HRP20000077A2 - Improved cooling of turbine blade - Google Patents

Improved cooling of turbine blade Download PDF

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Publication number
HRP20000077A2
HRP20000077A2 HR20000077A HRP20000077A HRP20000077A2 HR P20000077 A2 HRP20000077 A2 HR P20000077A2 HR 20000077 A HR20000077 A HR 20000077A HR P20000077 A HRP20000077 A HR P20000077A HR P20000077 A2 HRP20000077 A2 HR P20000077A2
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Croatia
Prior art keywords
graphite foil
foil
turbine blade
cooling channels
specified
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HR20000077A
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Croatian (hr)
Inventor
Ruueevljan Miroslav
Guzović Zvonimir
Tuković Aeeljko
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Ruueevljan Miroslav
Guzović Zvonimir
Tuković Aeeljko
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Application filed by Ruueevljan Miroslav, Guzović Zvonimir, Tuković Aeeljko filed Critical Ruueevljan Miroslav
Priority to HR20000077A priority Critical patent/HRP20000077A2/en
Priority to AU33984/01A priority patent/AU3398401A/en
Priority to PCT/HR2001/000007 priority patent/WO2001059262A1/en
Publication of HRP20000077A2 publication Critical patent/HRP20000077A2/en

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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01DNON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D5/00Blades; Blade-carrying members; Heating, heat-insulating, cooling or antivibration means on the blades or the members
    • F01D5/12Blades
    • F01D5/14Form or construction
    • F01D5/18Hollow blades, i.e. blades with cooling or heating channels or cavities; Heating, heat-insulating or cooling means on blades
    • F01D5/187Convection cooling
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01DNON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D5/00Blades; Blade-carrying members; Heating, heat-insulating, cooling or antivibration means on the blades or the members
    • F01D5/12Blades
    • F01D5/28Selecting particular materials; Particular measures relating thereto; Measures against erosion or corrosion
    • F01D5/288Protective coatings for blades
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05DINDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
    • F05D2260/00Function
    • F05D2260/20Heat transfer, e.g. cooling
    • F05D2260/221Improvement of heat transfer
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05DINDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
    • F05D2300/00Materials; Properties thereof
    • F05D2300/20Oxide or non-oxide ceramics
    • F05D2300/22Non-oxide ceramics
    • F05D2300/224Carbon, e.g. graphite
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02TCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T50/00Aeronautics or air transport
    • Y02T50/60Efficient propulsion technologies, e.g. for aircraft

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Turbine Rotor Nozzle Sealing (AREA)

Description

Područje na koje se izum odnosi The field to which the invention relates

Ovaj bi se izum mogao svrstati u područje hlađenja lopatica plinskih turbina. This invention could be classified in the field of cooling the blades of gas turbines.

Tehnički problem Technical problem

Plinske turbine imaju statorske i rotorske lopatice koje su izložene visokim temperaturama, pa ih je zbog toga potrebno intenzivno hladiti. Hlađenje se obavlja strujanjem rashladnog sredstva, najčešće uzduha, u kanalima unutar lopatica. Zbog oblika i veličine rashladnih kanala dolazi do odstupanja od aerodinamički najpovoljnijeg oblika i dimenzija lopatica, a sužavaju se i strujni kanali između lopatica. Intenzitet hlađenja može se pojačati suženjem rashladnih kanala, ali se pri tome povećava otpor strujanju, pa je potreban veći ulazni tlak rashladnog uzduha. Povećanje stupnja kompresije rashladnog uzduha, i/ili njegove potrošnje, smanjuje ukupni stupanj djelovanja turbine. Pri hlađenju lopatica strujanjem uzduha kroz kanale unutar lopatica naročito je izražen problem nepovoljne razdiobe lokalnih koeficijenata prijelaza topline s površine kanala na rashladni uzduh. Neusklađenost intenziteta hlađenja unutar lopatice i razdiobe toplinskog opterećenja na vanjskoj površini lopatice dovodi do velikih razlika temperature pojedinih dijelova stijenke lopatice. Najveća toplinska opterećenja nastaju na napadnom bridu i donjoj strani izlaznog brida lopatice. U području izlaznog brida rashladni kanali su najuži, pa je hlađenje tog dijela lopatice najteže ostvariti. U području napadnog brida rashladni kanali su širi, ali je hlađenje i tu problematično s obzirom na veliku koncentraciju toplinskog opterećenja. Nepovoljan oblik rashladnih kanala predstavlja glavnu prepreku za ostvarenje potrebnih vrijednosti lokalnih koeficijenata prijelaza topline. Nejednolikost temperature stijenke lopatice uzrok je toplinskim naprezanjima u materijalu lopatica, koja skraćuju njihov radni vijek. Posebno nepovoljni uvjeti nastaju pri puštanju motora u rad, kada se napadni i izlazni brid brže zagrijavaju od srednjeg dijela lopatice, te pri smanjivanju opterećenja, kada se napadni i izlazni brid brže hlade. Nagle promjene snage osobito su česte kod turbinskih motora zrakoplova. Gas turbines have stator and rotor blades that are exposed to high temperatures, so they need to be intensively cooled. Cooling is done by the flow of coolant, usually air, in the channels inside the blades. Due to the shape and size of the cooling channels, there is a deviation from the most aerodynamically favorable shape and dimensions of the blades, and the flow channels between the blades are also narrowed. The cooling intensity can be increased by narrowing the cooling channels, but this increases the flow resistance, so a higher inlet pressure of the cooling air is required. Increasing the degree of compression of the cooling air, and/or its consumption, reduces the overall degree of turbine operation. When cooling blades by air flow through channels inside the blades, the problem of unfavorable distribution of local heat transfer coefficients from the surface of the channels to the cooling air is particularly pronounced. The discrepancy between the intensity of cooling inside the blade and the distribution of the heat load on the outer surface of the blade leads to large differences in the temperature of individual parts of the blade wall. The highest thermal loads occur on the leading edge and the lower side of the blade's exiting edge. In the area of the exit edge, the cooling channels are the narrowest, so cooling that part of the blade is the most difficult to achieve. In the area of the leading edge, the cooling channels are wider, but cooling there is also problematic due to the high concentration of heat load. The unfavorable shape of the cooling channels is the main obstacle to achieving the required values of the local heat transfer coefficients. The non-uniformity of the temperature of the blade wall is the cause of thermal stresses in the material of the blades, which shorten their working life. Particularly unfavorable conditions occur when starting the engine, when the leading and trailing edges heat up faster than the middle part of the blade, and when the load is reduced, when the leading and trailing edges cool down faster. Sudden power changes are particularly common with aircraft turbine engines.

