Infrared simulation of aircraft rear fuselage based on a coupled CFD method

As an inner heat source, the propulsion system of aircraft obviously influences the rear fuselage thermal status and thus produced infrared signature. In this paper, a coupled flow-heat simulation method is established to calculate the inner and outer flow fields of a realistic aircraft exhaust system. Considering multi heat transfer modes and fluid-solid thermal interactions, the method is examined by available experimental data. Different nozzle layouts are then provided to analyse the influence of inner hot parts including combustion gas and solid walls on the outer fuselage temperature changes. Thermal radiation is individually researched and analysed since radiation flux heats the outer fuselage skin significantly, especially in the cold convection channel. The simulation results indicate that the appearance of intermediate shield device effectively suppresses the outer fuselage temperature-rise and therefore resulting infrared signatures. In comparison, the exhaust system equipped with intermediate shield could decrease outer fuselage infrared signatures by 69 and 40% for 3-5 mu m band and 8-12 mu m band, respectively.