《直升機空氣動力學(xué)與飛行原理》課件-模塊五：旋翼揮舞（雙語）

模塊五：旋翼揮舞Rotorwaving直升機空氣動力學(xué)與飛行原理Helicopteraerodynamicsandprinciplesofflight工作場景旋翼是直升機的升力面，產(chǎn)生使直升機升空的升力；又是直升機的操縱面，提供使直升機升降、俯仰和滾轉(zhuǎn)的操縱力和力矩；而且還是直升機的推進器，拉動直升機向任何方向飛行。Therotoristheliftsurfaceofthehelicopter,whichproducestheliftforcethatliftsthehelicopterintotheair;Itisalsothecontrolsurfaceofthehelicopter,whichprovidesthecontrolforceandtorquethatmakethehelicopterlift,pitchandroll;Anditisalsothethrusterofthehelicopter,pullingthehelicoptertoflyinanydirection.工作場景旋翼的揮舞運動對直升機的穩(wěn)定性和操縱性起著關(guān)鍵作用，是直升機穩(wěn)定性和操縱性分析的主要技術(shù)特點和難點，也是區(qū)別于固定翼飛機穩(wěn)定性和操縱性的主要根源，因而在分析直升機的平衡和運動之前，應(yīng)先了解旋翼結(jié)構(gòu)和旋翼的揮舞運動。Theswingingmotionoftherotorplaysakeyroleinthestabilityandmaneuverabilityofthehelicopter,whichisthemaintechnicalcharacteristicsanddifficultiesofthestabilityandmaneuverabilityanalysisofthehelicopter,andisalsothemainsourceofthestabilityandmaneuverabilityofthefixed-wingaircraft.了解旋翼的鉸接形式Learnaboutthearticulationoftherotors01Teachingobjective教學(xué)目標(biāo)熟悉槳葉的揮舞運動Familiarizeyourselfwiththemovementofthepaddleswing02理解旋翼的揮舞特性Understandtheswingingcharacteristicsoftherotor03了解直升機的振動與噪聲Learnabouthelicoptervibrationandnoise04模塊五：旋翼揮舞Rotorwaving任務(wù)一：旋翼的鉸接形式Articulatedformofrotors直升機空氣動力學(xué)與飛行原理Helicopteraerodynamicsandprinciplesofflight活動1：旋翼的形式有哪些？01.PARTONEWhataretheformsofrotors?活動1：旋翼的形式有哪些？旋翼的形式由槳轂形式?jīng)Q定，旋翼槳轂根據(jù)它的結(jié)構(gòu)設(shè)計，主要分為全鉸式旋翼槳轂、半剛性蹺蹺板式旋翼槳轂和剛性旋翼槳轂3類。旋翼形式大致分為全鉸式、半鉸式、無鉸式和無軸承式4種。Theformoftherotorisdeterminedbytheformofthepropellerhub,whichismainlydividedintothreecategories:fullyhingedrotorhub,semi-rigidseesawrotorhubandrigidrotorhubaccordingtoitsstructuraldesign.Therearefourtypesofrotors:fullyhinged,semi-hinged,unhingedandbearingless.全鉸式旋翼槳轂包含有軸向鉸、垂直鉸和水平鉸。Afullyarticulatedrotorhubconsistsofaxial,vertical,andhorizontalhinges.活動1：旋翼的形式有哪些？全鉸式旋翼Fullyarticulatedrotor半剛性蹺蹺板式特點：沒有擺振鉸，結(jié)構(gòu)簡單，兩片槳葉相連共用一個揮舞鉸。Semi-rigidseesawtypeFeatures:Thereisnooscillatinghinge,thestructureissimple,andthetwopaddlesareconnectedtoshareaswinginghinge.活動1：旋翼的形式有哪些？半鉸式旋翼Semi-articulatedrotor半剛性蹺蹺板式和萬向接頭式都屬于半鉸式旋翼。Boththesemi-rigidseesawtypeandtheuniversaljointtypebelongtothesemi-articulatedrotor.萬向接頭式特點：兩片槳葉通過各自的軸向鉸和槳轂殼體相連接，而槳轂殼體又通過萬向接頭與旋翼軸相連。