Zadatak konstruktora turbinskih lopatica je da prikladnim načinom hlađenja smanji neujednačenost temperature lopatice. Pri tome aerodinamički gubici prostrujavanja plina između lopatica trebaju biti što manji, a poboljšanje hlađenja ne smije biti praćeno smanjenjem ukupnog stupnja djelovanja turbine. The task of the turbine blade constructor is to reduce the non-uniformity of the blade temperature with a suitable cooling method. At the same time, the aerodynamic losses of the gas flow between the blades should be as small as possible, and the improvement in cooling must not be accompanied by a decrease in the overall degree of turbine operation.

Stanje tehnike State of the art

S obzirom na brojnost i složenost različitih rješenja hlađenja turbinskih lopatica, teško bi bilo cjelovito prikazati sve njihove prednosti i nedostatke. Općenito se postavljaju sljedeći ciljevi: Considering the number and complexity of different cooling solutions for turbine blades, it would be difficult to comprehensively present all their advantages and disadvantages. In general, the following goals are set:

◾ što niža temperatura lopatice za zadanu temperaturu plinova ◾ the lower the blade temperature for the given gas temperature

◾ što manji gradijenti temperature u lopatici ◾ temperature gradients in the blade as small as possible

◾ što manja potrošnju rashladnog uzduha ◾ as little cooling air consumption as possible

◾ što manji stupanj kompresije rashladnog uzduha ◾ the lowest possible degree of compression of the cooling air

◾ što veći ukupni stupanj djelovanja turbine ◾ the greater the overall degree of turbine action

◾ što manja masa lopatice ◾ the smaller the mass of the blade

◾ što jednostavnija i jeftinija proizvodnju lopatica ◾ simpler and cheaper production of blades

Konstruktivnim rješenjem lopatice nastoji se što bolje udovoljiti navedenim kriterijima. Teži se povećanju rashladne površine unutar rashladnih kanala te povećanju koeficijenta prijelaza topline na uzduh, uz što manju potrošnju rashladnog uzduha i što manje otpore strujanju. Prijelaz topline sa stijenke na uzduh pojačava se na različite načine, a pri tome se najveće pojačanje nastoji ostvariti na mjestima najvećeg toplinskog opterećenja. Na izrazito opterećenim mjestima, kao što je napadni brid lopatice, rashladni uzduh se često ispušta kroz sitne provrte u stijenki lopatice. Time se lokalno povećava rashladna površina, a izlazeći uzduh ujedno stvara “film” koji hladi vanjsku površinu brida i dio površine u blizini brida lopatice. Međutim, provrti u stijenki lopatica stvaraju koncentraciju naprezanja, bez obzira na visoku tehnologiju njihove izradbe, koja smanjuje radni vijek lopatica. U izlaznom bridu lopatice najčešće se izvode uski kanali kroz koje uzduh u obodnom smjeru istrujava van iz lopatice. Glavni razlog za primjenu ovakvog rješenja je nemogućnost izvedbe širokog radijalnog kanala u tankom izlaznom bridu lopatice, kroz koji bi, uz ograničeni stupanj kompresije, protjecala dovoljno velika količina rashladnog uzduha. The constructive solution of the blade tries to meet the stated criteria as best as possible. The aim is to increase the cooling surface inside the cooling channels and to increase the coefficient of heat transfer to the air, with as little consumption of cooling air as possible and as little resistance to flow as possible. The heat transfer from the wall to the air is enhanced in different ways, and the greatest enhancement tends to be achieved in the places of greatest heat load. In highly stressed areas, such as the leading edge of the blade, cooling air is often discharged through tiny holes in the blade wall. This increases the cooling surface locally, and the outgoing air also creates a "film" that cools the outer surface of the edge and part of the surface near the edge of the blade. However, the holes in the wall of the blades create a stress concentration, regardless of the high technology of their production, which reduces the service life of the blades. In the outlet edge of the vane, narrow channels are most often made, through which the air flows out of the vane in a circumferential direction. The main reason for using this solution is the impossibility of making a wide radial channel in the thin outlet edge of the blade, through which, with a limited degree of compression, a sufficiently large amount of cooling air would flow.

