轮机英语大证考试真题44期.docx

轮机英语大证考试真题44期.docx

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轮机英语大证考试真题44期

轮机英语第44期考试题

一、单项选择题

1.Thedieselengineissimilartothegasolineengineinthat______.

A.bothofthemareignitedbycompressedair

B.bothofthemaretheformofexternalcombustionengines

C.bothofthemhavesparkplugs

D.thepowerisdevelopedbythepistoninthecylinder

2.Theratioofthebrakehorsepowertotheindicatedhorsepowerofadieselengineisits______.

A.thermalefficiencyB.mechanicalefficiency

C.brakethermalefficiencyD.volumetricefficiency

3.Theignitionqualityofdieselfueloilisindicatedbythe______.

A.specificgravityB.cetanenumberC.viscosityD.calorificvalue

4.Howarethepressureandtemperatureaffectedinadieselenginecylinderduringcompression?

A.Pressureandtemperaturedecrease

B.Pressureandtemperatureincrease

C.Pressuredecreasesandtemperatureincreases

D.Pressureincreasesandtemperaturedecreases

5.Analuminumpistonhaslowerinertiaandhighercoefficientof______comparedtothatofcastiron.

A.viscosityB.twistingmomentsC.inertiaD.thermalexpansion

6.Eachcylinderisclosedatthetopbya______,madeofaspecialheat-resistantsteel.

A.cylinderlinerB.couplingflangeC.cylindercoverD.pistoncrown

7.Theamountoffueldeliveredbyahelicalplungertypefuelinjectionpumpiscontrolledby______.

A.rotationofthepumpplungerB.rotationofthepumpbarrel

C.varyingthepumpsupplypressureD.varyingthepumpreturnpressure

8.Inadieselenginelubeoilsystem,whichofthefollowingpartsshouldbelubricatedfirst?

A.CamshaftbearingsB.MainbearingsC.PistoncrownsD.Cylinderwalls

9.Sacrificialzincanodesareusedonthesaltwatersideofdieselengineheatexchangersto______.

A.reduceclectrolyticactiononheatexchangermetals

B.keepheattransfersurfacesshinyandclean

C.preventrapidaccumulationofmarinegrowth

D.provideaprotectivecoatingonheatexchangersurfaces

10.Inaturbocharger,inletairvelocityisincreasedinthe______.

A.inletnozzleringB.stationarydiffuserpassages

C.compressoroutletvoluteD.rotatingimpellervanes

11.Dieselenginecylinderairstartvalvetimingiscontrolledby______.

A.engineoperatingspeedB.anairmanifold

C.ahydraulicdistributorD.theairdistributor

12.Ifthecompensatingneedlevalveofahydraulicgovernorisopenedmorethannecessarythegovernorwill______.

A.havealargerthannormaldeadband

B.produceexcessivespeedresponsetoaloadchange

C.respondslowlytoanychangeinengineload

D.stabilizeenginespeedatthenewgovernorsetting

13.Apyrometerisaninstrumentcommonlyusedtomeasure______

A.cylinderpressureB.flameintensity

C.exhaustgastemperatureD.crankshaftaxialalignment

14.Pumpupthestartingairreservoirstotheirmaximumpressureand______theairreservoirsandairsystem.

A.openB.closeC.drainD.vent

15.Inreducingenginespeedtoanefficientpropellerspeedbytheuseofreductiongears,______.

A.speedandtorquearebothreduced

B.speedisreducedandtorqueremainsunchanged

C.speedisreducedandtorqueisincreased

D.speedissomethingunchangedwhiletorqueisincreased

16.Whichofthefollowingstatementsconcerningfire-tubeboilersiscorrect?

A.CombustiongasesflowthroughthetubesB.Flameimpinge（撞击）onthetubes

C.CombustionoccursinthetubesD.Waterflowsthroughthetubes

17.Thesafetyvalvesshouldbetestedandadjustedwhentheboilersurveyis______

A.completedB.carriedoutC.cleanedD.steamed

18.Whenanauxiliaryboilerispantingandemittingblacksmoke,youshould_______.

A.increasethefueloiltemperatureB.decreasethefueloiltemperature

C.decreasethefueloilsupplypressureD.increasetheairsupply

19.Ifthefeedpumpforanauxiliaryboilerfailstodeliverthefeedwatertotheboiler,thecausemaybe______.

A.highsteampressureintheboilerB.decreasethefueloiltemperature

C.abnormallyhighboilerwatertemperatureD.steamdemandexceedingfeedpumpcapacity

20.Avanepumpbelongsto______accordingtoitsworkingprinciple.

A.reciprocatingpumpB.positivedisplacementpump

C.centrifugalpumpD.centripetalpump

21.Thepackinginstalledinthepumpstuffingboxislubricatedby_______.

A.gravityandfeedoilcupsB.greasecups

C.handduringinstallationD.leakagethroughthestuffingbox

22.Ifthecapacityofacentrifugalpumpdecreasesgraduallyoveralongperiodoftime,youshouldreplacethe______.

A.packingglandB.mechanicalsealsC.lanternringsD.wearingrings

23.Whichofthelistedconditionscanleadtocavitationinacentrifugalpump?

A.VaporpocketsformedinthesuctionflowsteamB.Roughcasingvolutesurfaces

C.WornwearingringsD.Heavyliquidintheflowstream

24.Inacompressionrefrigerationplant,thehot,highpressurerefrigerantgasiscooledbytheseawaterandbecomesliquidinthe______.