UniversaljointtypeFeatures:Thetwobladesareconnectedbytheirrespectiveaxialhingesandthehubhousing,whichinturnisconnectedtotherotorshaftbyauniversaljoint.活動1：旋翼的形式有哪些？半鉸式旋翼Semi-articulatedrotor無鉸式旋翼沒有揮舞鉸和擺振鉸，只有變距鉸。其揮舞和擺振方向都是固定的，槳葉剛性連接到槳轂上，揮舞和擺振運動依靠槳根的彈性變形來實現(xiàn)，仍設(shè)有變距鉸。Theunhingedrotorhasnoswinghingesandoscillatinghinges,onlyvariablepitchhinges.Thedirectionofswingandoscillationisfixed,thebladesarerigidlyconnectedtothehub,andtheswingandoscillationmovementsrelyontheelasticdeformationofthepropellerroot,andthereisstillavariablepitchhinge.活動1：旋翼的形式有哪些？無鉸式旋翼Unhingedrotors無軸承式旋翼又稱為剛性旋翼，取消了軸向鉸、水平鉸和垂直鉸，除了周期變距，這種槳轂不提供旋翼任何的活動。槳葉的揮舞、擺振和變距運動都是由槳葉根部的柔性元件來完成?；顒?：旋翼的形式有哪些？無軸承式旋翼Bearinglessrotorasrigidrotors,eliminateaxial,horizontalandverticalhinges,anddonotprovideanymovementoftherotorexceptforperiodicpitchchanges.Theswinging,oscillatingandvariablepitchmovementsofthepropellersarealldonebyflexibleelementsattherootofthepropellers.活動2：旋翼上的鉸鏈發(fā)揮什么作用？02.PARTONEWhatroledothehingesontherotorplay?活動2：旋翼上的鉸鏈發(fā)揮什么作用？直升機隨著飛行狀態(tài)的變化和飛行員的操縱，旋翼槳葉發(fā)生揮舞運動、槳距改變和擺振運動。Withthechangeofflightstatusandthepilot'smanipulation,therotorbladesundergoswingingmotion,pitchchangeandoscillatingmotion.活動2：旋翼上的鉸鏈發(fā)揮什么作用？槳葉自由揮舞和擺振運動的目的就是在旋轉(zhuǎn)運動中尋找平衡。鉸鏈的作用就是讓每片槳葉獨立地作揮舞和擺振運動。Thepurposeofthefreeswingingandoscillatingmotionofthepaddleistofindbalanceintherotationalmotion.Thefunctionofthehingeistoalloweachpaddletoswingandoscillateindependently.活動2：旋翼上的鉸鏈發(fā)揮什么作用？軸向鉸（變距鉸）——改變旋翼的槳距，從而改變旋翼槳葉的升力。垂直鉸（擺振鉸）——消除旋轉(zhuǎn)過程中科氏力矩對槳葉的影響。水平鉸（揮舞鉸）——使槳葉繞揮舞鉸產(chǎn)生的力矩?zé)o法傳遞到機身上，從而消除橫側(cè)不平衡力矩。AxialHinge(VariablePitchHinge)-Changesthepitchoftherotorblades,thuschangingtheliftoftherotorblades.Verticalhinge(swinghinge)-eliminatestheeffectoftheKochmomentonthepaddleduringrotation.Horizontalhinge(swinghinge)-eliminatesthetransverseunbalancemomentbymakingitimpossibleforthemomentgeneratedbythepaddlesaroundtheswinghingetobetransmittedtothefuselage.活動2：旋翼上的鉸鏈發(fā)揮什么作用？旋翼槳葉分為無鉸外伸量和有鉸外伸量兩種形式。無鉸鏈外伸量旋翼的可操縱性會變差（受到重心位置的限制）；為了降低重心位置的限制，提高操縱性、加快操縱響應(yīng)，將旋翼鉸鏈設(shè)計成帶有鉸外伸量。Rotorbladesaredividedintotwoforms:unhingedoverhangoutandhingedoverhang.Maneuverabilityofarotorwithouthingeoutreachbecomesworse(limitedbythecenterofgravityposition);inordertoreducethelimitationsofthecenterofgravityposition,improvemaneuverability,andspeedupthemaneuveringresponse,therotorhingesaredesignedwithhingeoutreach.Summary總結(jié)01旋翼的形式有哪些？