Unutar kanala, prijelaz topline se nastoji pojačati raznim turbulizatorima, i/ili ugradnjom deflektora koji preusmjeravaju strujanje rashladnog uzduha prema mjestima jačeg zagrijavanja. Preusmjeravanjem struje rashladnog uzduha iz radijalnog u obodni smjer smanjuje se i njegovo zagrijavanje, do kojeg dolazi zbog stlačivanja djelovanjem sila tromosti uzduha pri velikim brzinama vrtnje radnog kola. Umjetnim ohrapavljenjem toplinski opterećenih dijelova površine rashladnih kanala pojačava se koeficijent prijelaza topline, a ujedno se povećava i rashladna površina. Međutim, u nekim slučajevima hlađenja rotorskih lopatica, poprečna rebra u rashladnim kanalima u tolikoj mjeri povećavaju naprezanja u stijenki lopatice, zbog sila tromosti u rebrima, da je taj negativni učinak veći od pozitivnog učinka pojačanog lokalnog hlađenja lopatice. Inside the channel, heat transfer is tried to be enhanced by various turbulizers, and/or by installing deflectors that redirect the flow of cooling air towards places of stronger heating. By redirecting the flow of the cooling air from the radial to the circumferential direction, its heating is also reduced, which occurs due to compression due to the inertial forces of the air at high speeds of rotation of the impeller. By artificially roughening the heat-stressed parts of the surface of the cooling channels, the heat transfer coefficient increases, and at the same time, the cooling surface increases. However, in some cases of rotor blade cooling, the transverse fins in the cooling channels increase the stresses in the blade wall to such an extent, due to inertial forces in the fins, that this negative effect is greater than the positive effect of enhanced local cooling of the blade.

Važnu ulogu pri rješavanju hlađenja lopatica strujanjem uzduha u kanalima ima tehnologija izradbe lopatica. Ako se lopatice izrađuju iz dva dijela, koji se spajaju zavarivanjem ili lemljenjem, mogu se postići veće točnosti izradbe rashladnih kanala, debljina stijenki, kao i konačnih izmjera lopatice. Ujedno je na taj način lakše ostvariti umjetnu hrapavost površine rashladnih kanala. Lopatice se najčešće izrađuju od superlegura kojima osnovicu čini nikal. Vrijednost koeficijenta toplinske vodljivosti takvih legura relativno je mala, oko 20 [image] . Iz tog je razloga važno da stijenke lopatica budu što tanje, kako u njima ne bi nastajali preveliki gradijenti temperature u smjeru poprečno na stijenku. U nekim se rješenjima hlađenje napadnog i izlaznog brida lopatice pojačava korištenjem materijala s većom toplinskom vodljivošću, primjerice nikal-aluminida. Materijal s većom toplinskom vodljivošću bolje razvodi toplinu uzduž stijenke, čime se smanjuje koncentracija velike gustoće toplinskog toka na maloj površini. U takvom slučaju se lopatica izrađuje iz tri dijela. Prednji i stražnji dio, koji su izrađeni od nikal-aluminida, lijepljenjem se spajaju na srednji dio izrađen od superlegure nikla. Pri tome svaki od triju dijelova lopatice ima zasebne rashladne kanale. S obzirom da nikal-aluminid ima manju gustoću od superlegure nikla, takvim se rješenjem ujedno smanjuje i ukupana masa lopatice. Slaba strana trodjelne lopatice je potreba osiguranja trajnog i pouzdanog spoja njezinih dijelova. An important role in solving the cooling of the blades by air flow in the channels is played by the technology of making the blades. If the blades are made from two parts, which are joined by welding or soldering, greater accuracy can be achieved in the production of cooling channels, wall thicknesses, as well as the final dimensions of the blade. At the same time, it is easier to achieve an artificial roughness of the surface of the cooling channels in this way. Shovels are most often made of nickel-based superalloys. The value of the coefficient of thermal conductivity of such alloys is relatively small, around 20 [image] . For this reason, it is important that the walls of the blades are as thin as possible, so that excessive temperature gradients do not occur in them in the direction transverse to the wall. In some solutions, the cooling of the leading and trailing edge of the blade is enhanced by the use of materials with higher thermal conductivity, for example nickel-aluminide. A material with a higher thermal conductivity distributes heat better along the wall, which reduces the concentration of a high density of heat flux on a small surface. In such a case, the spatula is made from three parts. The front and rear parts, which are made of nickel-aluminide, are glued to the middle part made of nickel superalloy. At the same time, each of the three parts of the blade has separate cooling channels. Given that nickel-aluminide has a lower density than nickel superalloy, this solution also reduces the total mass of the blade. The weak side of the three-part blade is the need to ensure a permanent and reliable connection of its parts.

