會計學1EAS航空航天設(shè)計英文培訓2ElementsoftheAirfoilLiftCurveclcl,max

cl,aa00a0

acl,maxa第1頁/共27頁3EvolutionofNACAairfoilsectionsThehistoricalevolutionofairfoilsections,19081944.Thelasttwoshapes(N.A.C.A.661-212andN.A.C.A.747A315)arelow-dragsectionsdesignedtohavelaminarflowover60to70percentofchordonboththeupperandthelowersurface.Notethatthelaminarflowsectionsarethickestnearthecenteroftheirchords.第2頁/共27頁4AirfoilConfigurationCharacteristicsChordlineMeancamberlineLeadingedgeTrailingedgeUppersurfaceLowersurface第3頁/共27頁5Uppersurface,cl=0.22Lowersurface,cl=0.22(v/V)2x/cVelocityratiooverupperandlowersurfaces第4頁/共27頁6TypicalNACAAirfoilData(NACATR824)SplitflapdF=60oNoflapclcM,c/4Dragbucketcm,a.c.AngleofattackAngleofattack3million<Re<9million;std.roughnessatRe=6million第5頁/共27頁7第6頁/共27頁80204060df(degrees)Cl,max3.22.82.42.01.6IncreaseinMaximumLiftCoefficient–DoubleSlottedFlapCl,max=1.6[1+(df

/45)]第7頁/共27頁9AirfoilwithSlat第8頁/共27頁10EffectofSlatonLift第9頁/共27頁11HighLiftDevicesforMaximumLiftCoefficientCl,maxFlapsSlatPlainairfoil第10頁/共27頁12SupercriticalAirfoils第11頁/共27頁13FlowoverconventionalandsupercriticalairfoilsPressuredistributionsStrongshockwave第12頁/共27頁14Integralsupercriticalairfoil,t/c=11%NACA641-212airfoil,t/c=12%Slottedsupercriticalairfoil,t/c13.5%.02

.012

00.72M.84SupercriticalAirfoilDragComparedtoNACAAirfoilDragCd第13頁/共27頁15SupercriticalAirfoil,t/c=11%NACA641-212Airfoil,t/c=12%1.41.0Cn

.40.64.72M.84NormalForceCoefficientofSupercriticalAirfoilComparedtoNACAAirfoil第14頁/共27頁16bcVLiftonaFiniteWing2-DLiftDistribution3-DLiftDistribution第15頁/共27頁17WingTrailingVortexSystemandAssociatedDownwashFieldBoundVortexTrailingWingtipVortex

TrailingWingtipVortexDownwash第16頁/共27頁18Boeing727TrailingVortexFlightTest第17頁/共27頁19centerlinerootchord,crtipchord,cthalf-span,b/2Wingconfigurationwithhigh-liftdevicesleading-edgeslatstrailingedgeflapsinboardaileronoutboardaileronWingareaSisfoundintheengineselectionprocessA=b2/Sisselected,therebydeterminingbLlemeanaerodynamicchord,MAC第18頁/共27頁20Liftingcharacteristicsofthe3-DwingLiftcurveslopeofthewingTaperratio:l=ct/crPrandtl-MeyerfunctionSweepbackangles:Airfoilliftcurveslope:

k=

cl,a

/2p

第19頁/共27頁21DATCOMMethodForUntwisted,Constant-SectionWings

wingmaximumliftairfoilmaximumliftfromFig.4.1.3.4-21a

MachnumbercorrectionfromFig.4.1.3.4-22(extrapolationtoM=0.8required)wingaformaximumliftWingliftcurveslopeMachnumbercorrectionfromFig.4.1.3.4-21b第20頁/共27頁22Condition

TypicalFlapDeflection(indegrees)Takeoff 15<dTE<25;dLE<20Landing 40<dTE<50or60;dLE<20CL,maxinLandingandTake-offConfigurationsairfoilwithtrailingedgeflaps

(Dclmax)baseisthesectionmaximumliftincrementfor25percent-chordflapsatthereferenceflap-deflectionanglefromFig.6.1.3.7a,k1isafactoraccountingforflap-chord-to-airfoil-chordratiosotherthan0.25fromFig.6.1.3.7b,k2isafactoraccountingforflapdeflectionsotherthanthereferencevaluesfromFig.6.1.3.8a,andk3isafactoraccountingforflapmotionasafunctionofflapdeflectionfromFig.6.1.3.8b.第21頁/共27頁23DCL,maxfortheWingwithTrailingEdgeFlapstrailingedgeflapsleadingedgeslats(Notethatleadingedgeflapsarerarelyused.Seep.251-258inTorenbeekregardinghighliftdevices)第22頁/共27頁24AirfoilChoice : NACA64,-212(ROOT) NACA64,-209(TIP)AspectRatio : A=6.25TaperRatio : l=.333FlapType(cf/c) : Fowler,(23%)SpanwiseExtent(hiandho) : 16.4%and76.0%RatedArea(SWf/S) : 0.53SummaryofDesignLiftCharacteristicsoftheWingConfigura-tionFlapdeflectionindegreesSlatdeploymentCL,max

LowspeedM=0.2CL,maxcruiseM=0.8Cruise0no1.230.99Take-off25yes1.64-Landing40yes1.92-第23頁/共27頁25HorizontalTailSizinglh0.05MACSh,horizontaltailplanformareaVh=Shlh/S(MAC)Volumecoefficientofthehorizontalta