Internal combustion engine

An internal combustion engine utilizes the gas expansion caused by the burning of a fuel, to produce mechanical energy to do work. The change in volume of the fuel and air mixture increases pressure when in a confined space—the combustion chamber—and is converted to mechanical force. The most common internal combustion engine—the piston engine—uses the mechanical force created to drive a rotating crankshaft which powers a flywheel and provides the compression for other combustion chambers in sequence.

A second common form, the jet turbine, uses air compression from forward motion or the action of a compressor fan to provide initial fuel-air compression. The energy captured from the fuel mixture's combustion may be captured through a mechanical linkage to a central shaft or through the direction of exhaust gases to provide thrust.

Internal combustion engines vary by type of fuel, manner of compressing the fuel-air mixture, and method of converting chemical energy from gas expansion into mechanical energy. Variations within types can include the use of the engine, manner of regulation, and general construction forms.