How A Jet Engine Works (Trimmed)

[qwunk12]

@ce4me, think of it like a big gas powerd fan with mulitple layers, each set up in smaller seccesion (sorry spelling is horrible) which the assmbly is called the gas generator, each rotating blade has a compainon vain, which are called stages, the first stage starts of big then gets smaller and smaller, being compressed, then it reaches the combustor section or hot section, it is super heating then rapidly expandes going over whats called the High Pressure turbine, then out the ass.

[Jbinkley79]

Thats actually pretty simple compared to a car at least

[ce4me]

The jet is open from front to back. In a stopped jet, if you were to blow smoke in the front it would come out the back. Since the jet is an open tube, why does not the combusted gas blow out the front? If to a stopped jet, if a large amount of compressed air were injected in the middle at the combustion chamber, which way would the air flow, out the back or front.

[666jet]

@ce4me finally a smart question. this video is crap. it is the air trying to escape the front that actually creates the forward thrust. what's missing in this video is the compression chamber which extends forward from the combustion chamber. this is where superheated air is trapped and continuously tries to escape towards the front.

[ce4me]

The jet is open from front to back. In a stopped jet, if you were to blow smoke in the front it would come out the back. Since the jet is an open tube, why does not the combusted gas blow out the front?

[aakarwas]

@BoltOfThundor Jet engine efficiency is usually measured by the engine's thrust specific fuel consumption TSFC. For turbofans the TSFC is ~0.6-0.7 where as a turbojet's is around 1. TSFC is pounds of fuel per hour per pound of thrust.

Also, to set previous posts straight no combusted air travels through the compressor, that is fresh air only! The hot gases pass through the turbine(s) which spin the compressor/fan/shaft depending on the engine's purpose.

[lonewolfintj]

Most modern jet airliners use turbofan engines, rather than the turbojet described in this video. Turbofan engines use a turbine at the rear to turn a fan at the front. The front fan is what provides most of the thrust. If you don't explain how turbofan engines work, you're not explaining "how a jet works". Hence my grade for this video is D. (True as far as it goes, but mostly irrelevant, because very few engines actually work as described in this video.)

[crankyboris]

@lonewolfintj

most military fighters do not use turbofans.

[LotsOMovies]

@crankyboris

FYI...

"Many modern fighter planes actually use low bypass ratio turbofans equipped with afterburners" from NASA's educational pages. Just look up your favorite modern, supersonic fighter and find out what sort of engine it uses. Probably a turbofan.

[GeneralRdot09]

Good thats all maths and science.

[pjtc85]

The intake of air is caused by the rotating turbofan, however, what spins the axel in which the fan itself sits on? I get the compression part though. Also, what kind of thrust barings do they use so that the fan or blades don't go hurdling.

[Schmoozer3348]

The exhaust gas drives a smaller prop in the rear connected via the axle. As for the bearings, I don't know, but I would imagine they are custom designed and fabricated for this specific application, not something you can just order from McMaster-Carr.

[kiml42]

That was most enlightening.

[chrisbaileyb]

Most of the air that a jet engine intakes is actually used to keep the engine cool ( about 75%) the rest ( 25%) is scheduled by the hydromechanical unit with fuel in the right proportion for combustion. Hydromechanical unit for jet engine is like a carburetor in a car.

[relativeair]

i was wondering....on the turbo-props, is it 100% the prop propelling the aircraft or both a thrust and propelled result?? anyone?

[wildblue2]

the video said the prop was auxiliary but it's usually the main source of thrust. Should be the other way around. The exhaust gas is auxiliary and any propulsion is minimal. With a turbofan it's a mixture of both. There seem to be many variations out there.

[miffballa50]

Though it varies by model, in a turbofan engine only about 10% (or less) of the thrust is generated by the air that is heated in the combustion chamber exiting the engine. The remaining 90% is generated by the fan in the front of the engine (which is spun by the hot gases going through the compressor) pulling in massive amounts of air and forcing it to exit through the much smaller aperture at the rear. It is this funnel effect that results in the massive thrust generated by a jet engine.

[miffballa50]

A turboprop engine is similar. The hot gas that is generated creates very little thrust in itself, but when it goes through the compressor it causes the prop to spin at very high speeds, ultimately generating a great deal of thrust.

[BoltOfThundor]

@miffballa50 So, how much more affective is a turbofan engine compared to other engines in its efficiency? I mean, they wouldn't use a hybrid time idea unless it was efficient... (first question that pop-ed in-mind)

[JetDriver1111]

most thrust is from the prop...although the engine will have some thrust from the exhuast it really isn't the useful kind....

[DG121480]

And there ya go!

[stachowi]

Great video, thanks for the post.

[divingisbest]

Thanks. This explained so much to me. 5 stars!