【MOOC】泵与风机-东北大学 中国大学慕课MOOC答案

【MOOC】泵与风机-东北大学中国大学慕课MOOC答案介绍Introduction1、【判断题】Workingmediuminpumpisliquid,butinfanisgas.本题答案：【正确】分类Classification1、【多选题】Thesortationofpumpincludestwokindsof()本题答案：【paddletypepump#displacementtypepump#ejector】基本性能参数Basicperformanceparameters1、【判断题】Staticpowerdenotesthattheactualpoweractedonfluid,whichisequaltothesumofeffectivepowerandlosspower.本题答案：【错误】2、【填空题】Pleasetranslatethefollowingwords:Flowrate,Energyhead,Powerandefficiency,Speedrate,Staticpressure.本题答案：【Flowrate,Energyhead,Powerandefficiency,Speedrate,Staticpressure.】能量方程的分析Analysisofenergyequation1、【多选题】Measurestoimrovingthetheoreticalheadwithinfinitebladeinclude本题答案：【Increaseimpellerouterdiameter#inreaserotatingspeedofimpeller】2、【判断题】Theheadofaxialflowimpellerislowerthanthatofcentrifugalimpeller.本题答案：【正确】实际能头和总压的计算Calculationofactualheadandtotalpressure1、【填空题】pleasetranslatethefollowingwords:Springvacuumgauge,U-tubemercurydifferentialmanometer本题答案：【弹簧真空测压计，U型管水银差压计】叶片数为有限数时理论能头的修正Correctionoftheoreticalheadwithlimitednumberofblades1、【多选题】Whichistheeffectofinfinitenumberofbladesontheoreticalhead?本题答案：【Changingthevelocitytriangle#Formingpressuredifferenceatbothsidesofblade#reducingthetheoreticalhead】2、【判断题】Whenthenumberofbladesislimited,theflowisstrictlyguidedbybladesurface.本题答案：【错误】离心式叶轮流体运动和速度三角形Fluidmotionandvelocitytriangleofcentrifugalimpeller1、【多选题】Theformsoffluidmotioninimpellerinclude本题答案：【Circularmotion#Relativemotion#Absolutemotion】2、【填空题】Theassumptionswhendrawingprojectionare(inEnglish)本题答案：【Infiniteblades,idealfluid,incompressiblefluid,steadyflow,axisymmetricflow】轴流式叶轮流体运动和速度三角形Fluidmotionandvelocitytriangleofaxialflowimpeller1、【判断题】Comparedtothecentrifugalimpeller,thesimilaritiyofaxialandcentrifugalimpelleristhattheabsulotevelocityatinletandoutletissame.本题答案：【错误】离心式叶轮型式分析Analysisoftypesofcentrifugalimpeller1、【填空题】Threetypesofcentrifugalimpellerare本题答案：【backardcurved,radialtipped,forwardcurve】轴向力Axialforce1、【多选题】Pleaseselectthepropermethodforbalancingaxialforce.本题答案：【Balancehole#Doublesuctionimpeller#balancingdiscandbalancingdrum#balancepipe】机械损失和机械效率Mechanicallossandmechanical?efficiency1、【填空题】Mechanicallossincludes:at,or.本题答案：【losspower,shaft/shaftseal,shaft/bearings,discfriction】容积损失和容积效率Volumelossandvolumeefficiency1、【判断题】Thevolumelossofpumpcouldbegeneratedatthegapofbalancingaxialforcedeviceandshaftseal.本题答案：【正确】流动损失和流动效率Flowlossandflowefficiency1、【多选题】Whichstatementistrueaboutimpactloss?本题答案：【Thepositivevalueisbenefittoimprovethecavitationofpump.#Thereistheminimumflowloss.】离心式叶轮性能曲线Performancecurveofcentrifugalimpeller1、【单选题】Whatistherelationshipofactualheadandflowratewithbackwardimpeller?本题答案：【linearlydownward】轴流式叶轮性能曲线Performancecurveofaxialimpeller1、【多选题】Whichiscorrectfordescribingthecharacteristicsofaxailflowimpeller?本题答案：【Thereisunsteadyregion#Oftenoperatingwithlowefficiency#Narrowhighefficiencyzone】离心式叶轮性能曲线的比较Comparisonwithcentrifugalimpellers1、【判断题】Forbackwardimpeller,TheperformancecurveofheadandflowratewillnothavetheS-shape.本题答案：【正确】离心式、混流式和轴流式叶轮性能曲线比较Comparisonwithcentrifugal,mixedflowandaxialflowimpellers1、【判断题】Thevariationtrendofpeformancecurveofshaftpowerandflowrateforcentrifugalandaxialimpellerarethesame.本题答案：【错误】预旋Prewhirl1、【填空题】Theprewhirliscomposedofand.本题答案：【Mandatoryprewhirl,Freeprewhirl】运行工况点Operatingpoint1、【多选题】Whichiscorrectaboutoperatingpoint?本题答案：【Itrepresentstherelationshipofheadofpipesysyemandlfowrate#Itistheintersectionpointofperformcecurveofpump/fanandpipeststem.#Itreflectsthebalancerelationshipbetweenenergysupplyanddemand.】并联运行paralleloperation1、【多选题】Whichiscorrectaboutparalleloperation?本题答案：【Thefluidistransferredfromtwopumpsintothesamepipesysyem.#Thetotalflowrateisthesumofeachpump.】通用曲线Commonperformancecurve1、【单选题】Whichoneisnotcorrectaboutcommonperformancecurveofpumpandfan本题答案：【drawingonaseriesofmaps】无因次性能曲线Non-dimensionalperformancecurve1、【判断题】Thenon-dimensionalperformancecurveshouldbedrawnwithoutunit.本题答案：【正确】相似定律介绍Similaritytheoryintroduction1、【多选题】Theproperdescriptionsinregardtosimilaritytheory:本题答案：【Itisusedfortheinsufficientoutput#Itisutilizedforperformanceconversionwhenrotatingspeedvaries.#Itisthebasicforsimilaritydesign.#Itisbasedongeometrysimilarity,motionsimilarityanddynamicssimilarity.】相似三定律Threelawsofsimilarity1、【填空题】Threelawsofsimilarityconsistsof,and(inEnglish)本题答案：【flowratesimilaritylaw,headsimilaritylaw,powersimilaritylaw】比转速Specificspeed1、【判断题】Thespecificspeeddoesnothavetheonlyvalue.本题答案：【错误】2、【判断题】Thespecificspeedisdifferentfromrotatingspeed.本题答案：【正确】3、【判断题】Itistheconditionofsimilarityandnottheconsequentresultofsimilarity.本题答案：【错误】比转速的应用Applicationofspecificspeed1、【判断题】Thepumpandfancanbesortedbyspecificspeed.本题答案：【正确】汽蚀现象和其影响Cavitationphenomenaanditseffect1、【单选题】Thesortationofcavitationincludes本题答案：【flowcavitation】2、【填空题】Theformationofcavitationisoftencausedbyand.本题答案：【chamicalcorrosion,mechanicalerosion】气蚀相似定律和汽蚀比转速Cavitationsimilaritylawandcavitationspecificspeed编辑教学内容1、【判断题】Astothesizeeffectandrotatingeffect,theconversionresidualofnecessaryNPSH