简介:Foralargefloatingvesselinwaves,radiationdampingisnotanaccuratepredictionofthedegreeofrollunlikeotherdegreesoffreedommotion.Therefore,togettheknowledgeofrollmotionperformanceofdeepwaterpipelaycranevesselsandtokeepthevesselworkingsafety,thepaperpresentstherelationshipbetweenaseriesofdimensionlessrolldampingcoefficientsandtherollresponseamplitudeoperator(RAO).Byusingtwokindsofempiricaldata,therolldampingisestimatedinthecalculationflow.Aftergettingtherolldampingcoefficientfromthemodeltest,apredictionofrollmotioninregularwavesisevaluated.Accordingtothewaveconditionintheworkingregion,shorttermstatisticsofrollmotionarepresentedunderdifferentwaveparameters.Moreover,therelationshipbetweenthemaximalrollresponseleveltopeakspectralwaveperiodandtherolldampingcoefficientisinvestigated.Resultsmayprovidesomereferencetodesignandimprovethiskindofvessel.
简介:Inthispaper,a3Dsourcedistributiontechniqueisusedtocalculatethecoupledmotionsbetweentwoshipswhichadvanceinthewavewiththesamespeed.Thenumericalresultsofcoupledmotionsforafrigateandasupplyshiphaveagoodagreementwiththeexperimentalresults.Basedonthe3Dcoupledmotionsoftwoships,aspectralanalysisisemployedtoclearlyobservetheeffectofspeed,clearanceandwaveheadingonthesignificantrelativemotionamplitude(SRMA)oftwoships.Themethodpresentedinthispaperwillbehelpfultoselectsuitableclearance,speedandwaveheadingforunderwayreplenishmentatsea(RAS).
简介:在这研究,为海洋的申请目的,我们评估了在微观结构,机械加强和经由电极淀积生产的Zn-TiO2-WO3nanocomposite的腐蚀抵抗性质上装载的过程参数和粒子的效果。我们与与一个精力散分光计(版本)装备的一台扫描电子显微镜(SEM)描绘了合成涂层的词法性质。我们用一个Dura扫描坚硬测试者和一件必然发生的事情执行了机械检查UMT-2多功能的tribological测试者。我们在3.5%NaCl由线性极化评估了腐蚀性质。结果证明涂层展出了好稳定性,极大地装载的量的粒子提高了结构、词法的性质,坚硬行为和涂层的腐蚀抵抗。我们观察到钢上的这合金的降水被合成特征极大地影响。
简介:鳍和控制的运动出现在水下在液体的车辆是一个有趣、挑战性的研究题目。典型地在如此的身体附近的液体流动上的鳍摆动的效果是高度不稳定的,产生旋涡并且要求液体结构相互作用的详细分析。如此的流动的复杂性的理解在他们的推进开发能够高有活力的性能的车辆并且调遣的工程师感兴趣。在现在的学习,CFD基于搬进来的3-D鳍身体的RANS模拟一粘滞液体被开发。它由评估水动力学系数调查了水动力学性能(电梯,拖并且时刻)在二不同震荡频率。影响鳍身体的水动力学性能的因素的参量的分析被做,与从实验的结果的比较一起。模拟的结果在对试验性的结果的靠近的同意被发现,这为3-D鳍的不稳定的水动力学系数的评估作为一个有效工具验证了模拟。这个工作能是进一步的被用于稳定性的分析和激活的鳍的可操作性在水下车辆。
简介:Thenumericalmodellingoftheinteractionsbetweenwaterwavesandfloatingstructuresissignificantfordifferentareasofthemarinesector,especiallyseakeepingandpredictionofwave-inducedloads.SeakeepinganalysisinvolvingsevereflowfluctuationsisstillquitechallengingevenfortheconventionalRANSmethod.Particlemethodhasbeenviewedasalternativeforsuchanalysisespeciallythoseinvolvingdeformableboundary,wavebreakingandfluidfragmentationaroundhullshapes.Inthispaper,theweaklycompressiblesmoothedparticlehydrodynamics(WCSPH),afullyLagrangianparticlemethod,isappliedtosimulatethesymmetricradiationproblemforastationarybargetreatedasaflexiblebody.Thisiscarriedoutbyimposingprescribedforcedsimpleharmonicoscillationsinheave,pitchandthetwo-andthree-nodedistortionmodes.Theresultant,radiationforcepredictions,namelyaddedmassandfluiddampingcoefficients,arecomparedwithresultsfrom3-Dpotentialflowboundaryelementmethodand3-DRANSCFDpredictions,inordertoverifytheadoptedmodellingtechniquesforWCSPH.WCSPHwerefoundtobeinagreementwithmostresultsandcouldpredictthefluidactionsequallywellinmostcases.