Whataretheformsofrotors?任務(wù)一：旋翼的鉸接形式Articulatedformofrotors02旋翼上的鉸鏈發(fā)揮什么作用？Whatroledothehingesontherotorplay?課后利用飛機模型，理解并感受旋翼揮舞的魅力吧！模塊五：旋翼揮舞Rotorwaving任務(wù)二：槳葉揮舞運動Paddlewavingmotion直升機空氣動力學(xué)與飛行原理Helicopteraerodynamicsandprinciplesofflight活動1：什么是旋翼槳葉的揮舞運動？01.PARTONEWhatistheswingingmotionofarotorblade?旋翼運動特點：旋翼槳葉一邊旋轉(zhuǎn)一邊隨著直升機機體一起運動，是兩種運動的合成。

Rotormotioncharacteristics:Therotorbladesrotateandmovewiththehelicopterbody,whichisasynthesisoftwomovements.活動1：什么是旋翼槳葉的揮舞運動？槳葉揮舞的目的：化解不對稱氣流對旋翼拉力的影響，避免直升機傾覆；也使空氣動力合力向前、后、左、右傾斜，從而得到在水平面內(nèi)任何方向的分力。Thepurposeofthebladeswingistoresolvetheinfluenceoftheasymmetrical活動1：什么是旋翼槳葉的揮舞運動？airflowonthetensionoftherotorandavoidthehelicopterfromcapsizing,andalsototilttheaerodynamicforceforward,backward,leftandright,soastoobtainthecomponentforceinanydirectioninthehorizontalplane.活動1：什么是旋翼槳葉的揮舞運動？槳葉揮舞運動包括Paddlewavingsportsinclude自然揮舞操縱揮舞隨動揮舞SwingnaturallyManipulativeswingingSwingwithyourmove活動2：槳葉是如何揮舞的呢？02.PARTONEHowdoyouswingthepaddles?活動2：槳葉是如何揮舞的呢？自然揮舞Swingnaturally操縱方法：直接控制——沒有揮舞鉸間接控制——安裝揮舞鉸Manipulationmethod:Directcontrol–noswinginghingesIndirectcontrol–installationofwavinghinges定義：把非操縱因素引起的槳葉揮舞運動稱為槳葉的自然揮舞。Definition:Themovementofthepaddlewavecausedbynon-manipulativefactorsiscalledthenaturalwavingofthepaddle.活動2：槳葉是如何揮舞的呢？自然揮舞Swingnaturally由于旋翼的揮舞促使槳葉繞揮舞鉸產(chǎn)生的力矩就無法傳遞到機身上，從而消除了橫側(cè)不平衡力矩。Sincetheswingoftherotorcausesthebladestoswingaroundthehinge,thetorquegeneratedbytheswinghingecannotbetransmittedtothefuselage,thuseliminatingthetransverseunbalancedmoment.揮舞運動包括上揮和下?lián)]。Swingmovementsincludeanupwardanddownwardswing.活動2：槳葉是如何揮舞的呢？自然揮舞Swingnaturally為了避免槳葉向上或向下?lián)]舞角超過規(guī)定值，一般通過彈簧機構(gòu)或旋轉(zhuǎn)離心力防止槳葉下垂過大。所以，直升機旋翼上一般會安裝揮舞限動器和下垂限動器。Inordertopreventthepropellerswingingangleupwardsordownwardsfromexceedingthespecifiedvalue,thepropellerisgenerallypreventedfromsaggingtoomuchbyspringmechanismorrotatingcentrifugalforce.Therefore,helicopterrotorsaregenerallyequippedwithwavelimitersandsaglimiters.活動2：槳葉是如何揮舞的呢？槳葉的擺振Oscillationofthepaddles當(dāng)直升機前飛時，槳葉繞揮舞鉸上下?lián)]舞，會使槳葉旋轉(zhuǎn)角速度發(fā)生變化。Whenthehelicopterfliesforward,thepropellersswingupanddownaroundtheswinginghinge,whichwillchangetheangularvelocityofthepropellers.