Adaptive Nozzle Technology for Mitigation of High Speed Jet Exhaust Noise

ABSTRACT: Current generation engines for Air Force platforms provide unprecedented levels of thrust and performance but also generate significantly higher jet exhaust noise than legacy tactical aircraft. Phase I work at CDI has identified first-generation actuation devices that can be tailored to enable a"smart nozzle"capability to mitigate exhaust noise. Components of a compound actuation system that can simultaneously adjust nozzle exit area and enhance exhaust flow mixing have been demonstrated in pre-prototype form; these demonstration and engineering analysis of full scale versions have established that these devices can provide the required force and displacement to enable effective noise mitigation strategies. Device actuation is provided using novel mechanisms and rapidly maturing SMA (Shape Memory Alloy) materials, in particular specialized high temperature"HTSMA"alloys. Phase II will build on Phase I results to develop full scale versions of the nozzle flap actuators and variable geometry chevrons in forms suitable for eventual testing under full scale temperatures and aerodynamic loads. The effort will involve: adaptation of Phase I designs to meet operational specifications; fabrication of HTSMA actuators and integration with full scale hardware; aerodynamic and high temperature testing; and initial studies of integration requirements and operational suitability. BENEFIT: The key motivation for the effort is mitigation of noise both for aircraft now entering the inventory (e.g., F-35 and F-22) and new vehicles that will enter service in future years; reducing noise while preserving or enhancing engine performance is critical for community acceptance of military operations and ground crew health and safety. If successful, a fielded system could yield 3-5 dB of noise reduction for legacy engines, with comparable reductions likely for next generation fighter engines. Much of the adaptive nozzle technology to be developed is directly transferrable to civil aviation, where noise reduction for commercial jet transports is a high priority.