1、NASA Contractor Report 198300/ .-/Aircraft Noise Prediction Program(ANOPP) Fan Noise Prediction forSmall EnginesJoe W. Hough and Donald S. WeirAlliedSignal Engines, Phoenix, ArizonaContract NAS1-20102April 1996National Aeronautics andSpace AdministrationLangley Research CenterHampton, Virginia 23681
2、-0001Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-AIRCRAFT NOISE PREDICTION PROGRAM (ANOPP)FAN NOISE PREDICTION FOR SMALL ENGINESFinal Report Prepare
3、d forNationalAeronautics and Space AdministrationLangley ResearchCenterContract NAS1-20102Task Order 6ByJoe W. HoughandDonald S.WeirSUMMARYANOPP has been successfullyrevisedtoincludea module which improvesfan noise prediction capability with small turbofan engines. Themodificationshave been verified
4、with measured data from three separateAlliedSignal fan engines. Comparisons of the revised prediction show asignificantimprovement in overalland spectralnoise predictions.Therevised technique provides predictions which now coincide with themeasured data spread from the AlliedSignal engines. The most
5、 notablerevisionsto the Heidmaun method include the reduction ofpeak discretetone levelsand combination tonelevels.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Provided by IHSNot for ResaleNo reproduction or networking permitted without license fr
6、om IHS-,-,-TABLE OF CONTENTS1.02.03.0STATEMENT OF WORK1.1 BackgroundI. 2 Objective1.3 SummaryRESULTS2.1 Technical Approach2.2 Update of Small Engine Data Base2.2.12.2.22.2.32.2.42.2.52.2.6Engine Fan DesignDominant Engine Fan Noise FrequenciesANOPP And GASP Predictions Versus DataFrom Engine 1ANOPP A
7、nd GASP Predictions Versus DataFrom Engine 2ANOPP And GASP Predictions Versus DataFrom Engine 3Generalized Small Engine Revisions2.3 Develop Small Engine Fan Noise Prediction Method2.3.12.3.22.3.32.3.42.3.5Inlet Discrete Tone NoiseInlet Combination Tone NoiseInlet Broadband NoiseDischarge Discrete T
8、one NoiseDischarge Broadband NoiseREVISED PREDICTION COMPARISONS WITH MEASURED DATA3.1 Engine 13.2 Engine 23.3 Engine 3SMALL ENGINE REVISION TEST CASEREFERENCESPa.e111233566789I0111317202325282829303132iiiProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,
9、-,-OF C_S (Contd)APPENDICESI ANOPP THEORETICAL MANUAL UPDATE (15 pages)II MEASURED DATA VERSUS REVISED PREDICTION, GASP, AND HEIDMANN,ENGINE I, (20 pages)III MEASURED DATA VERSUS REVISED PREDICTION, GASP, AND HEIDMANN,ENGINE 2, (28 pages)IV MEASURED DATA VERSUS REVISED PREDICTION, GASP, AND HEIDMANN
10、,ENGINE 3, (20 pages)V MEASURED DATA VERSUS REVISED PREDICTION, GASP, AND HEIDMANN,ENGINE 1, (5 pages)VI MEASURED DATA VERSUS REVISED PREDICTION, GASP, AND HEIDMANN,ENGINE 2, (7 pages)VII MEASURED DATA VERSUS REVISED PREDICTION, GASP, AND HEIDMANN,ENGINE 3, (4 pages)VIII SMALL ENGINE REVISION; FAN N
11、OISE PREDICTION TEST CASE(9 pages)IX SMALL ENGINE REVISION USERS MANUAL AND ANOPP CODEDEVELOPMENT (15 pages)X INTERIM PREDICTION METHOD FOR FAN AND COMPRESSOR SOURCENOISE, M. F. HEIDMANN, LEWIS RESEARCH CENTER (SELECTFIGURES ONLY) AND AIRCRAFT NOISE PREDICTION PROGRAMTHEORETICAL MANUAL, W. E. ZORUMS
12、KI, LANGLEY RESEARCH CENTER(SELECT TABLES ONLY) (20 pages)ivProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-FINAL REPORTAIRCRAFT NOISE PREDICTION PROGRAM(ANOPP)FAN NOISE PREDICTIONFORSM_LL ENGINES1.0 STATEMENT OF WORK1.1 BackgroundIn 1982, AlliedSign
13、al Engines (then Garrett Turbine EngineCompany) produced a “Computer Program to Predict the Noise of GeneralAviation Aircraft,“ (NASA CR-168050) under contract with NASA LewisResearch Center under the General Aviation Synthesis Program (GASP).This study identified a need to modify the Heidmann fan n
