流体力学复习资料及英文专有名词解释

1、Chapter1Fluidstatics流体静力学连续介质假定（Continuumassumption）：Therealfluidisconsideredasno-gapcontinuousmedia,calledthebasicassumptionofcontinuityoffluid,orthecontinuumhypothesisoffluid.流体是由连续分布的流体质点（fluidparticle）所组成，彼此间无间隙。它是流体力学中最基本的假定，1755年由欧拉提出。在连续性假设之下，表征流体状态的宏观物理量在空间和时间上都是连续分布的，都可以作为空间和时间的函数。流体质点（Flui

2、dparticle）:AfluidelementthatissmallenoughwithenoughmolestomakesurethatthemacroscopicmeandensityhasdefinitevalueisdefinedasaFluidParticle.宏观上足够小，微观上足够大。流体的粘性（Viscosity）:isaninternalpropertyofafluidthatoffersresistancetosheardeformation.Itdescribesafluidsinternalresistancetoflowandmaybethoughtasameasu

3、reoffluidfriction.流体在运动状态下抵抗剪切变形的性质，称为黏性或粘滞性。它表示流体的内部流动阻力，也可当做一个流体摩擦力量oTheviscosityofagasincreaseswithtemperature,theviscosityofaliquiddecreaseswithtemperature.牛顿内摩擦定律（NewtonslawofviscOsityT=UdzThedynamicviscosity（动力黏度）isalsocalledabsoluteviscosity绝对黏度）.Thekinematicviscosity（运动黏度）istheratioofdynamic

4、viscositytodensity.Uv=P6.Compressibility（压缩性）：Asthetemperatureisconstant,themagnitudeofcompressibilityisexpressedbycoefficientofvolumecompressibility（体积压缩系数）K,arelativevariationrate（相对变化率）ofvolumeperunitpressure.Thebulkmodulusofelasticity（体积弹性模量）EisthereciprocalofcoefficientofvolumeKcompressibility7

5、.流体的膨胀性（expansibility;dilatability）：Thecoefficientofcubicalexpansion（体积热膨胀系数）atistherelativevariationrateofvolumeperunittemperaturechange.dVVdVa=:=（1/K,1/C）tdTVdT8表面张力Surfacetension:Apropertyresultingfromtheattractiveforcesbetweenmolecules.c单位长度所受拉力表面力Surfaceforceistheforceexertedonthecontactsurface

6、bythecontactedfluidorotherbody.Itsvalueisproportionaltocontactarea.作用在所研究流体外表面上与表面积大小成正比的力。Stress（应力）isthesurfaceforceonperunitarea.质量力MassforceTheforceactingoneveryfluidmassparticlewithinthecontrolbody.Itsvalueisproportionaltoitsmass.Massforceisalsoknownasbodyforce.作用在流体的f=1dpxpQxf=1dpypdyf二1dpzpdz

7、1775年每一个流体质点上，其大小与流体所具有的质量成正比。EulerEquilibriumEquations欧拉平衡微分方程（分量式）PhysicalMeaning:Forthefluidinequilibrium,surfaceforcecomponentspermassfluidareequaltomassforcecomponentspermassfluid.Pressurevariationrateinaxesdirections（也,雀,氓）aredxdydzequaltomassforcecomponentsperunitvolumeinaxesdirectionsrespect

8、ively（pf,pf,pf）xyzconstant-pressureSurface（等压面）asurfacethatthepressureofeverypointinliquidisequal.Commonconstant-pressuresurfacesarefreeliquidsurfaceandinterfaceoftwounmixedfluidsinequilibrium平衡流体中压强相等的点所组成的平面或曲面。p=C或dp=0PressureDistributionintheStaticFluid重力场中流体的平衡p=-pgz+CConclusions:Pressureatapoi

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

10、ebetweentwopointsareknown,thepressureatanotherpointcanbecalculated.Absolutepressure（绝对压力），Gagepressure（相对压力，又称“表压力”）,andVacuum（真空度）：表压力=绝对压力一大气压力；真空度=大气压力一绝对压力15FluidinRelativeEquilibrium（相对静止流体）Equationofconstant-pressuresurface（等压面方程）：a）UniformLinearAcceleration等加速度直线运动流体：acosady+（asina一g）dz=0b)Un

