流體力學(xué)復(fù)習(xí)資料及英文專有名詞解釋

1、Chapter1Fluidstatics流體靜力學(xué)連續(xù)介質(zhì)假定（Continuumassumption）：Therealfluidisconsideredasno-gapcontinuousmedia,calledthebasicassumptionofcontinuityoffluid,orthecontinuumhypothesisoffluid.流體是由連續(xù)分布的流體質(zhì)點(diǎn)（fluidparticle）所組成，彼此間無間隙。它是流體力學(xué)中最基本的假定，1755年由歐拉提出。在連續(xù)性假設(shè)之下，表征流體狀態(tài)的宏觀物理量在空間和時(shí)間上都是連續(xù)分布的，都可以作為空間和時(shí)間的函數(shù)。流體質(zhì)點(diǎn)（Flui

2、dparticle）:AfluidelementthatissmallenoughwithenoughmolestomakesurethatthemacroscopicmeandensityhasdefinitevalueisdefinedasaFluidParticle.宏觀上足夠小，微觀上足夠大。流體的粘性（Viscosity）:isaninternalpropertyofafluidthatoffersresistancetosheardeformation.Itdescribesafluidsinternalresistancetoflowandmaybethoughtasameasu

3、reoffluidfriction.流體在運(yùn)動(dòng)狀態(tài)下抵抗剪切變形的性質(zhì)，稱為黏性或粘滯性。它表示流體的內(nèi)部流動(dòng)阻力，也可當(dāng)做一個(gè)流體摩擦力量oTheviscosityofagasincreaseswithtemperature,theviscosityofaliquiddecreaseswithtemperature.牛頓內(nèi)摩擦定律（NewtonslawofviscOsityT=UdzThedynamicviscosity（動(dòng)力黏度）isalsocalledabsoluteviscosity絕對(duì)黏度）.Thekinematicviscosity（運(yùn)動(dòng)黏度）istheratioofdynamic

4、viscositytodensity.Uv=P6.Compressibility（壓縮性）：Asthetemperatureisconstant,themagnitudeofcompressibilityisexpressedbycoefficientofvolumecompressibility（體積壓縮系數(shù)）K,arelativevariationrate（相對(duì)變化率）ofvolumeperunitpressure.Thebulkmodulusofelasticity（體積彈性模量）EisthereciprocalofcoefficientofvolumeKcompressibility7

5、.流體的膨脹性（expansibility;dilatability）：Thecoefficientofcubicalexpansion（體積熱膨脹系數(shù)）atistherelativevariationrateofvolumeperunittemperaturechange.dVVdVa=:=（1/K,1/C）tdTVdT8表面張力Surfacetension:Apropertyresultingfromtheattractiveforcesbetweenmolecules.c單位長度所受拉力表面力Surfaceforceistheforceexertedonthecontactsurface

6、bythecontactedfluidorotherbody.Itsvalueisproportionaltocontactarea.作用在所研究流體外表面上與表面積大小成正比的力。Stress（應(yīng)力）isthesurfaceforceonperunitarea.質(zhì)量力MassforceTheforceactingoneveryfluidmassparticlewithinthecontrolbody.Itsvalueisproportionaltoitsmass.Massforceisalsoknownasbodyforce.作用在流體的f=1dpxpQxf=1dpypdyf二1dpzpdz

7、1775年每一個(gè)流體質(zhì)點(diǎn)上，其大小與流體所具有的質(zhì)量成正比。EulerEquilibriumEquations歐拉平衡微分方程（分量式）PhysicalMeaning:Forthefluidinequilibrium,surfaceforcecomponentspermassfluidareequaltomassforcecomponentspermassfluid.Pressurevariationrateinaxesdirections（也,雀,氓）aredxdydzequaltomassforcecomponentsperunitvolumeinaxesdirectionsrespect

8、ively（pf,pf,pf）xyzconstant-pressureSurface（等壓面）asurfacethatthepressureofeverypointinliquidisequal.Commonconstant-pressuresurfacesarefreeliquidsurfaceandinterfaceoftwounmixedfluidsinequilibrium平衡流體中壓強(qiáng)相等的點(diǎn)所組成的平面或曲面。p=C或dp=0PressureDistributionintheStaticFluid重力場中流體的平衡p=-pgz+CConclusions:Pressureatapoi

