Chapter 320 (1/2)
At 12 o'clock sharp, yf-87 returned to zero for the second time, and the seminar on improving route officially began.
Although Li Zheng has gone a long way in the field of data, just like the last time, he did not know what the results he got meant. Just like an artificial intelligence machine, he did not know what the meaning of the language he feedback represented.
In the eyes of the engineers of the 17th Research Institute, the crack images and data obtained from these machine dismantling inspections point to a unique result -
sub synchronous precession.
In space, the effect of this word is equivalent to that of kesulu
A horrible and unreasonable existence.
Among them, ”precession” can also be called ”vibration”.
When it comes to vibration, this is an old friend of aerospace, which is equivalent to bug for programmers and probability for mobile game players.
In the process of launching, the rocket will encounter all kinds of vibration, and the structure and materials have their limits, which can not withstand the large vibration.
In the design stage, of course, these complex situations will be taken into account, and various vibration reduction measures will be used. Huang Er also adopts the latest damping and variable energy accumulator to suppress the vibration.
Under normal circumstances, there is no problem with this design, and 8.8 is a little lucky and successful.
But in the harshest vibration environment, the engine unexpectedly sends out the whisper of kesulu
This murmur, which sank into the sea during the first launch, was not captured.
In the recent shafting fracture accident, it was covered by numerous huge noises, which could not be captured.
But Liu Rui used his terrifying perseverance to capture clues in other test data.
On this basis, Li Zheng used mathematical and algorithmic tools to extract features, extending the scope of screening overnight to all historical data.
As he said, it's meaningless to take out such a ”low chant” sheet. It's just as dispensable as the wind blows the leaves, but it's stacked together countless times
At last he heard kesulu's voice.
It's just a mathematical sound.
Next, Zhu Mingyue further translated this chant into an engineering language -
in harsh vibration environment, when the turbine rotor runs at supercritical speed, some wonderful changes occur in the local dynamics and material properties, resulting in the change of its natural vibration frequency, and then coupled resonance with the working frequency.
This also means that this part produces ”rebellion”, trying to rotate and vibrate in its own way.
In this process, the turbine rotor is bound to bear huge structural stress.
Those tiny invisible cracks are created.
When the resonance intensity reaches a certain degree and the structural stress exceeds the yield limit of the material, the crack will expand rapidly, and then fracture in the violent rotation.
What's more, the subsynchronous precession is still a kind of self-excited vibration, which will produce greater vibration because of the vibration.
It's like 100 Liu Xiang holding hands to form a circle, running clockwise, according to the requirements, running a circle in a minute.
Because they are all Liu Xiang, this speed is nothing to them, so they run very happily.
But suddenly!
A chicken is so beautiful.
One of them, Liu Xiang, suddenly became an idol.
Start singing and dancing!
At this time, it became 99 Liu Xiang and a singing and dancing idol.
But it's not going to collapse.
After all, the next Liu Xiang will pull the idol to run together, although tired, but 99 Liu Xiang still can withstand an idol.
However, the horror is, this is pulled to run, is an idol.
He will not honestly spread his arms out in the air and be pulled by Liu Xiang before and after him.
He is going to sing and dance.
In fact, as soon as he became an idol, he sang the next chicken. You are so beautiful.
In an instant, two Liu Xiang around him were infected and began to sing and dance.
All of a sudden, the singers and dancers became three, which made the runners nearby miserable.
But that's just the beginning.
More chickens, you are too beautiful, have been in wave after wave hit
When the singer content is 1%, the lap run can still be maintained, only causing a few runners to produce subtle muscle tears.
When the content reaches 3%, runners can already feel the pain of arm pulling.
When the content reaches 5%, the pulling force will reach the endurance limit of the runner, either give up or break the arm.
This is the self-excited oscillation, which is both the cause and the result.
But the original ”chicken you too beautiful” from where, how to avoid, is still an engineering problem.
Just like a middle-aged man staying at home, there will always be an idol's name on his face.
Since then, the accident logic has been completely clear.In the conference room, Zhu Mingyue also launched reflection and summary.
”In the first zeroing, we did not find local small cracks, only focused on the damage to the exhaust system.”
”From the present point of view, the problem of the exhaust system is not isolated at all, it is a chain reaction caused by the resonance of the turbine system, but the exhaust system at that time was relatively fragile and broke before the turbine broke.”
”There is no doubt that this is the direct cause of the 8.8 launch failure, but it is not the root cause.”
