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  • I'm Jake O'Neal, creator of Animagraffs, and this is

  • How Jet Engines Work

  • Most jet propelled airplanes use a turbofan design.

  • The turbofan can be thought of as a high tech propellor inside of a duct called a diffuser,

  • driven by a gas generator.

  • The Core

  • The core of a jet engine is a gas generator that creates high pressure gas to power a

  • turbine.

  • This setup has compressor, combustor, and turbine sections.

  • The Compressor

  • Compressed air makes for a much more powerful combustion reaction relative to engine size.

  • Compression happens in stages that force incoming air into an increasingly narrow chamber.

  • A single compressor stage is comprised of a spinning rotor paired with a ring of stationary

  • stator vanes which are attached to the core casing.

  • Rotor blades swirl the air as they force it through the compressor.

  • Stator vanes slow this swirling momentum in exchange for increased air pressure.

  • This compressor has four low pressure and ten high pressure stages.

  • The Combustor

  • Air is mixed with fuel and ignited as it passes through the combustor, releasing a jet of

  • super high powered gas.

  • The design shown here is an annular combustor, meaning "ring shaped."

  • Compressed air enters the inlet nozzles.

  • Each nozzle is coupled with a fuel injector, and is designed to swirl the incoming fuel

  • and air for an even mix.

  • A couple of ignitor plugs, not unlike the spark plugs found in car engines, ignite this

  • mixture and the reaction spreads evenly around the ring.

  • Once started, combustion continues as long as air and fuel are supplied.

  • The turbine

  • Turbines at the rear of the jet engine are powered by exhaust gasses exiting the combustor.

  • Much of the turbine power is used to turn the fan while a smaller percentage powers

  • the compressor stages.

  • Turbine fins get extremely hot.

  • Some air from the compressor is diverted for cooling, and special coatings are used to

  • keep temperatures down.

  • The exhaust cone is specially shaped to mix

  • and accelerate exhaust streams.

  • It also covers sensitive internal engine parts.

  • The fan

  • Early jet engines were turbojets, where all incoming air flows through the core.

  • Most modern winged aircraft engines are turbofans, where only a fraction of air enters the core

  • or gas generator, and the resulting power turns a specially designed fan.

  • Again, the fan can be thought of as a high-tech propeller inside of a duct.

  • Air that does not enter the core is called bypass air.

  • High bypass engines are designed to move large quantities of air at slower cruising speeds

  • (a range of about 310 to 620 mph).

  • The exchange for high efficiency is engine sizehigh bypass engines can be very large,

  • with massive fans compared to core size.

  • Commercial airliners or military transport aircraft are example applications.

  • Exhaust velocity is a major factor in jet engine noise.

  • High bypass engines surround fast-moving core exhaust with large quantities of slower-moving

  • bypass air for quieter operation.

  • Military fighter aircraft use low bypass engines, which are more compact, have high power-to-weight

  • ratios, plus supersonic and afterburner capabilities, in exchange for things like poor noise control

  • and high fuel consumption.

  • Afterburner

  • High performance engines may have afterburner capability.

  • Additional fuel is sprayed into a jet pipe section where it mixes with exhaust gas, and

  • is ignited, producing a second stage of combustion.

  • Since afterburner is fuel inefficient, it's generally used in short bursts during takeoff,

  • climb, or combat maneuvers.

  • The exhaust nozzle is adjustable for maximum exhaust acceleration and to avoid undesirable

  • back-pressure which can harm forward engine parts.

I'm Jake O'Neal, creator of Animagraffs, and this is

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B2 US exhaust compressor air jet core bypass

How Jet Engines Work

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    OolongCha posted on 2021/02/23
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