9、ntinastaticfluidundergravityincreaseslinearlywithdepth.Pressureatapointinastaticfluidundergravityisequaltothesumofthepressureatthefreesurfaceandthefluidspecificweighttimingdepth.constant-pressuresurfaceinastaticfluidundergravityisahorizontalplane.Extended:whilethepressureatapointandthedepthdifferenc

10、ebetweentwopointsareknown,thepressureatanotherpointcanbecalculated.Absolutepressure（絕對(duì)壓力），Gagepressure（相對(duì)壓力，又稱“表壓力”）,andVacuum（真空度）：表壓力=絕對(duì)壓力一大氣壓力；真空度=大氣壓力一絕對(duì)壓力15FluidinRelativeEquilibrium（相對(duì)靜止流體）Equationofconstant-pressuresurface（等壓面方程）：a）UniformLinearAcceleration等加速度直線運(yùn)動(dòng)流體：acosady+（asina一g）dz=0b)Un

11、iformRotationaboutaVerticalAxis等角速度旋轉(zhuǎn)流體:Chapter2basicequationsoffluidmechanics16.17.跡線pathline：thetraceafterasingleparticletravelsinafieldofflowoveraperiodoftime.流體質(zhì)點(diǎn)的運(yùn)動(dòng)軌跡曲線dx_dy_dz_u(x,y,z,t)v(x,y,z,t)w(x,y,z,t)流線streamline:acurvethatshowthedirectionofanumberofparticlesatthesameinstantoftime.某一時(shí)刻處處

12、與速度矢量相切的空間曲線-瞬時(shí)性。dxdydzu(x,y,z,t)v(x,y,z,t)w(x,y,z,t)Stream-tube(流管)Consideraclosedcurve(notstreamline)intheflowfield,thendrawstreamlinesthrougheverypointonit,soastoformatube-shapingspacewhosewallsarestreamlines.Thistubeiscalledthestream-tube.在流場中任取一個(gè)有流體從中通過的封閉曲線，在曲線上的每一個(gè)質(zhì)點(diǎn)都可以引出一條流線，這些流線簇圍成的管狀曲面稱為流管

13、。Tube-flow流束Fluidfullingthestreamtubeiscalledthetube-flowandthelimitofatube-flowisastreamline.流管內(nèi)的全部流體稱為流束。Ministream-tube微小流束Thestreamtubewithaninfinitesimalsectionissaidtobemini-streamtube.Streamlineistheextremecaseofmini-streamtube.截面無窮小的流束。Totalflow總流Totalofcountlessmini-streamtubesiscalledtotal

14、flow.包含流動(dòng)中所有的微小流束。Crosssection(過水?dāng)嗝?-Thesectionisperpendiculartothedirectionoffluidflow.(suchaspipeflowandchannelflow)與流束或總流流線dA,A成正交的斷面。Discharge(流量)-Amountoffluidpassthroughacrosssectionperunittime(suchasthesectioninthechannelorpipe).單位時(shí)間內(nèi)通過某一過水?dāng)嗝娴牧黧w體積稱為體積流量，簡稱流量。Meanvelocity斷面平均流速-Thevelocitiesof

15、pointsonthesamecrosssectioninthetotalflowaredifferent,sousuallyanaveragevelocityisusedinsteadoftherealvelocityoverthecrosssection,thisaveragevelocityiscalledthemeanvelocity.Uniformflow均勻流：isdefinedasuniformflowwhenintheflowfieldthevelocityandotherhydrodynamicparametersdonotchangefrompointtopointatan

16、yinstantoftime（inwhichthecrosssectionofeachstreamtuberemainsunchanged.流場中每一空間點(diǎn)的各運(yùn)動(dòng)參數(shù)（速度，壓力）不隨空間位置而變化。（VV）O=0Nonuniformflow非均勻流：Flowsuchthatthevelocityvariesfromplacetoplaceatanyinstant.Steadyflow恒定流：theflowwhosemotionfactorsdontchangewithtime.流場中所有的運(yùn)動(dòng)要素不隨時(shí)間變化.28Unsteadyflow非恒定流：theflowthatatleastone

