Chapter 1308 Magnetohydrodynamics
Of course, Institute 240 and Han Chenfeng were not really planning to have sex for nothing.
Although Chang Haonan does not need the help of institutions specializing in plasma research at the moment, as the follow-up research gradually deepens, it will inevitably be insufficient to rely solely on the less professional technical forces of the Aerospace Power Group and the Institute of Mechanics.
Therefore, to a certain extent, it can be said that Han Chenfeng really arrived at a good time.
If it were a few months to a year later, when Chang Haonan really took the initiative to find a partner, the competitive pressure would be much greater:
"Since Director Han has been studying plasma-related issues for many years, he must be familiar with the theory of magnetohydrodynamics, right?"
Han Chenfeng was a little confused by this sudden question, but he quickly realized that this was actually equivalent to a positive response from the other party.
So he nodded quickly:
"Of course, the description method used to describe the interaction between magnetic field and fluid is the most basic part of our work..."
Then there was another pause, with an unexpected look in his eyes:
"But this is an approximate semi-theoretical and semi-empirical model... At least at this stage, relevant research basically assumes that the plasma Debye length is much smaller than its characteristic length, and it is also an ideal continuous medium... If it is in the laboratory, Or even in ground facilities, this premise can be considered to be approximately satisfied, but for aircraft, it may not be so easy to directly calculate reliable results, right?”
"No, no, no..."
Chang Haonan waved his hand when he heard this, stopping the other party from continuing:
"What you are talking about is already the revised theory of magnetohydrodynamics..."
"Corrected?"
The surprise in Han Chenfeng's eyes turned into confusion:
"If it is not modified, it is to directly combine the N-S equation that describes the laws of fluid motion and the basic Maxwell equation that describes the electromagnetic field..."
He originally wanted to say that this was a complete return to nature. Although it was simple and beautiful in form, the solution of the N-S equation alone was already a huge problem that had troubled generations of geniuses, not to mention the coupling of a Maxwell equation. ……
It is because the theoretical equations of magnetohydrodynamics (MHD) cannot be theoretically overcome, so researchers have developed various correction forms that are more complex, have a narrower scope of application, but are also more operable.
If the equation could be solved directly, then at least 90% of researchers in related fields would no longer have to work in the future...
However, considering that the person in front of him had won the Fields Medal after all, Han Chenfeng still considered some more possibilities:
"Hiss... You didn't really solve the MHD equation, did you?"
Although it was indeed a bit of a joke when he first asked the question, by the time he finished speaking, the pressure of unemployment had already enveloped his heart.
"Of course not..."
Chang Haonan also felt that the other party was just talking casually, so he smiled and gave a negative answer.
Although this was the answer he expected at the beginning, Han Chenfeng secretly breathed a sigh of relief.
However, before he could regain his composure, Chang Haonan changed the subject:
"But you may have heard that regarding the N-S equation, I have given some regularity criteria a few years ago... To put it simply, if the Leray-Hopf weak solution of the N-S equation satisfies certain special conditions, then the weak solution Smooth on the existence interval ”
"I..."
Han Chenfeng's breath was stuck in half, and it took him a long time to finally catch his breath:
"Theoretical mathematics is not my main research area...so I can only hear some rumors and don't know the causes and consequences..."
"In fact, there is no cause and effect... In fact, until a few months ago, even I always felt that this proof was far away from any application, and it almost only had value at the purely mathematical level."
Chang Haonan seemed very candid:
"However, after paying attention to the MHD equation, I gradually discovered that if we make full use of the regularity of high boundary values, we can avoid Bernoulli's criterion, allowing the term corresponding to B in the MHD equation to be regarded as the external force term of the N-S equation. There is no need to consider the contradiction between the change of Bernoulli's integral along the streamline and the N-S equation under this assumption..."
A sentence of only a hundred or ten words made Han Chenfeng, who was sitting on the other sofa next to him, start thinking rapidly.
