What is an afterburner engine?
An afterburner (or a reheat) is an additional component present on some jet engines, mostly military supersonic aircraft. Its purpose is to provide an increase in thrust, usually for supersonic flight, takeoff and for combat situations. Afterburners are generally used only in military aircraft, and are considered standard equipment on fighter aircraft. The handful of civilian planes that have used them include some NASA research aircraft, the Tupolev Tu-144, Concorde and the White Knight of Scaled Composites.
Why do afterburners use so much fuel?
When the afterburner is turned on, additional fuel is injected through the hoops and into the hot exhaust stream of the turbojet. The fuel burns and produces additional thrust, but it doesn’t burn as efficiently as it does in the combustion section of the turbojet. You get more thrust, but you burn much more fuel. Afterburners generate a larger amount of thrust by accelerating the air mass passing through the engine, without the need to increase the engine size. This rapid acceleration of air is achieved by injecting fuel into an extended exhaust nozzle section.