Turbofan | How Turbofan Engine Works

To move an airplane through the air, thrust is generated by some kind of propulsion system. Most modern airliners use turbofan engines because of their high thrust and good fuel efficiency. A turbofan engine is the most modern variation of the basic gas turbine engine. As with other gas turbines, there is a core, every gas turbine engine has a combustion section, a compressor and a turbine. The compressor, burner, and turbine are called the core of the engine, since all gas turbines have these components. The core is also referred to as the gas generator since the output of the core is hot exhaust gas.
In the turbofan engine, the core engine is surrounded by a fan in the front and an additional turbine at the rear. The fan and fan turbine are composed of many blades, like the core compressor and core turbine, and are connected to an additional shaft.
As with the core compressor and turbine, some of the fan blades turn with the shaft and some blades remain stationary. The fan shaft passes through the core shaft for mechanical reasons. This type of arrangement is called a two spool engine (one "spool" for the fan, one "spool" for the core.) Some advanced engines have additional spools for even higher efficiency.
How does a turbofan engine work?
Firstly, the air is sucked inside the engine via a fan, and air divides into two various paths.
Some part of the air enters the engine core where combustion takes place while the remaining part of the air (bypass air) moves outside of the engine core by a duct.
After suction, the air enters into a low-pressure compressor which increases the pressure of the air according to the requirements and sends it into a high-pressure compressor.
When the low compressed air comes into the high-pressure compressor, it further compresses the air up to very high pressure and also high increases its temperature.
The high-pressure compressor makes the air temperature so high that when it touches the fuel in the combustion chamber, the combustion process starts itself.
After combustion of the air-fuel mixture, the combusted gas enters into the low-pressure and high-pressure turbine.
After entering the turbine, the hot gases expand into the turbine and strike the turbine blades. The turbine blades extract enough power from the combusted mixture to move the low-pressure compressor and fan. The remaining power of the combusted mixture is sent toward the exhaust nozzle.
When the exhaust gases enter the nozzle, the nozzle converts their pressure energy into speed and converts them into very high-speed gases.
When high-speed gases are discharged from the nozzle into the atmosphere, they generate thrust, which moves the airplane forward.
The speed of the air flowing by the fan is slightly faster than the speed of the air flowing free. This flow of air is known as the bypass or fan airflow.