1、/6“,eOF-/_-?_.,X _7oli ( -4_-, 31176001401687 NASA-CR-1,9200198000166091- NASA Contractor Report 159200 1INTERIOR NOISE CONTROl_t_ PREDICTION STUDY FORi-, HIGH-SPEED PROPELLER-DRIVENI ;AIRCRAFTtD.C. Rennison_L J.F. WilbyA.H. Marsh _il E.G. WilbyI i BOLT BERANEK AND NEWMAN INC.iCanoga Park, Californi
2、a 91303l i (*DYTEC ENGINEERING INC.- Long Beach, California 90806)-r. . .- Contract No. NAS1-15426!_ September 1979 ,.NationalAeronautics andI i Space AdministrationLangley Research Center- Hampton, Virginia 236,S5!t _, AC 804 827 3966Provided by IHSNot for ResaleNo reproduction or networking permit
3、ted without license from IHS-,-,-I1,I iiIF-,Ii_!iJProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-i _- NASA Contractor Report 159200INTERIOR NOISE CONTROLPREDICTION STUDY FORHIGH-SPEED PROPELLER-DRIVEN: J AIRCRAFT,D.C. Rennison_ d.F. WilbyA.H. Marsh
4、*r-i! E.G. Wilbyi/ BOLT BERANEK AND NEWMAN INC.Canoga Park, California 91303_- (_DYTEC ENGINEERING INC., Long Beach, California 90806)Contract No. NAS!-15426-1! September 1979,-_ NationalAeronautics andi Space AdministrationILangley ResearchCenterHampton,Virginia 23665i AC 804 827-3966i,Provided by
5、IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-_j-!,! plProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-TABLE OF CONTENTSi.Section Page1.0 SUMMARY 1 2.0 INTRODUCTION 32.1 Noise Control Study 32.2 General Charact
6、eristics of Analytical Model 4! 2.3 Application of the Model to Propeller Aircraft 5_ 2.4 Study Aircraft Computations 82.5 Experimental Verification I0I i 3.0 ANALYTICAL MODEL 12_- 3.1 Power Balance Approach 123.2 General Formulation 133.3 Representations for the External Pressure Field 233.4 Tonal
7、Power Flow Equation 31i 3.5 Power Flow Statistics 33_ 3.6 Joint Acceptances 443.7 Internal Coupling 51_- 3.8 Test Conditions on Allowed StructuralWavenumbers 563.9 Sidewall Representation 59_- 3.10 Interior Acoustics 69, 3.11 Computational Procedures 734.0 BASELINE AIRCRAFT 75i 4.1 Study Requirement
8、s 764.2 Choice of Existing-Design Aircraft 77T_ 4.3 Propfan Sizing Analysis 784.4 Characteristics of Baseline Aircraft 844.5 Baseline Fuselage Designs 924.6 Propeller Noise Field 107r_5.0 MODEL OF STRUCTURE I167 5 1 General Representation 1165 2 Structural Representations 1225 3 Modal Density 1255 4
9、 Joint Acceptances 1305 5 Radiation Efficiency 1345 6 Loss Factors 1355 7 Structural Idealization forr- Computational Purposes 138Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Section Page !6.0 NOISE LEVELS IN BASELINE AIRPLANES 147.6.1 Hamilton St
10、andard Excitation Spectrum 147 i6.2 Alternative Excitation Spectra 161 -6.3 Conclusions 1647.0 ADD-ON NOISE REDUCTION METHODS 165 .7.1 General 1657.2 Maximizing the.Interior Absorption Coefficients 1667.3 Increased Structural Damping 1697.4 Double-Wall Sidewall Configurations 171 ,_7.5 Summary 179 !
