All three of the above tests are tests for swallowing foreign bodies in the core machine, and these tests can actually be counted as the same type.

What really gets attention is the surge test of the core engine, which is an important indicator to measure the operation of an engine in various harsh environments.

The surge margin in the civil aero engine can not be too much, after all, the civil aero engine will not have too many large-scale maneuvers, and the sudden reduction of the flow is generally difficult to have.

The military engine is very different from the working environment of the civil aviation engine, and all kinds of large-scale actions are continuous, and the engine surge margin is very high.

The current core machine was intended to be used for both military and civilian purposes from the beginning, and it must be measured in accordance with military indicators in terms of surge margin requirements.

To test the kick vibration margin of the engine, this kind of test is a bit troublesome, especially the special equipment for the test is difficult to align.

Usually there is a special smoke swallowing force to gasp, or other external means to force the engine into the special working condition of surge.

However, with the artifact of the high-altitude platform, the test of surge is very handy, in the final analysis, kicking surge is just caused by excessive distortion of the air flow inhaled by the compressor and too much deviation of the compressor speed from the design state.

This control of the air flow is a matter of the high-altitude platform, and the deviation of the engine speed from the design state can be achieved by controlling the engine.

This has led to the SB101 high-altitude platform of the 624 Institute under the supervision of Wu Lao of the review team here, and with the operation of the core machine on the right track, some routine tests were carried out on the core machine first. After all, it is also troublesome to start a high-altitude platform, and this must not be able to test only one project.

In the comprehensive test of the different heights of the core machine. Speed, after oxygen-rich and oxygen-poor combustion. The various data are also quite gratifying, and the data tested by the 624 Institute are the same.

Satisfied, he put down the data in his hand, and then this information was immediately taken by other members of the review team to study, and there is no need to guess what the final result will be.

"Although there is a sentence that I have said many times, I still have to go into it again, the design of this core machine is indeed very good, and all kinds of data perform excellently, as long as the kicking vibration test passes. The 624 Institute made the history of the aviation industry of the Republic again. ”

For what Wu Lao said, the 624 Institute is very calm, there is no way, these are all things that the 624 Institute knows, and it is naturally clear about the performance of this core machine.

There must be no fraud at all, it is all designed and tested according to the strictest requirements, and the final data is so good.

When everyone is ready, the high-altitude station monitoring and control personnel begin to control the airflow in various ways according to the predetermined plan.

First, the standard flow test of the engine design state, followed by the artificial control of the inlet flow, first of all, according to the compressor inlet flow design standard of 5% for rapid up and down.

When the tester has adjusted the air flow for the first time. Although the airflow changes quickly, the reality is that this change has no impact on the operation of the core machine.

Although the flow is insufficient, the core machine is still running smoothly, which also declares the first plan to force the core machine into a state of kicking and vibration aborted. But that's a good thing.

Looking at the compressor measured and controlled on the oscilloscope, there is no axial low-frequency, high-amplitude vibration, and it is still running smoothly.

"Okay, so that means the core has a kick margin of at least five percent. Now let's prepare for further testing, directly increasing to a margin test of 15 percent! ”

To skip the 10 percent test interval. Straight into the fifteen percent margin test, which shows the trust in this core machine.

Since the judging team has said so. Chief Engineer Wu naturally won't say anything, and it is understandable to go directly to the final test.

"According to the meaning of the review team, directly test the margin of 15 percent, let's start!"

As soon as he finished speaking, the staff who were in charge of controlling the high-altitude platform here also came to work, and suddenly increased the flow field change of the airflow again, and the test margin of 15% was indeed a little different.

The first is that the engine changes from the initial whistle to a low one at the first time of the airflow, which means that the engine is about to enter a dangerous surge state.

Surprisingly, however, the core only had a muffled sound for the second or two that changed the most, and then immediately changed to a normal whistle again.

This phenomenon is not a problem, and it would be strange if there was still no reflection when the distortion of the engine inlet air flow was so large.

As a core machine, it is definitely impossible to compare the surge margin with the complete engine, and it is very good to have such a performance in the case of 15% inlet air flow distortion.

After all, in a sense, the core machine can only be regarded as a small turbojet of a single rotor, and the surge margin of a single rotor cannot be compared with that of a double rotor.

The judging team does not make such a conclusion based on personal reasoning, they need to get the compressor vibration waveform within that one or two seconds for evaluation.

When Wu Lao got this picture, he saw the strange waveform in the middle of the long strip at a glance. Collect data immediately and gather people to analyze it.

"Elder Wu, this diagram shows that the surge of the core machine only stopped at the development stage, it seems that this 15% margin should be a limit value, even if there is a difference, I'm afraid it won't be too big."

Wu Lao was also the deputy leader of the review team, and it is not too simple to analyze this simple and clear vibration waveform, which is a typical manifestation of surge being overcome in the development stage.

There were not many people who could see this, and the next few people nodded in agreement with this analysis.

"Okay, then according to the 15 percent standard as the point, first down to the 14 percent margin, I'll see when the surge development trend of the core machine started."

As the test order was issued, I began to take a step back to test, 14 percent, there is still a little trend, 13 percent seems to be gone, and there is still some danger when the real wave shows it.

After dropping to 12% again, I finally understood the situation, not only did the sound of the core machine not change, but even the vibration waveform did not fluctuate, and I definitely couldn't see any airflow distortion just now.

"Okay, that's it, 12 percent surge margin, and there won't be any big movement in the core machine at this stage."

With the data coming out, everyone breathed a sigh of relief, and the surge margin of the core machine stipulated by the international data was more than 10 percent, and it seemed that this hurdle had passed.

In order to make the test more rigorous, the airflow distortion was directly increased to 16% in the test, which was like piercing the sky.

All the conditions of the core machine's surge came out in a moment, and it was absolutely impossible for the core machine to deal with these airflow distortions by itself.

Immediately stop the operation of the core machine, and take various emergency measures to solve the problem and prevent the core machine from being damaged.

"All the airflow distortion before 15 percent can be overcome by the whole core machine autonomously, but it is best to be safest at 12 percent stage." (To be continued.) )