Consideration of Operational Noise Impacts on Land use as a Part of the Weapons Systems Engineering Process

Transcription

1 Environment, Energy & Sustainability Symposium 6 May 2009 Denver CO Consideration of Operational Noise Impacts on Land use as a Part of the Weapons Systems Engineering Process Wayne R. Lundberg, Ph.D. Aerospace Engineer The content of this presentation is not sanctioned by HQ AFMC or it components, ASC & AFRL

2 Land Use and Community Noise Impacts are the problem: The intense noise generated by military fighter aircraft has a significant impact on communities near airbases as well as ground crews. This affects basing decisions, operations and training. - def: Operational Suitability, AFPD63-12 Operational Noise Prediction / Constraint in Systems Engineering Process is Crucial to Planning: Noise models for High-performance Aircraft Acquisition have not been validated for accuracy Problem has been known since the Concorde Time-domain vs. Frequency-domain confounds research Frequency-domain solution has existed for 14 years Time-domain solution confirms results recently

3 Technical Objectives To gain a fundamental understanding of military engine noise source mechanisms and propagation Develop methodology for using systems engineering performance models, with continuous improvement during engine and airframe development, to reliably predict full scale aircraft operational noise Airframe lift, engine installation, engine design and performance all effect the operational noise levels Drag polars, NASAs Flight Optimization and Performance System Validate physics-based environmental noise prediction model

4 Commercial and Military Aircraft Engines Turbofan Engine Turbojet Engine Used for commercial aircraft High bypass ratio Moves large mass of air at low speed Relatively quiet Used for military fighter aircraft Very low bypass ratio Moves small mass of air at high speed Very noisy

5 Commercial and Military Engine Noise preliminary design model Thrust = mass flow rate x velocity = mv Turbofan engine GE90-115B Thrust = 115,000 lbs Mass flow rate = 3641 lbs/s Exhaust velocity = 1017 fps Diameter = 120 inches Turbojet engine GE F Thrust = 16,000 lbs Mass flow rate = 142 lbs/s Exhaust velocity = 3628 fps Diameter = 24 inches SPL 80log10 V 20log10 D The turbojet engine is 30 db louder than the turbofan engine: Using only Lighthill s approximation- [Milestone Decision A] But airframe and aircraft operations are not considered in equation

6 Ops Noise as a Systems Engineering ~1994 Constraint on Aircraft Design AF/XOFM study of Stage 3 Compliance: - Invest No-Invest in A/C to Comply - Include FAA FAR Part 36 (latest Amendment) in A/C Specs -In JSSG, developed ~1998 C-5M (RERP) 8/00- ANOPP predictions valid, Design should meet proposed intermediate Stage 4 stringency std -- by 1-2dB Current M design ~0db margin wrt Stage 4 EO req EMS ISO stds New FAA-FAR 36/ICAO amendment? - Reforms can help- ref ICBEN 08 Team 9 Science of noise propagation identified problem: -Nonlinear INCREASE in sound exposure -WRL submitted SERDP requirement (FY94: 0$) High-performance jets ANOPP still not valid NOTHING used during A/C systems engineering BRAC 05 did not consider land-use compatibility concerns No systems egr, no ESOH planning =PROBLEMS

7 Example: Luke AFB with JSF flight ops (red) vs. legacy (green) Est as known in 2005 progam- Sun City very adversely affected BRAC 05 decision uninformed?

8 Well-established that military aircraft designs have historical trend of increasing noise levels that impact: Community Noise - Good neighbor Ground/shipboard personnel safety issues Pilot comfort Low bypass ratio (typical of supersonic-capable military aircraft) engine noise is dominated by Jet Noise including Shock-associated noise. Noise reduction technologies developed for civil aviation needs being evaluated and modified for use in military aircraft Engine Noise Sources Clearly NOT spherical spreading!

