How a Turbojet Engine Works?

The introduction of the turbojet engine brought about a revolution in the operating capabilities of many aircraft. Producing more power, faster speed, and higher fuel efficiency, turbojet engines became the staple for commercial and military aircraft. The turbojet is equally complex as it is impressive, but anybody with an interest in aviation should take the time to understand the fundamentals of these machines. In this blog, we will discuss the operating principle behind turbojets while also highlighting the various forms that may be found in standard aircraft.

Although the primary goal of a turbojet engine is to produce thrust in order to help an aircraft move, a similar design has long been used to generate significant amounts of electrical power from fossil fuels. Further, every later generation of engine that has come after the turbojet has been based on its operating principle. That principle can be summarized as the process of combusting air with fuel in an optimal ratio to facilitate power output. This process can be broken down into four distinct steps: intake, compression, combustion, and the turbine phase.

Intake

In order to create an optimal fuel-air mixture capable of combustion, there must be an air-intake system capable of bringing in continuous amounts of air with ease. To accomplish this, turbojet engines feature inlets, which help the air center directly on the fans, despite coming from various directions. For aircraft such as commercial jets, which are usually not capable of traveling faster than the speed of sound, a smooth, thick inlet suffices. However, supersonic aircraft such as military fighters require a narrower, skinny inlet.

Compression

The atmospheric air entering the intake is low pressure, particularly at higher altitudes. However, in order to optimize combustion, the air should be at a higher temperature that is under pressure. Therefore, downstream of the air intake section is the compressor, which consists of either centrifugal or axial fans. As the air passes through the fan, energy is added and the volume it occupies is reduced. As a result, the air leaves the compressor with higher pressure and temperature than it started with. Although the majority of air goes on to be combined with fuel and subsequently combusted, some enters the aircraft to be used for other operations, such as the ECS and fuel tank pressurization.

Combustion

Arguably the most important step in the engine cycle, combustion involves the ignition of the high-pressure, high-temperature fuel-air mixture. The combustion chamber, or burner, is a donut-shaped structure made from a material capable of withstanding several thousand degrees Fahrenheit. Combustion chambers are explicitly designed to ensure the exhaust maintains its high pressure and that it exits the engine uniformly.

Turbine/ Nozzle

The exhaust from the combustion chamber drives two separate processes. Over half of the kinetic energy in the exhaust is captured by the turbine, which is a fan that produces mechanical energy. This energy is used to drive several components, including the compressor fan and aircraft propeller. Therefore, once the engine is started and the plane is in motion, the turbojet can be considered self-sustaining, bolstering safety and efficiency. The rest of the kinetic energy from the exhaust is used to generate thrust after escaping through the nozzle.

Conclusion

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