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70 个结果
  • 简介:WithoutsimplifyingtheN-SequationsofGermano’s,westudytheflowinahelicalcircularpipeemployingperturbationmethod.Athirdperturbationsolutionisfullypresented.Thefirst-second-andthird-ordereffectsofcurvatureкandtorsionтonthesecondaryflowandaxialvelocityarediscussedindetail.Thefirst-ordereffectofcurvatureistoformtwocounter-rotatingcellsofthesecondaryflowandtopushthemaximurnaxialvelocitytotheouterbend.Thetwocellsarepushedtotheouterbendbythepuresecond-ordereffectofcurvature.Thecombinedhigher-order(second-,third-)effectsofcurvatureandtorsion,arefoundtobeanenlargementofthelowervortexofthesecondaryflowatexpenseoftheupperoneandaclockwiseshiftofthecentersofthesecondaryvorticesandthelocationofmaximumaxialvelocity.Whentheaxialpressuregradientissmallenoughorthetorsionissufficientlylargerthanthecurvature,thelocationofthemaximalaxialvelocityisneartheinnerbend.Theequationofthevolumefluxisobtainedfromintegratingtheperturbationsolutionsofaxialvelocity.Fromtheequationthevalidityrangeoftheperturbationsolutionsinthispapercanbeobtainedandtheconclusionthatthethreetermsoftorsionhavenoeffectonthevolumefluxcaneasilybedrawn.Whentheaxialpressuregradientislessthan22.67,thevolumefluxinahelicalpipeislargerthanthatinastraightpipe.

  • 标签: SECONDARY FLOW HELICAL PIPE PERTURBATION method
  • 简介:Inthispaper,aphotoelectricdeviceisintroduced,whichisusedinde-tectingthequalityoninternalsurfaceofthinandlongsteelpipe.Inthisdevice,theCCTVlensisusedforextracttheflawinformationoninternalsurfaceofthepipe,andmakeIBM-PC/AT486computerascontrollingandimageprocessingsystem.Bythisinstrument,thefunctions,suchasthedigitalconversiongofinputinformation,imageprocessing,classificationofrecognitionandoutputdisplaycanbeobtained,Inthepetroleumandchemicalindustry,byusingthisapparatus,wecandetectthequalithoninternalsurfaceofvariousmetalpipeswithreal-timeautomatically.

  • 标签: 探伤检验 图像处理 质量控制 钢管内表面 光电探测
  • 简介:AnewcentrifugebasedmethodfordeterminingtheresponseofcontinuousburiedpipetoPGDispresented.ThephysicalcharacteristicsoftheRPI's100g-tongeotechnicalcentrifugeandthecurrentlifelineexperimentsplit-boxaredescribed:Thesplit-boxcontainsthemodelpipelineandsurroundingsoilandismanufacturedsuchthathalfcanbeoffset,inflight,simulatingPGD.Inaddition,governingsimilituderelationswhichallowonetodeterminethephysicalcharacteristics,(diameter,wallthicknessandmaterialmodulusofelasticity)ofthemodelpipelinearepresented.Finally,recordedstrainsinducedintwoburiedpipeswithprototypediametersof0.63mand0.95m(24and36inch)subjectto0.6and2.0meters(2and6feet)offullscalefaultoffsetsandpresentedandcomparedtocorrespondingFEresults.

  • 标签: 地震 PGD 离心分离模型 有限元分析 地下管
  • 简介:Tosolvetheproblemoflowefficiencyinpiperoutingdesign,animprovedgeneticalgorithmbasedapproachisproposed.Topresentthisapproach,thepapermainlydescribesagenerationmethodofnodesconsideringthesafetydistanceofpipesandthedirectionalconstraintsatterminals,thedefinitionofadoublecodingtechnique,thecollisiondetectionmethod,theconceptofenergyandthedefinitionoffitnessfunctions.Thesimilaritydetectionisintroducedtopreventclosebreedinginthecrossoveroperator,theselectionpressureiscontrolledaccordingtotheevolutionsituationandaheuristicmutationmethodisusedtoboosttheevolution.Simulationcaseshowsthatthisapproachismorepracticalandcansatisfydifferentdesignrequirementsbychangingalgorithmparameters.

