Chapter 100 The Rebirth of Turbojet 14 (Part 2) (2-in-1)
Chang Haonan has good luck.
In other words, Yao Mengna is very lucky.
Although due to the problem of convergence speed, she did not actually get many complete results.
However, Chang Haonan still found an unexpected joy.
And it’s done with the naked eye.
In the numerical simulation of aeroengines, due to the very complex structure of the multi-stage axial flow compressor, it is very difficult to directly perform numerical calculations on the multi-stage axial flow compressor, and there are many limitations in modeling and calculation.
Even if it is calculated by force, it will not be possible to understand the vast number of results overnight.
Fortunately, after this period of training, Yao Mengna has become very skilled in model simplification.
Since the multi-stage axial flow compressor is composed of many "stages" with similar structures, the interaction between multiple stages can be ignored during research, and a single stage can be calculated and analyzed, and a single stage can be optimized. This means that the entire compressor is optimized.
The flow inside a single stage is still relatively complex, and further simplification is usually required. Neglecting the work done by centrifugal force on the fluid, and assuming that the flow at different heights along the radial direction is the same, the three-dimensional flow in the "stage" can be simplified into two-dimensional primitives. level flow.
For most aerospace engines, including the turbojet 14, a basic stage of the compressor consists of a moving blade cascade and a stationary blade cascade.
Therefore, this numerical simulation, which is only half done, has a very clear research object.
It didn’t take Chang Haonan too long to discover the key points.
"Senior sister, go and call the forest workers. The priority of the blade gap problem needs to be raised. If our efficiency is high enough, we should still have time to use it on the turbojet 14."
As he spoke, he took out a notebook and pencil from his pocket and began to record some key data on the screen, obviously preparing for a big fight.
“Huh?”
Yao Mengna, who felt guilty that she had delayed her progress, had been standing cautiously behind her. After hearing Chang Haonan’s request, she raised her head unexpectedly. , was stunned for about half a second before reacting.
"Oh...Okay, I'll go right away!"
After saying that, he turned around and ran out.
In her expectation, Chang Haonan would start making modifications immediately after reading the code. If he was in a good mood, he would probably make modifications while explaining his ideas to her.
But no matter what, she never expected that the other party would find something useful directly from the incomplete calculation results that she thought had little value.
She recalled that the first thing Chang Haonan did after entering the door just now was to stop calculating and then immediately start analyzing the data.
"Junior brother, he actually trusts me so much..."
Yao Mengna felt a touch of emotion in her heart, and the steps under her feet became more and more brisk, and her originally heavy heart became lighter. few.
Even after pushing open the office door, the tone when talking to Lin Shikuan couldn't help but have a slightly rising tone:
"Gong Lin, Chang Bo wants you to come over there!"
"Oh, okay, I'll go gather a few other people."
Lin Shikuan quickly got up and went to find his other subordinates.
From Yao Mengna's unstoppable smile, he logically concluded that there must be something good going on.
Perhaps the progress of compressor improvement has accelerated again?
He had never dared to dream about the fact that the research progress was ahead of schedule.
But it is indeed something that has happened frequently in the past month or two.
So much so that although the wings and power of Project 83 have been or are undergoing radical improvements, the overall progress of the project has not fallen behind due to this.
Thinking of this, Lin Shikuan's own mood improved a lot, because the fatigue caused by working overtime in recent days was almost gone.
Although since Chang Haonan and Yao Mengna came to this computing center, his status as the team leader has almost existed in name only, but after all, he has legs to hug, and other people in the 83 Project have gradually changed their view of their digital design team from contempt to contempt. Got respect.
In this case, not only did he not feel like he was being "emptied out" at all, he even wished he could give up his position in exchange for the two great gods being able to protect him all the time.
In short, on this ordinary morning, the entire computing center seemed to be filled with a happy atmosphere.
So when Yao Mengna and Lin Shikuan and others returned to the computer room, Chang Haonan turned around and saw several smiling faces appearing side by side.
He tugged at his hair in confusion.
"You...are you happy about something today?"
