Chapter 1401 A small problem


    While the engine gradually changes its working state, the accumulated relevant data is also processed synchronously and output to the rear terminal later.


    In the past, due to the insufficient performance of backend computers, in order to ensure reliability, data collection and processing were usually divided into two independent processes.


    Except for the part that can be directly distinguished by the naked eye, most of the information needs to be obtained after the test is completed. In addition to the subsequent manual analysis and organization, even if everything goes well, the time spent on each set of tests will be extended to several days or even weeks. Once something goes wrong, it needs to be reworked, it will often have to be calculated in months.


    Therefore, after the official project of the 20th project was officially approved, Yang Weida''s first funding application report was to comprehensively upgrade the equipment of the test workshop, which finally shortened the cycle by more than three-quarters.


    For example, now, they can view the working characteristic curves given by a series of sensors while the engine is running.


    "Fortunately, there is no problem with the flow distribution of the gas film cooling system, and the operating temperature does not exceed the safety threshold."


    Liu Yongquan lowered his head and stared at the data on the B-2 monitor.


    The pointer representing the temperature value trembled and kept moving closer in the clockwise direction, but it was like hitting a barrier, always at a considerable distance from the red area on the far right.


    He relaxed later and continued:


    "The initial version of the plan was to calibrate according to the bench data, and the cooling airflow was allocated to the turbine blades and combustion chamber walls under military thrust at a ratio of 73:27. However, it was later re-checked based on the Trough 900 installed operating data given by Mr. Chang. After considering the actual situation of installing inside the body, the actual allocation was changed to 65:35 in the final stage..."


    The 611 Institute does not specialize in engine design, and the other 606 technicians who came with them all know this clearly.


    Therefore, Liu Yongquan''s words are not so much about explaining to others, but rather about comforting one''s own emotions.


    In terms of flying-engine matching, the biggest difference between the J-20 and the two third-generation aircraft is that, both the J-10 and the J-11 do not consider the stealth and shape modification, so they directly expose a considerable area of ??the engine outer casing to the outside, or at most add a layer of protective bushing.


    The stealth aircraft needs to use additional skin to completely cover the entire engine structure except the tail nozzle.


    In addition to bringing additional structural weight, new requirements are also placed on the heat dissipation method.


    This is not simulated in any test before installation.


    At this time, Yang Wei''s attention was focused on the stress data of the engine''s fixed ring and the vibration data of the fan and compressor at different speeds:


    "I think that when the prototype stage is reached, the design of the engine fastener needs to be further strengthened... The increase in thrust brings greater burden on the body than expected. Although it will not directly affect flight safety, if you work for a long time and are close to the safety load, it will inevitably be detrimental to life."


    After saying that, he raised his head and turned to Liu Yongquan, with a smile on his lips:


    "The vibration characteristics of the turbofan 10G are almost the same as those of the turbofan 10A, with only a little difference in amplitude, which saves us a lot of trouble in adjusting the structure."


    “That’s…”


    The latter turned the focus of his sight to the distance. Through a layer of glass curtain wall, you can see the slender and strong No. 2003 machine slightly lowered its head because the landing gear was fixed by an electromagnetic lock, like a raging dragon ready to fly out:


    "After all, the overall design of the core machine has been the foundation of the fourth generation from the beginning. However, ten years ago, our materials and process levels were not up to standard, so we had to set the turbofan 10A to be a downgrade configuration."


    Speaking of this, his tone suddenly changed:


    "To be honest, although I have been involved since the Aerospace Engine Campaign, I didn''t know how limiting the design of this core machine is until I took over the design of the turbofan 10G..."


    Because there is no noteworthy data for the time being, Yang Wei also casts a curious look.


    Liu Yongquan shrugged his shoulder helplessly:


    "I have tried to use my experience in designing the two engines, M88-3 and SeA650, to modify some rotor blades of the high-pressure compressor. As a result, I found that many parameters cannot be compatible with the second-level fan and the third-level fan even if they are slightly adjusted. Even if they only consider adapting to the third-level fan, there is almost no obvious upgrade space."


    In order to increase the thrust-to-weight ratio, Chang Haonan subtracted the first-level fan to the turbofan 10A/B after completing the basic core machine structure of 3-7-1-1, which became a relatively less common 2-7-1-1 configuration.


