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1Lesson1condition[kən'diʃən]工况；状况annotate['ænəuteit]注释；作注解performance[pə'fɔ:məns]性能；特性planimeter[plæ'nimitə]侧面器；求积仪dynamometer[dainə'mɔmitə]测力计；功率计ambient['æmbiənt]周围的；外围的Thetwo-strokecycleiscompletedintwostrokesofthepistonoronerevolutionofthecrankshaft.Inordertooperatethiscyclewhereeacheventisaccomplishedinaveryshorttime,theenginerequiresanumberofspecialarrangements.二冲程循环是由两个行程的活塞运动或一个曲轴的旋转运动租成。为了操作这种每个行程时间都很短的循环，发动机需要一些特殊的设计。Dieselenginesaretypicallyfurnishedwitharatingoramaximumcontinuousrating(MCR),i.e,astatedvalueofpoweroutputatacorrespondingRPM.柴油机通常有一个额定或最大连续功率（MCR）的指标，即在相应的转速下，输出功率的规定值。Thisisandescriptionoftheperformancecharacteristicsoftheengine.theuniflow,直流;theloopand回流;thecrossflow.横流Loopscavengearrangementshavelowtemperatureairandhightemperatureexhaustgaspassingthroughadjacentports,causingtemperaturedifferentialproblemsforthelinermaterial.dieselengine柴油机stroke[strəuk]冲程scavengeport扫气口diagram['daiəɡræm]图表；用图解法示gudgeonpin活塞销indicator['indikeitə]示功器trunking['trʌŋkiŋ]筒；箱体第一讲ppt讲过的考锅炉制冷各一半第三讲两篇各一段第四讲值班postcontrol自学公约1234只挑一段2回流扫气使低温空气和高温废气通过相邻的管道，会产生缸套材料温差的问题。Thefuelpumpswilldischargehigh-pressurefueltotheirrespective(各自的）injectors.燃油泵将放电高压燃料各自（各自的）喷油器。Itisessentialtothescavengingprocessthattheairenteringthecylinderisatahigherpressurethanthegasintheexhaustmanifold.Ontwo-strokedieselsanelectricallydrivenauxiliarybowerisusuallyprovidedbecausetheexhaustgasdriventurbo-blowercannotprovideenoughairatlowenginespeeds.Highpressuresuperchargedenginesuseturbochargersinseries.Thepressurizedairisusuallycooledtoincreasethechargeairdensity.(译文5：对换气过程而言，进入气缸的空气压力高于排气总管的压力十分必要。就二冲程柴油机而言，由于废气涡轮增压器在低转速下不能提供足够的空气，通常配备一台电动辅助鼓风机。高增压发动机使用串联(多级)涡轮增压。增压后的空气均通过冷却来增加空气的密度。)[Intheexhaustturbochargedengines]thenecessaryscavengingisachieved[byprovidingasatisfactorypressuredifferencebetweentheairmanifoldandtheexhaustmanifold].Theairflow(throughthecylinder)[duringtheexhaust/scavengeoverlapperiod]hasavaluablecoolingeffect;ithelpstoincreasethevolumetricefficiencyandtoensurealowcycletemperatureandalsotoobtainarelativelycoolerexhaust(imposedontheturbineblades).(译文8：废气涡轮增压的柴油机，其必须的扫气过程是通过进排气总管之间足够的压差来实现的。排气／扫气重叠期间流过气缸的气流产生有益的冷却效果有助于增加容积效率，并确保循环温度较低，而且还使作用在涡轮叶片上的废气温度相对较低。)Theoperationbetweentwoinjectionsiscalledacycle,whichconsistsofafixedsequenceofevents.Thiscyclemaybeachievedeitherinfourstrokesortwo.Inafour-strokedieselengine,thecyclerequiresfourseparatestrokesofthepiston,i.e.suction,compression,expansionandexhaust.Ifwecombinethesuctionandexhaustoperationswiththecompressionandexpansionstrokes,thefour-strokeenginewillbeturnedintoatwo-strokeone,asisshowninFigures1(a)-(d).