11、iformRotationaboutaVerticalAxis等角速度旋转流体:Chapter2basicequationsoffluidmechanics16.17.迹线pathline：thetraceafterasingleparticletravelsinafieldofflowoveraperiodoftime.流体质点的运动轨迹曲线dx_dy_dz_u(x,y,z,t)v(x,y,z,t)w(x,y,z,t)流线streamline:acurvethatshowthedirectionofanumberofparticlesatthesameinstantoftime.某一时刻处处

12、与速度矢量相切的空间曲线-瞬时性。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.在流场中任取一个有流体从中通过的封闭曲线，在曲线上的每一个质点都可以引出一条流线，这些流线簇围成的管状曲面称为流管

13、。Tube-flow流束Fluidfullingthestreamtubeiscalledthetube-flowandthelimitofatube-flowisastreamline.流管内的全部流体称为流束。Ministream-tube微小流束Thestreamtubewithaninfinitesimalsectionissaidtobemini-streamtube.Streamlineistheextremecaseofmini-streamtube.截面无穷小的流束。Totalflow总流Totalofcountlessmini-streamtubesiscalledtotal

14、flow.包含流动中所有的微小流束。Crosssection(过水断面)-Thesectionisperpendiculartothedirectionoffluidflow.(suchaspipeflowandchannelflow)与流束或总流流线dA,A成正交的断面。Discharge(流量)-Amountoffluidpassthroughacrosssectionperunittime(suchasthesectioninthechannelorpipe).单位时间内通过某一过水断面的流体体积称为体积流量，简称流量。Meanvelocity断面平均流速-Thevelocitiesof

15、pointsonthesamecrosssectioninthetotalflowaredifferent,sousuallyanaveragevelocityisusedinsteadoftherealvelocityoverthecrosssection,thisaveragevelocityiscalledthemeanvelocity.Uniformflow均匀流：isdefinedasuniformflowwhenintheflowfieldthevelocityandotherhydrodynamicparametersdonotchangefrompointtopointatan

16、yinstantoftime（inwhichthecrosssectionofeachstreamtuberemainsunchanged.流场中每一空间点的各运动参数（速度，压力）不随空间位置而变化。（VV）O=0Nonuniformflow非均匀流：Flowsuchthatthevelocityvariesfromplacetoplaceatanyinstant.Steadyflow恒定流：theflowwhosemotionfactorsdontchangewithtime.流场中所有的运动要素不随时间变化.28Unsteadyflow非恒定流：theflowthatatleastone

17、ofitsmotionfactorschangeswithtime.流场中至少有一个运动要素随时间变化.Onedimensionalflow（一元流动）-allmainvariablesintheflowfieldcanbecompletelyspecifiedbyasinglecoordinateifthevariationofflowparameterstransversetothemainstreamdirectioncanbeneglected.流动参数只与一个坐标变量有关。Twodimensionalflow（二元流动）-fluidmotionfactorsarefunctionof

18、twospacecoordinates.流动参数与两个坐标变量有关。Three-dimensionalFlow（三元流动）:Fluidflowsmotionfactorsarefunctionsofthreespacecoordinates.流动参数与三个坐标变量有关。System（系统）isasetofdefinitefluidparticlesselectedintheinterestofresearcher.由确定的流体质点组成的流体团或流体体积丿。系统边界面s亿丿在流体的运动过程中不断发生变化。反映了拉格朗日观点Controlvolume（控制体CV）isdefinedasaninva

19、riablyhollowvolumeorframefixedinspaceormovingwithconstantvelocitythroughwhichthefluidflows.相对于坐标系固定不变的空间体积V。是为了研究问题方便而取定的。反映了欧拉观点ForaCV:1）itsshape,volumeanditscscannotchangewithtime.2）itisstationaryinthecoordinatesystem.（inthisbook）3）theremaybetheexchangeofmassandenergyonthecs.35.differentialfoContr

20、olsurface控制面：thesurfaceareacompletelyenclosestheCV边界面S称为控制面。mofxontinuityequation微分形式的连续性方程dpdpvvQpv1xHyHh0dtdxdydzForincompressiblefluiddvdvQv+zQzFor2-DincompressibleflowPhysicalmeaning:Thenetmassdischargeenteringthecontrolvolumeisequaltothemassincreasedinunittimeduetothechangeindensity.Fitfor:Stea

