An Introduction to Aircraft Engines
In my previous article, I made an introduction to aircrafts and explained the principles of flying. In this article, I will explain various aircraft engines and how the thrust is obtained.
An aircraft engine is the propulsion system for an aircraft that generates mechanical power. Engines used in aviation includes:
- Piston Engine, which is an internal combustion engine that uses one or more pistons to convert pressure into rotational motion,
- Turbojet Engine, which is a type of jet engine that produces all its thrust by spraying a high-energy gas stream from the engine exhaust nozzle,
- Turboprop Engine, which is a type of jet engine that optimized for running the propeller,
- Turboshaft Engine, which is a type of jet engine that optimized to generate shaft power to propel machines rather than generating thrust,
- Turbofan Engine, which is a type of jet engine that produces thrust using a combination of flow and bypass air driven by the jet core and accelerated by a ducted fan.
From now on, I will explain the process of obtaining thrust through the jet engine.
Jet engines are also called “gas turbines”. The working principle of the jet engine is based on Isaac Newton’s principle that “for every movement there is an equal and opposite reaction”.
The working cycle of the engine consists of the processes of intake, compression, ignition and exhaust occurring simultaneously in different parts of the engine. The air in the front is sucked by the engine with the help of the fan. The blades rotating at high speed in the compressor compress the air and the pressure of the air rises. Compressed air is sprayed with fuel, and an electric spark ignites the compressed air-fuel mixture. The burning gases expand and exit the nozzle at the rear of the engine at high speed, pushing the aircraft forward. This force pushing the plane forward is called “thrust”.
Let’s briefly talk about the parts of the jet engine, whose tasks given above in obtaining the thrust:
Fan: After absorbing large amounts of air, it accelerates the air and turns into two parts. Some of it goes to the core of the engine, the other part goes outside the engine core. The cold air passing through the duct surrounding this core both quiets the engine and helps add thrust to the engine.
Compressor: It is the first component of the engine core. It compresses the incoming air into smaller spaces, causing a pressure increase. The trapped air is forced into the combustion chamber.
Combustion chamber: Here, air is mixed with fuel. The combustion air — fuel mixture provides a high-temperature high-energy airflow.
Turbine: The turbine blades are rotated by the incoming high-energy air flow.
Nozzle: It is the “exhaust duct” of the engine. The combination of warm air and cold air is expelled, while producing exhaust, which causes the airplane to propel forward.
Gas turbine performance is directly affected by inlet air density and air ambient conditions. Gas turbine power is determined by altitude, temperature, inlet conditions, outlet conditions, humidity, and fuel conditions.
I wanted to continue my series of articles on aircrafts by explaining the aircraft engines and obtaining the trust on jet engine. In my next article, I will explain the malfunctions that may occur in the aircraft engines and the systems in the aircrafts to prevent these malfunctions.
Pelinsu Erimez