”After 8.8, after the first return to zero, we had serious fluke psychology in our analysis and treatment. We made the mistake of treating headache and treating foot pain. We only unilaterally strengthened the exhaust system, which was equivalent to prescribing cough medicine for a patient with pneumonia.”
”Finally, in the 10.5 test run, it led to the tragedy of complete shaft fracture.”
”I personally and the 17 yf-87 teams are to blame.”
”But although I am in the position of a criminal, I still want to thank the comrades of the first people's court for their hard work in the task of returning to zero.”
”Among them, Comrade Li Zheng and Lin Yujing have made outstanding contributions. Through profound data analysis, they have accurately identified the pulse twice and sent the pulse to my eyes. However, I was too anxious to achieve success and failed to dig it out deeply on this basis. I only wanted to put Huang Er into a dilemma. I know there's no point in apologizing, but... ”
Zhu Mingyue got up and bowed deeply to the audience.
”Leaders and comrades, I'm sorry.”
Almost at the same time, the entire conference room stood up, and did not intend to accept the apology.
”All right.” Zhao Zhenhua personally stepped forward, helped Zhu Mingyue back, waved to the audience, ”less on the whole point, sit, all sit.”
After everyone was seated, Zhao Zhenhua sighed and said:
”I also have responsibility. I'm too pressed.”
”In fact, when the fault model was determined for the first time when it returned to zero, Zhang Zhicheng thought that the accident was not simple. The exhaust system had been tested and would not fall off without cause.”
”His opinion is that we should take another half month or so to study the causes in depth.”
”It's me.”
”At that time, it was I who denied this opinion and demanded that the exhaust system should be improved as soon as possible and the test run should be carried out as soon as possible.”
”So, you should not have any psychological burden.”
”I said at the beginning that I'll make the route, follow me, and I'll be responsible for anything.”
”Now it is the same. This responsibility belongs to me. This should be implemented in the report. Before that, it was not Zhu Mingyue, Zhang Zhicheng or I, Zhao Zhenhua, who were eager for success.”
”So you, don't hesitate, don't feel guilty.” Zhao Zhenhua vibrated and waved his arm. ”I'll do it for me. I'll change it. I'll do it again.”
Zhao Zhenhua's words once again aroused the mood of the participants. No matter their age, their eyes were wet red.
If the head of the first hospital can achieve this level, what can be hesitated about?
Put it together!
With this momentum, Zhu Mingyue proposed three routes.
First, steel plates are made to strengthen the whole shafting.
Second, redesign to bypass this problem.
Third, list all possible causes of resonance, carpet type local improvement.
Obviously, Zhu Mingyue has mentioned two routes before.
Even if it is determined that the cause is a subsynchronous advance, there is no clear solution in the world, and it is still a frontier field in engineering design, otherwise, it will not be described by kesulu's crooning.
It can be said that in the face of this problem, there is no 100% guaranteed solution, even 90% solution.
Therefore, even if he did not know the cause, Zhu Mingyue had already proposed one or two ways.
As for the third way, it is full of ”gambling”.
For this reason, Zhu Mingyue used the most refined language to describe the root cause -
[local property change of turbine rotor under limit state. 】
maybe a little change in structure would not have happened.
Perhaps a slight reduction in the proportion of certain elements in the shafting material will not happen.
Maybe internal damping, maybe dry friction, maybe aeroelastic effect of turbine blade tip
Now Huang Er is confronted with such an inspiring and inconclusive situation.
In front of us is aerospace, the unknown territory of the whole engineering.
What they can do is just like every previous generation -
guess.
Try.
There's nothing like this to show gambling.
There's nothing more scientific than that.
And Zhao Zhenhua.
Whether he is a scientist doesn't know.
But it must be an old gambler.
An old gambling monster who has experienced ups and downs and has become a leader in gambling.There must be lucky factors in this, but it can not be separated from the judgment of the critical moment.
In his vision, three schemes represent three ideas, three costs and three results.
1、 To carry the past and thicken the steel plate, the cost is to give up the load advantage of the hydrogen oxygen engine, and the result is that he may struggle to keep his position temporarily, but it kills the future potential of the Yellow River series.
2、 Around the past, the cost of designing from scratch is to push the technology of hydrogen oxygen engine five years later, and the result is that they are finished. However, the Yellow River series may usher in new era of more abundant technology and resources in a few years.
3、 The cost of touching the past and crossing the river is to sacrifice the last time of huang'er team and his final authority, and the result is -