What Is a Turbojet? Definition, Meaning and Concept
A turbojet is a type of gas turbine engine commonly used in aircraft. These engines are used in some aircraft, although many use turbofan engines instead. Turbojets are also used in some missiles. The turbojet, like all gas turbines, collects the passing air to derive the oxygen needed for combustion. Air is compressed, mixed with fuel, and then ignited. The force of the exhaust gases moving through the nozzle at the rear of the engine creates the thrust that moves the craft.
At the front of the engine is the intake or intake. It collects outside air in the most efficient and aerodynamically optimal way possible and feeds the air to the compressor. The compressor is usually a series of rotating blades, acting as airfoils, arranged in successive rows. As the air passes through each set of blades, its temperature and pressure increase. To generate a substantial amount of thrust, the temperature and pressure of the air must build up before it enters the engine's combustion chamber.
In the combustion stage, oxygen in the air is ignited by adding fuel. The temperature of the air passing through this stage increases exponentially. It is forced through a turbine immediately after the combustion chamber, causing the turbine to rotate. It is this section of the engine that powers the other parts. The turbine and the compressor are connected through a central axis. The energy gathered from the turbine is used to power the compressor.
The last section of the turbojet is the nozzle. Once the gases have passed through the turbine, their temperature and pressure are even greater than those of the air passing out of the turbojet. This heated and pressurized air is pushed through the nozzle, causing the gases to accelerate and produce the thrust that moves the craft.
An afterburner can be added to the turbojet. This is a device in the exhaust section of the turbojet that adds additional fuel to the heated exhaust gases. The added fuel burns quickly, increasing the temperature and pressure of the air, and consequently the amount of thrust.
The downside of a turbojet engine is its relative inefficiency at lower speeds compared to a turbofan. The turbojet reaches optimal working conditions after Mach 2 or twice the speed of sound. The sound it creates is also quite detrimental to any nearby populations.