21、dyflow,unsteadyflow,compressibleandincompressiblefluid,idealfluidandrealfluid.Integralformofcontinuityequation积分形式的连续方程J空dV+JpvdS=0VQtSnPhysicalmeaning：在单位时间内，由于控制体内密度变化引起的质量变化量（增加量或减少量）与通过控制体表面的质量净流出量（流出与流入的质量差）之和等于零。Steadyflow定常流动T_pvdS-0csnincompressiblefluid不可压缩流体JvdS=0CSnvS=vS1122MotionDifferen

22、tialEquation运动微分方程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定常流动（2）incompressibleflow不可压缩（3）integrationalongastreamline沿流线积分（4）massforceisapotentialforce质量力有势pv2Forstreamlinez+=CPg2gForcompressibleflowingravityfieldV22gV222gForcompressibleflowwithfluidmachineryingravityfiel

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

25、ergyfrom1to2pointsperunitweightfluidHTTheeffectiveenergyobtainedaftertheunitweightoftheliquidflowsthroughthepump.单位重量液体流经泵后获得的有效能量。Headofdelivery扬程p-pv2-v2H=厶i+2i+zz2g21Thesumofthemiscalledthetotalhead（总水头）,denotedasH.Pumppower泵功率：Pw=HtQyFortheideal-fluidtotalflow理想流体总流的伯努利方程v2pv2z+a+a十1Pg】2gforther

26、eal-fluidtotalflow实际流体总流的伯努利方程momentumintegralequation动量积分方程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动量矩积分方程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流出动量矩CS-流入动量矩CS=合外力矩CV+cs41.Forcesonbend(弯头)F=pQ(vcos0-v)+(p-p)A-(p-p)Acos0 x211a12a2F=-pQvsin0-(p-p)Asin0y22a242fluidjetsondeflector(导流板)R=-pQ(vcos0-v)+(p-p)A-(p-p)Acos0 x211a12a2R=-pQvsin0-(p-p)Asin0y22a243Sprinkler(喷水器)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(管流和边界层概述)Laminarflow（层流）：Inthefluidflowthefluidparticlesmovealongsmoothpathinlayerswithouttransversevelocityinthedirectionofmainflow,onelayerglidessmoothlyoveranadjacentlayer.Turbulentflow（紊流,湍

29、流）orTurbulence：Ifthefluidparticleshaveatransversevelocitynormaltothemainflowdirection,thatleadstoparticlesmixingupeachother,withaviolenttransverseinterchangeofmomentum.Thisisturbulentflow（紊流,湍流）orturbulence.Reynoldsnumber雷诺数：isusedtodescribethecharacteristicofflow.Re=肥=巴卩vWettedperimeter（湿润长度）：Thele

30、ngthofwallcontactedwithliquid.thehydraulicdiameter（水力直径）DH:Thecharacteristicdimensionofnoncirculartube.49HeadLoses（能头损失，或水头损失）：thetotalenergylossesperunitweight（单位重量流体所损失的机械能为能头损失（水头）,whichduetotheresistancebetweentwosectionsofgraduallyvariedflow.（流体流动，克服粘性内摩擦力，消耗机械能为热能.）50FrictionLoss沿程水头损失（力）:Inth

31、eflowthroughastraighttubewithconstantcrossAsection,theenergylossincreaseslinearlyinthedirectionofflowandthelossiscalledfrictionloss.（原因:粘性内摩擦力,以及与管壁的摩擦阻力）Darcy-Weisbch（达西-韦斯巴赫）Equation:八D2g入:thecoefficientoffrictionloss沿程阻力系数，与流态和壁面有关51Locallosses局部水头损失（h）:Whentheshapeofflowpathchanges,suchassection

32、enlargementandsoon,itwillgiverisetoachangeinthedistributionofvelocityfortheflow.Thechangeresultsinenergyloss,whichiscalledminorlossorlocalloss.原因:流速急剧变化,流体质点剧烈撞击和摩擦.Z:minorlosscoefficientorlocallosscoefficient为局部阻力系数，与障碍物形式有关Headlosses总能量损失（h尸h+h）fAfh=Sh+工hf九gLAMINARFLOWTHROUGHCIRCULARTUBE圆管中的层流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:盖（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-泊肃叶）equation.Distributionofshearstress切应力分布：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）损失pressuredrop压强损失A8hLq128hLq32HLv8卩LvAp=v=v：兀R4兀d4d2R2=hpgHeadloss水头损失：h=p=8vLqv=128vLqv=32vLv=8vLv九pg兀gR*兀gd4=gd2gRTthecoefficientoffrictionloss：64v=64vdRePowerloss（功率损失）:W=pghq=Apq=ApAv=v九vv兀R4兀d455.PulsationPhenomenon（脉动现象）：Theph