14、oise predict-ion procedure in the NASA Aircraft Noise Prediction Program (ANOPP) tobetter correlate measurements of fan noise from engines in the 3000-to 6000-pound thrust range. Additional measurements made byAlliedSignal since that time have confirmed the need to revise theANOPP fan noise method f
15、or smaller engines.1.2 ObjectiveThe NASA ANOPP has been used successfully for predictions oflarge transport aircraft. Application of ANOPP to smaller regionaltransport and business aircraft has demonstrated a need to improve thefan noise prediction capability. The objective of this task is to in-teg
16、rate a fan noise prediction capability for smaller engines intoANOPP. Four subtasks include:(1) Update of small engine data base(2) Develop small engine fan noise prediction method(3) Code and validate a revised ANOPP fan noise module(4) Document and report results1Provided by IHSNot for ResaleNo re
17、production or networking permitted without license from IHS-,-,-1.3 S_aryANOPP has been successfully revised to include a module whichimproves fan noise prediction capability with small turbofan engines.The modifications have been verified with measured data from threeseparate AlliedSignal fan engin
18、es. Comparisons of the revisedprediction show a significant improvement in overall and spectralnoise predictions.Figure 1 shows the improved prediction as compared to theHeidmann and GASP predictions. The revised technique providespredictions which now coincide with the measured data spread from the
19、AlliedSignal engines. The most notable revisions to the Heidmannmethod include the reduction of peak discrete tone levels andcombination tone levels.The small engine revisions have been incorporated into the ANOPPfan noise module. The revised module has been verified with measureddata and a test cas
20、e has been included for demonstration purposes.I05.0,9s.oi o,- 85.0_ o/total soundpower levelsfor threesmallAE engines-“ W GASPB m - I:llS_8_ON(ltr)d : 1.5 _%.-I-I“I I I I I I I l0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4Rotortip retatJveinletroachnumber,MtrFigure 1.I R_isionimpmv_fannoisepredi_onby2_SdB I
21、Revised Fan Noise Module Shows Overall ImprovementIn AlliedSignal Small Engine Prediction.2Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-2.0 RESULTS2.1 Technical ApproachThe proposed fan noise prediction revisions in the small enginerevision are in
22、tended to improve upon the well-established sourcenoise prediction procedures originally developed by The Boeing Companyunder contract with NASA-Ames and later improved by full-scale enginedata from NASA Lewis under the direction of M. F. Heidmann. In theHeidmann prediction procedure fan noise is di
23、vided into five separatemodules:o Broadband noise emitted from the inlet and discharge ductso Discrete tone noise emitted from the inlet and dischargeductso Combination tone noise emitted from the inlet ductPredictions within each module provide a one-third octave bandspectrum shape function, a tota
24、l spectrum level, and a free-fielddirectivity at a radius of one-meter from the source. Total fan noisethen is calculated through the logarithmic summation of the soundlevels within each of the five modules.Several engine performance parameters and engine build parametersare specified within this pr