17、ofitsmotionfactorschangeswithtime.流場中至少有一個(gè)運(yùn)動(dòng)要素隨時(shí)間變化.Onedimensionalflow（一元流動(dòng)）-allmainvariablesintheflowfieldcanbecompletelyspecifiedbyasinglecoordinateifthevariationofflowparameterstransversetothemainstreamdirectioncanbeneglected.流動(dòng)參數(shù)只與一個(gè)坐標(biāo)變量有關(guān)。Twodimensionalflow（二元流動(dòng)）-fluidmotionfactorsarefunctionof

18、twospacecoordinates.流動(dòng)參數(shù)與兩個(gè)坐標(biāo)變量有關(guān)。Three-dimensionalFlow（三元流動(dòng)）:Fluidflowsmotionfactorsarefunctionsofthreespacecoordinates.流動(dòng)參數(shù)與三個(gè)坐標(biāo)變量有關(guān)。System（系統(tǒng)）isasetofdefinitefluidparticlesselectedintheinterestofresearcher.由確定的流體質(zhì)點(diǎn)組成的流體團(tuán)或流體體積丿。系統(tǒng)邊界面s億丿在流體的運(yùn)動(dòng)過程中不斷發(fā)生變化。反映了拉格朗日觀點(diǎn)Controlvolume（控制體CV）isdefinedasaninva

19、riablyhollowvolumeorframefixedinspaceormovingwithconstantvelocitythroughwhichthefluidflows.相對(duì)于坐標(biāo)系固定不變的空間體積V。是為了研究問題方便而取定的。反映了歐拉觀點(diǎn)ForaCV:1）itsshape,volumeanditscscannotchangewithtime.2）itisstationaryinthecoordinatesystem.（inthisbook）3）theremaybetheexchangeofmassandenergyonthecs.35.differentialfoContr

20、olsurface控制面：thesurfaceareacompletelyenclosestheCV邊界面S稱為控制面。mofxontinuityequation微分形式的連續(xù)性方程dpdpvvQpv1xHyHh0dtdxdydzForincompressiblefluiddvdvQv+zQzFor2-DincompressibleflowPhysicalmeaning:Thenetmassdischargeenteringthecontrolvolumeisequaltothemassincreasedinunittimeduetothechangeindensity.Fitfor:Stea

21、dyflow,unsteadyflow,compressibleandincompressiblefluid,idealfluidandrealfluid.Integralformofcontinuityequation積分形式的連續(xù)方程J空dV+JpvdS=0VQtSnPhysicalmeaning：在單位時(shí)間內(nèi)，由于控制體內(nèi)密度變化引起的質(zhì)量變化量（增加量或減少量）與通過控制體表面的質(zhì)量凈流出量（流出與流入的質(zhì)量差）之和等于零。Steadyflow定常流動(dòng)T_pvdS-0csnincompressiblefluid不可壓縮流體JvdS=0CSnvS=vS1122MotionDifferen

22、tialEquation運(yùn)動(dòng)微分方程ForIDEALFLOWTOC o 1-5 h zq1QpQvQvQvQvf=x+vx+vx+vxxpQxQtxQxyQyzQzp1QpQvQvQvQvf=y+vy+vy+vyypQyQtxQxyQyzQz1QpQvQvQvQvzpQzQtxQxyQyzQzforViscousFlowfxfy1QpQ2vQ2vQ2vQvQvQvQv+v(x+x+x)=x+vx+vx+vxpQxQx2Qy2Qz2QtxQxyQyzQz1Qp/Q2vQ2vQ2vQvQvQvQv+V(y+y+尸)=y+vy+vy+vypQyQx2Qy2口Qz2QtxQxyQyzQz1型+v(工p

