发动机.docx

发动机.docx

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发动机

1.发动机如何自己设计？

到哪里找材料，价钱如何？

Smallgasturbinesarenotscaleddownlargeengines.Anyattempttodosoislikelytofail.KurtSchrecklingistobe

commendedforhisoriginalapproachtothedesignofsmallenginesassetoutinhisbookontheFD364.Hecarriedoutthe

therorecticalconsiderationsandcametotheconclusionthatasimpleradialcompressorandturbinewheelwithasingle

annularcombustionchamberwouldproducethebestresults.Hisviewshavebeenconfirmedbytherapidprogressinrefining

thedesignsandextractingmorepowerfromthesamebasicsize.Spreadsheetshavebeendevelopedbyanumberofpeople

basedontheFormulasintheSchrecklingandKampsbooksthatmodeltheprocessesthatgoonintheengine.TheGTBAhas

alsocommissionedburstanalysisoftheturbinewheel.

英文来自（GTBA-英国涡轮发动机制作联盟）

模型用的发动机不是大的发动机的按比列缩小，任何试图这样做都很可能是失败。

值得推荐的是英国人-KurtSchreckling设

计的FD3-64航模涡喷发动机的设计，开创了小型发动机设计先河，用一个简单方法制作的放射式压气机，环型燃烧室，一个

用简单方法制做出来的涡轮，达到了良好的效果。

他的理念已被最新改进的各种新的设计所证实，并且都是以他的设计为基

础进行的提炼。

数字显示，许多爱好者根据他的著作理论，成功地将发动机用在了航模上。

涡轮喷气发动机材料为不锈钢为主，材料成本很低，如果从材料本身的价值来说，以广州为例，也就100元上下，但由于个

人爱好者，有些可能无机床，氩弧焊的话，到外面加工的人力成本会贵过材料费。

但也无妨。

再就是如果有认识不锈钢加工

厂的话，找到边角料足矣做一台涡轮,如果你想省事些，可以用涡轮增压器上的压气轮来代替木头的压气轮。

。

2.涡轮容易加工吗,没专业设备如何做动平衡？

涡轮是由型号为301,2.5mm不锈板剪口弯成，用一个小电钻配小砂轮可以打磨出翼型即可，关键的动平衡测试，记住这一点

很重要！

！

否则会导致发动机解体！

！

是用我们的大拇指与食指来感觉振动。

灵敏度相当高。

足以完成涡轮的动平衡调试。

3.散热与轴承问题

Bearings

Thecompressedairinthechamberpassesdownthebearingtubeandexitsbothendstoprovidecoolingtothebearings.The

bearingsaresimpleballracesandtheyareoiledwithoilmistsuppliedbuythepressurefromtheengineitself.Verylowflows

ofoilarebetterthanaconstantflowasthedropscancausetheballtoskidintheraceways.Turbineoilorthinmachineoilcan

beused.

压缩空气将穿过轴套为轴承提供冷却，轴承为简单的滚珠轴承，用自身的压缩空气压油提供油雾润滑。

可以用透平油，或低

粘度的机械润滑油。

FD3-64的设计合理的利用压气机的空气，将温度控制在600度以下，从而保证各部件的强度。

在运行中我们要注意发动机的温度不能超高。

4.fd3-64能推多重的模型，国内造价要多少？

对于航模飞机来说，0.5的推重比完成各种特技动作都已够了，这台发动机的设计推力约3kg力，也就是说，你的航模总重达

6kg在飞行中都没问题。

按fd3-64r材料本身来说不值钱，不锈钢在国内100元就买齐了，主要是加工费用问题，可能是材料的数倍。

Startingtheengine

启动发动机

Allenginesrequirealargevolumeofairtostartthem.SomeliketheAMTandJPXusescubatanks.Thehome-builtengines

mostlyarestartedwithafanheldontheairintake.Thefancanbeaconvertedhairdryerfittedwithamorepowerfulmotor.

Thealternativeistouseahighrevvingsmallelectricmotorontoafrictioncup.Thesupplementarygasislightedandthefan

increasestherevs.Theliquidfuelisslowlyfedinuntiltheenginespeedpicksupandtheengineselfsustains.Itcangethot

whenstartingiftoomuchfuelisfedintoquickly.Withpracticestartingissimpleandundramatic,thereshouldbenoflames

visibleeitherduringstartingorrunning.

Controllingthespeed

控制速度

Thisisachievedbytheuseofaspeedcontrollerthatcontrolsthefuelpumpmotor.Whenbenchtestingitismoreconvenient

tocontrolthespeedbyahandoperatedcontrollersuchasaminidrillspeedcontrollerratherthanuseatransmitterreceiver

andspeedcontroller.WhenmountedinaplaneamotorspeedcontrollerisusedorifavailableafullyprogrammedECU.

Overspeedshouldbecontrolledbyacombinationofbatterypowerandpumppressuresothatwhateverhappenstothe

receiverortransmitterthesupplyoffuelisrestricted.

Underspeedcanbecontrolledviaapressureswitchthatstopstheengineifpressuredropsbelowapredeterminedpoint.

Whatisasensiblerevlimit?

转速控制

IntheKampsbookthereisfulldetailonhowtocalculatethecriticalspeedfortheshaft.Thespeedwilldependonthematerial

theshaftismadeofandthethicknessaswellastheweightofthecompressorandturbineandtheirpositions.Inpractice

engineswitha316or310stainlesssteelturbineshouldhavetherevsrestrictedtoabout75,000rpm.Abovethisspeedthe

materialwillexpandandcauseittobindonthehousing.TheKampsengineislimitedtoabout103,000rpmandthenew

Schrecklingat117,000rpm.Thehighertherevsthemoreneedthereisfortheenginebeingwellbalanced.

HowdoIbalancetheengine?

如何做动平衡

Simplestaticbalancinghasprovedtobeadequate.ThemethodintheKampsbookproducesgoodresults.Heusesatubethat

contains2newbearingsandtheshafttobebalanced.Thisislaidonaflatsurfacesuchasapieceofglassandisrockedtoand

frountiltheheavypointreachesthebottom.Thisismarkedandalittleisgroundawayontheheavyside.Whentheshaftis

balancedthecompressorisbalanced.Thoughthisisfromthefactorythebalancehasinpracticefoundnottobeaccurate

enough.Thecompressorisremovedandtheturbinewheelisfittedandthisisbalanced.Thebladescanbethinnedorthe

rootscanbegroundawayslightlytoreducetheweight.

HowdoImaketheturbinewheel?

如何制作涡轮

Theearlywheelsaremadefromsheetthatisslitandtwistedtothecorrectangleandprofiledbyhandminigrinder.Better

wheelscanbegroundfromthickdiscs.ThisistimeconsumingbutwillgivebetterresultsparticularlywithInconel.CastInconel

wheelsarebecomingavailablenowforthosethatdonotfeeltheyhavetheskilltomakeone.

Aretheenginesnoisy?

Ifyoustandclosetoagasturbineyouwillfindthenoiselevelgreaterthanapistonengine.Howeverintheairthenoiseis

dissipatedsothatitismuchlessobtrusivethanapistonengine.Indeedifapistonengineandaturbineareflyingtogetheritis

difficulttoheartheturbineatall.

HowdoIweldstainlesssteel?

如何焊接不锈钢

Thisisnotaskilleveryonecanacquire.Thinstainlesscanbespot-weldedsothiscoversthecombustionchamber.TheNGV

assemblywillrequireTIGwelding.TIGsetsareexpensiveanditmaybenecessarytofindaspecialistwelderusedtowelding

stainlesssteeltodotheweldingforyou.

WhatinstrumentationwillIneed?

Attheveryleastwhentestingyouwillneedavacuumgaugethatcanmeasureupto1barandatemperaturegaugethatcan

measureupto1000degC.Akitchenscaleswillprovidethrustmeasurements.Arevcountercanbemadefromthedesignin

thenewsletter.Itishelpfulalsotobeabletomeasurethefuelpumppressurebutthisneedsascaleupto3bar.

WhatthrustwillIget?

推力是多大？

Thisdependsonthedesignthatyoumake.Thedetailedspecificationissetoutinthepagesforeachdesignbutyoucanexpect

togetbetween5.3lbsand16.6lbs.

Howmuchwillitcost?

做涡喷的费用是多少？

Thiswilldependonhowableyouaretogetscrapsfromyoulocalwelders/machineshop!

TheSchrecklingFD364isvery

cheaptobuildandwouldcostprobablynomorethan￡100.Theotherdesignsthathaveturbochargersandcastwheelswill

bemoreexpensive-perhaps￡300-400.