Analysis of cruise conditions on energy, exergy and NOx emission parameters of a turbofan engine for middle-range aircraft

Abstract

Studying efficiency and emissions of an aircraft engine at cruise phase is of high importance so as to help in finding optimum flight conditions. Especially, since exhaust emissions from the engine lead to climate change, quantifying exhaust emissions could show adverse effect of the aero-engine on environment. In this study, energetic and exergetic behaviour of high by-pass turbofan are parametrically examined. Besides, cruise NOx emission is measured by P3-T3, Boeing Fuel Flow Method 2 (BFFM2) and DLR methods. Moreover, the index as Specific NOx Production (SNP) is quantified for the turbofan engine. Thanks to this parameter, NOx effect of the engine is compared according to different flight conditions. For this aim, parametric cycle equations and emission calculation methods regarding turbofan engine are encoded so as to determine performance outputs for Mach changing from 0.7 to 0.9 and altitude between 9000 m and 11,000 m. According to performance results, the average specific fuel consumption (SFC) regarding turbofan engine is predicted as 19.65 g/kN.s at 9 km and 19.68 g/kN.s at 11 km. As for exergo-sustainability index, environmental effect factor is calculated as 1.19 at 9 km and 1.26 at 11 km. Also, the average cruise NOx emission index is found as 16.66 g/kg at 9 km and 13.93 g/ kg at 11 km. Finally, the mean SNP regarding the turbofan is measured as 0.5071 g/kN.s at 9 km and 0.3374 g/ kN.s at 11 km. The findings of this study provide useful insights to comprehend effects of flight conditions on aircraft emissions. In terms of environmental sustainability, decision mechanism could be enhanced to find out optimum flight conditions thanks to the presented results.