August 12, 2018

048 - Jet Engines

32 minutes

Love ‘em planes ✈️

Jet engine is a type of internal combustion engine that produces thrust based on a fast moving discharge of hot gases, widely used on airplanes.

History

Hero of Alexandria built Aeopile which was the earliest for of jet engine dating back to 1st century A.D.

It was a steam turbine which rotated when a central water container is heated. Much like a lawn sprinkler.

Was more of a curiousity thing and did not have practical application.

Chinese invented rocket fireworks in the 13th century, but since these were inefficient, did not develop for few more centuries.

The need

The propeller driven airplanes had their limitations in terms of max speed that could be achieved.

Pressure build up while approaching sound barrier caused many of these planes to crash.

Key components

Air intake

Compressor

Gas turbine

Combustion chamber

Exhaust nozzle

Types of Jet Engines

Turbojet: Basically a gas turbine that compresser air through an inlet and compressor. Fuel is mixed with th compressed air in the combustion chamber and the exhaust gases propel the engine forward and also run the compressor. All the ir passes through the inlet into the compressor, the combustion chamber and then through the turbines before escaping out.

Turboprop: Turboprop uses the exhaust to mainly drive a propeller that provides the thrust to move the engine forward. In this type of engine, the jet thrust is augmented by the propeller. They perform extremely well at low speeds. Another type of turboprop called turboshaft utilises all the power to run the propeller and produces almost no jet exhaust. This mainly used to power helicopters.

Turbofan: Turbofan is essentially a turbojet with a giant fan in the front of the compressor. The fan draws more ait and while a part of it enters the inlet, the rest of it goes around the engine providing additional thrust in a way similar to a turboprop. This is the way more efficient than a turbojet. The fan allows greater thrust at low speeds. In passenger jets, the engines have a biger fan and helps in reduced noise and increased efficiency whereas in military aircraft where flight is usually supersonic and noise isn’t a factor, turbofans with smaller fans are used to reduce drag and increase the menouverability of the craft.

Ramjet: Ramjet does not use a compressor instead depends on the air pressure to build up at the inlet duct. As a result, a ramject cannot work in subsonic speeds and requires it to be accelerated to supersonic speeds by a turbojet or a rocket engine. Practical applications are in missiles and unmanned vehicles.

Shoutout

Storiyoh

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