal oxide particles has poor fluidity. I'm afraid it needs a special fuel circulation system to maintain normal supply. It's hard to imagine that we have to go through such a winding flow path again..."

This analysis was quite reasonable and well-founded. Xing Muchun did not express any objection, but only showed a slightly confused expression:

"But there is currently no evidence that the Americans have mastered the same plasma heat dissipation technology as us... If no additional cooling methods are needed, the aerodynamic heating of hypersonic flight alone is enough to cause the flying body to expand and contract due to thermal expansion. Stretched a few centimeters or more..."

Chang Haonan was quite reasonable about this. After all, he only had part of the wreckage in his hands. He couldn't dig into such technical details and had to focus on the key parts.

So I simply answered:

"After all, the design speed of the X51A is only about Mach 6, and the aerodynamic heating is not particularly serious. If the distribution of aerodynamic heat can be calculated, it can still be resisted by structural design... Anyway, don't think so much, Let the First Hospital quickly build a full-scale aerodynamic model according to these parameters and prepare the wind tunnel. "

Xing Muchun immediately stood up and left the computer room to return to the office to make a call.

Jiang Zonglin, who was responsible for the operation of the wind tunnel and had been sitting silently on the side just now, also joined in:

"There are so many possibilities that could cause a test to fail. Which part are you going to start testing from?"

Regarding this issue, Chang Haonan has already made plans in the past few days.

Therefore, he analyzed it almost without thinking:

"Judging from the characteristic flight parameters obtained by the radar, the X51A maintained normal flight for about 143 seconds, reached a final speed of Mach 5.45 and maintained it for about 9 seconds, and then almost without warning... at least on the flight trajectory Disintegrated suddenly and without warning.”

"This situation is unlikely to be a cumulative problem. It is most likely that the working parameters of the scramjet engine were abnormal from the beginning. After accumulating to a critical point between Mach number 5.4-5.5, due to thermal congestion , or the shock wave train suddenly intensifies, causing the working cycle to be completely disrupted, and ultimately inducing structural damage. "

"So, starting from the gas heating amount and inlet overflow resistance corresponding to different characteristic Mach numbers, if this is really the problem, the abnormality should be found quickly..."

Jiang Zonglin stood up after hearing this:

"Then I'll get ready right away!"

…

It should be said that Chang Haonan's luck is quite good.

Although the most likely cause of the accident has been preliminarily analyzed, qualitative analysis and quantitative calculation are always two different levels of difficulty.

Originally, he was only planning to personally see the entire testing process of the previous few days to gain a preliminary understanding of the design level of his American counterparts on the other side of the ocean, and then focus on the detailed design of the gliding waverider.

As a result, just a few starts on the first day revealed a set of eye-catching data...

"Are you sure...the airflow entering the combustion chamber can exceed the speed of sound?"

Chang Haonan looked at the work cycle curve in front of him and asked the two people beside him doubtfully.

This question was so basic that the air in the wind tunnel control room was silent for a moment.

"certainly……"

Jiang Zonglin nodded:

"A single inlet compression surface cannot be used for complete wind tunnel testing, so we connected a standard kissing cone precursor and a standard equal-area-expansion series combustion chamber, which can theoretically meet the requirements of super combustion. Minimum conditions for ramjet start were simulated up to just above Mach 5.5 at which disintegration would occur..."

As he described it, he called up the compiled wind tunnel operation log from the computer:

"It can be seen that near the speed corresponding to the critical point of disintegration, the heat stuffing disappears, and the intensity of the string of the internal segments decreases. The swarms in front of the burning area move to the entrance of the combustion room. The airflow in the burning room must have reached the supersonic speed. "

Indeed, there seems to be no problem from the operation record.

"But these phenomena can only indicate that the exit of the ropper string has reached the supersonic speed. Because the border layer fails to fully attach the effect, the situation in the burning room is not necessarily ..."

"..."

Chang Haonan analyzed himself, and the expression on his face became puzzled first, and then quickly turned into a bright enlightenment.

"You see, at the critical point, the working cycle of the burning room is 0-3-4*-9*. The airflow that is compressed by the intake tract is first heated within the equivalent segment to 1 The heating of 1 until the fuel heat is completely released, the stuffing disappears, it really meets the characteristics of the supersonic modal. "

"But after the critical point came to Mach 5.5, the work cycle of the burning room became 0-3-3'-9'-9*, and this process from 3 'to 9' is still a limit. It is impossible to reach the ideal value, that is, when heating within the equal area, the fuel calorie has not been completely released ... "

There is no mistake, one, one, one, one, one, one, one, one 619, one book, one, one, one, one, one, one, a book!

Actually, as early as the end of the first half of the sentence, the other two had found something wrong.

"Is this a typical sub -speed speed transmission process?"

Xing Muchun exclaimed.

Chang Haonan was also quite surprised by this conclusion, so he did not rush to conclude, but instead checked it again.

It is finally determined that there is no problem with the analysis process just now.

"So, during the process of gradually approaching Mach 5.5, the X51A's ultra -burning stamping engine was abnormal back to the working status of Ya Ran Passens, which made the cycle abnormal. disintegration……"

He initially speculated that the entire process.

Of course, this is not the "cause" of the accidental accident, but it is also very close.

"If so, it can explain why the aircraft is limited by a 5.5 Mach speed wall for so long under the premise that the ultra -burning stamping engine is started normally."

The tone of Xing Muchun gradually became confusing:

"But it's weird ... how can this be?"

"This is not a thing that can be inferred by a period of air in the airway ..."

Chang Haonan dropped the report gently on the table:

"It may be that the ultra -burning stamping engine takes coincidence during the design process, and wants to obtain as high isolation section pressure ratio as much as possible through the transitional mode. The state may also be that the engine startup speed does not reach the preset value, which causes a problem with the starting point of the cycle, and it is possible ... "

Before talking about the third possibility, his voice stopped abruptly.

"What is possible ... what?"

Jiang Zonglin looked at it with curiosity.

"This is not important."

Chang Haonan re -pulled the report in front of him, and brought a pen from the side to the side of the circular parameter curve.

"I suddenly thought that if we reverse this process, it was to allow the engine to be in the sub -speed cycle mode at the low speed section, and the high -speed section entered the supersonic cycle modal. Two characteristics ""