1、NASA CR-! 14649AIRCRAFT NOISE SOURCEAND CONTOUR ESTIMATIONBy D. G. Dunn and N. A. Pealx!i,: July 1973Available to the public|NA%;A-CE-11_0_9 AIECA?T NOIS_ 3OU_CE NIJ=319_5AND CONTOUR ESTIHA_IG_ (dOeil_q CommeccialAirplane Co., Seattle) 233 p HC $13,75CSCL 2_A Jncla_G3/_2 IH1_JPrepared under contract
2、 NAS2-6969 byBoeing Commercial Airplane Company.0.r.O. Box 3707Seattle, Washington 98124forAmes Research CenterNA/auNAL AERONAUTICS AND SPACE ADMINISTRATION00000001Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-I. Report No. 2“. Government Accossion
3、 No. 3. Ret:ipientsCata(og No.NASA CR- I !4649 I4. Title and Subtitle 5. Report DateAIRCRAFT NOISE SOUqCE AND CONTOUR ESTIMATION July 1.9736. PerformingOrganization Code7. Author(sl 8. Performing Organization Report No.D. G. Dunn and N. A. Peart D6-6023310, Work Ur.it No.9. Performing Organization N
4、ame and AddressBoeing Commercial Airplane Company 11.contractorGrantNo,P.O. BOX3707Seattle, Washington 98124 NAS2-6969t 13. Type of Report and Period Covered12. Sponsoring Agency Name and Address Contractor ReportNational Aeronautics and Space Administration | 14,SponsoringAgencyCodeWashington, D.C.
5、 20546 I1,5.SupplementaryNotes Computer programs may be obtained fronaProject Manager, D. H. Hickey COSMIC, Computer Software Management Information CenterNASA-Ames Research Center 112 Barrow Hall, University of GeorgiaMoflktt Field, California 94035 Athens, Georgia 3060116 AbstractCalculation proce
6、duresare presentedfor predictingthe noise-timehistoriesand noisecontours(footprints) of five basictypesof aircraft: turbojet, turofan, turboprop, V/STOL, andhelicopter.The procedureshavebeencomputerizedto facilitate predictionof the noisecharacteristicsduringtakeoffs, flyovers,and/or landingoperatio
7、ns.The usersguidefor the computer programsisprovidedin a companionreport, NASA CR-i 146501/, gev Worsts IS ugl(jcsted bv Auehot(s) ) 18. Distribution Seato,mentAircraft noiseprediction Unclassified unlimitedNoise;uppressionAcoesticliningw_llnclas,_ific,I | Unclassified 241 53.00*For salt? bY tho Nfl
8、fion, ar, l_J Information ,3.3trice. Springfl01d. Virgima 221r_100000001-TSA03Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-CONTENTSPage1.0 SUMMARY 12.0 INTRODUCTION . 33.0 CONCLUSIONS 64.0 RECOMMENDATION . 65.0 DISCUSSION . 7if! 5.1 Macroscopic Vi
9、ew of the Problem . 7-_ 5.1.1 Definition,_/Limitations/Assumptions . 125.1.2 Geometry Solution !65.1.3 Noise Extrapolation . 2 i5.1.4 Lining Treatment 27 5.1.5 Configuration Corrections . 355.1.6 Summation of Component Noise . 355.1.7 Output for Noise Contour Estimation . 385.2 Noise Source Estimati
10、on . 385.2.1 Measured Noise Data . 405.2.2 Jet Noise 425.2.3 Core and Turbine Noise 1085.2.4 Compresso or Fan Nois_ . 1225.2.5 Propeller, Helicopter, and Tilt Rotor Noise . 1485.3 Noise Contour Estimation 1755.3.1 Acoustic Data 1785.3.2 Aero/propulsion Data . 1785.3.3 Noise Contour Calculation 1795.
