Monday, October 18, 2010

Afterburner (Jet Engine)

A jet engine afterburner is an extended exhaust section which contains extra fuel injectors. When the afterburner is turned on, fuel is injected, which ignites readily due to the relatively high temperature of the incoming gases. The resulting combustion process increases the afterburner exit (nozzle entry) temperature significantly, resulting in a steep increase in engine net thrust. Thus, jet engines achieve additional thrust by directly injecting fuel at the engine exhaust. The afterburner gives the aircraft a rocket-like boost as the fuel ignites in the exhaust chamber. The tradeoff is higher fuel consumption, a greater amount of heat, and consequently, greater visibility to the enemy.

The purpose of an afterburner is to provide a temporary increase in thrust, both for supersonic flight and for takeoff, as the high wing loading typical of supersonic aircraft designs means that take-off speed is very high. On military aircraft the extra thrust is also useful for combat situations. This is achieved by injecting additional fuel into the jet pipe downstream of the turbine. The advantage of afterburning is significantly increased thrust; the disadvantage is its very high fuel consumption and inefficiency, though this is often regarded as acceptable for the short periods during which it is usually used.

Afterburner Run on a Jet Aircraft