Although his mathematical skills are somewhat lacking and he cannot understand how the other party proved the smoothness of the weak solution, if he jumps directly to this step and believes in the correctness of this proof, then he can still figure out the rest of the part. .
But Chang Haonan obviously wasn't going to keep telling the truth, and revealed the answer before Han Chenfeng understood all the links:
"It can be proved that for steady-state incompressible fluids in a two-dimensional bounded domain, solutions to the MHD equation must exist... In this way, it is equivalent to removing the two most fatal assumptions based on the original theoretical model of plasma magnetofluid... …”
Having reached this point, the originally chaotic thoughts in the latter's mind were clarified almost instantly: "There is no need to assume that plasma is a continuous medium, and there is no need to ignore the work done by pressure?"
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"That's right!"
Chang Haonan stood up and strode back to the desk:
"After excluding these two of the original eight basic assumptions, six are left. Among them, the mean free path of particle collision is much smaller than the characteristic line of plasma, the plasma is stable and axially symmetric, and only two kinds of charged particles, electrons and ions, are considered. Artificial plasma is inherently easy to satisfy.”
"The local thermodynamic equilibrium, single fluid characteristics and low magnetic field magnetic Reynolds number may be a big problem for those of you who are engaged in nuclear science, but the magnetic Reynolds number of the aircraft surface, let alone an ordinary aircraft, even for hypersonic flow It is less than one thousandth, and the ionization rate itself is negligible..."
When Chang Haonan's words ended, the office suddenly fell into silence.
Han Chenfeng could even clearly hear his own heartbeat that was accelerating:
"So, it can be calculated according to the two-dimensional axial symmetry model..."
Although there are still some purely mathematical parts in the middle that are not fully understood.
But he still felt completely transparent.
Check out the 16-9 book bar and see the correct version!
As the saying goes, the more you know, the more you will discover your ignorance.
After investing in professional academic research, Han Chenfeng had almost forgotten the last time he had such a sudden enlightenment.
Although this is not his project and achievement, as a researcher in the field of plasma, there is nothing more exciting than hearing about an academic development that has real application value but will not cause him to lose his job. .
Perhaps to confirm Chang Haonan's statement, at this time, the laptop on the desk suddenly sounded a prompt.
Chang Haonan quickly clicked the mouse twice:
"The results from Yudu have been sent."
Han Chenfeng instinctively wanted to get up and go over to take a look, but he didn't know if he was within the knowledge range. As a result, he made a movement similar to Zamabu and stood still in mid-air. He didn't get up or sit back. For a moment, he was quite Awkward.
But Chang Haonan didn't have so many worries. He turned the computer directly and motioned for the other party to take a look.
The Turbofan 10 plasma demonstrator was originally developed by Institute 606 and Institute 240. Otherwise, even if Chang Haonan was free, he would not have chosen a place like Huairou Science City to meet.
Han Chenfeng walked forward in three steps and then found that it was a radar reflection intensity curve with the abscissa axis as the angle and the ordinate axis as the decibel value.
Or to be precise, one is real and the other is imaginary.
It’s just that the distance is very close,
Especially the part corresponding to the middle 60-120° almost completely overlaps.
The legend below the coordinate axes states that the dashed lines are calculated values and the solid lines are measured values.
Obviously, the difference between the two is almost negligible.
The picture has no sound, but it silently shows the correctness of Chang Haonan's theory just now...
While marveling, Han Chenfeng thought to himself with regret:
"It's a pity that the requirements for nuclear energy devices are too different. Otherwise, I might really be able to see fusion power generation become a reality in my lifetime..."
Controllable nuclear fusion is said to be "half a century away from practicality", which shows how difficult it is to realize the project.
Sometimes, even researchers themselves inevitably wonder whether they are striving for an unattainable goal.
Chang Haonan, on the other hand, seemed to have seen through his inner thoughts, and made a sudden turn when he opened his mouth:
"Although it is not realistic to control fusion with the current theory, if you are willing, I have an idea to directly use plasma to generate electricity. I still lack someone to verify it..."
(End of chapter)