Why does the exhaust nozzle expand or contract in jet engines equipped with afterburners?
Table of Contents
- 1 Why does the exhaust nozzle expand or contract in jet engines equipped with afterburners?
- 2 What do afterburners do on Jets?
- 3 Why is a variable exhaust nozzle required in an engine equipped with an afterburner?
- 4 How exactly does an afterburner increase the exhaust exit velocity?
- 5 How does nozzle size affect thrust?
- 6 How do afterburners increase the thrust of a jet engine?
- 7 What is an afterburner on a fighter aircraft?
- 8 How do high bypass engines produce supersonic exhausts?
Why does the exhaust nozzle expand or contract in jet engines equipped with afterburners?
The nozzle area is increased during afterburner operation to limit the upstream effects on the engine. To run a turbofan to give maximum airflow (thrust), the nozzle area may be controlled to keep the fan operating line in its optimum position.
What do afterburners do on Jets?
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.
What does the exhaust nozzle do in a jet engine?
All gas turbine engines have a nozzle to produce thrust, to conduct the exhaust gases back to the free stream, and to set the mass flow rate through the engine. The nozzle sits downstream of the power turbine.
Why is a variable exhaust nozzle required in an engine equipped with an afterburner?
Since the temperature of an afterburner can reach 1700 deg. An afterburning jet pipe is larger than a normal jet pipe would be so as to obtain a reduced velocity gas stream. Therefore, an afterburning jet pipe is equipped with either a two-position or a variable nozzle to provide for operation under all conditions.
How exactly does an afterburner increase the exhaust exit velocity?
A jet engine can produce more thrust by either accelerating the gas to a higher velocity or ejecting a greater mass of gas from the engine. The afterburner increases thrust primarily by accelerating the exhaust gas to a higher velocity.
How does a high bypass jet engine work?
The compressor absorbs all the mechanical power produced by the turbine. In a bypass design extra turbines drive a ducted fan that accelerates air rearward from the front of the engine. In a high-bypass design, the ducted fan and nozzle produce most of the thrust.
How does nozzle size affect thrust?
The length/diameter ratio of a nozzle affected the performance of an engine slightly and the averaged thrust declined slightly with the increase of length/diameter ratio.
How do afterburners increase the thrust of a jet engine?
Because of this, it is possible to inject additional fuel for burning downstream of the turbine, increasing the overall thrust of the jet engine. Since the temperature of an afterburner can reach 1700 deg.
How do afterburners work in a turbine engine?
A modern turbine engine is extremely efficient, and there is still a lot of oxygen available in the exhaust stream. The idea behind an afterburner is to inject fuel directly into the exhaust stream and burn it using this remaining oxygen. This heats and expands the exhaust gases further, and can increase the thrust of a jet engine by 50\% or more.
What is an afterburner on a fighter aircraft?
Most modern fighter aircraft employ an afterburner on either a low bypass turbofan or a turbojet. On this page we will discuss some of the fundamentals of an afterburning turbojet . In order for fighter planes to fly supersonically , they have to overcome a sharp rise in drag near the speed of sound.
How do high bypass engines produce supersonic exhausts?
High bypass engines send most air past the jet proper to be combined with the jet exhaust and form the actual engine exhaust. Pure jet or some “low bypass ratio” turbo fan engines may have supersonic exhausts while “high bypass ratio” turbofan are always subsonic.