35、enomenonthatthephysicalparameterfluctuatesaroundacertainaveragevalueiscalledpulsationphenomenon（脉动现象）.u=o+uwhere:aistime-averagevelocity（时均速度）;u-thecomponentofrandomfluctuatingvelocity（脉动速度）.hydraulicsmooth冰力光滑）:Ifviscoussublayer8morethanabsoluteroughnesse（ie.8s）,theeffectofeforthecoreofturbulentflo

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

37、y.Meantimetheinfluenceistransferredtothecoreofturbulentflow.Soeplaysanimportantroleintheenergyloss.Parallellines并联管路Byafewsimplelinesortandemlinewhichinletsideandoutletpipingconnectedrespectively.h=h=h=ff1f2dischargeQ=Q+Q+LL12Pipelineinseries/tandemlines（串联管路）：Byacoupleofdifferentdiameterordifferent

38、roughnesspipeline.v22g+TotaldischargeQ=vA=vA=LL1122BoundaryLayer边界层:Thefluidparticlesonasolidboundarymustadhereto（粘着，附着）thesolidwallinspiteof（不论）theReynoldsnumberReintheflow.Thevelocityoffluidneartheboundaryvariesrapidlyinasteep（陡的）velocitygradient（速度梯度）outwardnormaltothewallwherethefluidhasazerovel

39、ocity.Thevelocitygradientsetsup（产生）shearforceneartheboundaryandforthisreasontheeffectofviscositycannotbeneglectedintheregion.ThisregioncalledBoundarylayer.ThelargertheReynoldsnumberis,thethinnertheboundarylayeris.Chapter4OrificeOutflowandgapflow（孔口出流与缝隙流动）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（淹没出流）：thejetflowsdowntothewater.67.Contractedsection收缩断面：thestreamlineswerecontractedafterthehole,andthesectionreachedtheminimumatd/2,whichwasthecontractedsectionCC.68.contractioncoefficient收缩系数：theratiobetweenthecontractedsectionareaandtheholearea,labeledasCc:C=A/A1cc69.Thedi

42、schargecalculationofsteadyfreeflowinorifice孔口恒定自由出流流量计算Cvisthevelocitycoefficient流速系数Q=Av=ACC話=AC/2gHcccvrC=CCdischargecoefficient流量系数rcv70.gapflowbetweenstationary固定平板间的缝隙流动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具有相对运动的两平行平板间的流动velocityu=”Z2）土hz压差与平板运动方向相同取正号；方向相反取负号gapflowbetweenconcentriccylinders同心圆环间的缝隙流动discharge兀dh3Ap12yL兀dUh2Chap.5SimilitudeandDimensionalAnalysis相似理论和量纲分析Thethreesimilaritiesareessentialconditi

44、onsofDynamicSimilitudeofFluidMotion（流动相似）,inwhich,atanytime,alltheparametersofthemodelandprototypeareinthesameratiothroughouttheentireflowfield.DynamicSimilitudeofFluidMotion（流动相似）includesGeometricsimilarity几何相似,Kinematicsimilarity运动相似,andDynamicsimilarity动力相似;Geometricsimilarity几何相似isthebasicandthe

45、mostobviousrequirement;Kinematicsimilarity运动相似istheresult;Dynamicsimilarity动力相似istheconditions.dynamicsimilarityincludeskinematicsimilarity,whilekinematicsimilarityincludesgeometricsimilarity.Hence,ratiosofforce,timeandlengtharesameunderdynamicsimilarity,andotherquantitiesarealsoequal.动力相似包括运动相似，而运动相似又包括几何相似。所以动力相似包括力、时间和长度三个基本物理量相似。两系统的其它物理量由它们决定，也必然相似。Theinitialconditions（初始条件）andboundaryconditions（边界条件）alsomustbecoincidentfordynamicsimilitudeoffluidflowexceptabovethreesimilarities.Newtonnumber（牛顿数），-二Nep12V2Reynoldsnumber