Izlaganje suštine izuma Presentation of the essence of the invention

Ovim se izumom poboljšava hlađenje turbinskih lopatica smanjivanjem gradijenata temperature u stijenkama lopatice postavljanjem tanke grafitne folije s usmjerenom toplinskom vodljivošću na površinu rashladnih kanala unutar lopatice i/ili na vanjsku površinu lopatice. Osim usmjerene toplinske vodljivosti, bitne prednosti primjene grafitne folije su i njezina mala gustoća te mekoća i savitljivost koji omogućuju jednostavno ostvarivanje tijesnog nalijeganja na površine preko kojih se prenosi toplina. Prema podacima proizvođača, vrijednost koeficijenta toplinske vodljivosti grafitne folije u uzdužnom smjeru, pri temperaturama do 800 °C, veća je od 70 [image] , dok pri nižim temperaturama ta vrijednost raste, premašujući 100 [image] . U poprečnom je smjeru vrijednost koeficijenta toplinske vodljivosti grafitne folije mnogo manja: svega oko 4 [image] . Na grafitnu se foliju postavlja metalna folija, koja ima dvostruku ulogu: štiti grafitnu foliju od oksidacije i povećava joj čvrstoću. Zahvaljujući mekoći i savitljivosti grafitne folije, njezino tijesno nalijeganje na stijenku lopatice s jedne strane, i zaštitnu metalnu foliju s druge strane, može se postići isisavanjem uzduha i plinotijesnim zavarivanjem ili lemljenjem rubova metalne folije sa stijenkom lopatice. S takvim rješenjem postiže se neometan prijelaz topline između stijenke lopatice i grafitne folije, kao i između grafitne folije i zaštitne metalne folije. Po potrebi, kod rotorskih lopatica može se spoj grafitne folije sa stijenkom i zaštitnom metalnom folijom pojačati s vrlo tankim slojem temperaturno otpornog i toplinski vodljivog ljepila, u svrhu sprečavanja izvijanja grafitne folije pod djelovanjem masenih sila. U slučaju najvećih opterećenja mogla bi se primijeniti i grafitna folija s unutarnjim vlaknastim ili mrežastim metalnim ojačanjima, koja bi se proizvodila specijalno za tu namjenu. This invention improves the cooling of turbine blades by reducing the temperature gradients in the blade walls by placing a thin graphite film with directional thermal conductivity on the surface of the cooling channels inside the blade and/or on the outer surface of the blade. In addition to directional thermal conductivity, the essential advantages of using graphite foil are its low density and softness and flexibility, which enable easy close contact with the surfaces through which heat is transferred. According to the manufacturer, the value of the thermal conductivity coefficient of graphite foil in the longitudinal direction, at temperatures up to 800 °C, is greater than 70 [image] , while at lower temperatures this value increases, exceeding 100 [image] . In the transverse direction, the value of the thermal conductivity coefficient of the graphite foil is much smaller: only about 4 [image] . A metal foil is placed on top of the graphite foil, which has a double role: it protects the graphite foil from oxidation and increases its strength. Thanks to the softness and flexibility of the graphite foil, its tight fit on the blade wall on one side, and the protective metal foil on the other side, can be achieved by exhausting air and gas-tight welding or soldering the edges of the metal foil with the blade wall. With such a solution, an unhindered transfer of heat is achieved between the blade wall and the graphite foil, as well as between the graphite foil and the protective metal foil. If necessary, in the case of rotor blades, the connection of the graphite foil with the wall and the protective metal foil can be reinforced with a very thin layer of temperature-resistant and thermally conductive glue, in order to prevent the graphite foil from buckling under the action of mass forces. In the case of the highest loads, graphite foil with internal fibrous or mesh metal reinforcements, which would be produced specifically for that purpose, could also be used.

Grafitna folija mogla bi se primijeniti kod mnogih postojećih rješenja rashladnih kanala turbinskih lopatica, a mogu se konstruirati i novi rashladni kanali, koji bi bolje iskorištavali prednosti ugradnje grafitne folije. U skladu sa smanjenjem površine poprečnog presjeka rashladnih kanala, do kojeg dolazi zbog debljine grafitne folije, treba smanjiti protočnu količina rashladnog uzduha, kako ne bi došlo do povećanja pada tlaka. Koeficijent prijelaza topline neće se pri tome značajnije promijeniti. Povećanje prosječne temperature stijenke lopatice, do kojeg će doći zbog dodatnog otpora prolazu topline, koji stvara grafitna folija u rashladnim kanalima, bit će kompenzirano s većom jednolikošću razdiobe temperature stijenke, a to znači i manjim naprezanjima u stijenki. U ukupnom otporu prolazu topline, udio otpora koji nastaje pri prijelazu topline u graničnom sloju struje rashladnog uzduha uz stijenke kanala višestruko je veći od odgovarajućeg udjela otpora provođenju topline kroz stijenku lopatice. Zbog toga, negativni učinak dodatnog otpora, koji prolazu topline pruža grafitna folija, neće biti velik. Postavljanjem grafitne folije i zaštitne metalne folije na vanjskoj površini lopatice, na toplinski najopterećenijim mjestima, postiže se istovremeno i smanjenje prosječne temperature stijenke lopatice, i ujednačenija temperatura stijenke. Određivanje optimalne debljine grafitne folije je vrlo složen zadatak, pri kojemu je potrebno dobro poznavanje lokalnih koeficijenata prijelaza topline unutar kanala različitih oblika. Kada se veliko toplinsko opterećenje pojavljuje na dijelu površine rashladnog kanala nepovoljnog oblika, grafitna folija pomaže da se toplina znatnim dijelom prenosi u područje stijenke kanala gdje je koeficijent prijelaza topline veći. Na taj način grafitna folija može kompenzirati nejednolikosti prijelaza topline koje se pojavljuju s obje strane stijenke lopatice. Graphite foil could be applied to many existing solutions of turbine blade cooling channels, and new cooling channels can be constructed, which would better take advantage of the advantages of installing graphite foil. In accordance with the reduction of the cross-sectional area of the cooling channels, which occurs due to the thickness of the graphite foil, the flow rate of the cooling air should be reduced, in order not to increase the pressure drop. The heat transfer coefficient will not change significantly. The increase in the average temperature of the blade wall, which will occur due to the additional resistance to the passage of heat, created by the graphite foil in the cooling channels, will be compensated with a greater uniformity of the wall temperature distribution, which means lower stresses in the wall. In the total resistance to the passage of heat, the share of resistance that arises during the transition of heat in the boundary layer of the cooling air flow along the channel walls is many times higher than the corresponding share of the resistance to the conduction of heat through the blade wall. Because of this, the negative effect of additional resistance, which the graphite foil provides to the passage of heat, will not be large. By placing a graphite foil and a protective metal foil on the outer surface of the blade, in the most thermally stressed places, a reduction in the average temperature of the blade wall and a more uniform wall temperature are achieved at the same time. Determining the optimal thickness of the graphite foil is a very complex task, which requires a good knowledge of the local heat transfer coefficients within channels of different shapes. When a large heat load occurs on a part of the surface of the cooling channel with an unfavorable shape, the graphite foil helps to transfer the heat to a significant part in the area of the channel wall where the heat transfer coefficient is higher. In this way, the graphite foil can compensate for the non-uniformities of the heat transfer that appear on both sides of the blade wall.

