My Science School

JET ENGINES

There are four engines on a Boeing 747, two on each wing, contained within engine cowlings (casings) attached to the wing undersides. The front entrance to the engine, known as the intake, is so large a person could stand in it.

The 747 engine is a type of jet engine called a turbofan. All jets work in the same way: hot, compressed air is expelled from the back of the engine, driving it forwards. In a turbofan, air is sucked into the engine by a whirling fan in front of the compressor. It is driven by another turbine at the rear of the engine. Some of the inflowing air is ducted around the combustion chamber to join the exhaust gas. Besides being much more powerful than other types, the engine is cooler and quieter, and more economical in its use of fuel.

Turbofan engines are equipped with thrust reversers. When in use, the jet of hot exhaust gases is deflected forwards instead of backwards, producing a force which rapidly slows down the plane landing on the runway.

Besides driving the plane through the air, the engines supply the power needed for the electricity used on board. Air is also diverted from the engine compressor to pressurize the cabin.

Picture Credit : Google