How fast is the air going out of a commercial jet liner engine?

Question

How fast is the air going out of a commercial jet liner engine?

Answer 1

Ideally, the core engine is at sonic velocity, but the fan is somewhat less. Current designs do not regulate exhaust area except for afterburning engines.

The early German jet engine during WWII had a plug nozzle for setting sonic velocity. Flight idle was set at wide open area.

Answer 2

Conner, at take-off, the exhaust from most jet engines used for commercial jets is going between 600 and 700 mph. Much less at idle thrust. For the aircraft to go forward lots of air goes through the engine, both through the combustion chamber and through the by-pass. For wide body aircraft, the amount of air coming through them is unbelievable.

Regards,

Dan

Answer 3

a few people are wrong. most are correct.

the exhaust from the combusting part of the turbofan will exit faster

the bypass or the air from the non combusting part will exit at slower speed.

the exhaust is indeed powerful enough to blow away a truck at 100 feet. here's the vid : http://www.youtube.com/watch?v=DFP4xl0V0...

it isn't as fast as what lover not a fighter proclaims.

however, it is for sure, faster than the speed of the aircraft because otherwise, the exhaust wouldn't be propelling the aircraft forward and that is the whole concept behind aircraft propulsion.

Answer 4

It depends on where you measure.  The exhaust coming out of the core of the engine (where the combustion occurs) is moving at hundreds of miles per hour.  The air flow from the front fan (which flows around the exhaust from the core and provides most of the thrust) is moving more slowly.  And both slow down as you move further back from the engine.

Even so, the jetwash from the engines is sufficient to blow a truck off the road even 100 feet or more behind the aircraft, as some televised experiments have proved.

Answer 5

"lover not a fighter" you should probably stop contributing to the aircraft forum, as it seems like most of your answers are based on assumptions you gain from other fields. Most of the answers I've seen from you are erroneous and just contains a very basic knowledge at best...

On topic though, on normal turbofan engines which are used in normal jetliners, the air coming out of the jet engine is far below supersonic, and in normal flight they will be pretty close to the actual speed of the airplane itself

Answer 6

The top guy wrote:

>> is moving at hundreds of miles per hour.

The next guy wrote (jet engine designer - NOT):

>>  sonic velocity,

====

In physics there's a formula

MV = MV

Which means that

velocity of the jet * mass of the jet = velocity of the air * mass of the air

We know that the jet liner is VERY HEAVY and the air is VERY LIGHT.  So to compensate the air has to travel MUCH faster.  So given that the jet line is hundreds time heavier than air, the air has to travel much faster than the plane to compensate.

Basically that all means that the air traveling OUT the engine is going thousands of miles per mile.

Good luck...