EXERGY ANALYSIS OF AN AIRCRAFT TURBOJET ENGINE

In the present study, the exergy analysis was done on the different sections of the turbojet engine J85-GE-21 in three different flights Mach number (0.4, 0.6 and 0.8). Parametric analysis is carried out based on exergy analysis to see the effects of main cycle parameters on cycle efficiency. In this paper, second law analysis is performed to able to see exergy destruction throughout the turbojet engine. The results show that the greatest exergy loss in the after burner due to its high irreversibility. As the second major exergy loss is in combustion chamber, the optimization of after burner has an important role in reducing the exergy loss of total turbojet engine cycle. Using the small amount of information provided by cabin indicators and writing the computer code, the highest exergy efficiency can be calculated from a specified Mach number (0.4). It’s shown from results that mainly based on the operating parameters for 0.6 .09, 2700 K < T6 < 3600 K increase in the after burner temperature the on propulsion efficiency of the cycle increases for both. However, for all nozzles pressure ratio the SFC of the cycle increase by increase in the Mach number of the turbojet engine.