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 area 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 meet the requirements represented by the word "expert". .

"We may not be able to find anyone who meets your requirements in Nanzheng, 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 the 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 Chang Haonan's promotion, 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 promoted throughout the entire aviation industry.

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 last until the 1990s are already considered rare.

Liang Shaoxiu and several engineers skillfully took down a thick stack of materials packed in bags from one of the shelves.

Then came the second pile, the third pile...

Since what needs to be modified this time is not just the aerodynamic shape, but also involves structural changes inside the fuselage, although there are only two parts that need to be processed: the main wing and the horizontal tail, it is still the number of drawings Chang Haonan has handled. The most ever.

"In fact, from the time we started copying the An-12, we had some concerns about the Soviet-style de-icing device on board."

Liang Shaoxiu, who was out of breath from the continuous transportation, quickly opened the file bag and said to Chang Haonan:

"But the conditions here at that time were so poor that even if we had technical data and prototypes, we could hardly do any mapping and imitation. We also had to take into account the gap in aviation manufacturing, and there was 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 the Yun-8, especially the Yun-8C which still has an airtight cargo compartment. Are there no remedial measures in this regard?"

Although Chang Haonan knew what the problem was with the Yun-8 deicing device, that was already his experience gained on the heavily modified platform that would later be called the Yun-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 icing warning devices were only installed 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, and 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 that the pitch stability becomes worse, but also when the main wing expands the flap angle 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 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..."

"Well……"

Chang Haonan held his forehead helplessly.

It sounds like a very green solution.

Is it useful? It must be there.

After all, the oldest batch of Y-8s had never heard of any accidents due to icing on the wings.

But we certainly can’t keep doing this forever.

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.

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

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

"So on the Y-8F-400 currently 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..."

"However, 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 orders for several future aircraft, 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 him very discerningly laid a piece of white paper on top——

There was no blackboard or chalk in this room, so that was all.

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

Chang Haonan drew a schematic diagram of the wing section on the paper in front of him as quickly as possible, then turned around and looked at the engineers of 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 calculating and analyzing the icing conditions on the wing surface by analyzing the aircraft's operating environment, overall design, and flow field structure during flight, and then adjusting 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, which can reduce high-temperature gas and The loss of electrical energy can also improve the actual effect of de-icing, and pilots don’t have to worry about damaging the aircraft if they turn on the heating device in advance. It’s a multi-purpose solution!”

Chang Haonan added content to the schematic diagram he just drew while talking.

Although he obviously has no talent for painting, combined with the verbal description, he still made everyone understand his thoughts.

None of the dozen or so people standing opposite spoke, but the looks in their eyes towards Chang Haonan had somewhat changed——

If the idea of ​​the person in front of me can really be realized, it will be equivalent to solving the two biggest shortcomings of existing models at once.

You know, although the An-12 and the 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's all 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. It's almost as accurate 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 meteorologist just to do this?"

"Yes, I need to model and simulate the typical weather conditions common to aircraft during flight, so some knowledge of meteorology is required."

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. But if you lose it, it becomes good steel and can be used on the back of the knife.

If the heat source distribution is irrelevant to the actual ice accumulation situation, it will even be inferior to the original stupid method.

"Comrade, don't panic." Chang Haonan smiled and raised his palm, making a downward movement:

"I will talk about my specific ideas later. You'd better prepare paper and take notes, because there is a lot of work that requires your participation."

His confident posture and tone obviously affected others. After a brief noise, a dozen engineers had already picked up their notebooks and raised their heads to look at the drawing board again.

"Wing icing can be divided into two independent processes."

Seeing that everyone was ready, Chang Haonan immediately got to the point:

"First, supercooled droplets or ice crystals in the air adhere to the surface of the wing and flow. This is a fluid mechanics problem."

"The second is that the droplets captured by the wall undergo a phase change and form flakes of ice accumulation on the surface of the wing. This is a thermodynamic problem."

"Although strictly speaking, if these two processes are considered together, it will be an unsteady process, 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 calculated There is a one-way coupling, and both flow fields are considered 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, the computational mesh required for flow field solution is generated on clean geometry or icing geometry.”

"Secondly, the flow control equations are used to simulate the flow around the aircraft, and the velocity field, air shear stress at the wall, pressure gradient, convection heat transfer coefficient and other data related to water droplet movement and icing are obtained."

"Then, based on the air flow field, the movement trajectory of the water droplets is solved to obtain the impact characteristics of the water droplets. On the basis of the air and water droplet flow fields, the ice thickness of each control unit on the wall is solved through the icing heat and mass transfer model. …”

"Finally, the ice thickness is used to calculate the new ice 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, the numerical simulation of anti-icing needs to calculate the wall and water film temperatures with anti-icing heat flow input. At the same time, depending on the anti-icing method, the relationship between gas, liquid and solid also needs to be considered. Thermal coupling process between..."

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

The eyes of Liang Shaoxiu and others across from him gradually changed from curiosity at the beginning to confusion, and finally to shock and shock!

They got it.

Not only did I understand it, I even thought it made sense and was feasible!