《直升機(jī)空氣動(dòng)力學(xué)與飛行原理》課件-模塊三：理解翼型氣動(dòng)特性（雙語(yǔ)）

模塊三：理解翼型氣動(dòng)特性Learnaboutairfoilcharacteristics直升機(jī)空氣動(dòng)力學(xué)與飛行原理Helicopteraerodynamicsandprinciplesofflight工作場(chǎng)景機(jī)務(wù)人員進(jìn)行槳葉維護(hù)時(shí)，需要清潔槳葉并檢查槳葉外形，熟悉槳葉截面的外形特點(diǎn)并理解其作用，有助于認(rèn)識(shí)到槳葉相關(guān)維護(hù)的重要性；Duringblademaintenance,themaintenancepersonnelneedtocleanthebladeandchecktheshapeoftheblade.Beingfamiliarwiththeshapecharacteristicsofthebladesectionandunderstandingitsfunctionhelpstorealizetheimportanceofblademaintenance.認(rèn)識(shí)槳葉翼型Learnthebladeairfoil01Teachingobjective教學(xué)目標(biāo)理解翼型的升力特性Understandtheliftcharacteristicsofairfoils02理解翼型的阻力特性Understandthedragcharacteristicsofairfoils03能夠分析影響氣動(dòng)特性的因素Abletoanalyzethefactorsaffectingtheaerodynamiccharacteristics04模塊三：理解翼型氣動(dòng)特性Learnaboutairfoilcharacteristics任務(wù)一：認(rèn)識(shí)槳葉翼型Learnthebladeairfoil直升機(jī)空氣動(dòng)力學(xué)與飛行原理Helicopteraerodynamicsandprinciplesofflight活動(dòng)1：什么是槳葉翼型？01.PARTONEWhatisabladeairfoil？活動(dòng)1：什么是槳葉翼型？對(duì)稱(chēng)翼型非對(duì)稱(chēng)翼型活動(dòng)1：什么是槳葉翼型？（1）翼弦，翼型前緣到后緣的連線(xiàn)稱(chēng)為翼弦Thechord,thelinefromtheleadingedgetothetrailingedgeoftheairfoiliscalledthechord,，用符號(hào)C表示，其長(zhǎng)度稱(chēng)為弦長(zhǎng)。活動(dòng)1：什么是槳葉翼型？（2）厚度，翼型上、下表面與翼弦垂直的連線(xiàn)稱(chēng)為厚度Thickness,theverticallinebetweentheupperandlowersurfacesoftheairfoilandthechordiscalledthickness.?；顒?dòng)1：什么是槳葉翼型？（3）最大厚度位置是最大厚度到翼型前緣的距離與弦長(zhǎng)的比值，用百分比表示Themaximumthicknesspositionistheratioofthedistancefromthemaximumthicknesstotheleadingedgeoftheairfoiltothechordlength,expressedasapercentage活動(dòng)1：什么是槳葉翼型？（4）相對(duì)厚度，相對(duì)厚度是翼型最大厚度與弦長(zhǎng)的比值，用百分比表示Relativethicknessistheratioofthemaximumthicknessoftheairfoiltothechordlength,expressedasapercentage活動(dòng)1：什么是槳葉翼型？（5）中弧線(xiàn)，和翼型上、下表面相切的一系列圓的圓心的連線(xiàn)Meancamberline,thelineofthecenterofaseriesofcirclestangenttotheupperandlowersurfacesoftheairfoil。活動(dòng)1：什么是槳葉翼型？（6）彎度，中弧線(xiàn)與翼弦的垂直距離稱(chēng)為彎度Camber,theverticaldistancebetweenthecenterarcandthechordiscalledcamber。活動(dòng)1：什么是槳葉翼型？安裝角是指翼型弦線(xiàn)與垂直于槳轂旋轉(zhuǎn)軸的槳轂旋轉(zhuǎn)平面之間的夾角，也稱(chēng)為槳距。TheinstallationAnglereferstotheAnglebetweentheairfoilchordandthehubrotationplanealsoknownaspitch.幾何扭轉(zhuǎn)，是指槳葉從根部到尖部的安裝角發(fā)生變化活動(dòng)2：直升機(jī)主要用哪些翼型？02.PARTTWOWhatarethemainairfoiltypesusedinhelicopters?活動(dòng)2：直升機(jī)主要用哪些翼型？為使旋翼獲得最佳性能，往往要把槳葉翼型設(shè)計(jì)成沿槳葉展向變化，從根部到尖部采用成套的翼型族，分別滿(mǎn)足槳葉不同半徑處在不同方位角的不同要求，使槳葉在不同氣動(dòng)環(huán)境中發(fā)揮不同翼型的性能。