Thrust of Jet engines.?

Question

is it created by expelling a mass of air at velocity, to cause mass of plane to move opposite direction (mass1*velocity1 = mass2*velocity2), or is it a "push" of air aginst the air behind it, (kind of like pushing against a wall) to move plane forward. or is it just both. or is it the same thing.

Answer 1

thrust is created because of unbalanced forces due to change in momentum of air at inlet and outlet

Answer 2

In jets engines ignite the fuel and thrust is created wing Flaps are used to push the air downwards a turbulent flow of air is used to lift the jet.

Answer 3

propulsion of a turbine air flow, thrust pushed on a mass built to fly,

Answer 4

The thrust developed in a jet engine is the unbalanced force thet is caused by the difference in the momentum of the low -velocity air entering the engine and the high-velocity exhaust gases leaving the engine,and it is determined from Newton's second law.The pressures at the inlet and the exit of the jet also influence the thrust.so the formula is:

F=(m'V)exit-(m'V)inlet+(AP)exit-(AP)in...

m':mass flowrate

V:velocity

A:inlet or exit area

P:pressure

Answer 5

The volume of air intake causes a low pressure area ahead of the engines thereby creating a 'Pull' on the engine.

The large volume of air into the jet engine is greatly increased in the combustion chamber.

This huge volume of superheated, high energy air is exhausted from the rear nozzles of the engines at a tremendous velocity which, as it meets with the outside atmosphere, the high velocity decreases rapidly, it converts to a very high pressure (Thrust), acting against the lower pressure of the atmosphere. This causes a huge opposite force which drives the plane forward. The propellant is stored in the wing tanks as a liquid and is injected via atomisers (vaporisers) into the combustion chamber where some of the intake air is used as combustion air while the rest of the intake is mixed with and heated by the high temperature combustion gases.

The engine gives up some of its energy in driving the 'Fan' of the intake and, the remaining very hot, high velocity air is expelled at the rear of the engine. The heat of the exhaust gases is dispelled into the atmosphere.

(Newton: For every action, there's an equal and opposite reaction).

(A jet engine operates in exactly the same way as an Industrial Gas Turbine, the energy of which drives its intake air compressor via the compressor turbine, the exhaust from which drives a further turbine connected to a generator or other machine. Turbines are simply Drivers. The still very hot final exhaust gases are often used in 'Economisers' to pre-heat other processes).

A rocket engine operates on an entirely different principle due to the combustion chamber configuration (Enclosed with no intake from the outside), and the shape of the nozzles (Flared outwards).

Answer 6

It is NOT a push against the air behind it. It is conservation of momentum, as you note, following Newton's law -- equal and opposite reaction.

Many people thought that a rocket would not work in outer space for that incorrect reasoning, but it does. A jet would work in space if you could keep it supplied with oxygen.

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Answer 7

All jet engines are reaction engines that generate thrust by emitting a jet of fluid rearwards at relatively high speed. The forces on the inside of the engine needed to create this jet give a strong thrust on the engine which pushes the craft forwards.

Jet engines make their jet from propellant from tankage that is attached to the engine (as in a 'rocket') or from sucking in external fluid (very typically air) and expelling it at higher speed; or more commonly, a combination of the two sources.

http://en.wikipedia.org/wiki/Jet_engine#...