23、QzQx2Q2vQ2v+z+z)Qy2Qz2QvQvQvQvz+vz+vz+vzQtxQxyQyzQzBernoulliEquation伯努利方程（1）steadyflow定常流動(dòng)（2）incompressibleflow不可壓縮（3）integrationalongastreamline沿流線積分（4）massforceisapotentialforce質(zhì)量力有勢(shì)pv2Forstreamlinez+=CPg2gForcompressibleflowingravityfieldV22gV222gForcompressibleflowwithfluidmachineryingravityfiel

24、dV22gV22gz（m）theelevationheightabovedatumsurfaceo-o,calledtheelevationhead（位置水頭）.p/（Pg）risingheightoffluidwithunitweightundertheactionofpressureP,calledthepressurehead（壓力水頭）.u2/（2g）risingheightoffluidwithunitweightundertheaction,ocfallveedltohceityVvelocityhead（速度水頭）,denotedashuhfthelostmechanicalen

25、ergyfrom1to2pointsperunitweightfluidHTTheeffectiveenergyobtainedaftertheunitweightoftheliquidflowsthroughthepump.單位重量液體流經(jīng)泵后獲得的有效能量。Headofdelivery揚(yáng)程p-pv2-v2H=厶i+2i+zz2g21Thesumofthemiscalledthetotalhead（總水頭）,denotedasH.Pumppower泵功率：Pw=HtQyFortheideal-fluidtotalflow理想流體總流的伯努利方程v2pv2z+a+a十1Pg】2gforther

26、eal-fluidtotalflow實(shí)際流體總流的伯努利方程momentumintegralequation動(dòng)量積分方程ForCVjjja(pv)dv+ffpv(v-n)dS=B1pfdV+WpdSdtnSnnTOC o 1-5 h zVVSflow：sumofthefluidmomentumchangeinCVandthenetoutflowmomentuminCS,isequaltotheresultantforce.v(v-n)dS二fffpfdV+ffpdSSnSMoment-of-momentumintegralequation動(dòng)量矩積分方程fffg)dV+乙(rxv)p(v-n)d

27、S=fff(rxpf)dV+ff(rxp)dSQtsSnForsteadyflow：(rxv)p(v-n)dS=Svxf)dV+JJ(rxp)dSSn流出動(dòng)量矩CS-流入動(dòng)量矩CS=合外力矩CV+cs41.Forcesonbend(彎頭)F=pQ(vcos0-v)+(p-p)A-(p-p)Acos0 x211a12a2F=-pQvsin0-(p-p)Asin0y22a242fluidjetsondeflector(導(dǎo)流板)R=-pQ(vcos0-v)+(p-p)A-(p-p)Acos0 x211a12a2R=-pQvsin0-(p-p)Asin0y22a243Sprinkler(噴水器)角速度

28、：v(r+r)4Q(r+r)3=12=12r2+r2兀d2(r2+r2)固定所需力矩1212M=pQ(vr+vr)=4pQV+12兀d2Chapter3PipeFlowandBoundaryLayerTheory(管流和邊界層概述)Laminarflow（層流）：Inthefluidflowthefluidparticlesmovealongsmoothpathinlayerswithouttransversevelocityinthedirectionofmainflow,onelayerglidessmoothlyoveranadjacentlayer.Turbulentflow（紊流,湍

29、流）orTurbulence：Ifthefluidparticleshaveatransversevelocitynormaltothemainflowdirection,thatleadstoparticlesmixingupeachother,withaviolenttransverseinterchangeofmomentum.Thisisturbulentflow（紊流,湍流）orturbulence.Reynoldsnumber雷諾數(shù)：isusedtodescribethecharacteristicofflow.Re=肥=巴卩vWettedperimeter（濕潤長度）：Thele

30、ngthofwallcontactedwithliquid.thehydraulicdiameter（水力直徑）DH:Thecharacteristicdimensionofnoncirculartube.49HeadLoses（能頭損失，或水頭損失）：thetotalenergylossesperunitweight（單位重量流體所損失的機(jī)械能為能頭損失（水頭）,whichduetotheresistancebetweentwosectionsofgraduallyvariedflow.（流體流動(dòng)，克服粘性內(nèi)摩擦力，消耗機(jī)械能為熱能.）50FrictionLoss沿程水頭損失（力）:Inth

