In order to test the Tianxing I engine, Zhengxin Experimental Center specially purchased a system for testing aircraft engines. However, due to the tight time, the system purchased is relatively old. Although it does not delay the accuracy of the test results, there is some delay in the display due to the calculation method.

As the engine switches from a slow car and gradually increases the speed and rises towards the peak, the values ​​on the display panel of the test system are also slowly changing.

At this time, Tianxing I had entered the express working area, which was located at the top of the display panel. A value that was refreshed leisurely is thrust!

For an aircraft engine, especially a civil aircraft engine, you cannot use a certain data to determine its performance.

What is a civil aviation aircraft? To put it bluntly, it is just a bus in the air. It is definitely good if the bus runs fast and the engine is ejected strongly, but on the other hand, every minute of the plane in the sky consumes a huge amount.

Therefore, for civil aviation engineering, good performance is the best, but if the performance is mediocre and the economy is more significant, it is also an excellent driving force.

But, if you leave out economics, what is the most important thing?

Of course it's thrust!

What is the thrust? In fact, it is about the same horsepower as the car engine.

The speed of an aircraft depends on the balance value of its thrust, mass and drag. When the thrust is greater than the drag, the aircraft accelerates, and the acceleration is equal to the thrust divided by mass. Then, the speed is equal to the integral of acceleration to time. Since the greater the speed, the greater the drag, and the drag is proportional to the square of the speed. Therefore, when the resistance is equal to the thrust, the acceleration is zero and the speed will no longer increase.

Therefore, the thrust of the aircraft engine determines the acceleration and maximum speed of the aircraft.

At this time, the latest refreshed thrust value on the test panel has exceeded 30 thousand N!

"God! Did I read it wrong? As soon as I entered the express train work area, the thrust reached...30 thousand nm?"

"What's the matter? Now it seems that it has entered the mid-stage acceleration, and the increase in the thrust value will slowly decay with the increase in the speed. I remember that the target engine used by our military before could reach 50 kiloN at the maximum peak speed. Even if this small aircraft engine is a bit powerful, it is at best the level of a aircraft engine of a target aircraft engine. However... in such a short time, it is not bad, and well... Zhengxin is also good."

Immediately someone started to discuss the issue of Tianxing I.

Listening to the sensible comments by several engineers who were on the fly, Li Fanyu felt a little unhappy.

What does it mean at best is a target aircraft aircraft level? What does it mean is not bad?

Are you saying this contradictory?

What I have worked hard to pick up from a Level 6 car is comparable to those stunning sluts carried by military target aircraft?

joke!

Now I have just entered the highway working area, where is it?!

He casts contempt for the gossip engineer just now.

But before Li Fanyu could hit him, someone immediately jumped out, pointed to the latest data, and slapped the man just now!

"The military target aircraft you mentioned is a turbojet! This is a turbofan! Can it be the same?"

"Uh..." After being poked, the man couldn't feel anything on his face.

Indeed, most of the target engines used by the military are turbojet engines. One is that the structure of this type of engine is relatively simple and has a low cost, which can reduce the cost of the target engine. The other is that the bypass ratio of the turbojet engine is relatively low, and it can produce greater thrust under the same volume as the turbofan engine.

However, because the bypass ratio of the turbojet engine is very fuel-consuming.

The man thought for a while and argued: "It depends on the bypass ratio and thrust-weight ratio. If the thrust is high but the bypass ratio and thrust-weight ratio is low, then it will be meaningless. After all, the aircraft requires the most economicality. It is not like a car. No matter how high the horsepower is, it can be used at a gas station. In the sky, an aircraft engine that only knows the output power but does not consider fuel economy has no use value."

At this moment, someone shouted: "Look! The bypass is refreshed with data!"

“1:11?”

"Hmm?! I'm not mistaken!"

"Oh my God, how is it possible? The cross-section of the engine doesn't look big? How could it be such a high bypass ratio!?"

The bypass ratio is actually the ratio of the air flow rate of the turbofan aircraft external duct and the connotation channel. The air from the connotation channel enters the combustion chamber and mixes with the fuel. When the combustion is done, the air from the exterior duct does not enter the combustion chamber, but mixes with the gas flowing out of the connotation channel and is discharged.

The air in the outer duct only flows slowly and is low-temperature through the fan. The inner duct discharges high-temperature gas. After the two gases are mixed, the average flow rate and temperature of the nozzle are reduced. The lower flow rate brings higher propulsion efficiency and lower noise. According to the principle of the heat engine, lower temperature can bring higher thermodynamic efficiency.

Simply put, the higher the bypass ratio, the higher the thrust-to-weight ratio and the better the fuel economy!

The bypass ratio is an important design parameter of turbofan engines, and it has a great impact on the engine fuel consumption rate and thrust-weight ratio. Turbofan engines of different uses should choose different bypass ratios, such as the turbofan engines used by long-range transport aircraft and passenger aircraft. The bypass ratio range is generally 4 to 8. The bypass ratio of the afterburner turbofan engines selected for air-optimal fighters is generally less than 1, and may even be as small as 0.2 to 0.3.

It’s not that air-optimal fighter does not want a higher bypass ratio, but mainly because the cross-sectional area of ​​the turbofan determines the level of the bypass ratio. Because of combat needs, air-optimal fighter jets that often perform high-speed maneuvering and supersonic flights require a more streamlined fuselage, so they can only endure the pain of reducing the bypass ratio. To put it another way, for civil aviation technology, any air-optimal fighter is an oil tiger!

At present, general civil aviation turbofan engines, such as turbofan aircraft engines under General Electric, generally have a bypass ratio of around 1 and 8. It’s not that I don’t want to do it any larger, but because of technical reasons, if this value is large, it will make the engine cross-section too bulky, which will greatly affect the safety of takeoff and landing.

On the other hand, due to the relationship between the shape and internal structure of the blade fan, the bypass ratio has been increased to 1:11 while maintaining the overall proportion of the engine.

This is terrifying!

Seeing this value, just such a value, all the engineers present at Shangfei Company had only one word left in their minds.

Capitalized...shelf!
Chapter completed!