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Volpe National Transportation Systems Center

Volpe National Transportation Systems Center Environmental Measurement & Modeling Division - Acoustics Facility. Use of One-Third Octave-Band Spectral Data in Community Noise Models. 2003 International Congress and Exposition on Noise Control Engineering

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Volpe National Transportation Systems Center

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  1. Volpe National Transportation Systems Center Environmental Measurement & Modeling Division - Acoustics Facility Use of One-Third Octave-Band Spectral Data in Community Noise Models 2003 International Congress and Exposition on Noise Control Engineering Session PA-3: Environmental / Community Noise Christopher J. Roof

  2. Background One-Third Octave-Band Data: Spectral Class Concept Spectral Class Development Spectral Class Validation & Verification Potential Capabilities / Limitations Using Spectral Data PRESENTATION OVERVIEW

  3. BACKGROUND • Aircraft Noise Modeling Guidance Documents • Society of Automotive Engineers (SAE) “Procedure for the Calculation of Airplane Noise in the Vicinity of Airports” AIR-1845 • European Civil Aviation Conference (ECAC) “Report on Standard Method of Computing Noise Contours around Civil Airports” Doc 29 • International Civil Aviation Organization (ICAO) “Recommended Method for Computing Noise Contours around Airports” Circular 205 • Reference Conditions • Noise-Power-Distance Curves (NPDs) • Acoustically Soft, Flat Ground Surface • Reference Atmosphere

  4. Airport Conditions Vary from Reference Conditions Ground Type Hard Ground Mixed Hard / Soft Ground Terrain Features Non-Standard Temperature / Humidity Predictions Extrapolated from NPD Distances Advanced Models Can Address these Issues Acoustic Data Requirements Non-Acoustic Data Requirements BACKGROUND (cont.)

  5. BACKGROUND (cont.) More Advanced Models: Tradeoffs • Potentially Greater Accuracy versus • Increased Data Collection Requirements • Potential Instability (Sensitivity to Model Inputs vs. Actual Aircraft Changes)

  6. SPECTRAL CLASS CONCEPT • Representative Aircraft Spectra Required • Databases Include 100’s of AircraftINM v 6.1 = 248 • Older Aircraft • Newer Aircraft (Proprietary Data) • Smaller “Chapter 10” Aircraft • Can Aircraft Be Grouped Together for Calculations Requiring Spectral Data?

  7. SPECTRAL CLASS DEVELOPMENT Step #1: Group Similar Aircraft/Engine Combinations • Airframe • # Engines • Engine Bypass Ratio • Engine Type

  8. SPECTRAL CLASS DEVELOPMENT (cont.) Step #2: Visual Inspection

  9. SPECTRAL CLASS DEVELOPMENT (cont.) Step #2: Visual Inspection, Normalized

  10. Departure Spectral Class 104 Ground Effect 5 0 0.1 1 10 100 -5 Ground Effect (dB(A)) -10 -15 -20 -25 Elevation Angle (deg) F28/GIIB MD80 737N17/737N19 Weighted Average +-1dBA SPECTRAL CLASS DEVELOPMENT (cont.) Step #3: Verification

  11. SPECTRAL CLASS DEVELOPMENT (cont.) Step #4: Final Spectral Class

  12. POTENTIAL CAPABILITIES • Atmospheric Absorption Under SAE Review • Ground Impedance Effects Under SAE Review • Terrain Shielding • Building Shielding • Refraction

  13. SPECTRAL CLASS VALIDATION (Atmospheric Absorption) • Airbus INM Data Submission Comparison • NPD Comparison • Actual Airbus NPD's (Integrated Process) • Actual Spectra (Simplified Process) • Spectral Class (Simplified Process) • A321-232 • A330-343 • A300-622R • A310-304 Compared for SAE Atmosphere Compared for other Atmospheres

  14. SPECTRAL CLASS VALIDATION (cont.) (Atmospheric Absorption) • 2 Power Settings (1 Approach; 1 Takeoff) • Maximum Sound Level (LASmx) and Sound Exposure Level (LAE) • Multiple Atmospheric Conditions • 15C / 55 %RH • 25C / 55 %RH • 15C / 70 %RH • 25C / 70 %RH

  15. SPECTRAL CLASS VALIDATION - Results (Atmospheric Absorption - cont.)

  16. SPECTRAL CLASS VALIDATION - Results (Atmospheric Absorption - cont.)

  17. SPECTRAL CLASS VALIDATION - Results (Atmospheric Absorption - cont.)

  18. SPECTRAL CLASS VALIDATION - Results (Atmospheric Absorption - cont.)

  19. SPECTRAL CLASS VALIDATION - Results (Atmospheric Absorption - cont.)

  20. PRESENTATION SUMMARY Spectral Class Concept Successfully Implemented • Improved Calculations • Simple “Grouped” Spectral Data Approach • Lays Groundwork for Future Model Improvements • Guidance Documents Should Be Updated to Reflect the State-of-the-Art Including Tradeoffs: Increased Complexity vs. Benefit

  21. CURRENT INM Integrated Noise Model Version 6.1 > 700 Users > 50 Countries Distribution by Sector Total Distribution

  22. REFERENCES • Integrated Noise Model (INM) Version 6.0 User’s Guide • Integrated Noise Model (INM) Version 6.0 Technical Manual • Spectral Classes for FAA’s Integrated Noise Model, Version 6.0 • Society of Automotive Engineers (SAE), Aerospace Information Report (AIR), SAE-1845, “Procedure for the Calculation of Airplane Noise in the Vicinity of Airports” • European Civil Aviation Conference (ECAC) Doc 29 • International Civil Aviation Organization (ICAO) Circular 205

  23. CONTACT INFORMATION Christopher J. Roof U.S. Department of Transportation Volpe National Transportation Systems Center Acoustics Facility DTS-34 PH: (617) 494-6344 FX: (617) 494-3208 Roof@volpe.dot.gov http://www.volpe.dot.gov/acoustics/

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