31、eflowthroughastraighttubewithconstantcrossAsection,theenergylossincreaseslinearlyinthedirectionofflowandthelossiscalledfrictionloss.（原因:粘性內(nèi)摩擦力,以及與管壁的摩擦阻力）Darcy-Weisbch（達(dá)西-韋斯巴赫）Equation:八D2g入:thecoefficientoffrictionloss沿程阻力系數(shù)，與流態(tài)和壁面有關(guān)51Locallosses局部水頭損失（h）:Whentheshapeofflowpathchanges,suchassection

32、enlargementandsoon,itwillgiverisetoachangeinthedistributionofvelocityfortheflow.Thechangeresultsinenergyloss,whichiscalledminorlossorlocalloss.原因:流速急劇變化,流體質(zhì)點(diǎn)劇烈撞擊和摩擦.Z:minorlosscoefficientorlocallosscoefficient為局部阻力系數(shù)，與障礙物形式有關(guān)Headlosses總能量損失（h尸h+h）fAfh=Sh+工hf九gLAMINARFLOWTHROUGHCIRCULARTUBE圓管中的層流Velo

33、citydistributionincrosssectionu（r）=P（R2-r2）=wD4卩L4卩Dischargeumaxdq=udA=u（r）2兀rdrq=Jdq=JRu（r）2兀rdrvv0q=vAv=vR2=J:蓋（R2-忻忤Ap兀R2u2maxApR2_1v=u8卩L2maxq=JudA=r2）dAvAA4HL=J（R2-r2）2兀rdr=兀RAp=o4卩L8卩L兀D4,Ap128卩LHagen-Poiseuille（哈根-泊肅葉）equation.Distributionofshearstress切應(yīng)力分布：T=-hdu=Aprdr2L壁面剪切力t=ApR=沁w2LReF=t2

34、兀RL=ApR2兀RL=兀R2Ap=8卩Lv兀R2=8兀卩Lvw2LR254.Headlossalongthepath沿程能量（阻力）損失pressuredrop壓強(qiáng)損失A8hLq128hLq32HLv8卩LvAp=v=v：兀R4兀d4d2R2=hpgHeadloss水頭損失：h=p=8vLqv=128vLqv=32vLv=8vLv九pg兀gR*兀gd4=gd2gRTthecoefficientoffrictionloss：64v=64vdRePowerloss（功率損失）:W=pghq=Apq=ApAv=v九vv兀R4兀d455.PulsationPhenomenon（脈動(dòng)現(xiàn)象）：Theph

35、enomenonthatthephysicalparameterfluctuatesaroundacertainaveragevalueiscalledpulsationphenomenon（脈動(dòng)現(xiàn)象）.u=o+uwhere:aistime-averagevelocity（時(shí)均速度）;u-thecomponentofrandomfluctuatingvelocity（脈動(dòng)速度）.hydraulicsmooth冰力光滑）:Ifviscoussublayer8morethanabsoluteroughnesse（ie.8s）,theeffectofeforthecoreofturbulentflo

36、wisverylittle,namely,theinfluenceofeintheenergylossisverylittle.hydraulicrough（水力粗糙）:Ifviscoussublayer8lessthanabsoluteroughnesse（ie.8e）,thefluidparticleswithcertainvelocityimpactorcrashtheroughnessprojectionsofpipewall,sothevelocityoftheseparticleschangesradically.Itcauseseddy（渦流）orvortex（漩渦）locall

37、y.Meantimetheinfluenceistransferredtothecoreofturbulentflow.Soeplaysanimportantroleintheenergyloss.Parallellines并聯(lián)管路Byafewsimplelinesortandemlinewhichinletsideandoutletpipingconnectedrespectively.h=h=h=ff1f2dischargeQ=Q+Q+LL12Pipelineinseries/tandemlines（串聯(lián)管路）：Byacoupleofdifferentdiameterordifferent

38、roughnesspipeline.v22g+TotaldischargeQ=vA=vA=LL1122BoundaryLayer邊界層:Thefluidparticlesonasolidboundarymustadhereto（粘著，附著）thesolidwallinspiteof（不論）theReynoldsnumberReintheflow.Thevelocityoffluidneartheboundaryvariesrapidlyinasteep（陡的）velocitygradient（速度梯度）outwardnormaltothewallwherethefluidhasazerovel

