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1、32Sofarwe“vediscussedwhatresistanceisandhowiLcanguan【inedHn8-Rbymeasuringtheactualresistanceforce-CTdimensionlesscoefficientsthatcanbeusedtocompareresistancebetweenmilarhullshapesandstodesigninsashinspoyerplanMecannowneasure山resistanceinahullandusethedalta-Usingtheresistancedataaneffectiyepowerplant
2、canbedesigned-Takingintoaccounttherelationshipbetween-EffectiveHorsepowerEHIP-ShaftHorsepowerSHP25Resistanceandpowerarerelated!ResistancecinpeieasiredLngoans-Computermodeling-Canbeverydifficulttomathematicallymodelviscousflowin3dimensions-TowTankesting-Producingageometticallyanddynamicallysinilarmod
3、eltotest-RelatemodeperformancetoexpectedaetualshipperformanceTowTankModelin0TowTanktestingistheobviouswaytogo1Buttodoso,your“model“shipmustmeetsomecriteria:1GeometricSimilarity“Thedimensionsofthemodelandshipmustbescaledexactly-The“ScaleFactor“iscalled入(lanbd巴目阡一|日列en【AreAIe4VolumehercM=MadelS=Ship.N
4、oreiaravyninornerror训anyengdhImeasurenenfvilDecubedJinyoumescaing1TowTankModelin发2。DynamicSimilarit-Motonofthevesselmustalsobescaled.including:-Shipsvelocityccelerationosityofthewater-Dynamicsimilarigycanonlybeapproximatedaswaterviscositytycaniorsanipulatsd(duh0)-Thetrade-offisavpartialsimilarity“-F
5、roudesLawofComparisonorvLawofCorrespondingSpeeds“41TheLawofCorrespondingSpeedssays:CoefficientofViscousResistance52-ViscousFlowaroundashipRealship:TurbulentflowexistsnearthebowModelship:StudsorsandipsareattachedatthebowtocreatetheturbulentflowWiervealreadydefined.as:49=Ls(fD)Lvu0UIfwewantedtosolvefo
6、rthescalespeedforthemodel,Vu=VyLuTelVorNOTEITAegualio1.688JUbect4LLvelociiesaredoneinjeeyseclExample1:TheUSSMonitorwas197ftlongand40ffacrossthebeamandwasabletoIaintainaImasximumspeedof6Kts.Youwouldliketoreateamodelfortestingthatis5frlong:Howwideshouldthemodelbe2Howfastshouldhemodelbetowedtoepresenttheactualshipsmaxspeed?A=LeL=197北15ESolingforthewidthjWyWuWu=40fU39.4SolvingforthemaximumspeedVs=VVEsEVu=VsX12V井6kts(1.688ftlsec-ktsjx39.412Vw=10.128fUsx.1593