Ugradnja grafitne folije zanemarivo bi povećala masu lopatice. Gustoća grafitne folije je 700 do 1000 [image] , a to je desetak puta manje od gustoće koju imaju legure nikla, od kojih se lopatice izrađuju. Međutim, na rotorskim lopaticama pojavljuje se problem naprezanja u grafitnoj foliji zbog masenih sila koje se pojavljuju pri kružnom gibanju. Ovaj se problem može riješiti uz pomoć umjetne hrapavosti stijenki rashladnih kanala, čijem bi se obliku tanka grafitna folija, i njezina zaštitna metalna folija, lako prilagodile. Umjetna hrapavost površine može biti dvodimenzijska (rebra postavljena okomito na smjer strujanja) ili trodimenzijska. S trodimenzijskim tipom umjetne hrapavosti mogu se postići veća pojačanja prijelaza topline. Površinske izbočine bi u tom slučaju mogle prolaziti kroz grafitnu foliju i biti spojene sa zaštitnom metalnom folijom, čime bi se sprečavalo izvijanje grafitne folije pod djelovanjem masenih sila. Moguća su i mnoga druga rješenja učvršćenja grafitne folije. Tako je moguće načiniti tanku metalnu mrežicu (ili rešetku) u čije bi se otvore postavljala grafitna folija, koji bi bila nešto tanja od mrežice, pri čemu bi dijelovi mrežice koji strše iznad grafitne folije djelovali kao površinska hrapavost koja pojačava konvektivni prijelaz topline. Mrežica bi se mogla učvrstiti na površinu rashladih kanala lemljenjem ili zavarivanjem. Moguće je i umjetnu hrapavost površine rashladnih kanala tako oblikovati, da se komadići grafitne folije ugrađuju između uskih površinskih izbočina. S obzirom na brojne tehnološke mogućnosti stvaranja raznih tankih površinskih zaštita, moguće je postavljanje grafitne folije na površinu rashladnih kanala i bez zaštitne metalne folije. Takva bi rješenja bila primjenjiva u slučaju statorskih lopatica, ali i u slučaju rotorskih lopatica kod kombinacije metalne mreže i grafitne folije. Optimalna rješenja, koja bi za zadane uvjete definirala oblik, visinu i raspored elemenata umjetne hrapavosti, te debljinu grafitne i metalne folije, mogu se postići složenim inženjerskim postupcima, koji bi uključivali numeričke metode proračuna i eksperimentalna istraživanja. The installation of graphite foil would negligibly increase the mass of the blade. The density of graphite foil is 700 to 1000 [image] , which is ten times less than the density of nickel alloys, from which the blades are made. However, the problem of stress in the graphite foil appears on the rotor blades due to mass forces that occur during circular motion. This problem can be solved with the help of artificial roughness of the walls of the cooling channels, to the shape of which a thin graphite foil, and its protective metal foil, would be easily adapted. Artificial surface roughness can be two-dimensional (ribs placed perpendicular to the flow direction) or three-dimensional. With the three-dimensional type of artificial roughness, higher heat transfer enhancements can be achieved. In that case, the surface protrusions could pass through the graphite foil and be connected to the protective metal foil, which would prevent the graphite foil from buckling under the action of mass forces. Many other solutions for fastening the graphite foil are also possible. Thus, it is possible to make a thin metal mesh (or grid) in the openings of which a graphite foil would be placed, which would be somewhat thinner than the mesh, whereby the parts of the mesh that protrude above the graphite foil would act as a surface roughness that enhances the convective transfer of heat. The grid could be fixed to the surface of the cooling channels by soldering or welding. It is also possible to shape the artificial roughness of the surface of the cooling channels in such a way that pieces of graphite foil are embedded between the narrow surface protrusions. Given the numerous technological possibilities of creating various thin surface protections, it is possible to place graphite foil on the surface of the cooling channels even without a protective metal foil. Such solutions would be applicable in the case of stator blades, but also in the case of rotor blades with a combination of metal mesh and graphite foil. Optimal solutions, which would define the shape, height and arrangement of artificial roughness elements, as well as the thickness of graphite and metal foil for the given conditions, can be achieved by complex engineering procedures, which would include numerical calculation methods and experimental research.

