The Challenge
The environmental impact of noise emissions associated with the commercial aviation will continue to pose a challenge to aircraft designer well into the 21st century. Even though improvements in aircraft design and the introduction of noise reduction technology have been effective in reducing aircraft noise emissions over the years, the anticipated growth in air traffic and increased sensitivity to noise near airports will likely require even quieter aircraft to offset the projected growth. To eliminate the impact of aviation noise on the communities surrounding the airports, the objectionable aircraft noise must be contained within the airport boundary.

To address this challenge, NASA has adopted a generational approach to aircraft noise reduction and is working with industry and academia to develop technology portfolios that can provide the basis for meeting generational noise reduction goals. These goals are, respectively, 32, 42 and 52 dB noise reductions, on cumulative basis, relative to the Chapter 4 noise limits for the N+1, N+2 and N+3 generation aircraft where N denotes the current generation of aircraft. The community of scientists and engineers engaged in propulsion noise research will need to overcome many challenges in order to meet NASA’s aggressive aircraft noise reduction goals.

To complement the NASA and industry aeroacoustics research efforts, both new ideas and a rethinking of the old ones are needed to ensure an effective approach to noise reduction research that includes both near-term and long-term elements.

The Challenge Accepted
To address these needs, the AeroAcoustics Research Consortium (AARC) was established by NASA Glenn Research Center (GRC) and its industry partners in 2001. The consortium, which is administered by the Ohio Aerospace Institute partners, currently includes as members, Honeywell, NASA GRC, Pratt & Whitney, and Rolls-Royce. The goal of the consortium is to attract US and international experts to work on pre-competitive aeroacoustic research topics of interest to the consortium members. The researchers who are funded by the consortium are expected to stay connected with the AARC member organizations throughout the funding period and report results at the completion of the study. As such, AARC represents a dynamic, supplementary, workforce of researchers that is regularly replenished. Experienced university faculty, new PhD’s, as well independent scientist and engineers, who are performing cutting edge aeroacoustics research are sought in order to bring new ideas, methods, and concepts to the AARC partners. Researchers are also invited from U.S. industry and governmental laboratories to complement this virtual workforce. The research that is funded is not export controlled (i.e., subject to EAR or the ITAR rules).

The mission of the AeroAcoustics Research Consortium is:

To establish an organizational structure to promote world-class aeroacoustics research while providing a stimulating environment that can attract high quality researchers in this area and complement the AARC member organizations research activities in aeroacoustics.

Analytical (numerical) as well as experimental pre-competitive research is the focus of the Aeroacoustics Research Consortium focused on commercial airframe propulsion systems. Current areas of interest include:

• 3D and installed jet noise
• Computational aeroacoustics (CAA)
• Combustor and turbine noise
• Fan and open rotor noise (in particular broadband and installed noise)

The objectives of the Aeroacoustics Research Consortium are:

1. To attract acoustics experts from around the world to have direct interaction with GRC and industry researchers.
2. To concentrate research efforts on technical barrier problems associated with engine noise prediction and reduction.
3. To emphasize fundamental understanding of noise generation from engine components, e.g., propulsors, jets, and core through analytical and experimental methods.

The Aeroacoustics Research Consortium regularly organizes and hosts technical meetings, seminars, and workshops that bring additional focus and visibility to the aeroacoustics research.

Since its inception in 2001, the Aeroacoustics Research Consortium has continued to provide cost effective, targeted research efforts that complement the NASA and industry in-house research activities in aeroacoustics.

No Technical Data Subject to EAR or the ITAR