A combustor is a component in which air and fuel are mixed, ignited, and burned and is found in certain kinds of engines. Several types of engines use combustors, and they may take several basic design forms. Jet engines, turbines, and special classes of engines, called ramjets and scramjets, all use a combustor as part of their design. They can conform to one of three general design types, but all operate under the same principles.
All gas turbines, or jet engine, have a combustor where the fuel is mixed with air and burned. The component is analogous to a cylinder in a typical automobile engine. Jet engines use a compressor to inject air into the combustor, where it is mixed with vaporized jet fuel and ignited. The burning jet fuel creates hot gases which then turn the turbine. The turbine projects these exhaust gases at the the rear of the engine, through a nozzle, creating thrust.
A typical combustor can be one of three basic design types. All combustor assemblies tend to be circular in shape but can be distinguished by the specific configuration of the burner chambers. A can combustor consists of several independent burner chambers, each resembling a can, with their own distinct casing, fuel injection, and ignition components, arranged together in a ring.
Can annular or "cannular" combustors are similar to can combustors in that they consists of a series of smaller can shaped burner chambers, arranged in a ring. The difference is that the ring itself acts as a common casing for all of the burner chambers, although each chamber will have its own separate fuel delivery and ignition systems.
An annular combustor is also ring shaped, but the burner itself is one large ring shaped chamber. These types of combustors have many advantages over the other two basic types, including greater simplicity, which cuts down on maintenance, and improved efficiency. Injection and ignition assemblies are simpler, the ignition and burning processes are more even, and other technical performance aspects tend to surpass the other types as well. For this reason, most modern jet engines tend to use this type of combustor, and most of the efforts towards improving this engine component focus on this type of combustor.