活動2：槳葉是如何揮舞的呢？槳葉的擺振Oscillationofthepaddles槳葉向上揮舞時，槳葉旋轉(zhuǎn)角速度增大，槳葉加速旋轉(zhuǎn)；槳葉向下?lián)]舞時，槳葉旋轉(zhuǎn)角速度減小，槳葉減速旋轉(zhuǎn)。Whenthepropellerswingsupward,theangularvelocityofthepropellerrotationincreases,andthepropelleracceleratesandrotates;Whenthepropellerswingsdownward,theangularvelocityofthepropellerrotationdecreases,andthepropellerslowsdownandrotates.活動2：槳葉是如何揮舞的呢？槳葉的擺振Oscillationofthepaddles槳葉加速或減速旋轉(zhuǎn)時，受到的科氏力大小和方向周期變化，對槳葉的強度不利；槳葉旋轉(zhuǎn)時也會產(chǎn)生慣性離心力，結(jié)構(gòu)有可能疲勞受損。為解決這兩個問題就在槳轂上安裝擺振鉸（垂直鉸）。Whenthepropelleracceleratesordeceleratesandrotates,theCoriolisforceanddirectionperiodchangesarenotconducivetothestrengthofthepropeller.Inertialcentrifugalforceisalsogeneratedwhenthepaddlerotates,andthestructuremaybefatiguedanddamaged.Inordertosolvethesetwoproblems,apendulumhinge(verticalhinge)isinstalledonthepaddlehub.活動2：槳葉是如何揮舞的呢？槳葉的擺振Oscillationofthepaddles經(jīng)過槳葉受力狀態(tài)的分析可知，槳葉繞擺振鉸的擺振角分別與槳葉質(zhì)量和轉(zhuǎn)速成反比，轉(zhuǎn)速越大，擺振角越小；槳葉質(zhì)量越大，擺振角越小。Throughtheanalysisofthestressstateofthepropeller,itcanbeseenthattheoscillationangleofthepropelleraroundtheoscillatinghingeisinverselyproportionaltothepropellermassandrotationalspeed,andthelargerthespeed,thesmallertheoscillationangle.Thegreaterthemassofthepropeller,thesmallertheoscillationangle.活動2：槳葉是如何揮舞的呢？槳葉的擺振Oscillationofthepaddles如果在垂直鉸上安裝限動塊，槳葉擺振受到限制，即擺振限動，槳葉擺動最大角度受到限動塊的限制。Ifalimitingblockisinstalledontheverticalhinge,thepropelleroscillationislimited,thatis,theoscillationislimited,andthemaximumangleofthepropelleroscillationislimitedbythelimitingblock.活動2：槳葉是如何揮舞的呢？槳葉的變距Pitchchangeofthepropeller槳葉繞軸向鉸轉(zhuǎn)動來改變安裝角或槳葉角，稱為槳葉變距。Thepropellerrotatesaroundtheaxialhingetochangethemountingangleorbladeangle,whichiscalledthepropellerpitch.活動2：槳葉是如何揮舞的呢？槳葉的變距Pitchchangeofthepropeller自動傾斜器是直升機改變旋翼傾斜方向和槳葉傾角的專用裝置。周期變距操縱桿連接到自動傾斜器再連接到旋翼槳葉，通過操縱變距桿，槳葉就會繞著變距鉸轉(zhuǎn)動，從而實現(xiàn)槳距改變。Theautomatictilterisaspecialdeviceforthehelicoptertochangethedirectionofinclinationoftherotorandtheinclinationoftheblades.Thecyclicpitchleverisconnectedtoanautomatictilterandthentotherotorblades,whichrotatearoundthepitchhingebymanipulatingthepitchlever.活動2：槳葉是如何揮舞的呢？操縱揮舞Manipulativeswinging定義：由周期變距引起旋翼的揮舞作用稱之為操縱揮舞。Definition:Theswingingeffectoftherotorcausedbytheperiodicpitchchangeiscalledmanipulativeswing.