9 Third octave band SPL (db) NASA Research Announcement Subtopic A develop statistical model -narrow-focused research AF NoiseFile published data: Frequency (khz) Concorde B-1 A/B F-15E(229) A/B F-15E(220) A/B F-15A A/B F-18 A/B F-111F A/B F-16A A/B F-111D A/B Phantom A/B F-16(G132) A/B FB-111A A/B F-4C A/B F-111A A/B F-101B A/B F-22 est A/B F-18E/F A/B A-5C A/B B-52G T/O F-4C T/O F-16(G100) A/B Lightning B-52BDE T/O Vulcan F-105D A/B F-22 MIL F-14B A/B Jaguar Motivated by predicted/measured comparison: F-18 (flat-weighted) ALL high-performance A/C engines have the same problem with predicting sound exposure (A-weighted) New F-18, F-22 and F-35 measurements NOT available for analytical peer review

10 Third Octave Band SPL (db) Third Octave Band SPL (db) AIAA SIMPLIFIED Nonlinear Aeroacoustic Propagation m m (r r /r) 2 & =90 469m 82.6m 137m 238m 337m Measured ANSI prediction k 1.6k 2.5k 4k 6.3k 10k Third Octave Band (Hz) (r r /r) 2 & =90 469m 82.6m 137m 238m 337m Measured ANSI+SNAP8 prediction k 1.6k 2.5k 4k 6.3k 10k Third Octave Band (Hz) Proven modeling capability - quasi-linear frequency domain model - Easy to fix hard to FUND! - reqt for FAR 3.601?

11 Noise reduction is essential to military fighter aircraft operational suitability DoD R, AFI , AF/ASC - PESHE annex Testing at full scale is very expensive, yet results of smallscale tests can lead to concepts that do not scale up well. Noise reduction can be achieved with exploration at model scale, improved prediction capabilities, and practical engineering solutions. Capabilities have not been validated for military aircraft engines. This approach has been successful for commercial aircraft engines. The development of scaling methodologies, including detailed simulations and system-level assessment tools, will narrow the parameter range for fullscale noise reduction implementation and flight testing.

12 Derived acquisition requirement for far-field noise A bit more complicated than for near-field noise, calculation has to be done for the worst-case noise propagating acoustic signal (360 deg coverage) for each airbase, i.e., pick the worst number from, Derived requirement for noise = xxx db = near field equivalent of the 65 db outer contour (the requirement derives from the community compliance outer air base noise contour of 65 db a primary requirement and flows down to the propulsion system and airframe under standard DoD acquisition rules) Included in Tri-Service Engine Spec (~1995) Airframe lift and engine installation also affect community noise - Design for Noise Abatement Departure Profile

13 EXAMPLE ESOH RISK ASSESSMENT MATRIX HIGH:Requires Service Acquisition Executive approval Hazard Categories I II III IV Frequency Of Occurrence Catastrophic Critical Marginal Negligible (A) Frequent 1A 2A 3A 4A (B) Probable 1B 2B 3B 4B (C) Occasional 1C 2C 3C 4C (D) Remote 1D 2D 3D 4D (E) Improbable 1E 2E 3E 4E HAZARD RISK INDEX SUGGESTED CRITERIA 1A, 1B, 1C, 2A, 2B, 3A UNACCEPTABLE (HIGH) 1D, 2C, 2D, 3B, 3C UNDESIRABLE (MA DECISION REQUIRED(SERIOUS) 1E, 2E, 3D, 3E, 4A, 4B ACCEPTABLE WITH REVIEW BY MA(MEDIUM) 4C, 4D, 4E ACCEPTABLE WITHOUT REVIEW(LOW) NOTE: THESE ARE ONLY THE SUGGESTED CRITERIA. They may be adjusted IAW agreement with the Component Authority. 13

14 Aircraft Lift is an IMPORTANT Mitigator of Community Noise JSF F18C/D F18E/F ~2005 Footprint in db SEL for JSF faster (possibly UNSAFE) rate of climb

15 Design Options, Nozzle Questions Increase aircraft lift Increase engine by-pass ratio Effect of the airframe installation on the sources and radiation of jet noise? F-117, B-2 implement ducted cool air STAGE 3! ESDU model includes airframe installation Rear-fuselage turbofan or turbojet Underwing turbofan or turbojet Quiet Aircraft Initiative engines on top Optimal nozzle design to minimize noise? Compressor bleed air injection during takeoff Optimal (?) chevrons Are NOT mutually exclusive!

