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      Gas turbine is a kind of internal combustion power machine, which uses continuous flow gas as working medium to drive the impeller to rotate at high speed and change the energy of fuel into useful work. The structure of gas turbine is the simplest, and it can embody a series of advantages, such as small volume, light weight, fast start-up, less or no cooling water.In the main flow of air and gas, the gas turbine cycle consists of compressor, combustor and gas turbine, which is called simple cycle. Most gas turbines use simple cycle.The compressor sucks air from the outside atmosphere and compresses it step by step through an axial-flow compressor to make it pressurized, and the air temperature increases accordingly; the compressed air is pressed into the combustor and mixed with the fuel i...
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    • 2018 - 08 - 21
      Turbofan engine, also known as 'turbofan engine'. A gas turbine engine is a gas turbine engine which is ejected from a nozzle and ejected from a fan to produce reaction thrust. It consists of a compressor, a combustion chamber, a turbo (driven compressor), a low pressure turbine (driven fan) and an exhaust system. The first three parts are called 'core engines'. The available energy in the gas from the core engine is used to drive the low-pressure turbine to drive the fan, and the gas from the nozzle is used to accelerate the emission. Culvert ratio is closely related to fuel consumption rate. The first generation of turbofan engines appeared in the late 1950s, the bypass ratio, the compressor turbocharging ratio and the gas temperature in front of the turbine were relative...
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3 minutes to understand aircraft turbofan engine working principle!

Data: 2018-08-22
浏览次数: 5

Turbofan engine is a kind of aircraft engine, which is developed from Turbojet. Compared with turbojet, the main feature is that the primary compressor has a much larger area and is used as an air propeller (fan), pushing partially inhaled air back through the periphery of the jet engine.

The air passing through the core part of the engine is called the inner passage, and the outer passage is called the outer passage only when the fan air passes through the outer part of the core engine. Turbofan engines are best suited for speeds between 400 and 1,000 kilometers, so most aircraft engines now use turbofans as power sources.

Working principle

The turbofan engine is composed of a fan, a low-pressure compressor (special to turbofan), a high-pressure compressor, a combustion chamber, a high-pressure turbine driving the compressor, a low-pressure turbine driving the fan and an exhaust system. The high-pressure compressor, combustor and high-pressure turbine are collectively called the core engine. The available energy from the gas discharged by the core engine is transferred to the low-pressure turbine to drive the fan, and the rest to accelerate the exhaust gas in the nozzle.

The fan rotor is actually a compressor with a long blade of stage 1 or several. After air flows through the fan, it is divided into two paths: one is the inner flow, the air continues to compress through the compressor, combusts in the combustor and fuel mixture, the gas expands through the turbine and the nozzle, and the gas is discharged from the tail nozzle at high speed, producing thrust and flowing through the path. Low-pressure compressor, high-pressure compressor, combustion chamber, high-pressure turbine, low-pressure turbine, gas from the nozzle exhaust; the other way is the connotation of the air flow, the fan after the air directly into the air through the outer channel or with the connotation of the gas exhaust in the nozzle. The turbofan engine combines the advantages of turbojet and turboprop engine.

Turbofan engines convert most of the gas energy into torque that drives fans and compressors, and the rest into thrust. The total thrust of turbofan engine is the sum of thrust produced by the core engine and the fan. This turbofan engine with two internal and external ducts is also known as the internal and external engine. That is to say, turbofan engines can be separated or mixed exhaust, can be short culvert or long culvert (full culvert). The fan can be driven as the first stage of a low pressure compressor by a low pressure turbine or by a separate turbine. The thrust of turbofan engine consists of two parts: the thrust generated by the connotation and the thrust generated by the external culvert. For high bypass ratio turbofan engines, the thrust generated by fans is more than 78%. The ratio of air flow that flows through the culvert and connotations is known as bypass ratio or flow ratio. The bypass ratio has a great influence on the performance of turbofan engine. The bypass ratio is large and the fuel consumption rate is low, but the headwind area of the engine is large. The internal and external culvert two airflows are separated into the atmosphere, which is called the split type turbofan engine.

Mixed-row turbofan engine is a kind of turbofan engine with internal and external air flows into the atmosphere through the same nozzle after seeping and mixing with each other. Turbo fan engine can also be equipped with afterburner to become an afterburner turbofan engine. The afterburner on the split-row turbofan engine can be installed in the rear of the inner turbine or the outer channel respectively, and on the mixed-row turbofan engine can be installed in the rear of the mixer.

Advantages and disadvantages

The advantages of turbofan engine are high thrust, high propulsion efficiency, low noise, low fuel consumption and long flight range.

Disadvantages: large fan diameter, windward area, so the resistance is large, the engine structure is complex, difficult to design.

First case

During World War II, Germany's Daimler-Benz developed its first turbofan engine in 1943. In April, the static thrust reached 840 kilograms on the test bench, which is expected to reach 1,000 kilograms. However, it failed to develop because of a large number of defects and the lack of corresponding experts. After World War II, with the passage of time and technological updates, turbojet engines appear insufficient to meet the power needs of new aircraft. Especially after World War II, the rapid development of subsonic civil aviation aircraft and large transport aircraft, flight speed requirements can reach high subsonic speed, fuel consumption is small, so the engine efficiency must be high.

The efficiency of turbojet engines has been unable to meet this demand, making the flight of these aircraft shorter. Therefore, a large number of large aircraft using turboprop engines appeared in a period of time. In fact, as early as the 1930s, jet engines with culverts had some rough early designs. In early 40 and 50s, early turbofan engines were tested. However, due to the high requirements for the design and manufacture of fan blades, it was not until the 1960s that people were able to produce fan blades to meet the requirements of turbofan engines, thus unveiling the practical stage of turbofan engines. In the 1950s, NACA, the predecessor of NASA, carried out very important research work on turbofan engines. From 55 to 56 years, the research results were further developed by the Ge Corp (GE).

GE successfully launched the CJ805-23 turbofan engine in 1957, immediately breaking a large number of supersonic jet engine records. But the earliest practical turbofan engine was Pratt & Whitney's JT3D turbofan engine. In fact, Pratt & Whitney started the turbofan development project later than GE, they were listening to GE in the development of CJ805 secrets, hastened to work, the first to launch a practical JT3D. In 1960, Rolls Royce's '


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