Debljina grafitne folije mogla bi se smanjiti, ako bi između grafitne folije i površine rashladnih kanala bio postavljen tanki sloj metala velike toplinske vodljivosti, primjerice bakra ili, pri nižim temperaturama, aluminija. Takav bi sloj dodatno usmjeravao toplinski tok paralelno sa stijenkama rashladnih kanala. Ako se uzme u obzir da je toplinska vodljivost bakra oko četiri do pet puta veća od toplinske vodljivosti koju grafitna folija ima u uzdužnom smjeru, a čak dvadesetak puta veća od toplinske vodljivosti stijenke lopatice izrađene od superlegure nikla, mogao bi se jednaki učinak postići s tanjom grafitnom folijom. Takvo bi rješenje moglo biti naročito povoljno u području izlaznog brida lopatice, gdje su rashladni kanalu najuži. Postupak nanošenja bakrenog ili aluminijskog sloja morao bi osigurati siguran spoj sa stijenkom lopatice i pri povišenim temperaturama. Pri tome bi grafitna folija, koja bi se postavljala preko tog sloja, svojim relativno velikim poprečnim otporom prolazu topline poticala uzdužno širenje topline u tankom metalnom vodljivom sloju ispod nje. Uz to, grafitna folija bi sama po sebi preusmjerivala toplinski tok, te omogućavala tijesan spoj dodirnih površina, koji je potreban za prijelaz topline. Prednost tijesnog spoja dodirnih površina, koji bi se postigao korištenjem grafitne folije, je i u njegovom u relativno jednostavnom načinu ostvarivanja. Uprešavanje i isisavanje uzduha, te plinotijesno zavarivanje zaštitne metalne folije sa stijenkom lopatice, ne predstavlja osobito zahtjevne tehnologije. The thickness of the graphite foil could be reduced if a thin layer of metal with high thermal conductivity, for example copper or, at lower temperatures, aluminum, was placed between the graphite foil and the surface of the cooling channels. Such a layer would additionally direct the heat flow parallel to the walls of the cooling channels. If it is taken into account that the thermal conductivity of copper is about four to five times higher than the thermal conductivity of the graphite foil in the longitudinal direction, and even twenty times higher than the thermal conductivity of the blade wall made of nickel superalloy, the same effect could be achieved with a thinner graphite foil. Such a solution could be particularly advantageous in the area of the blade outlet edge, where the cooling channels are narrowest. The process of applying a copper or aluminum layer would have to ensure a safe connection with the blade wall even at elevated temperatures. At the same time, the graphite foil, which would be placed over that layer, with its relatively high transverse resistance to the passage of heat, would encourage the longitudinal expansion of heat in the thin conductive metal layer below it. In addition, the graphite foil itself would redirect the heat flow, and enable a tight connection of the contact surfaces, which is necessary for heat transfer. The advantage of the close connection of the contact surfaces, which would be achieved using graphite foil, is also in its relatively simple way of realization. Air extraction and extraction, as well as gas-tight welding of the protective metal foil with the blade wall, do not represent particularly demanding technologies.

Kratak opis crteža Brief description of the drawing

Slika 1 načelno prikazuje presjek turbinske lopatice, s grafitnom folijom 2 na površini stijenki 1 rashladnih kanala unutar lopatice te zaštitnom metalnom folijom 3, postavljenom preko grafitne folije. Figure 1 basically shows a section of a turbine blade, with a graphite foil 2 on the surface of the walls 1 of the cooling channels inside the blade and a protective metal foil 3 placed over the graphite foil.

Slika 2 prikazuje detalj stijenke lopatice turbine, sa slojem 5 metala velike toplinske vodljivosti na površini rashladnog kanala, između grafitne folije 2 i stijenke lopatice 1, pri čemu je grafitna folija pokrivena sa zaštitnom metalnom folijom 3. Figure 2 shows a detail of the turbine blade wall, with a layer 5 of metal of high thermal conductivity on the surface of the cooling channel, between the graphite foil 2 and the blade wall 1, whereby the graphite foil is covered with a protective metal foil 3.

Slika 3 prikazuje detalj stijenke 1 lopatice turbine, s izbočinama 4 trodimenzijski umjetno ohrapavljene unutarnje površine rashladnih kanala, na koju je postavljena grafitna folija 2 zaštićena metalnom folijom 3. Figure 3 shows a detail of the wall 1 of the turbine blade, with protrusions 4 of the three-dimensional artificially roughened inner surface of the cooling channels, on which a graphite foil 2 protected by a metal foil 3 is placed.

Slika 4 prikazuje detalj stijenke 1 lopatice turbine, s trodimenzijski umjetno ohrapavljenom unutarnjom površinom rashladnih kanala, na koju je postavljena grafitna folija 2 sa zaštitnom metalnom folijom 3, pri čemu površinske izbočine 4 umjetne hrapavosti prolaze kroz otvore u grafitnoj foliji. Figure 4 shows a detail of the wall 1 of the turbine blade, with a three-dimensional artificially roughened inner surface of the cooling channels, on which a graphite foil 2 with a protective metal foil 3 is placed, whereby surface protrusions 4 of artificial roughness pass through openings in the graphite foil.