After all, during the recent period, as the deputy leader of the temporary research team who actually presides over the work, he himself feels that he has gone too far in pushing team members.
In particular, several people in the digital design team are under great pressure because they look down and don't look up every day.
I haven’t shown such a relaxed smile for a long time.
Of course Chang Haonan didn't know how much drama Yao Mengna had added to herself in just a few minutes.
Because at the beginning, he really looked at the data with the mentality of digging for gold in shit.
The original purpose is just to see where the latter has been calculated, so that subsequent improvements can be made.
It’s just that he actually found it.
"The progress has accelerated again, of course it is worth being happy." Lin Shikuan replied without thinking: "We are ready for the next stage of work!"
Chang Haonan nodded, assuming that Yao Mengna had just understood what he was doing and told Lin Shikuan and others, so he didn't ask any more questions, turned around and walked to the blackboard on the other side of the computer room to prepare for assigning tasks.
Having a positive attitude is always a good thing.
“Now we need to put aside the work at hand.” Chang Haonan knocked on the blackboard, attracting everyone’s attention:
“I need to calculate what will happen in the next two days. Under the element-level model, the Mach number distribution, static pressure distribution and limit streamlines of several typical design points before and after the gap between the pressure surface and the suction surface of the blade are added, in addition to the entropy distribution at the trailing edge of the cascade." br>
“The specific calculation method is no different from before, and because it is a simplified model, it should not be difficult, but the workload will be more.”
Chang Haonan just said this and listened. There was a gasp of air coming from behind.
"Hiss——"
The smiles of Lin Shikuan and others froze on their faces:
"Both moving parts and static parts count?"
Moving blades and static parts The role of cascades in the compressor is not the same, so the previous calculation of the wall limit flow spectrum of blades with different curved and swept designs brought almost double the workload, which was very torturous.
“No need, just count Jingzi.” Chang Haonan made a gesture on the compressor structure diagram hanging on the blackboard:
"I looked at my senior sister's previous calculation results. In the model of the same stage of the compressor, the effects of stator slits and mover slits are almost the same, so she helped us reduce the workload by half."
< br>"I..."
Yao Mengna had an expression on her face like "Why didn't I know I was so powerful?"
But feeling the grateful looks from everyone, I also knew that now was not the time to explain.
After calming down a little, she gradually realized that the gap between herself and this junior brother was not just in the ability of numerical simulation.
What's more important is the mentality.
Because I was too eager to prove myself, I only focused on the goal at the end point, but ignored other results that may occur during the research process.
Thinking of this, Yao Mengna's expression became serious. She knew she hadn't been like this before.
If we follow the plot analogy of martial arts novels, her recent state is a bit like being possessed.
If it cannot be discovered and corrected in time, the development may even lead her astray on the road of scientific research.
"Huh..."
Yao Mengna looked at the keyboard in front of her and breathed a sigh of relief:
"Fortunately..."
Just as Yao Mengna While introspecting, Chang Haonan, who had been arranging tasks smoothly just now, suddenly stopped.
"Wait..."
While muttering to himself, he walked back to the monitor of the workstation and looked at the data on the screen again.
A few minutes later, he took out his pencil and notebook again, and began to calculate on them while everyone behind him looked at them blankly.
Of course it is impossible to calculate the complex numerical simulation process by hand, but the post-processing of the numerical simulation results is still within the range that the human brain can complete.
Many people have a feeling when they are in school that even though they have solved a problem, especially a difficult problem, they can still deepen their understanding in the process of explaining it to others.
Even many details that you didn't notice when you solved the problem will be noticed again.
Chang Haonan has just entered such a state.
In a flash of inspiration, he seemed to have thought of a better way of grooving.
Ten minutes later, Chang Haonan stopped writing.
“Senior sister, according to the research of the research group at Bingcheng University of Technology, after the blades are slit, will there be obvious performance advantages only when the angle of attack is relatively large?”
Although she didn't know what she was going to do, Yao Mengna nodded.
