In order to optimize the design of the thermodynamic cycle of a turbine (Brayton cycle) for using modern common rail as an “active” combustion chamber, it was intended to write the present paper. About the present case, the “active” combustion chamber produces a large amount of the mechanical energy that drives the fan. The incoming air is compressed by the compressor, then it is refrigerated and inputted in the diesel engine. A high pressure common rail system optimizes the combustion in the diesel combustion chamber and the expansion begins inside the diesel engine. At the exhaust of the combustion chamber, a turbine completes the expansion of the hot gases. A nozzle accelerates the exhaust from the turbine to increase the overall thrust