Inordertoobtainthebestperformanceoftherotor,itisoftennecessarytousethebladeairfoiltochangealongthebladedevelopmentdirection,andadoptacompletesetofairfoilfamiliesfromtheroottothetiptomeetthedifferentrequirementsofdifferentbladeradiiindifferentangles,sothatthebladecanplaydifferentairfoilperformanceindifferentaerodynamicsituation.活動(dòng)2：直升機(jī)主要用哪些翼型？NACA翼型活動(dòng)2：直升機(jī)主要用哪些翼型？法國(guó)的OA翼型系列波音VR翼型活動(dòng)2：直升機(jī)主要用哪些翼型？活動(dòng)2：直升機(jī)主要用哪些翼型？活動(dòng)3：槳葉翼型用的材料是金屬嗎？03.PARTTHREEArethebladesmadeofmetal?活動(dòng)3：槳葉翼型用的材料是金屬嗎？早期翼型采用鋼木混合式槳葉，在受力較大部位用鋼，其余部位采用木頭，后來(lái)采用全金屬槳葉能夠承受更大的拉力，現(xiàn)在用的都是全復(fù)合材料槳葉，能夠滿(mǎn)足不同狀態(tài)下的各種要求。Intheearlydays,theairfoilusedacombinationofsteelandwoodblades,steelwasusedinthepartofthelargerforce,andwoodwasusedintherestofthebody.Later,all-metalbladeswereusedtowithstandgreatertension.Nowallcompositebladesareused,whichcanmeetvariousrequirementsindifferentsituationSummary總結(jié)01什么是槳葉翼型？任務(wù)一：認(rèn)識(shí)槳葉翼型ELearnthebladeairfoil02槳葉翼型外形用哪些參數(shù)來(lái)描述？03槳葉翼型的幾何扭轉(zhuǎn)Summary總結(jié)04直升機(jī)主要用哪些翼型？課后請(qǐng)大家尋找直升機(jī)槳葉圖片，試著畫(huà)一畫(huà)槳葉靠近根部和尖部這兩個(gè)部位的翼型，仔細(xì)觀察二者的區(qū)別，并用相關(guān)參數(shù)來(lái)描述它們05槳葉翼型用的材料是金屬嗎？任務(wù)一：認(rèn)識(shí)槳葉翼型ELearnthebladeairfoil模塊三：理解翼型氣動(dòng)特性Learnaboutairfoilcharacteristics任務(wù)二：認(rèn)識(shí)翼型的阻力特性Learntheresistancecharacteristicsofairfoil直升機(jī)空氣動(dòng)力學(xué)與飛行原理Helicopteraerodynamicsandprinciplesofflight工作場(chǎng)景當(dāng)旋翼轉(zhuǎn)動(dòng)時(shí)，不僅產(chǎn)生拉力，而且還會(huì)產(chǎn)生阻止旋翼旋轉(zhuǎn)的阻力。阻止旋翼旋轉(zhuǎn)的空氣動(dòng)力，叫旋翼旋轉(zhuǎn)阻力，簡(jiǎn)稱(chēng)旋翼阻力。Whentherotorrotates,itnotonlygeneratestension,butalsocreatesresistancethatpreventstherotorfromrotating.Theaerodynamicforcethatpreventstherotorfromrotatingiscalledtherotorrotationresistance,referredtoastherotorresistance.工作場(chǎng)景按產(chǎn)生原因的不同，旋翼阻力可分為翼型旋轉(zhuǎn)阻力、誘導(dǎo)旋轉(zhuǎn)阻力和上升旋轉(zhuǎn)阻力。Accordingtothedifferentcauses,rotorresistancecanbedividedintoairfoilrotationresistance,inducedrotationresistanceandrisingrotationresistance.Teachingobjective教學(xué)目標(biāo)翼型阻力與形成原因Airfoilresistanceandformationreasons01哪些因素會(huì)影響翼型摩擦阻力大小？Whatfactorsaffectairfoilfrictionresistance?02壓差阻力的產(chǎn)生Thegenerationofpressuredifferentialresistance03學(xué)習(xí)壓差阻力的影響因素Learntheinfluencingfactorsofpressuredifferentialresistance04Teachingobjective教學(xué)目標(biāo)什么是翼型的阻力特性？