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  • 简介:Theinterfacialbehaviorofpipejointsisstudiedinthispaper.Firstly,throughnonlinearfracturemechanics,theanalyticalexpressionsofinterfacialshearstressandtheloaddisplacementrelationshipatloadedendofpipejointsundertorsionloadsareobtained.Thustheshearstresspropagationandthedebondingprocessofthewholeinterfacefordifferentbondlengthscanbepredicted.Secondly,throughtheanalyticalsolutions,theinfluencesofdifferentbondlengthsontheload-displacementcurveandtheultimateloadarestudied.Thestresstransfermechanism,theinterfacecrackpropagationandtheductilitybehaviorofthejointscanbeexplained.

  • 标签: 界面行为 载荷作用 管接头 扭转 荷载-位移曲线 极限荷载
  • 简介:Thesteelreinforcedplasticpipeisakindofgreenenvironmentalprotectionpipelineswithdouble-sidescorrosionresistingandbetterwithstandingtomediumworkingpressure.Thestructureandtechnicalprocessofthispipearedescribedbrieflyinthispaper,andthefiniteelementanalysishasbeendoneforthesakeofunderstandingthedistributionsofstressanddisplacementinsidethispipeunderhydrostaticpressure.Theanalysisresultsareveryimportantforsafetyapplicationofthesteelreinforcedplasticpipe.

  • 标签: STEEL REINFORCED PLASTIC pipe FINITE ELEMENT
  • 简介:Basedontheformerresearchworkoftheauthors,theresistanceofdifferentsolidparticlesuspensionflowinaverticalpipeisanalysed,andinvestigatedexperimentally.Theapplicableformulasofpressuredroparepresented.Twotypesofpar-ticles,talcumpowderandglassbeads,areconvcyedinthetestwhichhasbeencarriedoutatvariousairvclocitiesof10to28m/sandattheratioofsolids-airmassflowraterangedfrom0to2.Theexperimentalresultsshowagoodagreementwiththecalculatedones.

  • 标签: solid PANICLES PRESSURE drop/vertical PIPE PNEUMATIC
  • 简介:Inthispaper,weconsideraninverseproblemofdeterminingthecorrosionoccurringinaninaccessibleinteriorpartofapipefromthemeasurementsontheouterboundary.TheproblemismodelledbyLaplace'sequationwithanunknowntermγintheboundaryconditionontheinnerboundary.BasedontheMaz'yaiterativealgorithm,aregularizedBEMmethodisproposedforobtainingapproximatesolutionsforthisinverseproblem.Thenumericalresultsshowthatourmethodcanbeeasilyrealizedandisquiteeffective.

  • 标签: 迭代算法 反转问题 侵蚀状态 LAPLACE方程 边界条件
  • 简介:当流动正在波动时,实验被进行学习流动的特征。试验性的结果显示出流动率和压力落下变化之间的阶段差别。波动的流动率和压力落下之间的这阶段差别为laminar流动被分析。分析证明阶段差别随着流动变化,管子半径,密度和液体的动态粘性的时期变化。波动的管子流动然后数字地被模仿。数字模拟的结果与理论价值和试验性的结果相比。当流动率作为一个正弦波浪与时间波动时,压力落下与一样的频率波动,这被显示出,并且他们之间有阶段差别。

  • 标签: 周期性波动 压降 管流 流量波动 流动特性 数值模拟
  • 简介:Inthispaper,weproposeandexperimentallydemonstrateamethodtorealizeapolarizationdetectorbyusingacommerciallyavailablepolymethylmethacrylate(PMMA)pipe.Anasymmetricpolarization-relatedstructureisfabricatedbyetchingdifferentgratingstructuresontheexternalsurfaceofthepipe.Theresultsshowthatwhenthepiperotatesupto90°,thepeakofthetransmissionspectrumcanevidentlyshifttowardsthelowfrequency,whichmeansthepipewithgratingstructurescanserveasapolarizationdetector.Thisdesignpossessesthemeritsofasimplestructureandeasyfabrication.

  • 标签: 偏振相关 探测器 太赫兹 玻璃管 聚甲基丙烯酸甲酯 光栅结构
  • 简介:Thispaperconsidersthestationaryflowofincompressiblemicropolarfluidthroughathincylindricalpipegovernedbythepressuredropbetweenpipe'sends.Itsgoalistoinvestigatetheinfluenceoftheviscositycoefficientsontheeffectiveflow.Dependingonthemagnitudeofviscositycoefficientswithrespecttothepipe'sthickness,itderivesdifferentasymptoticmodelsanddiscussestheirproperties.

