Reaction kinetic simulation of the combustion and emission characteristics of a dual-fuel aero-engine

Compared with aviation kerosene, liquefied natural gas (LNG) has the characteristics of higher energy density, wider flammability limits, better cooling potential, better thermal stability, and lower cost. Using LNG as an alternative fuel to aviation kerosene will be an effective mean to solve the depletion of aviation kerosene and the environmental problems caused by this fuel. However, there are many technical difficulties for LNG used as a sole fuel for aero-engine. One possible way is mixing LNG with kerosene, as a mixed fuel for the aero-engine. In this paper, the characteristics of combustion and emissions of an aero-engine which respectively burning sole aviation kerosene and 50% aviation kerosene/50% methane mixed fuel were reaction kinetic simulated by adopting the reduced reaction mechanism of n-decane which was chosen as a surrogate fuel for aviation kerosene. The results show that, the flow distribution characteristics in a flame tube of the combustor under the condition that the aero-engine burning 50% aviation kerosene/50% methane mixed fuel is the same as the condition that the aero-engine burning aviation kerosene. However, the high temperature area in the main combustion zone is shorted, and the maximum temperature in the flame tube and the average temperature at the outlet of this flame tube are decreased by 15 K and 11 K, respectively. Moreover, the concentration field distribution characteristics of fuel under the condition that the aero-engine burning 50% aviation kerosene/50% methane mixed fuel is the same as the condition that the aero-engine burning aviation kerosene. However, the maximum concentration of fuel is increased, the maximum concentrations of C2H2, C2H4, C4H4 are decreased greatly in the flame tube, and the average concentrations of CO2 and CO at the outlet of this flame tube are decreased by 12% and 33%, respectively, but the average concentration of H2O is increased by 13%.