11、8.0 ADVANCED NOISE REDUCTION METHODS 1818.1 Variations in Frame Parameters 182 ._8.2 Variation in Fuselage Skin Thickness 1878.3 Honeycomb Skin Panels 1898.4 Summary 192 19.0 REQUIREMENTS FOR EXPERIMENTAL VERIFICATION OFANALYTICAL MODEL 196 -_9.1 Introduction 1969.2 Sensitivity Studies 197 -_9.3 Can
12、didate Noise Sources 227 I9.4 Validation Experiments with a Model Fuselage 240 _i9.5 Aircraft Tests 255I0.0 CONCLUSIONS 267 JREFERENCES 269 _APPENDIX A - JOINT ACCEPTANCE EXPRESSIONS FOR NON-HOMOGENEOUSPRESSUREFIELDS 274APPENDIX B - EXPECTEDVALUE OF THE MODALADMITTANCE fFUNCTION g(mb,mn) 280APPENDIX
13、 C - RELATIONSHIP BETWEEN ImIrr(_) AND f2(n,r), ,_28aJrAPPENDIX D - FINAL SIDEWALL DESIGN UTILIZING ADD-ON TREAT- 285 ,MENTSAPPENDIX E - LIST OF SYMBOLS 290 JiiProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-ILIST OF FIGURES! , Figure PageI. Periodic
14、 Source Located Adjacent to (x,y) Plane . . 26!, 2. Variation in Joint Acceptance with k /km andAmplitude Decay Constant a for m=4x andX_CX= 0 47ix/kin_ , 3. Variation in Modal Joint Acceptance with kand m for Amplitude Decay Constant ax 0 5 49_ 4. (a) Parallelepiped with Three Deformed Surfacesto i
15、llustrate representation of FuselageCabin 52! (b) Simplified Representation of Relationshipbetween Vibrating Structure and Cabin 52%_ 5. Mikulas Frequency Equation for a Simply-Supported_, Stiffened Cylinder . 586. Power Balance Representation of Sidewall Acoustics . 60_ 7. External Geometry of Pane
16、l-Pressure Field Con-figuration . 64_- 8. Sidewall Representation for Porous Layer Boundedby Impervious Septa Mounted over Airgap . 659. Cross Section View of Image Array for Point Source.L_ (S) located in Wall and Centerline Observer (0) . . 72I0. Flow Diagram for Computation of Internal Noise Leve
17、lsfor Study Airplanes . 74i-_ II. Performance Parameters for lO-Bladed Propfan; Free_ Stream Mach Number M0 = 0.80 . 8312. Baseline Wide-Bodied Airplane . 89_i 13. Baseline Narrow-Bodied Airplane . 9014. Baseline Small-Diameter Airplane . 91J 15. Typical Passenger Cabin Arrangements for thei, Study
18、Airplanes . . . . . . . . . 93T_ 16. Typical Skin,Stringer-Frame Construction fori _ Conventional Fuselages . 9417. Structural Details for Baseline Wide-Body Fuselage . . 96_- 18. Structural Details for Baseline Narrow-Body Fuselage . 97i19. Structural Details for Baseline Small-Diameter_-,_ Fuselag
19、e 9820. Baseline Transmission Loss for Add-On Sidewall I03! iiiProvided by IHS Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-LIST OF FIGURES (Contd) i-_Figure21. Comparison of Measured and Model Absorption ,_Coefficients 105 22. Sound Absorption Spectra Assumed f
20、or FurnishingComponents . 10623. Directivity as a Function of Tip Clearance I0824. Variation of External Sound Pressure Level Along ,_-the Cabin I0925. Circumferential Trace Velocity and AmplitudeVariation for Inboard Propeller of Wide Body Airplane III26. Harmonic Levels of External Sound Field . I
21、1227. Longitudinal Trace Velocity for Inboard Propellerof Wide Body Airplane 11528. Representation of Fuselage Structural Element ll929. Acceleration Coherence Measured on Adjacent Panelsof Boeing 737 Fuselage (M = 0.78, Jet and BoundaryLayer Noise) . 12330. Variation of Modal Density with Panel Are
22、a (TypicalNarrow Body Fuselage Element, Low Frequency Struc-tural Model) . 12631. Variation of Modal Density with Panel Element Area:Low Frequency Structural Models . 12732. Variation of Modal Density with Frequency . 12933. Effect of Panel Area on Band-Averaged ProgressiveWave Joint Acceptance (Typ
23、ical Narrow Body Fuselage. Element, Low Frequency Structural Model) 131 _34. Effect of Panel Area on Band-Averaged ProgressiveWave Joint Acceptance: Low Frequency StructuralModels 132 -35. Effect of Panel Area on Band-Averaged ReverberantField Joint Acceptance (Typical Narrow BodyFuselage Element, L
