Chapter 24 Parametric reconstruction of blade airfoil and stacking line
“As expected of a top student of Beijing Airlines, you can tell at a glance, but I can’t compare with you, I just went to a technical secondary school. After working, I came out to do business with my brother-in-law." Hao Dagang waved his hand.
“I’m being modest, the previous technical secondary schools were no easier to pass than the university exams.” Chang Haonan looked at the blade design in his hand: “If nothing else, I can think of a wicker leaf shape that is a combination of two Bezier curves. He is really very good, better than many undergraduates."
Wu Yifan next to me suddenly felt that there was something wrong with this...
"Oh...what's the point of saying this. It’s not that I can’t beat Fuji Electric. Although I don’t like laptops, I can’t beat a small fan.”
Hao Dagang touched the top of his head and sighed: "I wonder if you can improve it?"
Unconsciously, he called Chang Haonan you.
"Well...Although Bezier curves are used a lot in aircraft airfoils and turbine machinery, the problem is still quite obvious." Chang Haonan replied:
"Firstly, It cannot make local control modifications. Any changes will affect the entire curve. At least half of the 16 parameters in this design are not independent. Secondly, it cannot accurately express quadratic curves such as arcs, so no matter how the parameters are adjusted, , on the leaf outline, the smoothness cannot be guaranteed at the connection between Bezier curve and arc.”
Seeing Chang Haonan’s eloquent words, Hao Dagang’s face was full of excitement and expectation: “It seems. Do you have an idea?”
Chang Haonan nodded and looked at Wu Yifan next to him: "Old Wu, sign the contract."
Strictly speaking, Chang Haonan should be regarded as a subcontractor, but Party A of this subcontractor was informed and Agreed.
After signing, Hao Dagang took out a kraft paper envelope directly from his bag and stuffed it into Wu Yifan's hand.
Deposit, RMB 1,000.
At this time, it is not a small sum of money.
The latter opened the envelope and checked the amount of money, then took out two "four heads" and put them into his pocket. Finally, he handed the envelope together with the remaining money to Chang Haonan. The deal was concluded.
"I'll leave it to you two to optimize the leaf shape. This time our boss is bound to win the order for Changhong air conditioners. I hope you will take care of me."
Hao Dagang said After putting away the contract, he stood up and hugged Chang Haonan and Wu Yifan directly, looking like they were a bit of a gangster.
But it is reasonable. If you are doing business in this era and dare to run around with cash, you will always have something after all.
After sending Hao Dagang away, Wu Yifan took off the schoolbag behind him and handed it to Chang Haonan:
"Nan Shen, how long will it take?"
"It's hard to say, but it will only be about a week." Chang Haonan took the backpack, which contained the laptop and floppy disks that he had become very familiar with over the past half month. .
"One...a week?"
Wu Yifan's hand shook. Fortunately, Chang Haonan had already grabbed the strap of the backpack, otherwise the computer inside would not have been of sufficient value. The middle path collapses.
“They told me that the original plan took more than two months to design.”
"Well, their basic design is actually good. I will use non-uniform rational B-spline (NURBS) to parametrically reconstruct the fan blade airfoil and stacking line, and just make a few improvements."
"Non-uniform... what is it?"
Wu Yifan suddenly felt that not only did he not learn well in his professional courses, but he might not have learned Chinese well either.
“It seems that you didn’t attend class well last semester. Teacher Shi Fa taught you all about computer-aided geometric design in his class.”
In order to adapt to his current status, Chang Haonan also I spent half a day reviewing the classes I had taken in the previous semesters. It was impossible to make any mistakes this time.
"Ah? I'm stupid..." Wu Yifan suddenly felt a pain in his body. If he could listen to the class well last semester, he would be able to earn five thousand yuan now instead of just one thousand yuan. But this illusion was soon extinguished.
"Don't think too much. Teacher Shi only teaches the theoretical basis. The difficulty lies in the implementation." Chang Haonan patted Wu Yifan on the shoulder.
Actually, this is not the first time that Chang Haonan has done this job. At the beginning of the 21st century in his previous life, he also used a similar method to design a shaft with almost the same size for Chang Hong Group. flow fan.
The predecessor of Sichuan Changhong Group was, after all, a military industrial enterprise that manufactured fire control radars. Although it later became a civilian company, it still has inextricable ties with the aviation industry and entrusted the latter to help with technical work. It is not uncommon to tackle key problems.
"Okay, I can't earn your money." Wu Yifan shook his head and reluctantly accepted his fate, then took out a notebook from his pocket, wrote down a series of numbers and tore off a page.
“This is my pager number. After finishing it, I just have to ask the paging station to send me a completed message.”
In 1996, Chinese pagers were already very popular. It can not only display numbers, but also receive short messages with a limited number of characters, similar to the Youth Lite version of SMS service.
Chang Haonan had already put on his bag and walked towards the library. He just waved his hand behind to indicate that he heard.
……
Although the exam week for the second semester of the junior year in the Department of Aircraft Science is very leisurely, it does not mean that the same is true for other majors and grades.
Therefore, the library was undoubtedly overcrowded, and there were even many people sitting on the floor.
So after borrowing a few reference books, Chang Haonan had a simple lunch and went to the computer room again with his things.
Even though he didn't use the system this time, his work efficiency was still quite high. After all, he had a serious scientific research background in his previous life. How could he not even be able to handle such a small project.
It’s just that it was supposed to be a step-by-step process, but after doing it, Chang Haonan began to feel a little dissatisfied.
He was less than thirty years old when he worked on the project for Chang Hong. He was a newly graduated engineer. After that, he went through twenty years of experience and completed an overall design under the guidance of the system. The height has naturally far exceeded that of the past.
"It's done, and the performance should meet the requirements, but..."
Chang Haonanqie went out and took a look at the design document - there is no standard format for doing projects for a small business. It can be said that, therefore, he directly used the electronic version of the design document, and then just saved it on the computer and gave it to Wu Yifan.
After all, the design object is just an air conditioner blade, and the rotation speed and gas flow rate are not very fast, so there are a lot of approximations and omissions in the design documents.
"It's not transparent enough..." Chang Haonan said to himself in front of the screen.
These approximations and omissions are certainly acceptable in the field of home appliances, but now he has some new ideas.
I should be able to do better.
The axial flow fan can essentially be regarded as an extremely simple compressor. As an impeller machine, since the air flow in the compressor is a diffusion flow, flow separation is more likely to occur, and flow separation is more likely to occur. More serious.
Although axial flow fan blades with stable working conditions do not need to consider stall or surge problems, the efficiency loss caused by the continuous development and accumulation of the end arm boundary layer and the noise caused by the refraction of the boundary layer are still exist.
In the past, because most OEMs only required fans to meet flow requirements, and the requirements for efficiency, noise, etc. were not very strict, so no one paid attention to this issue, but now that If you want to compete with Fuji Electric on performance...
"It seems that we can refer to some design ideas for aircraft turbine compressors?"
(End of this chapter)