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  • 简介:NonlinearMHDKelvin-Helmholtz(K-H)instabilityinapipeistreatedwiththederiva-tiveexpansionmethodinthepresentpaperThelinearstabilityproblemwasdiscussedinthepastbyChandrasekhar(1961)andXuetal.(1981).Nagano(1979)discussedthenonlinearMHDK-Hinstabilitywithinfinitedepth.Heusedthesingularperturbationmethodandextrapolatedtheob-tainedsecondordermodifierofamplitudevs.frequencytoseekthenonlineareffectontheinstabilitygrowthrateγ.However,inourview,suchanextrapolationisinappropriate.Becausewhentheinstabili-tysetsin,thegrowthratesofhigher,ordertermsontherighthandsideofequationswillexceedthecor-respondingsecularproducingterms,sotheexpansionwillstillbecomemeaninglessevenifthesecularproducingtermsareeliminated.Mathematicallyspeaking,it’simpossibletoderiveformula(39)whenγ02isnegativeinNagano’spaper.Moreover,evenasearlyasγ02→O+,theexpansionbe-comesinvalidbecausethe2ndordermodifierγ2(inhisformula(56))tendstoinfinity.Thisweak-nessisremovedinthispaper,andtheresultisextendedtothecaseofapipewithfinitedepth.

  • 标签: NONLINEAR MHD INSTABILITY KELVIN-HELMHOLTZ INSTABILITY MHD
  • 简介:基于液体动力学,热转移和声学的结果,一个计算液体动力学(CFD)方法被利用在一根Rijke管子内学习声学的特征和自我刺激的跳动机制。为了避免解决有限振幅的站的荒谬的边界条件,在Rijkethermo声学的系统飘动,在流动领域里当模特儿的模拟,它联合了有它的外层空间的管子内部,被执行代替传统的方法处于良好的竟技状态内部流动地数字调查。为在包括在热来源,摆动压力和摆动速度附近的空气的不稳定的热上的关系的精力方程的热来源的一个假设被介绍。为了反映Rijke的本质,尖叫,自我刺激的摆动上的模拟借助于它压力,速度和温度的自己的跳动被进行。这个方法能使集中过程稳定并且有效地避免分叉。自我刺激的Rijke管子的物理现象被分析。而且,Rijke管子的自我刺激的摆动上的机制是这个方法上的explained.Based,关于有不同尺寸和嘴的不同形状的Rijke管子的声学的特征的比较研究被执行。模拟结果令人满意地同意了试验性的数据。结果证明这数字模拟能被用来为Rijke管子的设计申请学习嘴的健全压力。

  • 标签: 声学特征 数学模拟技术 脉冲流 外太空
  • 简介:Hydrodynamicandthermalcharacteristicsinapipewithsinusoidalwavysurfaceforsteadylaminarflowareinvestigatednumericallyinthepresentstudy.TheintegralformsofgoverningequationsarediscretizedusingcontrolvolumebasedFinitevolumemethodwithcollocatedvariablearrangement.SIMPLEalgorithmisusedandTDMAsolverisappliedforsolutionofsystemofequations.Apipeoflengthequalto4λisconsidered.Effectofsurfacewaviness,determinedbywavelength-amplituderatioλ/a(=L^*),onflowandthermalfieldispresented.ThesimulationworkhasbeencarriedoutforL^*=11.0-30.0foraReynoldsnumberrange50to2000.Resultsarepresentedintheformofstreamfunction,isothermallines,velocityandvorticityprofiles,changeofmeanfrictionfactor,variationinskinfriction,localandaverageNusseltnumberwithReynoldsnumber,wavenumber(n)andL^*.Foraparticulargeometry,lengthofcirculationzoneincreaseswithreynoldsnumberandapproachesalimitingvalueforhigherReynoldsnumber.Wallshearstressinthebulgepartofthechannelshowssmallervaluesthataffectlargely.therateofheattransferandNusseltnumbershowsminimumvaluesinthisregion.Thiscirculationzonedrasticallyincreaseswiththeincreaseofsurfacewavinessshowinghighmeanfrictionfactorperwavelength.MeanfrictionfactorinverselyvarieswithReynoldsnumber.Acorrelationisproposedforcalculatingfrictionfactorintheformf=C/(Re)^m,where‘C’and‘m’representstwopolynomialsofdegree4and2respectivelyandarefunctionofL^*.Higherwavinessofthesurfaceshowsthehigherheattransferratethanlowerwaviness.Heattransferratefallsalmostexponentiallyalongtheaxialdirectionwiththeincreaseofwavenumber.

  • 标签: 流体 波形管 热交换 特征