The combustor is an impingement cooled annular design. An open circuit gas turbine cycle has a compressor, a combustor and a turbine. The single annular combustor has 24 Spray Nozzles. This difference allows the combustor to generate much less NO than other combustors. Hot gases leaving the combustor expand through the turbine. Early gas turbine engines used a single chamber known as a can type combustor. An engine that uses an annular combustor is the CFM International CFM56. It has a single annular combustor and is controlled by an EEC. They consist of an inlet, a combustor, and a nozzle. One variation on the standard annular combustor is the "double annular combustor" (DAC). Ramjets always slow the incoming air to a subsonic velocity within the combustor. Most variants of the CFM56 feature a single-annular combustor. The burning process in the combustor is significantly different from that in a piston engine. Fuel is mixed with the compressed air and burns in the combustor. It is usually placed between the compressor outlet and the combustor.