"Meteorologists?"

Liang Shaoxiu was a little surprised by Chang Haonan's request.

The flight support department of the factory will have some positions responsible for weather forecasting, but they can only be regarded as technical personnel at most, and do not need relevant professional backgrounds.

"We may not be able to find anyone who meets your requirements in the whole of Nanzheng, but we can ask Jincheng University for help, and they will often guide us in weather forecasting."

"It's for the best." Chang Haonan nodded.

At this time, the two of them had already entered the data room next to them.

"All the information related to Yun 8 is stored here." Liang Shaoxiu looked at the rows of filing cabinets in front of him and said.

As a transport aircraft that has been imitated since the seventies, the relevant design materials are naturally completely paper, and even many of them are original in Russian.

Although under the promotion of Chang Haonan, the 611, 601 and 112 factories have begun to try to digitally design and produce new models, the relevant experience and technology have not yet been promoted throughout the aviation industry.

In addition, the 182 factory is relatively remote and has just changed to a new commander, and it is already short of manpower to deal with the design and manufacture of the two improved models of the Y-8F and Y-8J at the same time, and it is even more unable to actively track the advanced experience of these brother units.

This is not only the problem of the 182 factory itself, but also the current situation that many third-line construction units are facing.

Except for a very small number of those who were particularly competitive, and some who were lucky enough to leave the third line and move back to the big cities, most of the third-line factories had a very difficult time in the eighties and nineties.

Factory 182, which can be maintained until the 90s, is already rare.

Liang Shaoxiu, along with several engineers, skillfully removed a thick stack of materials from one of the shelves that was packed in a bag.

This was followed by a second and third stacks......

Because what needs to be modified this time is not, or not only the aerodynamic shape, but also involves the structural changes inside the fuselage, so although only the main wing and the horizontal tail need to be processed, it is still the largest number of drawings Chang Haonan has ever handled.

"In fact, from the beginning of the imitation of the An-12, we had some concerns about the de-icing device full of Soviet-style characteristics on the plane."

Liang Shaoxiu, who was a little out of breath because of the continuous handling, quickly opened the file bag and said to Chang Haonan:

"But at that time, the conditions on our side were too poor, even if there were technical data and prototypes, it was very reluctant to engage in surveying and mapping imitation, and we had to take into account the gap in aviation manufacturing, so it was too late to make major changes to these parts."

Although the Y-8 is a copy of the An-12, in fact, the two aircraft are not even the same in size - the fuselage of the former is about 1 meter longer than the latter, just to reduce some difficulty in the production and assembly process.

"And what about the back? After all, the Y-8 has also produced so many improved models, especially the Y-8C is still an airtight cargo hold, so didn't he do some remedies in this regard? ”

Although Chang Haonan knew where the problem of the Yun-8 de-icing device was, it was already an experience gained on the overhaul platform known as Yun-9 in later generations.

As for what happened in the middle from the basic type of Yun 8 to the three types of platforms of Yun 8, he did not know anything.

"Absolutely." Liang Shaoxiu finally found the part about the wing de-icing device from the pile of drawings and laid it on the drawing board in front of the two

"On the original An-12, the icing warning device was only installed on the left side of the nose and above the engine intake, and we later set up two cameras in front of the horizontal tail, so that the mechanic could monitor the situation of the flat tail in real time through a monitor, and once ice was found, the electric heating device was quickly turned on and the flaps were retracted to abort the landing procedure, and then re-landed after the de-icing was completed."

Flat-tail icing not only means poor pitch stability, but also when the main wing zooms in on the angled flaps during the landing phase, the airflow will also have a downwash effect on the flat-tail, causing the nose to press down sharply, which often means a dive crash at low altitudes.

"However, this change requires the data cable to penetrate the cabin from the bottom, so only the Y-8 basic and Y-8B models that use non-airtight cargo holds can be installed......"

"Uh......"

Chang Haonan held his forehead a little helplessly.

Sounds like a very green solution.

Is it useful, there must be.

After all, the oldest batch of Y-8s really haven't heard of an accident due to wing icing problems.

But we can't just keep it that way.

Moreover, the main users of the Y-8J, as well as a considerable part of the Y-8 platform special aircraft in the future, will be naval aviation, and the environment in which they perform missions is even worse than that of the Air Force.

HNA aircraft, even land-based, often have to be redesigned.

"Well, it's a bit rudimentary indeed."

Liang Shaoxiu, who finished introducing the situation, also felt a little embarrassed and scratched his head a little embarrassed:

"So on the Y-8F-400 that is currently being designed, our initial idea is to design three sets of electric heating systems with different powers for the horizontal tail, and then the pilot will decide which set of equipment to turn on according to the specific situation......"

"However, because of this accident, our improvements had to be completed ahead of schedule so as not to delay the progress of the Y-8J project and the delivery of orders for several aircraft in the future, so ...... I can only trouble Academician Du and you. ”

After listening to the other party's narrative, Chang Haonan thought for a while, then picked up a sharpened red and blue pencil from the table and came to the drawing tablet.

An engineer next to him had the insight to spread a blank sheet of paper on it—

There is no blackboard or chalk in this room, so that's all there is to it.

