Chapter 25 Thoughts inspired by fan blades
Chang Haonan thought like this, and saved the completed first version of the design file, and then copied a copy to another new folder.
No matter what field you are in, as long as you are a drawing dog, you must bear in mind the six words "save diligently and keep many files".
Because this is the experience gained by countless ancestors with bloody lessons.
Folder renamed: Blade Design 2nd Edition.
Although Chang Haonan gained some status before his rebirth, he could only be regarded as a cog in the aviation industry. He did not have much experience in the structural design of aeroengines, but he still knew some basic theories and methods.
Therefore, it is equivalent to practicing on this low-difficulty project.
"It is impossible to apply flow separation active control technology to such a small fan. It is better to consider starting from the blade shape."
"In this case, we can consider changing the original radial blade design to a curved blade..."
"Select three points in the blade span direction and use Lagrangian interpolation to obtain the equations used after the model is updated. The distance from the rotor center to each blade section must also be constrained to ensure that the blade area cannot increase after the design changes..."
Chang Haonan pulled out a piece of scratch paper from the side and began to outline the steps on it.
The first step is to define the three points from the leftmost to the rightmost on the straight blade as A', B', and C', and the corresponding three points A, B, and C on the curved blade. Let A and A' be The coordinates are the same and set as the origin, and then Lagrangian interpolation is used for the three points of the curved blade.
In the second step, a constraint is added to the coordinates of point C, that is, the length of the connection between AC cannot exceed the original straight blade radius R, otherwise it will cause friction with the inner wall of the duct.
The third step is to use Isight to integrate ICEM-CFD and Fluent to numerically optimize the blade design and ensure that the swept area of the curved blade is equal to that of the original straight blade, and the airfoil chord length and placement angle at each radius section remain consistent.
As for this optimization process, it is another process that requires finding rules and optimal solutions through trial and error.
After determining the basic idea, the remaining work is only one word.
liver!
Chang Haonan reopened CATIA and began to make modifications based on the first version of the blade.
However, as the design of the second version became more and more perfect, his movements slowed down.
The main value of simulation is to find direction. After all, it cannot completely replace experiment.
In the absence of insufficient theoretical basis, relying on luck to reduce the consequences of experiments and forced simulations has been proven by the Boeing 737max in later generations.
When the improved J-7 was designed before, the last step given by the system was to go to the wind tunnel, but it was not possible due to objective conditions.
Therefore, Chang Haonan used a double ellipsoid model to verify the credibility of the calculation method despite the system's endorsement.
Besides, it is just a course design after all, and there is no need to actually produce a product.
But this fan is different.
There is neither systematic guidance nor a standard model with known performance to verify the simulation method.
And they were going to take the stuff to confront Fuji Electric.
Especially after he carried out the curved design of the improved first version of the blade, the applicable simulation methods have changed.
This makes it more difficult to accurately obtain improved performance.
Not only did Party A feel unsure when holding the items, but Chang Haonan, as the designer, also didn’t know how much he had improved after being so busy.
"We still have to find a place to do experiments."
He also saved the second version of the design on the screen, and then realized that it was completely dark outside.
Looking at the time, it's almost time for the computer room to close.
"I'll go find Academician Du tomorrow and see if he can help me find a place to conduct experiments..." Chang Haonan stretched out and began to put the things on the table into his schoolbag, and secretly felt lucky that he went to the cafeteria for lunch. Had lunch, otherwise I might faint from hunger now.
The public security in this era is far from what it will be in the future, where you can go out and wander around in the middle of the night with peace of mind.
In order to prevent students from getting into trouble, the school is strictly closed at night.
So even though Chang Haonan carried 800 yuan in cash, he couldn't find a place to eat.
I had to go to bed hungry.
……
Early the next morning, Chang Haonan took a simple shower and went to Du Yishan's office with his computer on his back.
"Hey, Xiao Chang?"
Du Yishan was startled when he saw that the person who came in was Chang Haonan. He looked at the phone he just picked up and thought to himself, why didn't he call before the other party came?
"Teacher Du!" Chang Haonan was not angry and moved a stool directly to sit next to Du Yishan.
"How do you know that I have finished revising the paper?" Du Yishan packed up the manuscript in front of him and pulled out Chang Haonan's paper from the pile of books next to him.
"Uh……"
"There is almost nothing I can change about your paper." Du Yishan just asked casually, so he continued without waiting for Chang Haonan to answer: "In this case, it would be inappropriate to put my name on it."
"Teacher Du, what are you talking about?"
Chang Haonan was interrupted by Du Yishan in the middle of his words: "Do you think I am not the fifth author of an article?"
"Then...you hang up the communication?"
Du Yishan's hand reached out to the triangle ruler placed on the table.
"No, no, no, I'm just kidding..." Chang Haonan quickly stopped him.
"You will be contacted for writing and communication. If people within the aviation system are interested in this thing, they can contact you." Du Yishan sorted out the manuscript paper in his hand: "In this case, if you want to send the paper out as soon as possible, You can consider the "Journal of Aeronautics" co-sponsored by our school and the Chinese Aeronautical Society."
"Are you just submitting it to the journal of your own school? If you say it out loud, it might seem a bit watery. If you polish this article properly, it will be fine if it is submitted to the Progress of Aerospace Science. It's a bit aggrieved."
Progress in Aerospace Sciences, the top journal in the field.
Although in principle, only review articles commissioned by the editor-in-chief will be accepted, articles with significant pioneering significance submitted by veterans in the field will also be included exceptionally, which shows the importance of Chang Haonan's article in Du Yishan's eyes.
The latter had previously considered adding his name at the end for this reason, otherwise the editor would have just glanced at the author and title and thrown it into the trash.
Although the Journal of Aeronautics and Astronautics already has an English version, it has not been included in SCI in this era, and the quality is indeed inferior.
However, for Chang Haonan, with more than 20 years of experience and systematic guidance, he does not care too much about where the paper is published.
As long as you can be seen by your own people.
"It doesn't matter. I believe that the contribution of our China Airlines people is not reflected in the paper." Chang Haonan replied without hesitation: "The purpose of publishing this article is also to communicate with my own people. The Journal of Aviation is here It’s enough.”
Chinese journals in the engineering field, especially top Chinese journals such as Journal of Aeronautics and Astronautics, are still read by people in the industry.
If what Chang Haonan has produced is a basic result in the field of mathematics or physics, then he will definitely publish it to SCI without hesitation, because I am afraid that even his own people will not read the Chinese journals in these fields...
"It's good to have this kind of attitude. But you don't have to hide what should be published." Du Yishan smiled happily. He found that he had underestimated the consciousness of the undergraduate in front of him:
"If there are really results that cannot be published even after declassification, it will be written into a national defense report. At that time, it can be recognized as an equivalent paper, and it will still be counted against you."
Chang Haonan didn't answer, just smiled and nodded.
Compared with these, he is still looking forward to what kind of butterfly effect the content of the paper will trigger.
