How does a jet engine's afterburner work?

The afterburner on a jet engine adds thrust to the engine. Tune in as Marshall Brain explains how an afterburner works -- and the pros and cons of using one -- in this episode of BrainStuff.

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Episode Transcript

Speaker 1 (00:00):
Welcome to Brainstuff from house stuff Works dot com where
smart happens. Hi Am Marshall Brain with today's question, how
does an afterburner work on a jet engine? A jet engine,
like a rocket engine, is a reaction engine. It works

(00:22):
by throwing mass in one direction and taking advantage of
the reaction in the opposite direction. In the case of
a jet engine, the engine bird's fuel like kerosene with
error from the atmosphere. The burning fuel heats and expands
the air, and this hot air shoots out the exhaust
end of the engine to create thrust. Most modern jet

(00:44):
engines use a turbine to improve the efficiency of the
engine and allow the engine to work at low speeds.
One part of the turbine sucks in airror and compresses
it before the fuel is injected. The back portion of
the turbine acts like a windmill, extracting entered from the
exhaust gases and using the energy to spin the compressor portion.

(01:05):
A modern turbine engine is extremely efficient and there's still
a lot of oxygen available in the exhaust stream. The
idea behind an afterburner is to inject fuel directly into
that exhaust stream and burn it using the remaining oxygen.
This heats and expands the exhaust gases further, and it
can increase the thrust of a jet engine by fifty

(01:28):
or more. The big advantage of an afterburner is that
you can significantly increase the thrust of the engine without
adding much weight or complexity to the engine. And afterburner
is nothing but a set of fuel injectors, a tube
and flame holder that the fuel burns in, and an
adjustable nozzle. A jet engine with an afterburner needs that

(01:49):
adjustable nozzle so that it can work with and without
the afterburners on the disadvantage of an afterburner is that
it uses a ton of fuel for the power it generates. Therefore,
most planes use afterburners sparingly. For example, a military jet
would use its afterburners when taking off from a short
runway on an aircraft carrier or during a high speed

(02:13):
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