Assessment of emission and environmental parameters of different commercial high by-pass turbofan engines throughout landing and take-off cycle

Abstract

Achieving more eco-friendly aircraft propulsion systems is of paramount importance in the aerospace industry since their exhaust emissions possess an important influence on the depletion of ozone layer. In this work, 24 turbofan engines having the close thrust ranging from 117 to 133 kN are examined using energetic, exergetic, and exergo-environmental tools throughout the LTO cycle involving take-off, climb-out, approach, and taxi-out phases. According to emission findings, the highest CO emission indexes (CO EIs) of the engines vary from 13.77 to 40.1 g/kg fuel in the idle phase; whereas the highest NOx EIs change from 18.4 to 64.36 g/kg fuel at take-off phase. Moreover, the highest exergy efficiency (ExEFF) of the turbofan engines vary between 15.88% and 24.31% at the climb-out phase whilst the lowest ExEFF change between 4.59% and 7.46% at the idle phase. Moreover, the idle phase is observed to have the highest wasted exergy ratio (WExR) varying from 18.5% to 19%; whereas the climb-out phase enjoys the lowest WExR changing from 15.11% to 16.8%. As a new index, specific irreversibility production (SIP) of the engines is observed to range from 0.297 to 0.497 MW/kN at the taxi-out phase; while SIP becomes the minimum at the climb-out phase, changing from 0.138 to 0.269 MW/kN. It could be deduced that since by-pass ratio and compressor pressure ratio of the engines have significant influences on exergetic and emission values, increasing the thrust of the engine does not mean raising its emission value or wasted exergy ratio. It is thought that this study helps find optimum design variables leading to the lowest environmental effect.