    Although similar operations are not the first time in the history of human engine design, the few precedents are not very successful.


    For example, a turbofan 5 using a rear fan.


    It is rare to be able to have no trouble throughout the whole process like the turbofan 10...


    …


    After the engine ran at its maximum speed for 30 minutes, a long-depressed cheer erupted in the backstage inspection room.


    The first round of start-up test does not include the afterburner section.


    Therefore, after the two engines reached and maintained military thrust for a period of time, the test of the power part itself came to an end.


    If it is an ordinary model, then you just need to wait until night before dragging the plane back to the assembly workshop to check whether the test process has caused any hidden dangers.


    But the combination of J-20 and turbofan 10G has an additional task.


    Yang Wei once again came to the microphone and issued a new instruction to the operator downstairs: "Inject ionizing seed gas into the combustion chamber and start the plasma generator!"


    Soon, the indicator light marked with the word Ar on the status display changed from yellow to green, indicating that the high-pressure argon gas has begun to be injected into the plasma generator.


    The color of the tail flame ejected by the 10G of the two turbofans seems to be slightly darker, just like the afterburner is opened, showing a more obvious blue-purple color.


    But the light is not that dazzling yet.


    "Open the magnetron, work mode...default one."


    Yang Wei is still a little less skilled in this plasma stealth system.


    In fact, if the plasma control strategy in each flight condition is fine-tuned, the distribution effect of the sheath can be better.


    But obviously, the fighter pilot cannot be expected to write code in the cockpit while driving the plane, so you can only preset four default control methods according to typical situations, and then automatically or manually switch to the most suitable one.


    The default is the normal flat flight status.


    Sure enough, a strange light blue glow quickly appeared at the tail of the No. 2003 machine.


    In infrared imagers, the pure white area representing the high-thermal radiation signal is spreading from the tail and ventral fins to the front fuselage at a speed visible to the naked eye.


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    "Wait, this infrared signal..."


    Yang Wei''s hands suddenly clenched into fists, but he still resisted the urge to stop the test.


    On the one hand, I believe in Chang Haonan''s calculations, and on the other hand, I believe in his own plane.


    About half a minute later, the data analyst looked up and gave the results:


    "Reported, the temperature sensor installed on the trailing edge of the vertical tail wing and the ventral fin did not alarm, and the maximum temperature point only rose by 15 degrees compared to before, and it will not have a significant impact on the stealth coating..."


    Speaking of this, he even doubted his judgment a little.


    However, since Yang Wei did not call for a stop, he had to bite the bullet and continue talking:


    "On the contrary, the skin temperature in the middle of the fuselage has increased significantly, and the data of the 17D sensor has been increased by 50 degrees..."


    The maximum working temperature of the new stealth coating is above 240℃, and the tolerance temperature can reach the level of 300℃. It will not cause irreversible damage due to this increase in temperature. At most, it only needs to be re-applied more frequently.


    What Yang Wei is most worried about is another part:


    "Talk about the situation of the lip of the air intake!"


    To solve the century-old problem of narrow working width of the DSI air intake, they were very bold in using partially flexible skin material on the cocoon pack structure.


    The high temperature tolerance of this new thing is much worse than that of stealth paint, and it will directly affect flight safety.


    The interrupted technician swallowed a little nervously, but fortunately, the result was given in time:


    "From the front wing part, it is basically unaffected..."


    "call-"


    Even though it was only more than a minute, when Yang Wei let go of his hand again, his palms were already sweating.


    “So, why—”


    What he wants to ask is why the thermal signals captured by infrared imaging systems are so obvious, but the temperature given by the skin sensor is almost unchanged.


    But Liu Yongquan had predicted this problem long ago and had not finished talking about it:


    "I don''t understand the specific theoretical part very well, but with the help of a magnetic field, the energy of the plasma can be isolated in a certain space."


    Afterwards, perhaps because I felt that this explanation was a bit abstract, I added a metaphor I heard from Han Chenfeng before:


    “Like Tokamak.”


    Yang Wei didn''t expect that his plane would be related to nuclear fusion, but after thinking for a while, he decided not to worry about these details.


    But the topic is changed:


    "For fighter jets, in addition to thermal insulation, there is actually another problem."


    He looked at the almost white screen:


    "The problem of radar stealth is now solved, but such a high surface temperature seems not good news for infrared stealth..."


    (End of this chapter)