周期變距桿操縱旋翼時，變距拉桿上下運動引起旋翼斜盤傾斜，槳葉旋轉(zhuǎn)時其槳葉角就會周期性發(fā)生改變。Whentheperiodicpitchlevercontrolstherotor,theupanddownmovementofthepitchlevercausestherotorswashplatetotilt,andthebladeanglewillperiodicallychangewhenthebladerotates.活動2：槳葉是如何揮舞的呢？操縱揮舞Manipulativeswinging由于斜盤的傾斜引起的槳葉角變化，在9點鐘位置槳葉角最大，在3點鐘位置槳葉角最小。Thechangeinthebladeangleduetothetiltoftheswashplateisthelargestat9o'clockandthesmallestat3o'clock.活動2：槳葉是如何揮舞的呢？隨動揮舞Swingwithyourmove定義：隨直升機運動而發(fā)生的旋翼揮舞稱為隨動揮舞。Definition:Therotorswingthatoccurswiththemotionofthehelicopteriscalledfollowerswing.直升機作曲線機動飛行時；直升機的俯仰或滾轉(zhuǎn)等角運動終止時。Whenthehelicopterisflyinginacurvedmaneuver;Whenthepitchorrollisometricmovementofthehelicopteristerminated.Summary總結(jié)01什么是旋翼槳葉的揮舞運動？Whatistheswingingmotionofarotorblade?任務(wù)二：槳葉揮舞運動Paddlewavingmovement課后玩一玩竹蜻蜓，結(jié)合上課內(nèi)容，深入理解槳葉的揮舞運動。02槳葉是如何揮舞的呢？Howdoyouswingthepaddles?模塊五：旋翼揮舞Rotorwaving任務(wù)三：旋翼揮舞特性RotorWaveCharacteristics直升機空氣動力學(xué)與飛行原理Helicopteraerodynamicsandprinciplesofflight活動1：什么是方位角？01.PARTONEWhatisazimuth？活動1：什么是方位角？直升機在懸停時，旋翼流場軸對稱，所以每片槳葉受到的氣動力也是相同的，與槳葉方位無關(guān)。Whenthehelicopterishovering,therotorflowfieldaxisissymmetric,sotheaerodynamicforceoneachpaddleisalsothesame,independentofthepaddleorientation.在前飛狀態(tài)下，旋翼流場軸不對稱，出現(xiàn)旋翼周向相對氣流不對稱現(xiàn)象，槳盤產(chǎn)生的氣動力與各槳葉方位有關(guān)。Whileintheforwardflightstate,therotorflowfieldaxisisasymmetric,thephenomenonofrotorcircumferentialrelativeairflowasymmetryoccurs,andtheaerodynamicforcegeneratedbythepaddlediskisrelatedtotheorientationofeachpaddle.活動1：什么是方位角？沿著旋翼旋轉(zhuǎn)方向按遞增方式確定方位角，正后方0°方位表示為方位角ψ=0°,或表示為ψ=360°,正右方的方位角為ψ=90°,正前方的方位角為ψ=180°,正左方的方位角為ψ=270°。Determinetheazimuthinanincrementalmanneralongthedirectionofrotationoftherotor.0°azimuthatthebackisexpressedasazimuthψ=0°,orasψ=360°,azimuthattherightisψ=90°,azimuthatthefrontisψ=180°,andazimuthattheleftisψ=270°.活動1：什么是方位角？活動2：什么是相位滯后現(xiàn)象？02.PARTONEWhatisthephaselagphenomenon?活動2：什么是相位滯后現(xiàn)象？當(dāng)一個外力沿軸線方向作用在轉(zhuǎn)動中的陀螺上，則陀螺的旋轉(zhuǎn)平面將傾斜，傾斜的最大位移量發(fā)生在沿陀螺轉(zhuǎn)動方向90°滯后的點上。這是陀螺進動性原理。Whenanexternalforceisappliedtoarotatinggyroscopeintheaxialdirection,theplaneofrotationofthegyroscopewillbetilted,andthemaximumdisplacementofthetiltoccursatthepointwherethegyroscoperotateswitha90°lag.Thisistheprincipleofgyroscopicmotion.