(译文4：两次喷油期间的运转过程叫一个工作循环。它由一些程序固定的过程组成。这个循环可在二个行程或四个行程内完成。四冲程柴油机的工作循环需四个独立的活塞行程，即吸气、压缩、膨胀和排气。如果我们把吸气和排气行程与压缩和膨胀行程结合起来，四冲程柴油机就变成了二冲程柴油机，如图1(a)～(d)所示。)Thecrankshaftresetsinbearingsbuiltintocrossgirdersofthebedplate.Thesebearings,knownasmainbearings,eachconsistoftwoshellswhicharesupportedinhousingsmachinedinthebedplateandsecuredbymeansofstudsandbearingcaps.Thethrustblockorthrustbearing,locatedattheaftendoftheengine,maybeintegralwith,orseparatefrom,thebedplate.(译文2：曲轴安放在机座横梁的轴承上，这些轴承称作主轴承。每个轴承由两块轴瓦组成，两块轴瓦由在机座上加工出的瓦座支撑，用双头螺栓和轴承盖固定。推力轴承位于发动机的尾部，可同机座制成一体也可同机座分开。)whichisbuiltofanumberofsectionsprovidedwithverticalflanges(法兰)enablingthemtobeboltedtogethertoformablockfor1-3cylindersinfrontofthechain3transmission(链传动装置),andablockwith4-6cylindersaftofthechaintransmission.这是建立一个带有垂直法兰部分（法兰）使它们能够整合在一起，在链传动前1-3缸一块的形式（链传动装置），和一个4-6缸尾部的链传动块。[Inaclosedfreshwatersystem],theenginejackets,theheatexchangerandthecirculatingpumpsformacontinuouscircuitwhichisnotopentotheatmosphere.Thecylinderjacketcoolingwater(afterleavingtheengine)passestoaseawatercirculatedcooler-heatexchangerandthenintothejacketwatercirculatingpumps.Itisthenpumpedaroundthecylinderjackets,cylinderheads,exhaustvalvesandturbo-blowers.However,provisionhastobemade[fortheexpansionofthewaterduetotheincreaseintemperatureandduetosmallamountsofair(whichmayenterthesystemandbecomeentrained)andforwatermake-upduetoleakages].(译文6：在闭式冷却系统中，发动机的缸套、热交换器和循环泵构成了一个连续的回路，不对外敞开。发动机的缸套冷却水在离开发动机后进入一海水循环的冷却器一热交换器一然后到缸套冷却水循环泵，之后被泵人缸套、缸头、排气阀和涡轮增压器。然而，必须为因水温的增加和空气的进入并滞留在系统内而产生膨胀以及补偿漏泄设置装置。)Thevariouscoolingliquids(whichcirculatetheengine)arethemselvescooled[byseawater].Theusualarrangementusesindividualcoolersforlubricatingoil,jacketwater,andthepistoncoolingsystem,eachcoolerbeingcirculatedbyseawater.Somemodernshipsusewhatisknownasacentralcoolingsystemwithonlyonelargeseawatercirculatedcooler.Thiscoolsasupplyoffreshwaterwhichthencirculatestotheotherindividualcoolers.[Withlessequipmentincontactwithseawater]thecorrosionproblemsaremuchreduced[inthesystem].(译文13：在发动机内循环的各种冷却液自身被海水冷却。通常，滑油、缸套和活塞冷却系统都使用独立的冷却器，各冷却器通过海水循环冷却。有些现代船舶使用所谓的中央冷却系统，仅有一个大型的海水循环冷却器冷却淡水，其他各独立的冷却器则用淡水循环冷却。由于较少的设备与海水接触，从而大大降低了因海水而引起的腐蚀。)Thehightemperature(oftheworkingcycle)wouldquicklyheatupthemetal(formingthecylinders,cylindercoversandpistons)ifstepswerenottakentopreventthishappening.Itisnecessarytokeepthepistonringsattemperaturessufficientlylow[forthelubricatingoilsurroundingthemtosurvive]