2. The passenger plane has a large bypass ratio, so the fan has a large diameter and saves fuel, but the windward resistance is also large.
Modern fighters generally use turbojet engine, which is a kind of turbine engine. It is characterized by completely relying on airflow to generate thrust. Usually used as power for high-speed aircraft. Fuel consumption is higher than that of turbofan engine. There are two types of turbojet engines: centrifugal and axial. Centrifugal type was patented by British Sir Frank Whittle in 1930, but it was not until 194 1 that the aircraft equipped with this engine went to heaven for the first time and did not participate in World War II. Axial flow was born in Germany and was used as the first practical jet fighter Me-262 in the summer of 1944. Compared with centrifugal turbojet engine, axial flow has the advantages of small cross section and high compression ratio. Today's turbojet engines are all axial flow.
Large commercial passenger aircraft generally use turbofan engines. Turbofan engine is a kind of aircraft engine, which is developed from turbojet engine. ?
Compared with turbojet, the main feature is that the area of the first-stage compressor is much larger, and it also acts as an air propeller (fan) to push back a part of the sucked air through the periphery of the jet engine. The part of the engine core through which air passes is called the internal duct, and the part outside the engine core through which only fan air passes is called the external duct. The turbofan engine is most suitable for the flight speed of 400 to 1000 km, so most aircraft engines now use turbofans as power sources.