Whatarethedragcharacteristicsofairfoil?05活動(dòng)1：翼型阻力與形成原因01.PARTONEAirfoilresistanceandformationreasons活動(dòng)1：翼型阻力與形成原因垂直于相對(duì)氣流方向的分力叫升力，平行于相對(duì)氣流方向的分力叫阻力。Thecomponentperpendiculartothedirectionoftherelativeairflowiscalledlift,andthecomponentparalleltothedirectionoftherelativeairflowiscalleddrag.活動(dòng)1：翼型阻力與形成原因根據(jù)作用力與反作用力定律，這些被減慢的空氣必然要給槳葉一個(gè)沿旋轉(zhuǎn)方向相反的反作用力。Accordingtothelawofactionandreaction,thisslowedairmustgivethebladesareactionforceintheoppositedirectionofrotation.為什么翼型會(huì)有阻力？活動(dòng)1：翼型阻力與形成原因這個(gè)反作用力就是槳葉表面產(chǎn)生的摩擦阻力，對(duì)于某一截面的翼型而言，這產(chǎn)生了翼型阻力。Thisreactionforceisthefrictionalresistancegeneratedbythebladesurface,whichcreatestheairfoilresistanceforacertainsectionoftheairfoil.活動(dòng)2：哪些因素會(huì)影響翼型摩擦阻力大小？02.PARTTWOWhatfactorsaffectairfoilfrictionresistance?活動(dòng)2：哪些因素會(huì)影響翼型摩擦阻力大??？附面層分為層流層和紊流層，層流層與紊流層的過(guò)渡區(qū)域稱(chēng)為轉(zhuǎn)擯點(diǎn)。Theboundarylayerisdividedintolaminarlayerandturbulentlayer,andthetransitionareabetweenlaminarlayerandturbulentlayeriscalledtheturnpoint.活動(dòng)2：哪些因素會(huì)影響翼型摩擦阻力大小？槳葉表面光滑程度會(huì)影響附面層轉(zhuǎn)捩：槳葉表面的油污水跡。凸起。裂紋等。保持槳葉表面的干凈整潔，能夠有效推遲附面層轉(zhuǎn)捩，減小翼型摩擦阻力，繼而降低槳葉旋轉(zhuǎn)所需功率?；顒?dòng)3：壓差阻力的產(chǎn)生03.PARTTHREEThegenerationofpressuredifferentialresistance活動(dòng)3：壓差阻力的產(chǎn)生即使槳葉表面絕對(duì)光滑，只要相對(duì)流動(dòng)存在，翼型還是存在阻力，這就是壓差阻力。壓差阻力主要由于翼型上的氣流分離有關(guān)。活動(dòng)3：壓差阻力的產(chǎn)生圖中給出了翼型的氣流運(yùn)動(dòng)情況。相對(duì)氣流在槳葉前緣會(huì)受到阻滯，流速減慢，壓力增大。Theairflowmotionoftheairfoilisshowninthefigure，Therelativeairflowwillbeblockedattheleadingedgeoftheblade,theflowratewillslowdownandthepressurewillincrease.活動(dòng)3：壓差阻力的產(chǎn)生在槳葉后緣，產(chǎn)生氣流分離。由于氣流分離會(huì)形成渦流區(qū)壓力減小，槳葉前后便產(chǎn)生壓差阻力。Atthebackedgeoftheblade,airseparationisgenerated.Duetotheflowseparation,thepressureinthevortexzoneisreduced,andthepressuredifferencebetweenthefrontandbackofthebladeisgenerated.活動(dòng)3：壓差阻力的產(chǎn)生仔細(xì)觀察翼型上附面層的流動(dòng)，會(huì)發(fā)現(xiàn)氣流從順流過(guò)渡到逆流，之后發(fā)生分離，分離點(diǎn)之后會(huì)形成了渦流區(qū)。Carefullyobservingtheflowoftheboundarylayerontheairfoil,itisfoundthattheairflowtransitionsfromtheforwardflowtothereverseflow,andthentheseparationoccurs,andthevortexzoneisformedaftertheseparationpoint.活動(dòng)4：學(xué)習(xí)壓差阻力的影響因素04.PARTFOURLearntheinfluencingfactorsofpressuredifferentialresistance活動(dòng)4：學(xué)習(xí)壓差阻力的影響因素壓差阻力與翼型前后壓力差值有關(guān)。Pressuredifferenceresistanceisrelatedtothepressuredifferencebetweenfrontandrearairfoil.活動(dòng)4：學(xué)習(xí)壓差阻力的影響因素由此可知，在前緣狀態(tài)不變時(shí)，分離點(diǎn)越靠后，壓差阻力越小。Itcanbeseenthatwhentheleadingedgestateisunchanged,thefartherbacktheseparationpointis,thesmallerthepressuredifferentialresistanceis.活動(dòng)5：什么是翼型的阻力特性？05.PARTFIVEWhatarethedragcharacteristicsofairfoil?活動(dòng)5：什么是翼型的阻力特性？阻力特性表示翼型阻力系數(shù)隨著其迎角的關(guān)系曲線(xiàn)。

