Chapter 152 Isn’t this better than the weather forecast?
"Meteorology expert?"
Liang Shaoxiu was a little surprised by Chang Haonan's request.
The flight support department in the factory will have some positions responsible for weather forecasting, but they can only be regarded as technical personnel at best and do not require relevant professional background. They can take up the post after short-term training. They definitely do not qualify as "experts" The requirements represented by the two words.
“We may not be able to find anyone in Nanzheng who meets your requirements, but we can ask Jincheng University for help. They often guide us in weather forecasting.”
"This is best." Chang Haonan nodded.
At this time, the two of them had entered the data room next to them.
"All information related to Yun 8 is stored here." Liang Shaoxiu said, looking at the rows of filing cabinets in front of him.
As a transport aircraft that has been imitated since the 1970s, the various related design materials are naturally entirely on paper, and many of them are even original in Russian.
Although under the promotion of Chang Haonan, 611 Institute, 601 Institute and 112 Factory have successively begun to try to digitally design and produce new models, but the relevant experience and technology have not yet been carried out throughout the entire aviation industry. Promotion.
In addition, Factory 182 is relatively remote and has just changed its management. It is already short of manpower and has to deal with the design and manufacturing of two improved models of Yun 8F and Yun 8J at the same time. It is even more incapable of actively tracking the advanced experience of these brother units.
This is not only a problem of Factory 182 itself, but also a situation faced by many third-tier construction units.
Except for a few who were particularly successful, and some who were lucky enough to leave the third tier and move back to big cities, most third-tier factories had a difficult time in the 1980s and 1990s.
Those like Factory 182 that were able to survive into the 1990s can be considered rare.
Liang Shaoxiu skillfully and several engineers took down a thick stack of materials packed in bags from one of the shelves.
Then came the second and third piles...
Since what needs to be modified this time is not just the aerodynamic shape, but also involves structural changes inside the fuselage, so although only the main wing needs to be processed and horizontal tail, but it is still the largest number of drawings Chang Haonan has ever handled.
“Actually, from the time we started to imitate the An-12, we had some concerns about the Soviet-style de-icing device on board.”
A little out of breath due to continuous transportation Liang Shaoxiu quickly opened the file bag and said to Chang Haonan:
"But the conditions here at that time were really poor. Even if we had technical data and prototypes, it was very difficult to carry out surveying, mapping and imitation. Taking into account the gaps in aviation manufacturing, there is no time to make major changes to these parts.”
Although the Y-8 is a copy of the An-12, in fact the two aircraft are even different in size - the fuselage of the former is about 1 meter longer than the latter, in order to reduce the difficulty of the production and assembly process.
"What about the back? After all, there are so many improved models of Yun-8, especially the Yun-8C which still has an airtight cargo compartment. Haven't some remedial measures been taken in this regard?"
Chang Haonan Although we know what the problem is with the Y-8 de-icing device, that is already the experience gained on the heavily modified platform that will later be called the Y-9.
As for what happened between the Y8 basic model and the Y8 three-category platform, he didn’t know much about it.
"Of course." Liang Shaoxiu finally found the part about the wing de-icing device from the pile of drawings, and laid it out on the drawing board in front of the two of them
“On the original An-12, a total of five ice warning devices were installed only on the left side of the nose and above the engine inlet. We later installed two cameras in front of the horizontal tail, allowing the mechanics to monitor them in real time through a monitor. Monitor the condition of the horizontal tail. Once ice is detected, quickly turn on the electric heating device and retract the flaps to abort the landing procedure, and wait until the de-icing is completed before landing again.”
Icing on the horizontal tail not only means pitch stability. Moreover, when the main wing expands the angle flaps during the landing phase, the airflow will also have a downwash effect on the horizontal tail, causing the nose to press down sharply, which often means a dive and crash at low altitudes.
“But this change requires the data cable to penetrate the cabin from the bottom, so only the Y8 basic model and Y8B models that use non-airtight cargo compartments can be installed...”
“ Uh..."
Chang Haonan held his forehead helplessly.
It sounds like a very green solution.
Is it useful? There must be some.
After all, the oldest batch of Y-8s have never heard of any accidents due to icing on the wings.
But we definitely can’t keep going like this.
Moreover, the main users of the Y-8J, and a considerable number of future Y-8 platform special aircraft, will be the naval aviation, and the environment in which they perform their missions is even worse than that of the air force.
HNA aircraft, even land-based HNA aircraft, often need to be redesigned.
"Okay, it is indeed a bit crude."
After introducing the situation, Liang Shaoxiu also felt a little embarrassed and scratched his head awkwardly:
"So at the moment On the Y-8F-400 that is being designed, our initial idea is to design three sets of electric heating systems with different powers for the horizontal tail. At that time, the pilot will decide which set of equipment to turn on based on the specific situation..."
"But , because of this accident, our improvements must be completed in advance so as not to delay the progress of the Yun-8J project and the delivery of several future aircraft orders, 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 board.
