TECHNOLOGY AREAS: Air Platform, Materials/Processes, Sensors

ACQUISITION PROGRAM: F-35 - Joint Strike Fighter, ACAT I

The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), which controls the export and import of defense-related material and services. Offerors must disclose any proposed use of foreign nationals, their country of origin, and what tasks each would accomplish in the statement of work in accordance with section 3.5.b.(7) of the solicitation.

OBJECTIVE: Develop innovative acoustic liners for jet noise reduction as alternatives to current perforated designs.

DESCRIPTION: Aircraft engines generate noise levels that are deemed unacceptable for 21st century survivability and community noise objectives. Recent government funded research programs have set aggressive goals for jet noise reduction for the near future. Reductions of the order of 20 dB to be achieved in the next 15 years require the development of new technological solutions for the control of noise generated by jet engines.

Current design configurations mostly feature passive acoustic liners consisting of honeycomb panels with perforated face sheets. Single-, double- or triple-layer configurations have been proposed and analyzed in an effort to increase design flexibility and broadband absorption characteristics. Other configurations employ woven wires, slots and micro-perforates as well as bulk absorber materials such as fiberglass, Kevlar felts, and ceramic foams. Most of these design solutions suffer from major drawbacks in terms of manufacturing and in-service durability. In addition, these liners typically do not contribute to the structural capability of the engine, and therefore they introduce weight penalties. Finally, passive liners do not have the ability to adapt their absorption characteristics in response to varying flight regimes. New concepts for acoustic liners should reduce the drawbacks of current designs in terms of manufacturing and structural reliability and should have tunable properties.

Smart acoustic technology is sought for liners that contribute to the structural strength of the engine nacelles and have the ability to adapt their noise absorption characteristics to different flight regimes through the application of smart or tunable materials while maintaining current engine performance levels. The developed technology must ensure no adverse effect on infrared (IR), fatigue, flutter, or engine performance.

PHASE I: Develop an innovative approach to a smart acoustic system that detects and reduces aircraft engine noise as a function of flight regime. Demonstrate the feasibility of the approach using computational methods.

PHASE II: Develop and demonstrate a prototype smart acoustic system in a simulated environment where a representative engine noise environment can be produced. Both experimental evaluation and verification via proven computational methodologies must be demonstrated.

PHASE III: Further develop the smart acoustic system for production. Prepare a complete package with a users manual, hardware and software for the system to be integrated onto Navy platforms. Provide the Navy with computational tools capable of assessing the system across a spectrum of Navy aircraft.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Smart acoustic system technology will have broad application in both the commercial and military aerospace industries where community aircraft engine noise is an issue. This technology can be applied to reduce civilian noise footprints for airports and heliports.

REFERENCES:
1. Bielak G. et al. "Advanced Turbofan Duct Liner Concepts," NASA Technical Report (CR-1999-209002).

2. Gutmark et al. "Measurements of the Acoustic Attenuation By Single Layer Acoustic Liners Constructed With Simulated Porous Honeycomb Cores," Journal of Sound and Vibration 286(2005) 21-36.

KEYWORDS: Smart System; Engine; Acoustics; Noise; Structural Tailoring; Structural Control.

** TOPIC AUTHOR (TPOC) **

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