ThedragcharacteristicrepresentstherelationcurveofairfoildragcoefficientwithitsAngleofattack.活動(dòng)5：什么是翼型的阻力特性？在表面質(zhì)量一定的情況下，阻力特性特點(diǎn)為：(1)在任何迎角下阻力系數(shù)都不會(huì)為零，因?yàn)槟Σ磷枇Σ荒転榱恪?1)AtanyAngleofattackthedragcoefficientwillnotbezero,becausethefrictionresistancecannotbezero.活動(dòng)5：什么是翼型的阻力特性？在表面質(zhì)量一定的情況下，阻力特性特點(diǎn)為：(2)在迎角較小時(shí)，摩擦系數(shù)隨著迎角增加，翼型阻力基本不變。當(dāng)迎角較大時(shí)，翼型阻力隨著迎角增長(zhǎng)很快。(2)WhentheAngleofattackissmall,thefrictioncoefficientincreaseswiththeAngleofattack,andtheairfoilresistanceisbasicallyunchanged.WhentheAngleofattackislarge,theairfoilresistanceincreasesrapidlywiththeAngleofattack.這是黏性作用導(dǎo)致附面層分離所致的一個(gè)重要因素Summary總結(jié)01翼型阻力與形成原因Airfoildragandthecausesofitsformation任務(wù)三：認(rèn)識(shí)翼型的阻力特性Learntheresistancecharacteristicsofairfoil02翼型摩擦阻力的影響因素Factorsinfluencingthefrictionalresistanceofanairfoil03壓差阻力的產(chǎn)生CreationofdifferentialpressureresistanceSummary總結(jié)04壓差阻力的影響因素Factorsinfluencingdifferentialpressureresistance任務(wù)三：認(rèn)識(shí)翼型的阻力特性Learntheresistancecharacteristicsofairfoil請(qǐng)思考，對(duì)于槳葉而言，是不是槳葉阻力就等于各個(gè)截面上的翼型旋轉(zhuǎn)阻力之和呢？05翼型的阻力特性Resistancecharacteristicsofanairfoil模塊三：理解翼型氣動(dòng)特性Learnaboutairfoilcharacteristics任務(wù)三：理解翼型氣動(dòng)特性的影響因素Learntheresistancecharacteristicsofairfoil直升機(jī)空氣動(dòng)力學(xué)與飛行原理Helicopteraerodynamicsandprinciplesofflight工作場(chǎng)景通過(guò)學(xué)習(xí)翼型的升力特性和阻力特性，我們知道，在臨界迎角范圍內(nèi)，迎角增大，升力系數(shù)就會(huì)增加，但這時(shí)候的阻力系數(shù)也會(huì)增加。實(shí)際使用的翼型肯定是綜合考慮升力特性和阻力特性，通過(guò)本節(jié)課學(xué)習(xí)，能夠看懂翼型氣動(dòng)特性曲線(xiàn)，理解氣動(dòng)特性中的重要概念。迎角迎角迎角翼型的空氣動(dòng)力特性有哪些參數(shù)？Whataretheparametersoftheaerodynamiccharacteristicsofanairfoil?01Teachingobjective教學(xué)目標(biāo)認(rèn)識(shí)極曲線(xiàn)Learningpolecurve02翼型上的壓力分布Thepressuredistributionontheairfoil03認(rèn)識(shí)壓力中心、重心和焦點(diǎn)Recognizepresscenters,centersofgravity,andaerodynamiccenter04活動(dòng)1：翼型的空氣動(dòng)力特性有哪些參數(shù)？01.PARTONEWhataretheparametersoftheaerodynamiccharacteristicsofanairfoil?活動(dòng)1：翼型的空氣動(dòng)力特性有哪些參數(shù)？