活動2：什么是相位滯后現(xiàn)象？揮舞角最大(最小)對應(yīng)的方位角比揮舞角速度最大(最小)對應(yīng)的方位角恰好滯后90°。Theazimuthanglecorrespondingtothemaximum(minimum)swingangleisexactly90°behindtheazimuthanglecorrespondingtothemaximum(minimum)swinganglespeed.活動3：槳葉各剖面氣流有什么特點？03.PARTONEWhatarethecharacteristicsoftheairflowineachprofileofthepaddle?活動3：槳葉各剖面氣流有什么特點？由槳葉后緣流向前緣的氣流叫返流，或反流。槳葉上存在返流的區(qū)域稱為返流區(qū)，或反流區(qū)。Airflowfromthetrailingedgeofthepaddletotheleadingedgeiscalledbackflow,orcounterflow.Theareaofthepaddlewherethereturnflowexistsiscalledthereturnzone,orbackflowzone.活動3：槳葉各剖面氣流有什么特點？返流區(qū)的大小與飛行速度和旋翼轉(zhuǎn)速有關(guān)。前進比越小，返流區(qū)越??；前進比越大，返流區(qū)越大。Thesizeofthereturnareaisrelatedtotheflightspeedandrotorspeed.Thesmallertheforwardratio,thesmallerthereturnarea;thelargertheforwardratio,thelargerthereturnarea.活動3：槳葉各剖面氣流有什么特點？直升機在前飛、后退飛行或側(cè)飛中，旋翼槳葉的周向相對氣流會出現(xiàn)不對稱現(xiàn)象。旋翼槳葉的周向相對氣流不對稱的現(xiàn)象，叫作相對氣流不對稱性。Helicoptersexperienceasymmetryinthecircumferentialdirectionoftherotorbladesrelativetotheairflowinforwardflight,backwardflight,orsidewaysflight.Thephenomenonofcircumferentialrelativeairflowasymmetryofarotorbladeiscalledrelativeairflowasymmetry.活動3：槳葉各剖面氣流有什么特點？前進比越大，旋翼相對氣流的不對稱性越大；前進比越小，旋翼相對氣流的不對稱性越小。Thegreatertheforwardratio,thegreatertheasymmetryoftherotorrelativetotheairflow;thesmallertheforwardratio,thelesstheasymmetryoftherotorrelativetotheairflow.活動3：槳葉各剖面氣流有什么特點？由于旋翼相對氣流的不對稱性和返流區(qū)的存在，造成的旋翼兩側(cè)拉力不對稱現(xiàn)象，就形成了橫側(cè)不平衡力矩。Thephenomenonofasymmetrictensiononbothsidesoftherotorcausedbytheasymmetryoftherotorrelativetotheairflowandthepresenceofthereturnzonecreatesatransverseunbalancemoment.活動3：槳葉各剖面氣流有什么特點？在槳葉相對氣流不對稱性的影響下，因揮舞速度不同所引起的槳葉迎角不對稱性。前行槳葉區(qū)內(nèi)的迎角小，而后行槳葉區(qū)內(nèi)的迎角大。Asymmetryinthepaddleheaderanglecausedbydifferentwavingspeedsundertheinfluenceofthepaddlerelativeairflowasymmetry.Theangleofapproachwithintheforwardpaddleareaissmall,whiletheangleofapproachwithinthebackwardpaddleareaislarge.活動4：旋翼自然揮舞有什么特性？04.PARTONEWhatarethepropertiesofanaturalswingofarotor?活動4：旋翼自然揮舞有什么特性？Therotorconeisbackedup:Whenthehelicopterisinforwardflight,therotorbladetensionoftherotatingrotorbladevariesinasinusoidalpattern.Themaximumbladeupswingspeedandthehighestswingposition(maximumupswingdistance)arenotinthesameorientation;theydifferby90°azimuth.