Slika 5 prikazuje detalj stijenke 1 lopatice turbine, s dvodimenzijski umjetno ohrapavljenom unutarnjom površinom rashladnih kanala, na koju je postavljena grafitna folija 2 sa zaštitnom metalnom folijom 3, pri čemu površinske izbočine 4 umjetne hrapavosti prolaze kroz otvore u grafitnoj foliji. Figure 5 shows a detail of the wall 1 of the turbine blade, with a two-dimensional artificially roughened inner surface of the cooling channels, on which a graphite foil 2 with a protective metal foil 3 is placed, whereby the surface protrusions 4 of artificial roughness pass through the openings in the graphite foil.

Slika 6 prikazuje detalj lopatice turbine u području napadnog brida, s grafitnom folijom 2 i zaštitnom metalnom folijom 6 na toplinski najopterećenijem dijelu vanjske površine stijenke 1 lopatice, te grafitnom folijom 2 i zaštitnom metalnom folijom 3 na površini rashladnog kanala u sredini lopatice, u području manjeg opterećenja. Figure 6 shows a detail of the turbine blade in the area of the leading edge, with graphite foil 2 and protective metal foil 6 on the most heat-stressed part of the outer surface of the blade wall 1, and graphite foil 2 and protective metal foil 3 on the surface of the cooling channel in the middle of the blade, in the area of smaller loads.

Slika 7 kao i slika 6 prikazuje detalj lopatice turbine u području napadnog brida. Površina stijenke lopatice sadrži bradavičaste površinske izbočine 7 koje prolaze kroz grafitnu foliju. Figure 7 and Figure 6 show a detail of the turbine blade in the leading edge area. The surface of the blade wall contains warty surface protrusions 7 that pass through the graphite foil.

Opis načina ostvarivanja izuma Description of the method of realization of the invention

Slikom 1 je u presjeku prikazan tipičan oblik rashladnih kanala u turbinskoj lopatici, na čijim je stijenkama 1 postavljena grafitna folija 2 sa zaštitnom metalnom folijom 3. Detalji tehnološkog postupka postavljanja grafitne folije i zaštitne metalne folije na stijenke rashladnih kanala nisu predmet ovog izuma, ali se načelno može ustvrditi da bi se pri tom uglavnom koristili postupci koji su već uobičajeni u proizvodnji turbinskih lopatica, kao što su lijevanje, kovanje, zavarivanje, lemljenje, lijepljenje itd. Isisavanjem uzduha iz prostora između stijenke lopatice, grafitne folije i zaštitne metalne folije, po potrebi uz dodatno uprešavanje, te plinotijesnim zavarivanjem ili lemljenjem rubova metalne folije sa stijenkom lopatice, mogao bi se postići zadovoljavajući prijelaz topline na dodirnim plohama. Moguća je i primjena ljepila velike toplinske vodljivosti. Za zaštitu grafitne folije od oksidacije, na temperaturama većim od 500 °C, mogla bi i njezina površina sadržavati zaštitni sloj kao sastavni dio. U tom slučaju ne bi bila potrebna zaštitna metalna folija. Figure 1 shows a cross-section of a typical form of cooling channels in a turbine blade, on whose walls 1 graphite foil 2 with a protective metal foil 3 is placed. in principle, it can be stated that the procedures that are already common in the production of turbine blades would be used, such as casting, forging, welding, soldering, gluing, etc. By extracting air from the space between the blade wall, graphite foil and protective metal foil, if necessary, with additional refinement, and by gas-tight welding or soldering of the edges of the metal foil with the blade wall, satisfactory heat transfer on the contact surfaces could be achieved. It is also possible to use glue with high thermal conductivity. To protect the graphite foil from oxidation, at temperatures higher than 500 °C, its surface could also contain a protective layer as an integral part. In that case, a protective metal foil would not be needed.

