简介:Inthisstudy,thepassageofwavesthroughpilegroupswithdifferentarrangementsisinvestigatedusingathree-dimensional(3D)numericalmodel.Forthesimulations,wavesofthreedifferentheightsof36,58,and81mm,afixedperiodof0.88s,andafixedwavelengthof1.128mwereused.Tosimulatethewavesandflowpatternthroughthepiles,Reynolds-averagedNavier–Stokes(RANS)equationsoffluidmotionweresolvedbasedonthefinitevolumemethod(FVM).Pilesweredefinedasobstaclesintherectangulardomainusingthefractionalarea/volumeobstaclerepresentation(FAVOR)method.Thevolume-of-fluid(VOF)andre-normalizationgroup(RNG)methodswereusedtosimulatethefreesurfaceandturbulencephenomenon,respectively.Byperformingdifferentnumericalsimulations,theeffectofcoastalpilearrangementsonwavepatternwasstudiedandwascomparedwithexistingexperimentaldata,andanacceptableagreementwasachieved.
简介:随着船舶技术的发展,现代船舶对船用隔离器系统提出了越来越高的要求,即船用隔离器系统应同时具备低频减振和高频抗冲击的能力,这是传统的船用减振器系统所无法做到的.为了解决此问题,本文提出了一种新的船用隔离器系统,该系统由钢丝绳弹簧和磁流变阻尼器相并联组成.文中对该船用隔离器系统的减振和抗冲击性能进行了模型试验研究。减振试验的激振力频率为1-15Hz,力幅为2.94.11.76kN;冲击试验的最大冲击输入加速度为20g,脉宽为10ms,减振试验和冲击试验均采用MTS液压加载系统来进行.试验结果表明,该船用隔离器系统具有较好的减振效果,使用了MR阻尼器后系统得共振峰值被明显的削弱;在冲击试验中,冲击响应的衰减速度随着MR阻尼器的阻尼增加而明显加快,但是MR阻尼器再冲击瞬间的出力特性明显与低频振动情况下不同,MR阻尼器的出力表现为受控制电流强度影响不大.
简介:随着船舶技术的发展,现代船舶对船用隔离器系统提出了越来越高的要求,即船用隔离器系统应同时具备低频减振和高频抗冲击的能力,这是传统的船用减振器系统所无法做到的.为了解决此问题,本文提出了一种新的船用隔离器系统,该系统由钢丝绳弹簧和磁流变阻尼器相并联组成.文中对该船用隔离器系统的减振和抗冲击性能进行了模型试验研究。减振试验的激振力频率为1-15Hz,力幅为2.94-11.76kN;冲击试验的最大冲击输入加速度为20g,脉宽为10ms,减振试验和冲击试验均采用MTS液压加载系统来进行.试验结果表明,该船用隔离器系统具有较好的减振效果,使用了MR阻尼器后系统得共振峰值被明显的削弱;在冲击试验中,冲击响应的衰减速度随着MR阻尼器的阻尼增加而明显加快,但是MR阻尼器再冲击瞬间的出力特性明显与低频振动情况下不同,MR阻尼器的出力表现为受控制电流强度影响不大.
简介:GiventherecentsuccessinthedevelopmentofseveralsubmersiblesinChina,people’sinterestinthehistoryofsubmersibledevelopmentisincreasing.ThispaperpresentsthehistoryofsubmersibledevelopmentinChina,whichcanbebrieflydividedintothreeperiods.Thefirstoneistheearlyperiodofhardship(1971–2000).ManyprototypesubmersiblesofHOVs,ROVs,andAUVsweredevelopedatthistime,butthemainachievementwastheestablishmentofspecialresearchorganizationsandthetrainingofresearchanddevelopmentpersonnel.Thesecondperiodcanberegardedasthequickdevelopmentperiod(2001–2015).Allcurrentlyusedsubmersiblesweredevelopedduringthisperiod.Themostremarkableachievementwasthesuccessfuldevelopmentof7000m-deepmannedsubmersibleBJiaolong.^Thethirdperiodaimstodevelop11000msubmersiblesforchallengingthefulloceandepth(2016–2020).Inthisperiod,twounmannedsubmersiblesandtwomannedsubmersibleswillbethesignificantindicatorsofachievement.Ifthis5-yearplancanbesuccessfullycompleted,Chinacanplayasignificantroleintheinvestigationofthedeepestpartoftheoceans,namely,thehadaltrenches(6500–11000m).