Jet Engineconsist of an air
inlet, an air compressor,
a combustion chamber, a gas turbine (that
drives the air compressor) and a nozzle. The air is compressed into the
chamber, heated and expanded by the fuel combustion and then allowed to expand
out through the turbine into the nozzle where it is accelerated to high speed
to provide propulsion.Turbojets are quite inefficient if flown below about Mach
2and very noisy. Most modern aircraft use turbofans
instead for economic reasons. Turbojets are still very common in medium range cruise missiles,
due to their high exhaust speed, low frontal area and relative simplicity.
Propulsion
Fig showing balloon with no
escape path for the air inside.
Propulsion is the net force
that results from unequal pressures. Gas
(air) under pressure in a sealed container exerts equal pressure on all
surfaces of the container; therefore, all the forces are balanced and there are
no forces to make the container move.
If there is a hole in the
container, gas cannot push against that hole and thus the gas escapes. While the air is escaping and there is still
pressure inside the container, the side of the container opposite the hole has
pressure against it. Therefore, the net
pressures are not balanced and there is a net force available to move the
container. This force is called thrust.
The simplest example of the
propulsion principle is an inflated balloon (container) where the stem is not
closed off. The pressure of the air inside
the balloon exerts forces everywhere inside the balloon. For every force, there is an opposite force,
on the other side of the balloon, except on the surface of the balloon opposite
the stem. This surface has no opposing
force since air is escaping out the stem.
This results in a net force that propels the balloon away from the
stem. The balloon is propelled by the
air pushing on the front of the balloon.
JET ENGINE:
DEFINATION:
An
engine that burns fuel and uses the expanding exhaust gases to turn a turbine
and/or produce thrust.
TYPES OF JET ENGINE:
a.Turbojet
b.Turbofan
c.Turboshaft
d. Ramjet
e. Scramjet
