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Quiet Performance - Airframe Noise

Description:

Scope Title:

Airframe Noise

Scope Description:

Innovative methods and technologies are necessary for the design and development of efficient and environmentally acceptable aircraft. In particular, the impact of aircraft noise on communities around airports is the predominant limiting factor on the growth of the Nation's air transportation system. Reductions in aircraft noise could lead to wider community acceptance, lower airline operating costs where noise quotas or fees are employed, and increased potential for air traffic growth on a global scale. In support of the Advanced Air Vehicles Program (AAVP), Integrated Aviation Systems Program (IASP), and Transformative Aeronautics Concepts Program (TACP), improvements in noise prediction and noise control are needed for subsonic, transonic, and supersonic vehicles. Solutions are sought that target airframe noise sources and the noise sources due to the aerodynamic and acoustic interaction of the airframe and engines. Innovations in the following specific areas are solicited:

Noise Prediction:

  • Prediction and/or mitigation of aerodynamic noise sources including those from the airframe, propulsion-airframe interactions, or aeroacoustic integration effects associated with high-aspect-ratio truss-braced vehicles. However, engine-only noise sources are excluded from this call.
  • System-level noise prediction methodologies for operational aspects (as opposed to certification conditions) of high-aspect-ratio truss-braced subsonic transports or technology variants thereof.
  • Prediction of sound propagation from the aircraft through a complex atmosphere to the ground. This should include interactions between noise sources and the airframe and its flow field.

Noise Analysis and Characterization:

  • Fundamental and applied computational fluid dynamics techniques for aeroacoustic analysis that can be adapted for design purposes.
  • Innovative source identification techniques for airframe (e.g., landing gear and high-lift systems) noise sources, including turbulence details related to flow-induced noise typical of separated flow regions, vortices, shear layers, etc.  However, noise sources attributed solely to the engines are excluded from this call.

 

Noise Reduction:

  • Concepts for active and passive control of broadband aeroacoustic noise sources for conventional, truss-braced, and other advanced aircraft configurations. Technologies of interest include adaptive flow control and noise control enabled by advanced aircraft configurations, including integrated airframe-propulsion control methodologies.
  • Innovative design approaches or technologies, including acoustic liner or porous surface concepts, to reduce airframe noise sources and/or propulsion/airframe aeroacoustic interactions. However, engine nacelle liner applications are specifically excluded.

Expected TRL or TRL Range at completion of the Project: 2 to 5

Primary Technology Taxonomy:

  • Level 1 15 Flight Vehicle Systems
  • Level 2 15.1 Aerosciences

Desired Deliverables of Phase I and Phase II:

  • Research
  • Analysis
  • Prototype
  • Hardware
  • Software

Desired Deliverables Description:

Concepts, technologies, and tools that enable rapid assessment of the noise impact of novel engine/airframe configurations, mitigate component noise issues associated with novel aircraft configurations, and/or aid in the development and optimization of noise control approaches for component noise sources that enable new aircraft configurations such as truss-braced wing and small-core turbofan engines. Example Phase I deliverables include laboratory demonstrations that establish proof of concept of noise reduction technologies and also applications of novel computational tools with limited scope that demonstrate the potential for success on problems of greater scope. Example Phase II deliverables include system or subsystem demonstrations concurrent with the establishment of a realistic path to concept production and also incorporation of novel computational tools into existing modeling toolchains with validation cases to document capabilities.

State of the Art and Critical Gaps:

State-of-the-art technologies for noise reduction on conventional transport aircraft are generally passive and do not incorporate advanced material systems or adaptive mechanisms that can modify their performance based on the noise state of the vehicle. Advanced material systems for airframe noise control are still in their infancy, especially in the context of certifiability and robustness. Novel material systems that could be applied to component noise sources on the aircraft are needed, such as shape memory alloy actuators and active or adaptive systems. In addition, future sustainable aircraft design configurations are envisioned that either leverage noise benefits of complex geometrical configurations or introduce noise challenges with engine/airframe integration. Efficient computational tools that enable rapid-turn evaluations of multiple configurations at the design stage are lacking. Numerical methods to study complex engine/airframe configurations are complex and difficult to leverage at the aircraft design stage where configuration details are not specified. Improvements to numerical methods and models for studying the noise aspects of advanced airframe configurations, including engine integration, would ease consideration of acoustics in the design, rather than leaving acoustics to the late design stage where noise control solutions are costly and less effective. Improved tools would also enable more rapid evaluation and development of innovative noise control approaches that may be needed for these novel aircraft configurations.

Relevance / Science Traceability:

AAVP: The Advanced Air Transport Technology (AATT) and Commercial Supersonic Technology (CST) Projects would benefit from noise reduction technologies that could reduce the aircraft noise footprint at landing and takeoff. Configurations with novel engine placement, such as above the fuselage, can reduce the noise footprint, but technologies are needed to efficiently model the performance and noise impacts of these novel engine installations. In addition, novel configurations and technologies such as truss-braced wing and small-core turbofan engines will introduce new noise challenges that must be addressed to enable their successful deployment.

TACP: The Transformational Tools and Technologies (TTT) Project would benefit from tool developments to enhance the ability to consider acoustics earlier in the aircraft design process. The TTT project would also benefit from the development and demonstration of simple material systems, such as advanced liner concepts with reduced drag or adaptive material and/or structures that reduce noise, as these component technologies could have application in numerous vehicle classes in the AAVP portfolio, including subsonic and supersonic transports as well as vertical lift vehicles.

References:

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