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1、覆冰導(dǎo)線的舞動(dòng)機(jī)理及其數(shù)值模擬摘要輸電導(dǎo)線不僅承受其白重、覆冰等靜荷載,而且還要承受風(fēng)產(chǎn)生的動(dòng)荷載。在一定的氣象條件下,覆冰導(dǎo)線受穩(wěn)態(tài)橫向風(fēng)作用,可能會(huì)引起大幅、低頻的自激振動(dòng),即舞動(dòng)。覆冰導(dǎo)線的舞動(dòng)現(xiàn)象頻繁發(fā)生,對(duì)線路的安全可靠運(yùn)行構(gòu)成嚴(yán)重威脅。由于導(dǎo)線覆冰狀況具有隨機(jī)性,產(chǎn)生舞動(dòng)的因素又非常復(fù)雜,給舞動(dòng)的研究帶來了巨大困難。總之,覆冰導(dǎo)線舞動(dòng)的研究具有重要的理論和應(yīng)用價(jià)值,也有很大的經(jīng)濟(jì)和社會(huì)意義?;诟脖鶎?dǎo)線舞動(dòng)的空氣動(dòng)力特性,結(jié)合典型冰型準(zhǔn)橢圓形(新月形)的特點(diǎn),依據(jù)流體動(dòng)力學(xué)原理,對(duì)覆冰導(dǎo)線繞流模型的流場進(jìn)行數(shù)值模擬分析。數(shù)值計(jì)算采用了有限差分的
2、迎風(fēng)格式,模擬出準(zhǔn)橢圓形(新月形)覆冰導(dǎo)線模型在各種不同攻角、不同風(fēng)速下的阻力系數(shù)、升力系數(shù),并探討風(fēng)速、攻角等對(duì)舞動(dòng)的影響。同時(shí)以索單元模擬輸電導(dǎo)線的狀態(tài),建立覆冰導(dǎo)線舞動(dòng)的力學(xué)模型,運(yùn)用ANSYS軟件對(duì)覆冰導(dǎo)線舞動(dòng)進(jìn)行模態(tài)分析,采用諧波疊加法,研究了覆冰導(dǎo)線的風(fēng)振響應(yīng),得出覆冰導(dǎo)線模型的前六階振型,并繪制導(dǎo)線上對(duì)應(yīng)振型的位移圖和導(dǎo)線上某些特殊點(diǎn)的位移響應(yīng)曲線。數(shù)值模擬的結(jié)果在一定程度上反映了覆冰導(dǎo)線的舞動(dòng)機(jī)理,可為覆冰導(dǎo)線的優(yōu)化設(shè)計(jì)提供依據(jù)。最后提出了導(dǎo)線舞動(dòng)研究中尚待解決的問題和進(jìn)一步的研究方向。.關(guān)鍵詞:覆冰導(dǎo)線空氣動(dòng)力特性索單元數(shù)值模態(tài)諧波疊加法
3、GallopingMechanismsandNumericalSimulationsofIcedConductorsABSTRACTTransmissionwiresaresubjectedtotheirownweightsandiceweights,aswellasdynamicloadsfromthewind.Incertainmeteorologicalconditions,steadytransversalwindmaycauseicedconductorsthelargeamplitude,lowfrequencyoscillation,name
4、lythedance.Icedconductorgallopingoccursfrequently,whichposesaseriousthreattothesafetyandreliabilityofthegrid.Becausetheshapeoftheicearoundwiresisrandom,andthereasonofthedancingisverycomplex,SOtheresearchongallopingisverydifficult.Inaword,theresearchhasimportanttheoreticalandpracti
5、calvalueandhasgreateconomicandsocialsignificance.Basedontheaerodynamiccharacteristicsofconductorgalloping,withthepropertiesofthetypicaliceshape,andbytheprincipleoffluiddynamics,thefluidfieldaroundicedconductorsisanalyzed.Thecrescentshapemodeloficearoundconductorsisused.Thewindward
6、formatoffinitedifferenceisappliedfornumericalcalculation.Thedragcoefficientsandliftcoefficientsatvariousanglesofattackarecalculatedthroughnumericalsimulation.Theinfluenceofthewindspeed,attackangleonconductorgallopingisdiscussed.Besides,thecableelementsareusedtosimulateicedconducto
7、rs.UsingtheANSYS,themechanicsmodeloficedconductorgallopingisestablished.Thewind-induceddynamicresponseoficedconductorsisstudiedbythemodalanalysisbyusingharmonicⅥravesuperimposingmethod.Sixnaturalfrequenciesandeigenvectorsaregotandthedisplacementresponsecurvesofsomevibrationmodeoft
8、helinearedrawn,whichcanoffersomer