The military-industrial scientific research system of the academic master.

The test engineers present almost all turned their attention to the door.

"Surge sign?"

One of them gently pushed up his glasses on the bridge of his nose.

Now Chang Haonan's name has gained a certain reputation in the industry, so he hesitated a little at first.

But after repeatedly confirming that there was no obvious abnormality in the curve displayed on the computer screen, I decided to show my fearless spirit of authority:

"But the data we collected just now is all normal... No problems were found?"

"Yes, if the working curve is abnormal, fluctuations should be seen from the working Reynolds number and compressor flow..."

In the end, it was Xue Chishou who gave the final word:

"No matter what, stop the engine first!"

Even if the engine is running at idle, it is still working under high temperature and pressure. If a problem does occur, the consequences will be serious.

"Yes!"

The chief engineer who was able to make the final decision spoke, and the somewhat overwhelmed atmosphere in the control room finally dissipated a little.

The roar in the test workshop gradually weakened and finally became quiet.

A group of people looked solemnly at the fighter jet in the test workshop that glowed with metallic luster under the light.

"Export the data and let Chang Gong and Yang lead people to analyze the situation first."

After a few seconds of silence, Song Wencong spoke first.

Only Chang Haonan and Yang Wei participated in the entire development of this active stability system, so this matter naturally had to be completed by them.

"Lao Xue, Lao Song."

At this time, another man wearing a long-sleeved shirt and looking a little sick said:

"Should we try driving again? After all, the comrades at the test station are right. We didn't observe any signs of failure just now."

Chang Haonan thought briefly in his memory, and then confirmed that he had no impression of this face.

But being able to address the chief engineer and chief engineer in such a casual way obviously shouldn't be ordinary people.

However, Xue Chishou's first reaction after turning around and seeing the visitor was surprise, and then he quickly walked up to him:

"Old Yang? Why did you come back from the hospital again?"

The visitor waved his hand to indicate that it was okay:

"Didn't I hear that you have already started ground testing? How will my body get better even if I stay in the hospital? Why don't I come over and take a look."

Xue Chishou sighed upon hearing this, opened his mouth but said nothing in the end.

After a while, he turned sideways again, stretched out his palm to indicate the direction of Chang Haonan and introduced:

"Lao Yang, this is..."

"I know Comrade Chang Haonan. I've heard about it in the hospital."

The man cheered up, walked to Chang Haonan, looked at it for a few times, and then stretched out his hand:

"My name is Yang Baoshu, Comrade Xiao Chang. A young talent is better than hearing about it once."

This name made the latter suddenly realize it, and then he felt a little sore at the corners of his eyes——

Yang Baoshu, general manager of Rongfei, was diagnosed with advanced lung cancer in 1995, but still continued to work despite the illness, and died of the disease in 1999 on the original timeline.

"Mr. Baoshu, hello."

On this occasion, Chang Haonan couldn't say much else, so he stretched out his hands and shook the other person's hand tightly.

"Xiao Chang, I have just checked with the on-site engineer to understand the situation. I don't mean to take it personally, but if no obvious signs of failure are observed, can we repeat the test again?"

After getting to know each other, Yang Baoshu quickly returned to the topic.

"If the problem just now can be reproduced, it will not be too late for us to terminate the test and disassemble it for inspection."

If it makes sense, Yang Baoshu's suggestion is actually fine.

When it comes to fault identification, it’s actually hard to tell who is right and who is wrong. Problem recurrence is indeed a part of solving the problem. After all, the probability of problems with the sensor or algorithm itself is not small. One test alone cannot explain too many problems.

But Chang Haonan had read the script, and he knew that this engine did have problems during testing in the previous life.

And now that his active stability control system has called the police again, he definitely can't continue to take risks.

Maybe something will really go wrong next time if the measurement reaches 40% or 50%.

Surge prediction can only predict surge caused gradually due to normal intake distortion. If the plane suddenly hits a bird or inhales a large foreign object, even the gods will not be able to save it.

"Don't worry, Mr. Baoshu, we haven't reached the stage of dismantling the aircraft yet."

Chang Haonan could only choose to stabilize the opponent first.

"The current test system integrates the latest technology I developed. It can predict the upcoming surge or rotational stall through small-amplitude disturbance waves with certain characteristics. The comrades at the test station will bring the data later. I can conduct an on-site analysis, and if I can find hidden dangers, I can make targeted troubleshooting or improvements. If I can’t find them, I can restart the test run, which won’t take too long.”

After hearing that there was no need for extensive rework, Yang Baoshu finally breathed a sigh of relief and did not raise any objections.

About half an hour later, a staff member from the test flight station walked out of the test control room carrying a laptop.

"Chang Gong, the test data just now are all in it."

Chang Haonan took the computer and connected the power supply to the socket next to it.

Everyone in the room came behind him as quickly as possible and formed a tight semicircle.

In the end, a few people in the inner circle voluntarily squatted down so that everyone could see the small screen.

Everyone here is an expert in aerospace engineering.

Whether they believe Chang Haonan's statement or not, everyone wants to see what this surge sign is about.

After several rounds of data processing within the software, only a few curves remain.

An insider can see that Chang Haonan's operation just now was to separate the components of the measurement signal at a specific frequency.

"look here."

Chang Haonan pointed to one of the curves and said,

"The component of the engine operating curve modal wave at the surge characteristic frequency was absent at the beginning. It suddenly appeared when the test reached 540 seconds, and then gradually increased. By the 580th second, it was detected by the surge prediction system. It monitored and then forcibly closed the throttle opening, and after 20 seconds, this component disappeared again."

"This……"

Of course everyone can understand a curve, but many people still don’t understand why this curve is related to surge.

At this time, Yang Wei, who also participated in the entire software development process, turned around and briefly introduced the basic working principles of the system to other colleagues.

"Let me explain, when the engine is far away from the surge boundary, the system has a strong attenuation effect on small random disturbances inside the system. At this time, even if there are some disturbances, they will be quickly wiped out and will not continue. Deterioration. As the engine stability margin decreases, the system's damping to small random disturbances also gradually decreases. When the stability margin is reduced to a certain extent, the small random disturbances within the system will occur into a more stable frequency. Modal wave initial disturbance..."

"Starting from 580 seconds..."

Someone noticed the timestamp Chang Haonan just mentioned, and compared it with the test log recorded by another computer, and then shouted in surprise:

"Wait a minute, Commander Zhou gave the 570% command at 70 seconds, which means that at 540 seconds, when the routine analysis started to show abnormalities, the throttle should still be at the 60% position!"

As soon as these words came out, a burst of discussion broke out among the surrounding crowd again.

Obviously, it is not the action of pushing the throttle to 70% that induces the surge precursor, but the hidden danger existed earlier.

Or, it is possible that there is a problem with the surge prediction logic of this active stability control itself.

On the one hand, although Chang Haonan has gained a certain degree of popularity now, most people at the scene have not worked with him before, so what they hear is false after all.

On the other hand, the basic principles that Yang Wei just introduced are indeed quite complicated in mathematics. Most people can only understand them roughly. It is naturally difficult to agree with them from the bottom of their hearts without a thorough understanding.

Fortunately, several key persons in charge, including Xue Chishou and Song Wencong, had a deeper understanding of Chang Haonan. After a brief discussion, they ordered the suspension of this startup test.

Chinese people pay attention to getting off to a good start. The first trial ended in an anticlimactic manner. Although many people present obeyed the order, their emotions were still affected.

At this time, a loud voice sounded from the outside of the crowd:

"Well, there's no need to overhaul the aircraft as a whole. I can get into the air inlet and see the condition of the fan and low-pressure compressor blades!"