A.compressorB.condenserC.throttlevalveD.evaporator

25.Thetemperatureatwhichwatervaporintheatmospherebeginstocondenseiscalledthe______.

A.dewpointtemperatureB.condensationtemperature

C.psychometrictemperatureD.absolutehumiditytemperature

26.Inanairconditioningsystem,moistureisremovedfromtheairby______.

A.filtersB.separatorsC.ductedtrapsD.dehumidifiers

27.Sludgemayforminthecrankcaseofanairconditioningcompressorasaresultof______.

A.bubblingrefrigerantB.loweredoperatingtemperature

C.overheatingandoxidationD.reducingthecloudorflocpoint

28.Coalescenceisthebreakdownofsurfacetensionbetweenoildropletsinanoil/watermixture,whichcausesthemtojoinand______insize.

A.expandB.extractC.increaseD.decrease

29.Whenstarted,acompleteoilywaterseparatingunitisfirstfilled______.Theoilywatermixtureisthenpumpedthroughtheinletpipeintothecoarseseparatingcompartment.

A.withdirtywaterB.withcleanwaterC.byoilywaterD.bymixedwater

30.Whichisthepollutionpreventionequipment?

A.boosterpumpB.evaporatorC.incineratorD.cooler

31.The______isusedtoburnoilsludge.

A.clarifierB.oilywaterseparatorC.incineratorD.distiller

32.Insewagetreatment,theterm‘maceration’referstotheprocessof______.

A.breakingupsolidmatterintofineparticles

B.precipitatingnon-decomposedwasteinacollectiontank

C.chemicallyadjustmentthesewagepHto7.0

D.eliminatingbacteriumcolifromthesewage

33.Whichofthesubstanceslistedissatisfactorilyremovedfromthefuelbyacentrifugaloilpurifier?

A.CarbonparticlesB.LubeoilC.GasolineD.Dieselfuel

34.Ifthebowlofadisktypecentrifugalpurifierwhenoperatedasaseparatorisnotprimed,the______.

A.oilhastendencytoemulsifyinthebowl

B.purifierwillactasaclarifieratthedischargering

C.oilwillbelostthroughthewaterdischargeports

D.oilsolidswillbedepositedonlyattheintermediatetopdisk

35.Theprocessofboilingseawaterinordertoseparateitintofreshwatervaporandbrineisusuallydefinedas______.

A.dehydrationB.condensationC.evaporationD.dissolution

36.Whattypeofvalveisusedtodirecttheflowofhydraulicfluid?

A.reliefvalveB.directioncontrolvalve

C.stopvalveD.pressurecontrolvalve

37.Thedeliveryrateofavariablestrokeaxialpistonhydraulicpumpiscontrolledbyvaryingthepositionofthe______.

A.slideblockB.tiltingboxC.pintleD.reactionring

38.Thedrivemotorwillhaveabrakearrangedtofail-safe,i.e.itwill______theloadifpowerfailsormachineisstopped.

A.liftB.putC.takeD.hold

39.Ontankvesselswithanelectrically-drivencapstan,themotorshouldbemeggeredperiodicallytotest______.

A.insulationresistanceB.eddycurrentsC.capacitanceD.armaturereactance

40.Overheatingofahydraulicsystemmaybearesultof_______________.

A.changingpumpdischargepressureinresponsetonormalloadvariations

B.ahighoillevel

C.incorrectfluidviscosity

D.continuedslowre-circulationoftheoil

41.Purgingairfromahydraulicsystemisnecessarywhen______.

A.addingsmallamountsofoiltothesystem

B.thesystemhasbeenoverheated

C.thesystemhasbeendrainedandthenfilledwithnewoil

D.thesystemhasbeenidleforalongperiodoftime

42.Adirectcurrentpassingthroughawirecoiledaroundasoftironcoreisthedescriptionofasimple______.

A.magneticshieldB.electromagnet

C.piezoelectric（压电的）D.electromagneticdomain

43.Theoperationof______twoalternatorsrequiresthevoltagestobeequalandalsoinphase.

A.parallelingB.series-mountingC.runningD.controlling

45.ThepowerfactorofanACgeneratoroperatingsingularlyisdeterminedbythe______.

A.connectedloadB.primemoverspeed

C.fieldexcitationD.generator’sratedvoltage

46.Afterashipentersserviceitis______forthemainbus-bartobemadedead.

A.usuallyB.commonlyC.exceptionalD.unavoidably

47.Atransformerinanelectriccircuitservesto______.

A.generateitsownelectricalpower

B.transformelectricalenergyintomechanicalenergy

C.increaseordecreasecircuitvoltageasrequired

D.convertACtoDC

48.Theseparatesuppliesareconnectedineitherstarordeltaformation.Thestarformationismostcommonlyusedandrequires______slip-ringsonthealternator.

A.twoB.threeC.fourD.five

49.Mostconductingmaterialssuchascopper,aluminum,iron,nickel,andtungsten（钨）______.

A.increaseinresistancewithincreasedtemperature

B.increaseinresistancewithdecreasedtemperature

C.decreaseinresistancewithincreasedtemperature

D.increaseinconductancewithincreasedtemperature

50.Whichofthefollowingstatementsrepresentsthemai