11、3.4 Area Calculation . 1815.3.5 Noise Estimate on Sideline . 182APPENDIX A-Theoretical Ground Reflection Predictiop Procedure 183APPENDIX B-Theoretical Ejector Performance 191REFERENCES 22700000001-TSA04Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,
12、-AIRCRAFT NOISE SOUHCEAND CONTOUR ESTIMATIONBy D. G. Dunn end N. A. PeartBoeingCommercial Airplane Company1.0 SUMMARYReflecting the need for analyzing and, if possibl:, red_)cingthe community noise resultingfrom aircraft operations, the Boeing Commercial Airphme Company, under contract to NASA-Ames,
13、 has developed a computer program for predicting the noise generatedby live basictypes ofaircraft: turbojet, turbofan, turboprop, V/STOL, and helicopter. A second program has been0developed which calculates contours of equal noise level (footprints) and the area within thecontours for an airplane du
14、ring takeoff and approach operations. The footprint program iscompatible with the NASA-Ames flight simulator. The flight simulator provides aerodynamic andengine performance data, and _he footprint program calcul_es contours for equal noise level,thereby providing an estimate of the noise exposure p
15、roduced by an aircraft operation. Typicalresults from the computer programs are shown in figure 1. These computer programs are intendedto _ssist air,:raft designers by identifying the noise characteristics of various aircraft and engineconfiguratio_ls. These noise levels can then be compared to comm
16、unity noise goals.Aircraft noise prediction techniques used within the aviation community arc usually based onempirical d;_ta and the resulting procedures vary. These differences arise in numerous ways; e.g.,(I the sanlt acoustic data can be formulated into prediction procedures with varying degrees
17、 ofsophistic_ttion and complexity, (2) differences in noise measurements do occur in similar tec_ whensome of tl,c important variables can not bc controlled, and (3) the complexities in noise _. .erationand propa_.,ation have fostered more than oac theoretical view of the phenomena involved.lhc sour
18、ce noise prediction and extrapolation techniques presented in this report represent thestate of the art durii,g the contract time period. The procedures are primarily empirical. Some parisof the procedures were obtained from published literature and in some inslances unpublishedmelhods ustd within t
19、he Boeing Commercial Airplane Company were employed. The selection oftcchuiqucs wcrc m_lde to provide a base for comparisons among aircraft design choices and forcv;duatio_ of aircraft operations. ItoweveL results from these procedures can not be expected toagree c;clly with absolute noise levels ca
20、lculated hy other schemes. In many instances, ancugine/air_rame confi_.,uration has its own peculiarities. These peculiaritie_ may require cmxections00000001 -TSAO.RProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-ZNOISE $3URCE ESTIMATOR PROGRAM RESUL
21、TS SOU_ID PRESSURE LEVEL (SPL) SPECTRA vs. TIME _vX PERI_EIVED NOISE LEVEL (PRL) vs. TIUE EFFECTIVE PERCEIVED NOISE LEVEL (EPNL)Y/aEERVERNOISE CONTOUR ESTIMATION PROGRAM RESULTS EPNL OR MAXIMUN PNL CONTOUR POINTS AREA WITHIN EACH CONTOUR ._ ._./ j_TYIqC_L) NOISE ESTIMATES (EPRL CwmAX. PNL) ON _ /“ “
22、/“ “_“_“_“ “SIDELINES FROtl FLIGHT TRACK| i 1 !XRESULTS GIVEN FOR EACH NOISE COIIPO_ENT AT EACH ,._ /_( / Tn_r,xOBSERVER / FLIGHT PATH SEGMENT OEFi01ED BY THE USER. _ _,_REQUIRES NOISE SOURCE PREDICTIONS OR EEASURENENTS AI“_YA SERIES OF POINTS AS DISCUSSED W SECTION 5.3.FIGURE 1.-RESUL TS FROM NOISE
23、 SOURCE AND CONTOUR COMPUTER PROGRAMS00000001-TSA06Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Iobc app;,c.I to the predict.d levelsfor a parth:ular m)is source .onipotlentOI eh;,Ing,_ ill one ormore of the variouscai_:ul.ltionmethodsoflured in t
24、his report.it is extremely difficult to assess the ,tcuracy of noise prediction procedures. This difficultyresults froni i_sufficient data for known sources (individual component sources which combine togive the total nois_, of _he system), anomalies in measured data. and the small number of differe
25、ntengine/source configuratioqs. Cemparison_ of predicted with measured noise levels (EffectivePerceived Noise Levels, EPNdB) tor cu,e.nt airplanes have shown tha*. the tolerance for thesemethods is generally +5 EPNdB. It should be recognized that noise levels are logarithmic quantities,and an error
26、in a noise estimate can result in a large error in a contvu: estimate such as area. Hence,the tolerance for the contour estimation procedure largely depends on the confidence levelassociated with the acoustic data that is used.A description of how to use the computer programs is contained in a tompa
27、nion report(ref. I) This portion of th,: report contains the engineering description of ti_e noise predictionprocedures embodied in the ,:omputer programs.2.0 INTRODUCTION-i he increase in commercial aviation in the last decade has been accompanied by increased_ complaints rrom communities directly
28、exposed to the higher noise levels associated with aircraftreduce the noise have included changes inoperations. initial attemptsto community exposuretakeoff and approach procedures, development of acoustically treated inlets and mounting jet noiseSUl_pressorson the exhaust nozzles. Also, Federal noi
29、se regulations (ref. 2) have established noiselimils for new airplanes that are significantly lower than first generation jet operation levels. “l_aisrecent emphasis on reducing airplane noise has resulted in considerable acoustics-related research_,_,1dew/ol_ment activities_ These activities have b
30、een primarily directed toward defining the noiset_,.eratinga_cchanisms of aircraft engines and defining ways of reducing noise at its source throughdesign innovations and suppression devices.The implementation of noise reductiop technology in engine, nacelle, and acoustic liningde._tgn has Jesulh:d
31、in a generation of quieter airplanes, e.g., the Boeing 747, Douglas DC-IO,Lockheea L-101 I, and Cessna Citation. Numerous other programs are currently under way, eachwith the objective of either reduch_g the noise of current airplanes or developing noise technologyfor applic thon to future aircraft.
