JET ENGINE

Contents

• History

• Types of Jet engines

• Major components

• Working

• Advanced Jet planes

History of Jet Engines

• Sir Isaac Newton in the 18th century was the first to theorize that

a rearward-channeled explosion could propel a machine forward at a great

rate of speed. This theory was based on his third law of motion.

As the hot air blasts backwards through the nozzle the plane moves forward.

• Henri Giffard built an airship which was powered by the first aircraft engine,

a three-horse power steam engine. It was very heavy, too heavy to fly.

• In 1874, Felix de Temple, built a monoplane that flew just a short hop

down a hill with the help of a coal fired steam engine.

• Otto Daimler in the late 1800's, invented the first gasoline engine.

• In 1903, the Wright Brothers flew, "The Flyer", with a 12 horse power

gas powered engine.

• From 1903, the year of the Wright Brothers first flight,

to the late 1930s the gas powered reciprocating internal-combustion engine

with a propeller was the sole means used to propel aircraft.

• It was Frank Whittle, a British pilot, who designed the first turbo jet engine

in 1930.The first Whittle engine successfully flew in April, 1937.

This engine featured a multistage compressor, and a combustion chamber,

a single stage turbine and a nozzle.

• The first jet airplane to successfully use this type of engine was the

German Heinkel He 178 invented by Hans Von Ohain.

It was the world's first turbojet powered flight.

The W2/700 engine flew in the

Gloster E.28/39, the first British

aircraft to fly with a turbojet

engine, and the Gloster Meteor.

A jet engine is an engine that

discharges a fast moving jet of fluid to

generate thrust in accordance with

Newton's third law of motion.

Types Of Jet engines

•Water Jets

•Motor Jets

•Turbo jets

•Turbo fans

•Rockets

•Ramjets

Working principleJet engines are also called as gas turbines. The

engine sucks air in at the front with a fan. A

compressor raises the pressure of the air. The

compressed air is then sprayed with fuel and an

electric spark lights the mixture. The burning gases

expand and blast out through the nozzle, at the

back of the engine. As the jets of gas shoot

backward, the engine and the aircraft are thrust

forward.

TURBO JET ENGINES

Major components

• Air intake

• Compressors

• Combustors

• Turbines

• Nozzles

• Fuel system

• Cooling system

Intermediate components

• Turbo pumps

• Afterburners( reheat)

• Thrust reversers

Fan-The fan is a first component in a turbo fan.

The large spinning fan sucks in large quantity of

air. Most of the fan blades are made up of titanium.

It then speeds this air up and splits it into two

parts. One part continues through the “core” or

center of the jet engine, where it is acted upon by

other jet engine components.

AIR INTAKE

The second part “bypasses” the core of the

jet engine. It goes through a duct which

surrounds the core to the back of jet engine

where it produces much of force that propels

the airplane forward. This cooler air helps to

quiet the jet engine as well as adding thrust

to the jet engine.

Compressor - The compressor is the first

component in the jet engine core.

The compressor is made up of fans with many

blades and attached to a shaft. The compressor

squeezes the air that enters it into progressively

smaller areas, resulting in an increase in the air

pressure. This results in an increase in the energy

potential of the air. The squashed air is forced into

the combustion chamber.

Combustor - In the combustor the air is mixed with fuel

and then ignited. There are as many as 20 nozzles

to spray fuel into the air stream. The mixture of air and

fuel catches fire. This provides a high temperature,

high-energy airflow. The fuel burns with the oxygen

in the compressed air, producing hot expanding gases.

The inside of the combustor is often made of ceramic

materials to provide a heat-resistant chamber.

The heat can reach 2700°.

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Turbine - The high-energy airflow coming

out of the combustor goes into the turbine,

causing the turbine blades to rotate. The turbines

are linked by a shaft to turn the blades in the

compressor and to spin the intake fan at the front.

This rotation takes some energy from the high-energy

flow that is used to drive the fan and the compressor.

The gases produced in the combustion chamber move

through the turbine and spin its blades.

The turbines of the jet spin around thousands of

times. They are fixed on shafts which have

several sets of ball-bearing in between them.

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displayed.

Nozzle - The nozzle is the exhaust duct of the

jet engine. This is the jet engine part which actually

produces the thrust for the plane. The energy depleted

airflow that passed the turbine, in addition to the colder

air that bypassed the engine core, produces a force

when exiting the nozzle that acts to propel the engine,

and therefore the airplane, forward. The combination of

the hot air and cold air are expelled and produce an

exhaust, which causes a forward thrust.

The nozzle may be preceded by a mixer, which

combines the high temperature air coming from the jet

engine core with the lower temperature air that was

bypassed in the fan. The mixer helps to make the jet

engine quieter.

Variable Exhaust Nozzle,

on the GE F404-400 low-

bypass turbofan installed

on a Boeing F-18

Turbo pumps are centrifugal pumps which are spun

by gas turbines and are used to raise the propellant

pressure above the pressure in the combustion

chamber so that it can be injected and burnt.

Turbo pumps are very commonly used with rockets,

but ramjets and turbojets also have been known to use

them.

Turbopumps

Due to temperature limitations with the gas turbines,

jet engines do not consume all the oxygen in the air

('run stochiometric'). Afterburners burn the remaining

oxygen after exiting the turbines, but usually do so

inefficiently due to the low pressures existing at this

part of the jet engine; however this gains thrust, which

can be useful.

Afterburners (reheat)

Thrust reversal, also called reverse

thrust, is the temporary diversion of

an aircraft engine's exhaust or

changing of propeller pitch so that

the thrust produced is directed

forward, rather than aft. This acts

against the forward travel of the

aircraft, providing deceleration.

Thrust reversers

Apart from providing fuel to the engine,

the fuel system is also used to control

propeller speeds, compressor airflow

and cool lubrication oil. Fuel is usually

introduced by an atomized spray, the

amount of which is controlled

automatically depending on the rate of

airflow.

Feul system

. It also increases the energy extracted

by the turbine which drives the

compressor even faster and so there is

an increase in air flowing into the

engine as well.

Cooling air then passes through complex

passages within the turbine blades. After

removing heat from the blade material,

the air (now fairly hot) is vented, via

cooling holes, into the main gas stream.

Cover plates are incoperated on blades

Cooling system

This acts as a centrifugal compressor to

pressurize the cooling air before it enters

the blade. Another solution is to use an

ultra-efficient turbine rim seal to

pressurize the area where the cooling air

passes across to the rotating disc.