An engineer next to me had the insight to lay a piece of white paper on it——
There is no blackboard or chalk in this room, so this is the only way.
“There is nothing wrong with your idea, but I think it is a bit too conventional.”
Chang Haonan drew a schematic diagram of a wing section on the paper in front of him as quickly as possible. Then he turned around and looked at the engineers in Factory 182 in front of him:
"I have a more radical method, which can not only completely eliminate the hidden danger of wing icing from the root, but also greatly improve the take-off, landing and low-speed flight performance of the Y-8." "That is, by analyzing the aircraft's operating environment , the overall design and the flow field structure during flight, calculate and analyze the icing conditions on the wing surface, and then adjust the distribution of de-icing heat sources in a targeted manner based on the analysis results.”
“Configure stronger electric heating devices or gas outlets in places that are more likely to freeze, and make the opposite change in places that are less likely to freeze. Use good steel on the blade, so that you can It reduces the loss of high-temperature gas and electric energy and improves the actual effect of de-icing. Pilots don’t have to worry about damaging the aircraft if they turn on the heating device in advance. It serves multiple purposes!” Supplementary content on the schematic diagram.
Although he obviously has no talent for painting, combined with his verbal description, he still made everyone understand his ideas.
The dozen or so people standing opposite did not speak, but their eyes when looking at Chang Haonan changed somewhat -
If the idea of the person in front of me can really be realized, then it will be equivalent to solving the existing problem at once. The two biggest shortcomings of the model.
You must know that although the An-12 and C130 appear to be the same level of aircraft, the performance of the former, especially the take-off and landing performance under heavy load conditions, is far weaker than that of its opponents.
The Y8 is limited by the level of the domestic turboprop 6 engine, which is even worse than the An 12.
This makes it difficult to compete with the American C130 and the C160 jointly developed by France and Germany in the international market.
But it all seemed too good to be true.
Especially the key step, predicting the ice formation on the wing surface, sounds like a fantasy.
Just kidding, even a city’s weather forecast is not very reliable these days. The accuracy is almost the same as direct divination.
You actually said that you want to simulate the extremely complex icing process within the scale of an airplane wing?
The atmosphere in the data room was silent for a few seconds, and finally Liang Shaoxiu came to his senses first:
"So...you said you wanted to find a meteorological expert just to do this?"
"Yes, I need to model and simulate the typical climate conditions common to aircraft during flight. So some knowledge of meteorology is needed."
Chang Haonan nodded and replied.
"This... with our current technical conditions, 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 walk. Once you understand it, it's okay. If you lose it, it becomes good steel and can be used on the back of the knife.
In case the heat source distribution is irrelevant to the actual ice accumulation situation, That would even be worse than the original stupid method.
“Comrade, don’t panic.” Chang Haonan raised his palm with a smile and made a downward movement:
“I will talk about my specific ideas later, 伱We'd better prepare some paper to take notes, because there is a lot of work that requires your participation."
His confident posture and tone obviously affected other people. After a brief noise, a dozen engineers had already taken it. He raised his head and looked at the drawing board again.
"Wing icing can be divided into two independent processes."
Seeing that everyone was ready, Chang Haonan immediately went straight to the topic:
"The first is the supercooling in the air Liquid droplets or ice crystals adhere to the surface of the wing and flow, which is a fluid mechanics problem. "
"The second is that the liquid droplets captured by the wall undergo a phase change and form flakes of ice on the surface of the wing. This is a thermodynamic problem. ”
“Although strictly speaking, these two processes will be an unsteady process when considered together, but in the calculation and simulation process, a quasi-steady calculation strategy can be used. . That is, the air flow field and the water droplet flow field are only coupled in one direction, and both flow fields are considered to remain unchanged when performing phase change calculations.”
"Based on 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, generate the computational grid required for flow field solution on clean geometry or icing geometry.”
“Second, use the flow control equations to simulate the flow around the aircraft, The data related to the movement and icing of water droplets, such as the velocity field, air shear stress at the wall, pressure gradient, and convection heat transfer coefficient, are obtained through the solution. ”
“Then, the water droplets are solved based on the air flow field. The motion trajectory is used to obtain the impact characteristics of water droplets, and based on the air and water droplet flow fields, the ice thickness of each control unit on the wall is solved through the ice heat and mass transfer model..."
"Finally, the ice thickness is used to calculate the new icing geometry. Of course, because we only need to consider the de-icing problem, the fourth step does not need to be done."
"Based on the numerical simulation of icing , Anti-icing numerical simulation needs to calculate the wall surface and water film temperatures with anti-icing heat flow input. At the same time, depending on the anti-icing method, the thermal coupling process between gas, liquid and solid also needs to be considered..."< br>
As the explanation progressed, more and more formulas were written by Chang Haonan.
The eyes of Liang Shaoxiu and others on the opposite side gradually changed from curiosity to confusion, and finally to shock and shock!
They understood.
Not only did I understand it, I even thought it made sense and was feasible!
(End of this chapter)