输液管道颤振失稳的时滞控制

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1、同济大学航空航天与力学学院硕士学位论文输液管道颤振失稳的时滞控制姓名：齐欢欢申请学位级别：硕士专业：工程力学指导教师：徐鉴20090201摘要通过对时滞控制策略的改进，利用时滞控制提高临界流速的优点，同时又避免了激起系统低流速失稳，有效地提高了系统的临界流速。关键词：输液管，时滞控制，流固耦合，颤振，稳定性，有限差分法IIAbstractABSTRACTInadditiontoroad，rail，waterwaysandairtransportation，pipelinetransportisthefifth-largestmodesoflogistic

2、s．Itasaneffectivemeansoftransportationplaysanimportantroleinthemodemindustrial，agriculturalproductionandpeople。Slives．Theproblemofflow-inducesvibrationshasbeenakeyfactorimpactingpipelineworkperformance，suchassecurity,lifeexpectancyetc．．Thisproblemhadbeenleadinginterestinacademics

3、，notonlyasitsextensiveindustrialbackgroundandpracticalsignificance，butalsoforthesysteminvolvesamajorityperformanceoffluid。structureinteraction，asasimplephysicalmodelitiseasiertoachievesynergyoftheoreticalandexperimental．Theproblemofflow．inducesvibrationswillbemoreandmoreseriousas

4、themodemdevelopmentdirection-longdistance，largediameter,andhi曲flowvelocity．Therefore，furtherclarifyingthevibrationmechanismanddesigningwaystoreducethevibrationplayanimportanttheoreticalandpracticalapplicationvalue．First，dynamicbehaviorofcantileverpipesconveyingfluidhavebeenstudie

5、dusingtwomethods：thefirstmethodandGalerkinmethod．Theresultsshowthat：thenatural疳equencyofsystemwouldnormallybedecreasedwiththevelocityofflowincreasing．Whenthenaturalfrequencyisdroppedtoacertainvalue，thesystemwillbecomeunstablebyflutter．Thecomparisonsofsolutionsusingtwomethodsshowt

6、hat：ThereexiststruncatederrorwhenweuseGalerkinmethod．Thoughwecanensureaccuracybytruncatingmoremodes，itwillbringanexponentialgrowthincomputing．Therefore，weshouldchoosetheappropriatenumberofmodaltruncationaccordingtotheactualsituation．Then，anovelactivecontroltechniquecalleddelayedf

7、eedbackcontrolisproposedtocontroltheflutterinacantileverpipeconveyingfluid．It’Smotivatedtoincreasethecriticalflowvelocityatwhichapairofpureimaginaryoccursandthesystembecomesunstablebyflutter．Firstly,acontrollablestrategy,i．e．delayedfeedbackcontrol，isdesignedSOthatanonlinearpartia

8、ldifferentialequation(PDE)withdelayiSmod