24、ow Frequency Structural Model . . . 13336. Variation of Loss Factor with Frequency . 13737. Sketch Showing Locations of Structural Elements andPropellers: Wide Body Airplane 139ivProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-! LIST OF FIGURES (Cont
25、d)I , Figure PageJ-;j 38. Sketch Showing Locations of Structural ElementsJ and Propellers: Narrow Body Airplane . 140_-_ 39. Sketch showing Location of Structural Elements andi Propeller: Small Diameter Airplane 141j-,40. Variation of Power Flow into the Cabin Along Cabin_-, Length 148_ 41. Calculat
26、ed Power Flow Through Fuselage Structures . . . 15042. Axial Variation in Sound Level for Different Interiori Absorption Coefficients _NarrowBody) 152I o 43. Comparison of Calculated and Measured Variation of_-i Sound Level Along Cabin of a Small Diameter Propeller-Driven Aircraft 15344. Axial Varia
27、tion of Cabin A-Weighted Sound Level for_- Different Sidewall Treatments (Hamilton Standard_, / Excitation 6) 15445. Cabin Spectra at Location of Maximum dBA Levelsfor Bare and Baseline Treated Fuselages 156i_ 46. Comparison of Calculated Baseline Noise Reductionswith Empirical Data for Narrow-Bodie
28、d Fuselages 159_- 47. Expected Error Limits for the Acoustic Power Flow into“ the Airplane Cabins . 160T- 48. Axial Variation of Cabin A-Weighted Sound Level for! _ Different Excitation Spectra (Baseline Structure,Transmission Loss and Absorption) . 162“ 49. Cabin Spectra at Location of Maximum Soun
29、d Level for Different Excitation Spectra . 16350. Sound Absorption Spectra assumed for Furnishingr- Co pon ts 167m en . . “ 51, Effect of Cabin Absorpition on Cabin A-WeightedSound Levels . 168_ , 52. Airplane Test Data on the Effect of Damping Treat-“ “ ments on Airplane Interior Noise Levels 35 17
30、0_ 53. Effect of Structural Damping at Location ofI Maximum A-Weighted Sound Levels . . . , . 172IProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-LIST OF FIGURES (Contd)Figure Page54. Additional Sidewall Transmission Loss (Double WallConfiguration Wi
31、thout Flanking) 17455. Effect of Flow Resistance and Trim Surface Densityon Add-On Sidewall Transmission Loss for Double WallSidewall (No Flanking) 177 -i56. Variation of Sidewall Treatment Surface Density ,“along Cabin Length to Achieve 80 dBA Maximum CabinSound Level 178 t Q p Q !57. Cabin Spectra
32、 at Location of Maximum Sound Levels,for Changes in Frames . 18358. Cabin Spectra at Location of Maximum Sound Levels, :for Changes in Skin 18859. Representation of Frame-Stiffened Honeycomb FuselageShelI . l91 , ,i60. Effect of Structural Changes on Space-Averaged CabinA-Weighted Sound Levels 194 _
33、61. Effect of Structural Scaling on . 20062. Predicted Additional Sidewall Transmission Loss,Full and Half-Scale Fuselage Models . 208, !63. Effect of Changes in Frame Stiffness and Skin Thicknessand of Pressure Difference on ( ) and _ forWide Body Aircraft (Element 4). r.,n.,_ 211 -_ 64. Effect of
34、Changes in Frame Stiffness and Skin Thicknessand of Pressure Difference on ,_m(m, ) and _.for. _Narrow-Body Airplane (Element 4.)r b 212 !65. Effect of Changes in Frame Stiffness and Skin Thicknessand of Pressure Difference on , n(_b) and _ for -_Small-Diameter Airplane 21366. Effect of Variations i
35、n Amplitude Decay Rate andCoherence on Band-Averaged Joint Acceptance: Wide-BodyAirplane (Element 4): Low Frequency Structural Model . 215 _67. Dependence of on Changes in (axa,), showingConstraints on (_,a, as determined b_ Required _-Accuracy in ._J. . 216 _-68. Effect of Variations in Trace Wave
36、Speed on Band- -_Averaged Joint Acceptance: Wide Body Airplane (Element 4):. iLow Frequency Structural Model . 217. !viProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-i_ LIST OF FIGURES (Contd),!_- Figure PageIJ69. Effect of Variations in Frame Prope
37、rties for Wide Body_r- Airplane - Variation in Frame Bending Stiffness 219_ , 70. Effect of Variations in Frame Properties for Wide BodyAirplane - Variation in Frame Membrane Stiffness 22071. Effect of Variations in Stringer Properties for WideBody Airplane - in Stringer Bending Stiffness . 221_ 72.