旋翼錐體后倒：當(dāng)直升機在前飛時，旋轉(zhuǎn)旋翼的槳葉拉力按正弦規(guī)律變化。槳葉上揮速度最大和揮舞最高位置(上揮距離最大)不在同一方位，它們之間相差90°方位角?；顒?：旋翼自然揮舞有什么特性？由于槳葉的周向氣流速度不對稱引起的自然揮舞運動，相對于槳轂旋轉(zhuǎn)平面，軌跡前高后低，旋翼呈現(xiàn)為倒錐體向后傾斜，旋翼產(chǎn)生后倒姿態(tài)。Duetothenaturalwavingmotioncausedbytheasymmetricairflowvelocityinthecircumferentialdirectionofthepaddles,thetrajectoryishighinthefrontandlowinthebackwithrespecttotherotationalplaneofthepaddlehub,andtherotorispresentedasaninvertedconetiltedbackward,andtherotorproducesabackwardinvertedattitude.活動4：旋翼自然揮舞有什么特性？旋翼錐體側(cè)傾：由于旋翼錐度角的存在，經(jīng)過旋翼前半部分區(qū)域的槳葉會產(chǎn)生額外的上沖氣流；經(jīng)過旋翼后半部分區(qū)域的槳葉會產(chǎn)生額外的下沉氣流。Therotorconeistiltedsideways:Asaresultoftherotortaperangle,paddlespassingthroughthefronthalfoftherotorareacreateadditionalupwashairflow;paddlespassingthroughthebackhalfoftherotorareacreateadditionaldownwashairflow.活動4：旋翼自然揮舞有什么特性？根據(jù)陀螺進動性原則，旋翼錐體向90°方位傾斜，旋翼產(chǎn)生側(cè)傾姿態(tài)。右旋旋翼則錐體右傾，左旋旋翼則左傾。Accordingtotheprincipleofgyro-incidence,therotorconeistiltedina90°orientation,andtherotorproducesasideways-tiltedattitude.Aright-handedrotortiltstheconetotheright,whilealeft-handedrotortiltsittotheleft.Summary總結(jié)01什么是方位角？Whatisazimuth？任務(wù)二：旋翼的揮舞特性RotorWaveCharacteristics02什么是相位滯后現(xiàn)象？Whatisthephaselagphenomenon?課后玩一玩地陀螺，感受一下陀螺的進動性和穩(wěn)定性03槳葉各剖面氣流有什么特點？Whatarethecharacteristicsoftheairflowineachprofileofthepaddle?04旋翼自然揮舞有什么特性？Whatarethepropertiesofanaturalswingofarotor?模塊五：旋翼揮舞Rotorwaving任務(wù)四：直升機振動與噪聲Helicoptervibrationandnoise直升機空氣動力學(xué)與飛行原理Helicopteraerodynamicsandprinciplesofflight工作場景由于直升機是一個復(fù)雜的動力系統(tǒng)，其轉(zhuǎn)動部件很多。只要發(fā)動機和旋翼在工作，不管在空中還是地面，都不可避免地存在振動，產(chǎn)生噪聲。Sincethehelicopterisacomplexpowersystem,ithasmanyrotatingparts.Aslongastheengineandrotorbladesareinoperation,whetherintheairorontheground,vibrationisinevitableandnoiseisgenerated.工作場景隨著軍用直升機對隱身要求的提高和適航條例對民用直升機噪聲的嚴(yán)格限制，旋翼噪聲機理及其降噪技術(shù)已經(jīng)成為直升機技術(shù)研究的熱點之一。直升機飛行員和維修人員都必須掌握直升機振動和噪聲的類型，了解引起共振的原因。Withtheimprovementofmilitaryhelicopters'stealthrequirementsandthestrictlimitationofcivilhelicopternoisebyairworthinessregulations,therotornoisemechanismanditsnoisereductiontechnologyhavebecomeoneofthehotspotsofhelicoptertechnologyresearch.Helicopterpilotsandmaintenancepersonnelmustmasterthetypesofhelicoptervibrationandnoiseandunderstandthecausesofresonance.活動1：直升機的振動可以分為哪幾類？