"There's nothing wrong with your thinking, but I think it's a little too conventional."

Chang Haonan drew a schematic diagram of the wing section on the paper in front of him as quickly as possible, and then turned around and looked at the engineers of Factory 182 in front of him:

"I have a more radical approach, which can not only completely eliminate the hidden danger of wing icing from the root, but also greatly improve the take-off and landing and low-speed flight performance of the Y-8."

"That is, through the use environment, overall design and flow field structure of the aircraft during the flight, the icing situation on the wing surface is calculated and analyzed, and then the distribution of de-icing heat sources is adjusted in a targeted manner according to the analysis results."

"Configure a stronger electric heating device or gas outlet in a place that is more prone to freezing, and make the opposite change in a place that is not easy to freeze, and use good steel on the blade, which can not only reduce the loss of high-temperature gas and electric energy, but also improve the actual effect of de-icing, and the pilot does not have to worry about opening the heating device in advance will cause damage to the aircraft, killing multiple birds with one stone!"

Chang Haonan added content to the schematic diagram he had just drawn as he spoke.

Although he obviously has no talent for painting, combined with language description, he still allows everyone to understand his own ideas.

The dozen or so people standing opposite didn't speak, but the eyes that looked at Chang Haonan changed somewhat-

If the idea of the person in front of him can really be realized, then it is equivalent to solving the two biggest shortcomings of the existing model at one time.

You know, although the An-12 and C130 seem to be aircraft of the same class, the performance of the former, especially the take-off and landing performance under heavy load conditions, is far weaker than that of the opponent.

The Yun-8 is subject to the level of the domestic turboprop 6 engine, which is even worse than the An-12.

This makes it difficult to compete with the C130 of the United States and the C160 jointly developed by France and Germany in the international market.

But it's too good to be true.

In particular, predicting ice formation on the surface of the wing, a crucial step in the equation sounds like a fantasy.

Just kidding, the weather forecast for even a city is not very reliable these days, and the accuracy is similar to direct divination.

You even said that you want to simulate the extremely complex icing process within the scale of a wing?

The atmosphere in the data room was silent for a few seconds, and finally Liang Shaoxiu was the first to come back to his senses:

"So...... You said you were looking for a meteorologist to do that? ”

"That's right, I need to model and simulate the typical climatic conditions that are common to aircraft during flight, so I need some knowledge of meteorology."

Chang Haonan nodded and replied.

"This ...... With our current state of the art, is it really possible to make very accurate predictions? ”

Soon a second person asked the question that everyone was most concerned about.

After all, this idea is a bit of a tightrope, it's okay to play clearly, if you get rid of it, it will become a good steel used on the back of the knife,

In the unlikely event that the distribution of the heat source is not in line with the actual ice accumulation, it will not be as good as the earliest stupid method.

"Don't panic, comrade." Chang Haonan raised his palm with a smile and made a downward pressing motion:

"I'm going to talk about my specific ideas later, and you'd better prepare paper notes because there's a lot of work that needs your involvement."

His confident posture and tone had apparently affected the others as well, and after a brief cacophony, a dozen engineers had already picked up their small notebooks and looked up at the drawing board again.

"Wing icing, which can be divided into two separate processes."

Seeing that everyone was ready, Chang Haonan immediately went straight to the topic:

"One is that supercooled droplets or ice crystals in the air attach to the surface of the wing and flow, which is a hydrodynamic problem."

"The second is that the droplets trapped by the wall undergo a phase change, forming patches of ice on the surface of the wing, which is a thermodynamic problem."

"Although strictly speaking, these two processes would be an unsteady process when considered together, a quasi-steady calculation strategy can be used in the computational simulation process. That is, the air flow field and the water droplet flow field are only one-way coupled, and when the phase transition is calculated, it is considered that both flow fields remain unchanged. ”

"On the basis of this principle, the entire calculation process can be divided into the following steps."

Chang Haonan wrote a big (1) on the white paper next to him.

"First, the computational mesh required for the flow field solution is generated on either the clean geometry or the icing geometry."

"Secondly, the flow around the aircraft is simulated using the flow governing equations, and the data related to water droplet motion and icing are obtained, such as the velocity field, the air shear stress at the wall, the pressure gradient and the convective heat transfer coefficient."

"Then, on the basis of the air flow field, the motion trajectory of the water droplet is solved, the impact characteristics of the water droplet are obtained, and the ice thickness of each control unit of the wall is solved by the ice heat and mass transfer model on the basis of the air and water droplet flow field......

"Finally, the new ice geometry is calculated using the ice thickness, and of course, since we only need to think about de-icing, the fourth step can be left out."

"On the basis of the numerical simulation of icing, the numerical simulation of anti-icing needs to calculate the temperature of the wall and the water film in the presence of anti-icing heat flow input, and at the same time, depending on the anti-icing method, it is also necessary to consider the thermal coupling process between gases, liquids and solids......"

As the explanation progressed, more and more formulas were written by Chang Haonan.

And the eyes of Liang Shaoxiu and the others on the other side also changed from curiosity at the beginning, gradually turned into dazedness, and finally turned into shock and shock!

They understood.

Not only did I understand it, but I even felt that it made sense and was feasible!

(End of chapter)