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1、FLUIDMECHANICS——双语教学课程2.FLUIDSTATICS2.流体静力学返回主目录点击此本章教学内容2.1StaticPressureandCharacteristics2.2BasicEquationofFluidStatics2.3UnitsandScalesofPressureMeasurement2.4Manometers2.5ForcesonPlaneAreas点击进入相应章节返回本页点击此HomeWork返回主目录点击此2.1StaticPressureand Charac
2、teristics2.1静压强及其特性2.1.1StaticPressureDefinition:thepressurep,isthenormalforceperunitareainafluid.SIunitofpressureisN/m2,calledthepascal.(帕斯卡,Frenchphilosopherandmathematician,1623-1662).Fluidisatrest,thepressureiscalledstaticpressure(静压强).2.1.2Charact
3、eristicsoftheStaticPressureFluidstaticpressurehastwocharacteristics1.Thedirectionofpressureisperpendiculartotheactingsurface(作用面)andinthesamedirectionofinwardnormal(内法线)ofthesurface.2.Thepressuresatapointinafluidatrestarethesameinalldirections.Ithasnot
4、hingtodowiththedirectionoftheactingsurface.pisdecomposedintotwocomponents:tangentialpressurept;normalpressurepn.ToprovethefirstcharacteristicsDiscuss:thefluidwilldeformcontinuouslywhensubjectedtoashearstress,nomatterhowsmallthatshearstressmaybe.tangent
5、ialpressurept=0;2.1.2CharacteristicsoftheStaticPressureThestaticpressuresonABC,ACD,ABDandBCDarepxpypzandpn.pnhasanglesofα,β,γwiththex,y,zaxis.Thetotalpressureforcesonthefourfaceare:2.1.2CharacteristicsoftheStaticPressureTherearemassforces(质量力)actingont
6、hetetrahedron.Thecomponentsofforceperunitmassarefx,fy,fzinthex,y,zdirectionsandthecomponentsofmassforcesinthethreeaxisarerespectively:2.1.2CharacteristicsoftheStaticPressureThesumofcomponentsofallforcesinanyaxisisequaltozero.Inthexdirection2.1.2Charact
7、eristicsoftheStaticPressureThelasttermontheleftofequationisaninfinitesimalandmaybeneglected.SimilarlyThedirectionofnisarbitrary.Henceinastaticfluidthepressureatapointisthesameinalldirections.2.1.2CharacteristicsoftheStaticPressure2.2BasicEquationofFlui
8、dStatics2.2流体静力学基本方程2.2.1Differentialequilibriumequationofstaticfluid2.2.1DifferentialequilibriumequationofstaticfluidSupposethatthestaticpressureatthecenterofparallelepipedelementisp.Thestaticpressuresexertedonthecentersofsixfacescanbe