32、 Throughout these research programs, there has been only minima:effort dcvot-d to developing the methodology required for predicting the total community noisep_rtbrmancc of new airplanes. This report represents the state of the art calculation procedure foraircraft totmnunily ,i_ise ptcdiction.00000
33、00-TSA07Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-The current contract, NAS2-6969, has been completed in tw0 parts_-ph_ses A and B (ref. 3).Phase A (ref. 4) consisted of providing rela_:ively“crude“ compu_eJ_i_edprocedures applying tonoise sour
34、ce estimation of conventional turbojets or turbofans. Also, part of the Phase A effort wasthe development of computerized procedure_F_rnoise contour estimation adaptable to “reabtime“flight simulation. The computer programswere designed to operate on the IBMSystem 360167 withthe additionalrequiremen
35、tthat thenoisecone.ourprogramwouldoperateon theXeroxSigmaViiand VIII computersin conjunctionwith the NASA-Amesflight simulator,phaseB consistedofsupplyingmore advancedcomputerizedproceduresf(Jr noise sourceprediction.The computerprogramfor this purposehasbeenwritten to provide I/3 octaveband nolle e
36、_timatesfor suchconfigurationsasadvancedtechnology“quiet“ engines,rift fans,lift/cruisefans,ejector/suppressor,e-t blown-flap, propeller, helicopter, and tilt rotor aircraft,etc., in addition to that for conventional jetaircraft. Also, the contour program has been updated to be applicable for the mo
37、re generalizedrequirements.The discussi,3n_ection of this report has been divided into three parts. The first deals with *,heoverall view of the noise prediction procedures.The second deals with the description of the variouscomputer modules for noise source estimation. T=b!e ! lists the computer mo
38、dules included.In each of the computer modules, the user has the option to specify reductions on a spectralbasis when suppression devices are employed. For these situations where lining is installed, acalculation procedure applicable to optimized, single or double layer linings is available. Thesepr
39、ocedure._are included in the noise _ource estimation program for those items noted in the list forthe noise source computer modules in table !.After the individual noise source spectra are computed for a datum condition (free-field,1 meter from source), extrapolation technique are then used to adjus
40、t the datum spectra tocorrespond to the noise observed as the aircraft ,des by an observer. The spectra obtained arefunctions of time and permit the calculation of the effective perceived noise level during takeoffand/or landing.The third part of the discussion deals with the procedures used to calc
41、ulate noise contours. Atthe discretion of the user, an additional output of the noise source program can be a set of tabulardata on IBM cards to define an acoustic data routine for the noise contour program. The acousticfunction can be either peak perceived noise level or effective perceived noise l
42、evel versus someengine performance parameter, range at the closest point of approach, and elevation angle. Thisfunction is then used for calculating noise contours as described in section 5.3. The computerprograms for this task are designed to run in real time“ on the Xerox Sigma Vll or VIll compute
43、rsfor flight silnulationsa.d in “batch mode“ on theIBM System360/67.00000001-TSA08Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-TABLE I.-NOISE SOURCEESTIMATION COMPUFERMODULESNO. of Modules Measured Data 1 Jet Noise 5a. Single exhaust nozzleb. Co-a
44、nnular exhaust nozzlesc. Ejector/suppressor* , d. Slot nozzle wtth augmenter ?lap* e. Externally-blown flap Noise Generated Inside Primary Duct 2: a. Core*I b. Turbine*1 Compressoror Fan Noise 3a. Inet compressor _r fan*b. Discharge fan*c. Lift-fans* Propeller, Helicopter and Ttlt Rotor 2a. Empirica
45、l wopeller procedureb. Theoretical propeller/rotor proceduresTotal 13*Denotesoptionaluseof lining00000001-TSA09Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-3.0 CONCLUSIONSThis is the final report for contract NA$2-6969. It describesthe restAtsfor
46、the Phase B portionof the contract. Empirical procedures are described which represent the s:ate of the art and are thebest approachesreadily at hand for estimating the community noise levels fo; the five basic types of_ircraftmentioned in the summary. At the present time, comprehensive theoretical
47、procedures donot exist for noise prediction for all the aircraft mentioned. In some cases, theoretical methods canbe computerized, but they are computationaily expensive, requiremore detailed information than isreadily available,and do not provide significantly more accurate absolute levelsthan that
48、 obtained_,_,_ by empirical means._ Past experience has shown that when suppressiondevices are t_,sedto reduce the acoustic levelsof major noise source(s); new noise sources always appear. New prediction procedules must becontinually developed to reflect the noise contribution of the new sources. Also, the existingprocedures must be continually refined to reflec_ the change in engine design and the demand forincreasedaccuracy.4.0 RECOMMENDATIONin general, aircraft noise prediction methods will change as technology improves;therefore, itis recommended that these procedures and