25、ocedure and drive the predictions. Giventhat only three engines were available for AlliedSignals proposed re-vision procedure, some of these parameters did not appreciably varyfrom engine-to-engine, and were not fully investigated in this proce-dure. The influential prediction parameters are shown b
26、elow:Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Performance Parameterso Mass flow rateo Total temperature rise across the fano Design rotor tip relative inlet Mach number - This parameterremained nearly constant for the three engines, (Mtr) d -
27、1.55 percent. No attempt was made to modify the Heichnann cor-rections where (Mtr) d was usedo Operating rotor tip relative inlet Mach numberEngine Build Parameterso Rotor-Stator Spacing (RSS) - RSS for the three engines didnot vary enough to improve the RSS correction.o Presence of Inlet Guide Vane
28、s (IGVs) - AlliedSignal“s en-gines do not have IGVs. Therefore, the corrections whichvary due to IGVs could not be adjusted.o Presence of Inlet Flow Distortion (ground effects; staticoperation) - During acoustic testing, AlliedSignal uses aninlet flow control device (ICD) to eliminate flow distortio
29、ninto the inlet. Therefore, inlet flow distortion effectswere not examined in this investigation. AlliedSignal doeshave separate engine data with and without the ICD and canuse this data for future studies.AlliedSignals revised predictions concentrate on the adjustmentsto the spectrum level, spectru
30、m shape, and directivity adjustmentswithin each module based on the measured data of three small engines.4Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-No attempt was made to add new modules to the prediction or to incor-porate different prediction
31、 procedures not related to the Heidmannapproach.2.2 Update Of Small Engine Data BaseSubtask 1 calls for the identification of strengths and weak-nesses of the Heidmann and GASP predictions based on the AlliedSignalengine data. Figure 2 shows a comparison of small engine fan noisedata with the correl
32、ation of NASA Lewis full-scale fan data. Clearly,it is evident that the small engine fan noise data does not obey thesame correlation function for large fan data. Specifically, thecurrent Heidmann fan noise routine significantly overpredicts inletand discharge fan tone noise levels, inlet buzz-saw p
33、eak noise andspectrum content, and, to a lesser degree, broadband peak noise leveland spectrum content.140.=“3“ ,30:.1.oo. 1201000Correlation of totalsound power levels for/Ulk_lS_md fan data“ Engine #1 u Engine #2 a Engine #3 I_ DmaCowelatmPWL = 98.5 + 101og_TI,aTo) + 101og(SHP) 0o o u 8 1.05L=Lc-8
34、;k=I L =Lc+3-3k; k241 2 3 4 5 6Harmonic order, k8 1.05_ k=lL = Lc - 8 8 3Figure 8.Reference Figure 8a shown in Appendix XInlet And Discharge Discrete Tone Noise RevisionsImprove Interaction Tone Harmonic Levels.16Provided by IHSNot for ResaleNo reproduction or networking permitted without license fr
35、om IHS-,-,-2.3.2 Inlet Combination Tone NoiseThe characteristic peak sound pressure level for the fundamentaltone is:Lc = 20 log(_T/ATo) + I0 log(m/m o) + FlMtr + F2el + C(a) Changes to FlMtr: Figures 9, 10, and 11 show the revi-sions to the normalized peak SPL function, F1. The peaklevels for the 1
36、/2, 1/4, and 1/8 tones were reduced signifi-cantly. The slopes of the F 1 curves were also changed tobetter match the peak measured levels. Furthermore, notethe “201ogMtr“ distribution rather than the “Mtr distri-bution which is used in the Heidmann curves.(f/fb = 1/2)Lc = 201og(AT/ATo) + 101og(m/m
