Advanced fighter aircraft engine performance improvements associated with the nozzle can represent important thrust gains as well as reductions in fuel consumption, with the consequent mission range extension and superior acceleration capability.

ITP is currently developing a multi-axis Thrust Vectoring Nozzle concept with the necessary exit area independent control capability to allow the engine to operate close enough to its optimum condition over the complete flight envelope and at different power settings. This variation is achieved with an innovative system, instead of using the conventional double actuation system already developed.

In this paper both installed and uninstalled thrust losses have been evaluated for a conventional mono-parametric axi-symmetric nozzle fitted on a low bypass ratio turbofan. The optimum exit to throat area ratio schedules are determined for the complete operating range at Max-Dry and Max-Reheat conditions. Several geometric and Fluid-Dynamic constraints have been considered during the optimisation.

Two axi-symmetric schedules have been identified for the multi-axis Thrust Vectoring Nozzle, resulting in two different exits to throat area ratio independent control ranges. The performance improvements in terms of thrust are presented for both cases, showing that at almost every condition the optimum schedule is achievable.

The computer code developed for nozzle performance has been validated with conventional axi-symmetric Con-Di nozzles showing an excellent agreement between measured and calculated thrust.

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