The modern turbofan afterburner is characterized by its high boost and efficiency and by its compact geometry which is achieved by locating the flameholding baffles immediately downstream of the turbine exhaust plane of the engine core and bypass gas stream. At the confluence, the stream divider may be a simple cylinder or it may be of lobed configuration to encourage mixing between the two gas streams in the downstream jet pipe in order to improve the unboosted thrust of the engine. The geometry of the afterburner hardware must be adapted to suit the choice of mixed or unmixed configurations. In flight, selection of the afterburner must be fast and reliable under all flight conditions with times to full thrust of the order of only a second or two. Both the light up and the subsequent acceleration to full thrust are expected to be smooth with no excessive initial thrust jump. Synchronization and matching of the afterburner fuel with the variable final nozzle must be accurate at all times to maintain the engine turbomachinery on its required running lines. The afterburner must always be free of combustion driven pressure oscillations which can occur either in cross stream modes or in longitudinal modes, both of which can be mechanically damaging and, in some cases, cause fan surge and other intolerable effects in the engine. The afterburner must incorporate appropriate measures to avoid various potential thermal problems including fuel boiling and gumming in the supply manifolds and excessive heat transfer to the jet pipe and aircraft engine bay.


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    Title :

    High Performance Turbofan Afterburner Systems


    Contributors:
    A. Sotheran (author)

    Publication date :

    1988


    Size :

    9 pages


    Type of media :

    Report


    Type of material :

    No indication


    Language :

    English