She has almost memorized the content of that article: "When Ma=0.4 and the incoming flow angle of attack is 0°, the total pressure recovery coefficient is only improved by 7% compared to without grooves, and if Mach When the number increases to Ma=0.6, the total pressure recovery coefficient of the slotted blade decreases by about 1% when the incoming flow attack angle is 0°. "
"That's right," Chang Haonan said excitedly. He slapped the pencil in his hand on the table: "Comrades, I need to revise the task I just assigned!"
After finishing speaking, he came to the blackboard again.
“The basic principle of this jet gap is that the mixing loss competes with the blowout effect. When the mixing loss is greater, the total pressure recovery coefficient decreases, and vice versa, it increases.”
Chang Haonan said as he picked up the chalk and slightly modified the blade diagram on the blackboard, changing the original straight jet slit into two corners.
“We can use these two arcs with different concave and convex directions to form an ‘S’-shaped jet slit.”
“The S-shaped slit is a convergent expansion channel that can further accelerate The airflow improves the jet effect, and the modified airflow inlet and outlet direction is closer to the mainstream direction, which can also reduce the mixing loss.” Modify the design.
They have become accustomed to this person's various magical operations, but they still feel a sense of unreality when faced with this situation.
In the end, Yao Mengna was the first to understand what she meant:
“So this S-shaped jet slit can have a very good effect even in level flight?”
“No. Wrong.”
Chang Haonan’s own tone was also filled with excitement.
Such a flash of inspiration is of course not uncommon when there is help from the system.
However, this time the research on the jet seam was not included in the system generation project.
And it is not a field that he had been involved in before his rebirth.
In other words, it appeared entirely due to the improvement of Chang Haonan's own abilities.
......
After such an "epiphany", Chang Haonan became more comfortable with the improvement work of the turbojet 14.
According to the original fault analysis, the location where the surge was induced was above the secondary rotor blades of the high-pressure compressor.
Therefore, his subsequent curved sweep design optimization was mainly aimed at the moving blade cascades of a total of 7-stage high-pressure compressors. He did not make overly complicated modifications to the stationary blade cascades whose main function is to compress the incoming flow. .
And it just so happens that the magical S-shaped jet slit can be set on the stationary blade cascade.
This makes two parallel divisions of labor possible.
Development progress*2
So only half a month later, an almost brand-new turbojet 14 engine design was finally presented to everyone.
Although due to project schedule issues, the design of the combustion chamber and turbine has not changed.
However, as one of the three major components of the core engine and the most criticized part of the turbojet 14 in the past, the high-pressure compressor part has been completely changed.
Submitted together with the design plan was a schematic diagram of the compressor performance and flow field structure that Chang Haonan and his digital design team spent more than a week working out.
And the most fundamental purpose of this large-scale design improvement - the compressor universal characteristic curve.
Compared with before the improvement, the surge margin has increased by a full 25%.
Even if severe working conditions similar to those of the last No. 01 prototype occur again, the new turbojet 14 engine can maintain normal operation on the common operating line without causing surge.
More importantly, after a lot of modifications, the compressor design of the turbojet 14 no longer shows any trace of the P11Ф-300 and "Spey".
It truly becomes our own engine.
Yan Zhongcheng stretched out his hand and tremblingly touched the computer screen with the overall design drawing of the compressor.
"This is the 'Kunlun'."
"This should be our 'Kunlun'..."
Chang Haonan stood aside and looked at the almost old man quietly. Yan Zhongcheng burst into tears.
In the original timeline, due to limitations of objective conditions, although the turbojet 14 engine was not discontinued along with the August 3rd Project, it was not until almost ten years later that a relatively stable design was developed.
At that time, the J-8 series had been discontinued, and the Chinese Air Force no longer needed a turbojet engine with a thrust of 7.5 tons.
Although the QD series gas turbines based on the turbojet 14-core engine have achieved certain success in the field of power generation, it can be regarded as giving this ill-fated aerospace engineering project a justifiable end.
But there are still regrets after all.
......
"Such a regret will never happen again."
"It will never happen again."
The business trip is over, updates will resume next week
(End of this chapter)