Revolutionary Technologies for the Reduction of Aircraft Jet Noise

ABSTRACT: This Phase I program proposes conceptual design and proof-of-concept acoustic testing of a unique nozzle concept for providing significant reductions in jet noise. These reductions are achieved through application of nozzle design features that address different jet noise reduction mechanisms, or physics, to provide an additive effect on the acoustic attenuation. Subscale models will be configured to meet the goal of 10 dBA reduction of jet noise compared to a conventional convergent-divergent nozzle with equivalent performance. In parallel to this jet noise test, effects of the proposed nozzle configuration on engine cycle, thrust, and fuel consumption will be analytically evaluated using accurate SPIRITECH-developed tools and industry standard CFD solutions. The Phase II program will further mature this concept or a derivative airframe-integrated exhaust system, and will include additional acoustic tests with more detailed models and external flow, extending Phase 1 proof of concept to component validation TRL 4 status. Performance assessments will be refined and extended to include installed aircraft characterization. Test and analyses results will then be used to quantify jet noise and integrated system performance trades. BENEFIT: The proposed nozzle concept and/or derivatives developed and validated in Phases I and II provide enabling technologies for achieving substantial jet noise reductions in future commercial and strategic military aircraft. As jet noise reduction associated with increasing bypass ratio approaches a limit, new techniques for further improvements will be needed. The proposed technology is sufficiently general to have broad potential for commercialization, with applicability to numerous types of jet propulsion systems. Potential end users include both military (Air Force, Navy, Army, NASA and DARPA) and commercial (aircraft and propulsion system) customers.