Performance Evaluation of a Turbojet Engine by Exergy Analysis of its Components

In this research, the performance of the J85-GE21 turbojet engine by exergy analysis of engine components was evaluated. The performance of the engine and its components for different power loads, at S.L. and 11000 meters and several different speeds, was investigated by the equilibrium exergy and energy equations. The highest exergy efficiency at sea level was related to the compressor by 96.72%, and then the nozzle and turbine by 93.70% and 92.31%, respectively. By reducing the inlet air speed to the engine at any altitude, the efficiency of all engine components and overall efficiency decreased. The lowest exergy efficiency at sea level related to afterburner was 54.81%, and then the combustion chamber was 80.42%. Increasing the altitude reduces the exergy destruction of the engine by 70%. It was found that the overall efficiency of the turbojet engine was reduced by 0.45% due to increasing one air inlet engine temperature rise by assuming that the air pressure was constant.