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

2. 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

3. Progress in Noise Reduction Year of Initial Service
120
Sideline
110
Noise Level,
EPNdB
(1500’ Sideline)
100
A321
A330
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.

4. 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

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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

11. 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

12. 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