16 Notional Systems Engineering process including Community NOISE prediction PROGRAM Laboratory Scale Isolated Jet UM 1/10 th Scale Suppression Studies FSU 1/10 th Scale Suppression Studies GEAE 1/4 th Scale Suppression Studies Laboratory Scale Dual Engine/Afterbody w & wo Forward Flight UM 1/10 th Scale Twin Jet Effects Ext. / Int. Geo. FSU 1/10 th Scale Twin Jet Effects Micro-Jets Full Scale Engine Testing CFD Scale-UP Mods For Real Engine Aircraft drag polar and engine CRAFT CFD performance Studies model feed ANOPP (and its CRAFT derivatives, CFD including With Boeing s Installed duct acoustic model) Modeling Engines Model Scale ANOPP output at 325m, std day feeds NoiseMap a/c lift and NASA s FLOPS used to optimize departures UM/FSU/CRAFT F Engine Test NAS Lakehurst Simplified Nonlinear Aeroacoustic Model is inherently compatible UM/FSU/Craft 15% with BOTH ANOPP and NoiseMap Full-Span Model - LSAF Frequency domain models Boeing/FSU Beveled Nozzle Studies Boeing- Single and Twin Jets Beveled Nozzle LSAF GEAE Thermal Shield GEAE Plumbrook Engine Test Acoustic Flight Testing Flight Test Unsuppressed Engines F/A-18 E/F Aircraft System Noise Prediction - ANOPP Installed CFD For Real Aircraft NAS Patuxent River Flight Test Suppressed Engines Preliminary Noise Reduction Concepts Noise Reduction Concepts Accounting for Geometry & Flight Full-Scale Performance & Noise Suppression Technology Demo Low Noise FCLP Mission Profile 16

17 Engine Noise Reduction - Technical Approach Nozzle & Chevron Geometry Numerical simulations Small scale experiments Moderate scale experiments Benchmark nozzles Adjoint design method for shock noise reduction Flow and acoustic measurements for unsuppressed and suppressed nozzle geometries Installation and flight effects Full scale predictions Reduced noise military engine nozzle designs Enhanced community noise model NoiseMap reqt encoded in LAW

18 JSF Sponsored AFRL SBIR Near-field Acoustic Holography System (SBIR) Define the near-field 3-D acoustic field from a supersonic jet flow generated by a full scale engine Levels at 50 up to 160 db Non-linear source characteristics and non-linear propagation Time domain model vv$$ Accurate near-field measurements and data are required to validate accuracy of source noise models Sole-Source Award should be made in 2007 (?) for Phase I SBIR 13 years later? MIT s NoiseSim, Frequency-domain Nonlinear models not considered

19 Single-event modeling of weather-induced aircraft performance effect on civil aircraft noise, NOISIM model developed by MIT International Center for Air Transportation, J. Huber et al, AIAA CP-3276, 2003 Reprinted with permission by MIT

20 Third Octave Band SPL (db) Third Octave Band SPL (db) Lateral attenuation effects - not all good ft 472ft 70 (r r /r) 0.87 & =90 Measured 1043ft ANSI S predction k 1.6k 2.5k 4k 6.3k 10k Third Octave Band (Hz) r r /r 0.87 = < cylindrical spreading (r r /r) 2.92 & = ft 472ft 1043ft 50 Measured ANSI S predction k 1.6k 2.5k 4k 6.3k 10k Third Octave Band (Hz) r r /r 2.92 ~ quadrupole spreading Aeroacoustic directivity produced by the B-1B in high-speed flight, at 90 and 130 degrees emission. AIAA CP-2792, WRL Gauss s Law is inviolable! - Extra attenuation to flight sideline Reduced attenuation under flight path

21 Use Single-event Noise Model to validate Community Noise Modeling Shown is a snapshot of a dynamic model (2005) This is currently being extended into NoiseRunner Incorporating more extensive and more accurate data on exhaust jet source noise plus time-domain nonlinear propagation effects - Below is an updated source hemisphere produced by the Penn State group A/C Nose Input to NoiseRunner NO Competition considered with MIT s NOISIM?

22 New AFRL Noise Measurement Facility Acoustic Instrumentation Range Two 1210 towers with microphones and weather lateral microphone and weather arrays longitudinal microphone and weather arrays Accurate collection of in-flight 3-D noise signature HOW MANY AIRCRAFT involved in more extensive?? Min $10-20K/flight hour each power setting! $$$!!

23 EO Reforms pending Audit against ISO standards, ISO CAN implement nonlinear effects directly Information Quality Act peer review req d NoiseMap modules & Tech Reports NOISIM vs NoiseRunner; ESDU lateral atten. vs AF Quasi-linear vs compute-intensive nonlinear models 4 March Presidential Memo Review sole-source justifications Restore and allow source competition Integrity FIRST! Excellence - requires reform