01.PARTONEVibrationsfromhelicopterscanbeclassifiedintowhichcategories?活動1：直升機的振動可以分為哪幾類？振源就是作用于結(jié)構(gòu)、系統(tǒng)的激振力的來源。直升機的振源主要有旋翼、尾槳和發(fā)動機等旋轉(zhuǎn)部件。Thesourceofvibrationisthesourceoftheexcitationforceactingonthestructureorsystem.Themainsourcesofvibrationinhelicoptersarerotatingpartssuchasrotorblades,tailrotorandengines.振動頻率指單位時間內(nèi)振動發(fā)生的次數(shù)，是識別振動來源的一個主要指標(biāo)，單位為赫茲(Hz)。根據(jù)振源的振動頻率，直升機振動分為低頻振動、中頻振動和高頻振動。Vibrationfrequencyreferstothenumberoftimesavibrationoccursperunitoftime,andisaprimaryindicatorforidentifyingthesourceofthevibration,measuredinhertz(Hz).Accordingtothevibrationfrequencyofthevibrationsource,helicoptervibrationisdividedintolow-frequencyvibration,medium-frequencyvibrationandhigh-frequencyvibration.活動1：直升機的振動可以分為哪幾類？活動2：直升機的噪聲主要包括哪些？02.PARTONEWhatarethemaincomponentsofhelicopternoise?直升機的振動通過結(jié)構(gòu)自振源傳至座艙，同時，當(dāng)這些噪聲作用在座艙壁板上時，形成壁板結(jié)構(gòu)振動，進而產(chǎn)生結(jié)構(gòu)性噪聲，形成具有周期振動的性質(zhì)。Thevibrationofthehelicopteristransmittedtothecockpitthroughthestructuralself-oscillationsource,andatthesametime,whenthesenoisesactonthecockpitwallpanels,itformsthestructuralvibrationofthewallpanels,whichinturngeneratesstructuralnoises,formingthenatureofhavingperiodicvibration.活動2：直升機的噪聲主要包括哪些？直升機噪聲主要包括：旋翼噪聲、尾槳噪聲和發(fā)動機噪聲。直升機旋翼是直升機的主要噪聲源。旋翼的噪聲起源于旋翼非定常運動而引起其周圍流體快速的非定常變化。Helicopternoisemainlyincludes:rotornoise,tailrotornoiseandenginenoise.Helicopterrotoristhemainnoisesourceofhelicopter.Therotornoiseoriginatesfromthenon-constantmotionoftherotorandtherapidnon-constantchangeofthefluidaroundit.活動2：直升機的噪聲主要包括哪些？旋翼噪聲包括旋轉(zhuǎn)噪聲和寬帶噪聲，又可分為厚度噪聲、載荷噪聲、BVI噪聲等。Rotornoiseincludesrotationalnoiseandbroadbandnoise,whichcanbefurthercategorizedintothicknessnoise,loadnoise,BVInoise,andsoon.活動2：直升機的噪聲主要包括哪些？活動3：與飛行狀態(tài)有關(guān)的振動包括什么？03.PARTONEWhatarethevibrationsassociatedwiththestateofflight?活動3：與飛行狀態(tài)有關(guān)的振動包括什么？飛行速度過大時的振動：直升機飛行速度過大，會引起從旋翼傳來的激振力和力矩增大，使直升機強烈振動。Vibrationatexcessiveflightspeeds:Excessivehelicopterflightspeedscauseanincreaseintheexcitationforceandmomentfromtherotorblades,causingthehelicoptertovibratestrongly.活動3：與飛行狀態(tài)有關(guān)的振動包括什么？“過渡速度”的振動：直升機在起飛增速和著陸消速階段，在某一飛行速度范圍內(nèi)，會出現(xiàn)明顯的抖動現(xiàn)象，這個出現(xiàn)抖動的飛行速度范圍，習(xí)慣上稱之為“過渡速度”?！癟ransitionspeed”vibration:Helicoptersinthetakeoffspeedincreas