39、ocity.Thevelocitygradientsetsup（產(chǎn)生）shearforceneartheboundaryandforthisreasontheeffectofviscositycannotbeneglectedintheregion.ThisregioncalledBoundarylayer.ThelargertheReynoldsnumberis,thethinnertheboundarylayeris.Chapter4OrificeOutflowandgapflow（孔口出流與縫隙流動(dòng)）Thin-walledorifice（薄壁孑L口）：1/d-2,theedgethick

40、nessslightlyeffectsthejetflow,andonlyminorlosswasconsidered,thecontractedsectionlocatedatd/2afterthehole.Thick-walledorifice（厚壁孑L口）：210,thehead,pressure,velocityonthesectionwillNOTbechangedwiththeheight.65.freeoutflow（自由出流）:thejetflowsintoatmospheredirectly,thepressureonthecontractedsectionwasBAR,p=

41、p.ca66submergedoutflow（淹沒出流）：thejetflowsdowntothewater.67.Contractedsection收縮斷面：thestreamlineswerecontractedafterthehole,andthesectionreachedtheminimumatd/2,whichwasthecontractedsectionCC.68.contractioncoefficient收縮系數(shù)：theratiobetweenthecontractedsectionareaandtheholearea,labeledasCc:C=A/A1cc69.Thedi

42、schargecalculationofsteadyfreeflowinorifice孔口恒定自由出流流量計(jì)算Cvisthevelocitycoefficient流速系數(shù)Q=Av=ACC話=AC/2gHcccvrC=CCdischargecoefficient流量系數(shù)rcv70.gapflowbetweenstationary固定平板間的縫隙流動(dòng)velocitydistributionu=丄dPZ2+Cz+C2卩dxi2umaxz=h/28yLdischargeq=Bfhudz=也Jh（hz-z2）dz=少坐vo2pLo12pLaveragevelocityv=2=二=型AhB12yL12卩L

43、qpressurelossAp=vBh3dischargeBh3ApUBhqv=12yL土T71.gapflowbetweenrelativelymovedparallelplates具有相對(duì)運(yùn)動(dòng)的兩平行平板間的流動(dòng)velocityu=”Z2）土hz壓差與平板運(yùn)動(dòng)方向相同取正號(hào)；方向相反取負(fù)號(hào)gapflowbetweenconcentriccylinders同心圓環(huán)間的縫隙流動(dòng)discharge兀dh3Ap12yL兀dUh2Chap.5SimilitudeandDimensionalAnalysis相似理論和量綱分析Thethreesimilaritiesareessentialconditi

44、onsofDynamicSimilitudeofFluidMotion（流動(dòng)相似）,inwhich,atanytime,alltheparametersofthemodelandprototypeareinthesameratiothroughouttheentireflowfield.DynamicSimilitudeofFluidMotion（流動(dòng)相似）includesGeometricsimilarity幾何相似,Kinematicsimilarity運(yùn)動(dòng)相似,andDynamicsimilarity動(dòng)力相似;Geometricsimilarity幾何相似isthebasicandthe

45、mostobviousrequirement;Kinematicsimilarity運(yùn)動(dòng)相似istheresult;Dynamicsimilarity動(dòng)力相似istheconditions.dynamicsimilarityincludeskinematicsimilarity,whilekinematicsimilarityincludesgeometricsimilarity.Hence,ratiosofforce,timeandlengtharesameunderdynamicsimilarity,andotherquantitiesarealsoequal.動(dòng)力相似包括運(yùn)動(dòng)相似，而運(yùn)動(dòng)相似又包括幾何相似。所以動(dòng)力相似包括力、時(shí)間和長度三個(gè)基本物理量相似。兩系統(tǒng)的其它物理量由它們決定，也必然相似。Theinitialconditions（初始條件）andboundaryconditions（邊界條件）alsomustbecoincidentfordynamicsimilitudeoffluidflowexceptabovethreesimilarities.Newtonnumber（牛頓數(shù)），-二Nep12V2Reynoldsnumber