Investigation of effects of component and fuel parameters on performance of jet engine and main units

The studies addressing the fuel efficiency of jet engines are of critical significance in terms of mitigating the environmental impact of aviation. In this context, examining aviation engines at the component level reveals the fuel consumption of engine behavior more clearly. In the present study, the influences of design variables (combustor pressure ratio, isentropic efficiencies of compressor and turbine) and fuel lower heating value on performance and exergetic parameters (exergy destruction, exergy efficiency, and exergetic improvement potential) of a micro turbojet engine producing approximately 240 N thrust are investigated on a component basis and for the entire engine. As the isentropic efficiency of compressor raises from 0.9 to 0.98, the exergy destruction of compressor diminishes from 10.297 kW to 0.87 kW, whereas with the influence of isentropic efficiency of turbine, the exergy destruction of turbine drops from 5.915 kW to 0.474 kW. The exergy efficiencies belonging to turbomachinery vary in the ranges of 86.82%-98.63% for compressor and 93.95%-99.48% for turbine, respectively. The exergy efficiency of the overall engine changes between 12.8% and 16.75% due to the effect of isentropic efficiency of turbine. Finally, the influence of combustor pressure ratio is limited to below 1% for the combustor efficiency, whereas the exergy efficiency of the whole engine is measured to be between 11.87% and 14.9% with the change in fuel lower heating value. This study demonstrates that thermodynamic indicators are very beneficial for observing the degree of influence of each variable, and the energy and exergetic metrics of the micro jet engine are highly sensitive to changes in internal design parameters.