38、 Effect of Variations in Stringer Properties for Widei Body Airplane - in Stringer Membrane Stiffness . 22273. Effect of Variations in Skin Thickness for Wide Body_- Airplane . 224 74. Effect of Panel Curvative on n(_ b) and a for WideBody Aircraft (Element 4) . r 225I 75. Sketch of Possible Arrange
39、ment of Model Propfan and jFuselage Within the Anechoic Flow Facility, NSRDC,Carderock 44 . 231! 76. Spatial Variation of Propeller Overall Sound Level in Longitudinal Direction: Comparison of Propfan Pre-dictions and General Aviation Measurements 232I 77. (a) Variation of Axial Trace Velocity with
40、X/D for3 Study Airplanes (Ray Acoustics Model withSource Location at 0.7 Propeller Radius) -X-! Aero Commander Data 8 234(b) Variation of Circumferential Trace Velocity._- Propfan Predictions Based on Rigid BodyRotation of Hydrodynamic Propeller Pressure Field 23478. Required Axial Directivity feren
41、tial Direction 239./,81. Schematic End View of Test Configuration 242_ 82. Schematic Diagram of Signal Generation and Data_ , Acquisition Systems . . 25183. Schematic Diagram of Data Reduction System 253I84. Differences Between Predicted and Measured PayloadBay Levels for Space Shuttle Validation Te
42、sts . 256. vii( Provided by IHS Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-I_rLIST OF FIGURES (Contd)Figure85. Use of Small Diameter Fuselage to Scale Model WideBody Fuselage 26186. Use of Small Diameter Fuselage to Scale Model Wide -Body Fuselage 262viiiProvi
43、ded by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-1 LIST OF TABLESI Table Page_“ 1 Performance Parameters for Propfan-Powered Baseline Study Airplanes . 862. Performance Parameters Common to Each Baseline;_- Study Airplane . 88 3. Characteristics of Baselin
44、e Fuselages 99_ 4. Structural Segmentation Details: Wide-Body . 143! 5. Structural Segmentation Details: Narrow-Body 1446. Structural Segmentation Details: Small-Diameter. . . 145_ 7. Structural Data for Typical Element of BaselineAirplanes 1468. Minimum Additional Noise Reduction Required forBaseli
45、ne Structure 1579. Calculated error limits for the acoustic power flow. abi 161_ _ into airplane c ns I0. Predicted Weight Increase, relative to BaselineAircraft, to achieve 80 dB A-Weighted Sound Level_- 179Criterion .II. Fuselage Details for Advanced Noise ControlStructures: Wide Body . 184ii 12.
46、Fuselage Details for Advanced Noise Control Struc-tures: Narrow Body. 185. 13. Fuselage Details for Advanced Noise Control Struc-I tures: Small Diameter 18614. Dimensions for Honeycomb Structures 19015. Summary of Noise Reductions Achieved with AdvancedConcepts 193f- 16. Comparison of Study and Exis
47、ting Aircraft . 257r rixProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-I(ItProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-!1 1.0 SUMMARYi An analytical model has been developed to predict the trans-
48、mission of propeller nois_ into the cabin of a high-speed_ propeller-driven airplane. The model is then used to determineJ the noise control treatments required to achieve a goal of aninterior A-weighted sound level of 80 dB for three study air-planes with different fuselage diameters but with a commoncruise Mach number of 0.8 at an altit