37、o) +IF,I_I+ F20 + CB ECombinationtonenoiselevelsat 1/2 of bladepassagefrequencyI O_ &GASP X Smmll_ _ ), 80.0-J _ 70.0m _ ,_.o4o.0Z .j_ 30.0 I I I ! I I0.0 1.0 2.0 3.0 4.0 5.0 6.02010g(RotorTip RelativeMachNumber)Figure 9.I Reference Figure 15a shown in Appendix X Inlet Combination Tone Noise Revisio
38、ns Improve PeakSPLCorrection.17Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Notes for future investigation of FI: The peak combinationtone levels currently are predicted by GASP to occur at Mtr= 1.0 for 1/2 and 1/4 tones, and Mtr - 3.0 for 1/8 ton
39、es.The measured data suggests that the actual peak levels maynot be solely dependent on the value of Mtr. Also, furtherinvestigation likely will reveal the need to improve theslopes of the normalized peak level curves.(f/fb = 1/4)Lc : 201og(ATIATo) + 101og(mlmo) +IFIM I+ F20 + CCombination tone nois
40、e levels at 1/4 of blade passage frequencyI 13 HeidmannX GASP Small Engine Revision I. A 80.0.oo600“_ so.om ._ 40.0E,-OZ o“ 30.00.0I I I I I I1.0 2.0 3.0 4.0 5.0 6.020log (Rotor Tip Relative Mach Number)I Reference Figure 15a shown in Appendix X JFigure I0. Inlet Combination Tone Noise Revisions Imp
41、rove PeakSPL Correction.18Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-(f/fb = 118)L = 20log(AT/To) + 101og(m/mo) +IF,Mt,I+ F20 + CCombination tone noise levels at 1/8 of blade passage frequencyI D Heidmannx GASP Small Engine Revision I80.0._- .L.
42、m oi _ 70.0_!60.0so0_ 40.0Z_ 30.00.0. I “_ “ “ _ . “& t I I I1.0 2.0 3.0 4.0 5.0 6.020log (Rotor Tq:) Relative Mach Number)I Reference Figure 15a shown in Appendix X IFigure 11. Inlet Combination Tone Noise Revisions Improve PeakSPL Correction.(b) Changes to F2e: Figure 12 shows the revision to thed
43、irectivity function, F 2. The slope of the function hasbeen decreased.The sound pressure level spectrum is:(c)SPL(f) = L c + F 3(f/fb )Changes to F3(f/fb): Figure 13 shows the revision to thecombination tone noise spectrum content. The distributionwas decreased from 301og to 151og for the 1/2 combin
44、ationtone spectrum. The 1/4 and 1/8 combination tone spectrawere not changed.19Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Lc = 201og(ATIATo) + 10log(mira o) + FIM_ _ CTheta Heidmann GASP, Revision10203O405O607O8O90100110120130140150150170180-_5-
45、7.0-5.0-2.00.00.0-,%5-7.5-9.O-9.5-10.0-10_-11.0-11._-12.0-12.5-13.0-1:L5-4.5-3.O-1.50.00.00.00.0-2.5-5.0-6.0-6.9-7.9-8.8-9_-10.7-11.7-12.6-13.6Reference Figure 16 shown in Appendix XFigure 12. Inlet Combination Tone Revisions Improve DirectivityCorrection.Notes for future investigation of F3: The co
46、mbination tonelevels were so highly overpredicted that revisions to thespectral content were not thoroughly investigated. Measureddata suggests significant room for improvement for F3.2.3.3 Inlet Broadband NoiseThe characteristic peak sound pressure level for the single fanstage is:Lc : 20 log(AT/AT
47、 o) + i0 log(m/m o) + FlMtr, (Mtr)d + F2RSS + F3e20Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-(f/fb = 1/2)SPL(f) = Lc +IFa=(flfb) I, I Revision: “151og(f/fb) I0Relative 1/3 -10Octave Band-20 g(flfb)I-300.1 0.5 1.0 5.0Dimensionless frequency, flf
48、bI Reference Figure 14a shown in Appendix X JFigure 13. Inlet Combination Tone Noise Revisions ImproveSpectrum Content.(a) Changes to FlMtr, (Mtr)d: Figure 14 shows the revisionsto the normalized peak SPL function, FI. A 3-dB decreasewas made for an overall improvement of the inlet broadbandnoise. The parameter of Mtr = 0.9 is agreeable with themeasured data.The sound pressure level spectrum is:
