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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.