Jet engine hot parts (e.g., jet nozzle) are a crucial source of aircraft’s infrared (IR) signature from the rearview, in 1.9-2.9 μm and 3-5 μm bands. The exhaust nozzle design used in a jet aircraft affects its performance and IR signature (which is also affected just by performance) from the engine layout. For supersonic aircraft (typically for M ∞ > 1.5), a converging-diverging (C-D) nozzle is preferred over a convergent nozzle for optimum performance. The diverging section of the C-D nozzle has a full range of visibility from the rearview; hence, it was not considered a prudent choice for low IR observability. This theoretical study compares the IR signature of the C-D nozzle with that of the convergent nozzle from the rearview in 1.9-2.9 μm and 3-5 μm bands for the same thrust. It is found counterintuitively that the IR signature of the engine with a convergent nozzle is higher than that of an engine with a C-D nozzle for the same thrust, in spite of the lower visibility of engine hot parts mentioned earlier. For an engine with a C-D nozzle, directional IR radiance from the boresight is reduced by ~25% and ~12% (relative to the engine with a convergent nozzle) in 1.9-2.9 μm and 3-5 μm bands, respectively.


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    Title :

    Analytical Estimation of Infrared Signature of Converging and Converging-Diverging Nozzles of Jet Engine


    Additional title:

    Sae Int. J. Aerosp


    Contributors:

    Published in:

    Publication date :

    2021-04-21


    Size :

    18 pages




    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English




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