Noise Reduction Research Langley Research Center Bill Willshire Home & Home Langley Research Center November 16, 1999 AT H&Hnr-vk

Noise Reduction Program Drivers Environmental Concern Increased Quality of Life Public Good Increased Capacity Enables Growth Public Good Improved Competitiveness Balance of Trade Public Good

Progress in Noise Reduction Year of Initial Service 120 Sideline 110 Noise Level, EPNdB (1500’ Sideline) 100 A321 A330 777-200 MD90-30 90 1950 1960 1970 1980 1990 1995 Year of Initial Service • Without new noise reduction technology, increasing demand coupled with increasing population will result in increased community noise impact.

Current Program Objective and Scope Noise Reduction Current Program Objective and Scope Objective: 10 dB Community Noise Impact Reduction Relative to 1992 Production Technology Scope: A broad, $200M joint program with the FAA Initiated in FY1994, ends in FY2001 Technical program is result of an extensive NASA inter-center, FAA, and industry partnership. Note: With the termination of the Advanced Subsonic Technology Program in FY00, the Noise Reduction Element was transferred to the Aerospace Vehicle Systems Technology Program

Noise Reduction Current Program Management Structure Aerospace Vehicle Systems Technology Program NASA Langley Research Center Darrel Tenney, Director Industry/Government Steering Committee FAA Noise Reduction Program NASA Langley Research Center Bill Willshire, Manager Loretta Shaw, GRC; Brian Smith, ARC Industry/Government Technical Working Group Ames Research Center • Engine Noise Reduction • Nacelle Aeroacoustics Airframe Noise Reduction Clif Horne Just go through it - I like to mention the SC and TWG and mention our special relationship with the FAA. Might not go through the names to save time. Langley Research Center • Engine Noise Reduction • Nacelle Aeroacoustics Joe Posey • Airframe Noise Reduction • Interior Noise Reduction Rich Silcox • Community Noise Impact Kevin Shepherd Glenn Research Center • Engine Noise Reduction Dennis Huff • Nacelle Aeroacoustics Primary Support

Noise Reduction Engine Noise Reduction NASA/Allison Low-Noise Fan in Glenn Research Center 9’x15’ Wind Tunnel Demonstrated 3 EPNdB Fan Noise Reduction Baseline Swept Stators Swept/Leaned Stators Numerical predictions indicated that the rotor stator interaction tone could be reduced to broadband noise levels of a fan utilizing swept and leaned stators These predictions were used to verify the concept for the 3 EPNdB fan noise reduction L1 Milestones (1Q97) 22 inch model fan hardware tested in the 9x15 Wind Tunnel verified the predictions The design was done by Allison

Noise Reduction Flap-edge Airframe Noise Reduction Airframe noise: Today major source on approach Tomorrow major source on takeoff Components: flap, slat, and gear CFD/CAA Model in LTPT* Flap-edge Airframe Noise Reduction Physics-based mechanism identification Source localization Non-intrusive reduction concepts discovered and optimized 4 dB flap-edge noise reduction Reduction Mic Array Frequency, Hz SPL, dB *Langley Research Center Low Turbulence Pressure Tunnel

Noise Reduction Propulsion Airframe Interaction Experiment Low Speed Aeroacoustic Facility Microphone Array Results Boeing 20 kHz Jet with Wing Isolated Jet Presence of wing/fuselage dramatically impacts apparent noise source Jet with wing up to 8 dB nosier Interactions not understood and therefore not exploited

Validation of Noise Prediction Model in Community Noise Impact Models Noise Reduction Validation of Noise Prediction Model in Community Noise Impact Models Measured, dB Predicted, dB 60 80 100 120 5001 Departures from DIA 6 Aircraft Types ≥ 60 Degrees Above Horizon Contour Plot Perfect Agreement Predicted, dB 10 dB Measured, dB

National Need for Noise Reduction Objectionable aircraft noise contained within airport boundary. Vision Reduce the perceived noise levels of future aircraft by one half (10 dB) from today’s subsonic aircraft within 10 years, and by three quarters (20 dB) within 25 years Enterprise Noise Goal Benefit 10-year Goal: 65 LDN at airport boundary 25-year Goal: 55 LDN at airport boundary Justification Air transport system is constrained by noise Current planned program will achieve 50% of 10-year goal Broad-based customer support Technology for 2020 and beyond needed soon FAA relies on NASA for long-term noise solutions No national noise program after 2001

O’Hare Yearly Average Day Night Level (DNL) Noise Contours Benefit O’Hare Yearly Average Day Night Level (DNL) Noise Contours 20 10 5 1997 Baseline Not acceptable 20 10 5 Current Program* 5 dB Reduction Improvement - significant reduction Does not meet public expectations Constrained growth 20 10 5 Key 55 dB 65 dB Airport 10-Year Enterprise Goal 10 dB Reduction 65 dB contour contained within airport Enable projected air travel growth Reduce community noise impact Scale 10 Miles *TRL 6 relative to 1997

Noise Reduction Concluding Remarks Aircraft noise is a critical international environmental issue Very visible public concern in the US Noise will continue to constrain air travel growth until objectionable noise contained within airport boundary Current noise reduction program will achieve half of 10-year goal (-5 dB) Slow fleet turnover dictates near-term solution of far-term problems No national noise reduction program exists or is planned for the future Noise reduction research is about public good and enhances quality of life Technical solutions should lead /guide national policy NASA alone of the federal labs has the expertise/capability/track record to make the required contributions