Copyright © 2007 Dorling Kindersley
Many modern machines, from motorbikes to jet aircraft, are powered by engines. An engine is a machine that turns fuel into movement. The fuel is burned to generate heat energy. The heat is then converted into mechanical power. In a car or motorbike engine, the power comes from pistons and cylinders. In a jet aircraft, power comes from hot gases rushing past a spinning wheel called a TURBINE. Engines also produce various waste gases, which cause pollution.
These are machines that extract and use the energy from a moving liquid or gas. Windmills and waterwheels were the very first turbines. Their sails and paddles took power from the movement of wind and water. Turbines are still important today, especially as they are used in power stations and jet engines.
An aeroplane’s jet engine has one or more large fans at the front. These mix air with fuel and compress the mixture. In the combustion chamber, the fuel ignites, burns, and produces hot gases. As the gases expand, they turn a turbine that spins the fans. The force of the hot gases rushing backwards out of the engine propels the aircraft forwards.