Aerodynamiccharacteristicsofairfoilincludeliftcharacteristics,dragcharacteristicsandaerodynamicmomentcharacteristics,whicharerespectivelyexpressedbytherelationshipbetweenliftcoefficient,dragcoefficient,momentcoefficientvarieswithAngleofattack.翼型氣動(dòng)特性包括升力特性、阻力特性和氣動(dòng)力矩特性，分別用升力系數(shù)、阻力系數(shù)、力矩系數(shù)與迎角的關(guān)系來(lái)表示。活動(dòng)2：認(rèn)識(shí)極曲線(xiàn)02.PARTTWOLearningpolecurve活動(dòng)2：認(rèn)識(shí)極曲線(xiàn)翼型極曲線(xiàn)把翼型的升力系數(shù)和阻力系數(shù)隨迎角變化的情形，用一條曲線(xiàn)表示出來(lái)。ThepolarcurveoftheairfoilrepresentsthevariationoftheliftcoefficientanddragcoefficientoftheairfoilwiththeAngleofattackbyacurve.翼型極曲線(xiàn)活動(dòng)2：認(rèn)識(shí)極曲線(xiàn)極曲線(xiàn)橫坐標(biāo)為阻力系數(shù)，縱坐標(biāo)為升力系數(shù)。Thehorizontalcoordinateofthepolarcurveisthedragcoefficient,andtheverticalcoordinateistheliftcoefficient.翼型極曲線(xiàn)活動(dòng)2：認(rèn)識(shí)極曲線(xiàn)曲線(xiàn)上的每一點(diǎn)代表一個(gè)升力系數(shù)和阻力系數(shù)對(duì)應(yīng)的迎角。EachpointonthecurverepresentstheAngleofattackvarieswiththeliftcoefficientanddragcoefficient,asshowninthefigure.翼型極曲線(xiàn)活動(dòng)2：認(rèn)識(shí)極曲線(xiàn)翼型極曲線(xiàn)最大升力系數(shù)和臨界迎角?；顒?dòng)2：認(rèn)識(shí)極曲線(xiàn)左側(cè)最小阻力系數(shù)迎角和最小阻力系數(shù)阻力。翼型極曲線(xiàn)活動(dòng)2：認(rèn)識(shí)極曲線(xiàn)迎角為零處的升力系數(shù)是否為零判斷出翼型的對(duì)稱(chēng)性。翼型極曲線(xiàn)活動(dòng)2：認(rèn)識(shí)極曲線(xiàn)此外，極曲線(xiàn)能夠反映出升阻比大小。升阻比就是同一迎角下升力系數(shù)和阻力系數(shù)之比，用K來(lái)表示。Inaddition,thepolecurvecanreflectthelift-dragratio.Thelift-dragratioistheratiooftheliftcoefficientandthedragcoefficientatthesameAngleofattack,expressedbyK.翼型極曲線(xiàn)活動(dòng)3：翼型上的壓力分布03.PARTTHREEThepressuredistributionontheairfoil活動(dòng)3：翼型上的壓力分布?jí)毫Ψ植紙D通常采用矢量表示法和坐標(biāo)表示法兩種形式來(lái)表示?；顒?dòng)4：認(rèn)識(shí)壓力中心、重心和焦點(diǎn)04.PARTFOURRecognizepresscenters,centersofgravity,andaerodynamiccenter活動(dòng)4：認(rèn)識(shí)壓力中心、重心和焦點(diǎn)壓力中心是氣動(dòng)力合力與翼弦的交點(diǎn)。直升機(jī)旋翼槳葉的壓力中心通常設(shè)置在重心的后側(cè)。Thecenterofpressureistheintersectionoftheaerodynamicforceandthechord.壓力中心與重心活動(dòng)4：認(rèn)識(shí)壓力中心、重心和焦點(diǎn)焦點(diǎn)如果在翼弦線(xiàn)上選擇一點(diǎn)，它至前緣的相對(duì)距離使得空氣動(dòng)力繞該點(diǎn)的力矩系數(shù)始終等于零升力時(shí)的力矩系數(shù)，那么繞該點(diǎn)的力矩系數(shù)與升力系數(shù)(或迎角)的改變無(wú)關(guān)，該點(diǎn)稱(chēng)之為焦點(diǎn)(AerodynamicCenter,，簡(jiǎn)稱(chēng)AC)。某翼型壓力中心與焦點(diǎn)的關(guān)系活動(dòng)4：認(rèn)識(shí)壓力中心、重心和焦點(diǎn)進(jìn)一步理解，焦點(diǎn)是這樣的一個(gè)點(diǎn)，即當(dāng)翼型迎角發(fā)生變化時(shí)，飛機(jī)的氣動(dòng)力對(duì)該點(diǎn)的力矩始終不變，因此它可以理解為氣動(dòng)力增量的作用點(diǎn)。Furtherunderstood,thefocusissuchapointthatwhentheairfoilA