[squilliam]

A modern jet engine is just a shrouded propeller that happens to be powered by a jet turbine. An electric ducted fan would be the battery-powered equivalent.

[aphextron]

>A modern jet engine is just a shrouded propeller that happens to be powered by a jet turbine.

No, it's not. A propellor creates thrust by slicing the air and creating lift just like a wing, but in a forward direction. A jet engine's fan blades create no thrust in themselves. They provide the compression needed for combustion to occur within the engine, and thrust is created by the expelling of hot exhaust gasses.

[agurk]

That is a description of a turbojet - the earliest type of aero jet engines[0]. GP is referring to modern turbofans which are defined by having a bybass - i.e. air that is compressed and then expelled rearwards without passing through the main turbine body[1].

This is done to trade the high speed of the jet exhaust for a larger amount of air moving more slowly. Making the speed of the jet plume closer to the true airspeed of the aircraft makes it more efficient.

[0] https://en.wikipedia.org/wiki/Turbojet

[1] https://en.wikipedia.org/wiki/Turbofan

[darksaints]

No, the exhaust is not the primary thrust generator, unless you're talking about military jets. The fans themselves are creating the majority of the propulsion. Modern high bypass designs have bypass ratios of ~10:1, meaning for every 1 lb thrust generated from the exhaust, 10 lbs comes from the fan.

https://en.wikipedia.org/wiki/Bypass_ratio

[Tuna-Fish]

Most of (>80%) the thrust of modern turbofan engines is directly produced by the fan, which mostly just pushed air past the engine, not into it.

[throwawaysea]

The bypass part of a turbofan does generate thrust.