Kod statorskih se lopatica zadovoljavajuće prianjanje grafitne folije na stijenke lopatice može postići isisavanjem uzduha ispod grafitne i metalne folije. Potreban pritisak na vanjsku plohu metalne folije u pogonu bi stvarao tlak rashladnog uzduha. Kod rotorskih lopatica, kod kojih djeluje veliko centripetalno ubrzanje, treba računati s relativno malom vlačnom čvrstoćom grafitne folije, oko 4 [image] , koja nije uvijek dovoljna da spriječi njezino izvijanje. Zbog toga se u radijalnom smjeru ne smiju postavljati dugački ravni dijelovi grafitne folije, osim u slučaju kada se spoj sa stijenkom lopatice ostvaruje lijepljenjem. Duljina ravnih radijalnih dijelova grafitne folije može se smanjiti uz pomoć umjetne hrapavosti površine rashladnih kanala, koja može biti dvo- i trodimenzijskog tipa. Iz literature je poznato da se najveća pojačavanja prijelaza topline postižu s trodimenzijskim tipom hrapavosti. Također je utvrđeno da se pri jednakim stupnjevima pojačavanja prijelaza topline najmanji otpori strujanju pojavljuju u slučaju zaobljenih površinskih izbočina. Na slici 3 prikazan je primjer trodimenzijske hrapavosti površine rashladnih kanala, sa zaobljenim površinskim izbočinama. Na stijenku 1 lopatice naliježe grafitna folija 2, pokrivena sa zaštitnom metalnom folijom 3. Površinske izbočine 4 su u “šahovskom” rasporedu. Kod ovakvog rješenja, u slučaju rotorskih lopatica bi spoj grafitne folije sa stijenkom lopatice i zaštitnom metalnom folijom trebalo pojačati lijepljenjem, barem u području površinskih izbočina. U primjeru na slici 4 površinske izbočine 4 prodiru kroz provrte u grafitnoj foliji 2 i metalnoj foliji 3, stršeći iznad površine metalne folije. U tom je slučaju potrebno osigurati plinotijesan spoj metalne folije i svih površinskih izbočina. Slično je na slici 5 prikazana dvodimenzijska umjetna hrapavost sa rebrima koja strše iznad površine metalne folije. Slikom 2 prikazan je detalj stijenke 1 lopatice, za slučaj kada se između grafitne folije 2 i površine rashladnih kanala nalazi tanki sloj 5 metala velike toplinske vodljivosti, primjerice bakra ili aluminija. Taj bi se sloj mogao nanositi neposredno na površine rashladnih kanala, primjerice galvanskim postupkom. Bez obzira kakav bi se tehnološki postupak usvojio, bitno je da se ostvari tijesno nalijeganje svih slojeva. U slučaju lijepljenja grafitne folije, ljepilo bi moralo imati veliku toplinsku vodljivost i biti naneseno u vrlo tankom sloju. Slika 6 prikazuje detalj lopatice turbine u području napadnog brida. Grafitna folija 2, sa zaštitnom metalnom folijom 6, postavljena je preko napadnog brida lopatice izvana, dok rashladni kanal ispod napadnog brida može biti i bez grafitne folije. U tom se slučaju materijal metalne folije 6 svojom otpornošću na visoke temperature razlikuje od materijala metalne folije 3, koja se postavlja unutar rashladnih kanala, pa je izložena nižim temperaturama. Rashladni kanali koji se prostiru u sredini iste lopatice mogu imati grafitnu foliju na svojoj površini. Slika 7 također prikazuje detalj lopatice turbine u području napadnog brida. Površina stijenke lopatice sadrži bradavičaste površinske izbočine 7 koje prolaze kroz grafitnu foliju 2. Zaštitna metalna folija 6 spojena je s površinskim izbočinama stijenke lopatice, točkastim zavarivanjem, lemljenjem ili lijepljenjem, čime se postiže stabilnost vanjskog oblika lopatice, a ujedno se ukrućuje i grafitna folija. Rashladni kanali su obloženi na način opisan uz sliku 1. In the case of stator vanes, satisfactory adhesion of the graphite foil to the walls of the vane can be achieved by vacuuming the air under the graphite and metal foil. The required pressure on the outer surface of the metal foil in the drive would create the pressure of the cooling air. In the case of rotor blades, where a large centripetal acceleration works, the relatively low tensile strength of the graphite foil, around 4 [image] , should be taken into account, which is not always sufficient to prevent its buckling. For this reason, long flat sections of graphite foil should not be installed in the radial direction, except in the case when the connection with the blade wall is achieved by gluing. The length of the flat radial parts of the graphite foil can be reduced with the help of artificial roughness of the surface of the cooling channels, which can be of two- or three-dimensional type. It is known from the literature that the greatest heat transfer enhancements are achieved with a three-dimensional type of roughness. It was also established that with equal degrees of heat transfer enhancement, the lowest flow resistances appear in the case of rounded surface protrusions. Figure 3 shows an example of three-dimensional surface roughness of cooling channels, with rounded surface protrusions. Graphite foil 2, covered with a protective metal foil 3, rests on the wall 1 of the blade. The surface protrusions 4 are in a "chess" arrangement. With such a solution, in the case of rotor blades, the connection of the graphite foil with the wall of the blade and the protective metal foil should be strengthened by gluing, at least in the area of the surface protrusions. In the example in Figure 4, the surface protrusions 4 penetrate through the holes in the graphite foil 2 and the metal foil 3, projecting above the surface of the metal foil. In this case, it is necessary to ensure a gas-tight connection between the metal foil and all surface protrusions. Similarly, Figure 5 shows a two-dimensional artificial roughness with ribs protruding above the surface of the metal foil. Figure 2 shows a detail of the wall 1 of the blade, for the case when there is a thin layer 5 of metal with high thermal conductivity, for example copper or aluminum, between the graphite foil 2 and the surface of the cooling channels. This layer could be applied directly to the surfaces of the cooling channels, for example by electroplating. No matter what technological procedure is adopted, it is important to achieve a close fit of all layers. In the case of gluing graphite foil, the glue should have high thermal conductivity and be applied in a very thin layer. Figure 6 shows a detail of the turbine blade in the leading edge area. Graphite foil 2, with a protective metal foil 6, is placed over the leading edge of the blade from the outside, while the cooling channel under the leading edge can be without graphite foil. In this case, the material of the metal foil 6 differs in its resistance to high temperatures from the material of the metal foil 3, which is placed inside the cooling channels, so it is exposed to lower temperatures. The cooling channels that extend in the middle of the same blade can have a graphite foil on their surface. Figure 7 also shows a detail of the turbine blade in the leading edge area. The surface of the blade wall contains warty surface protrusions 7 that pass through the graphite foil 2. The protective metal foil 6 is connected to the surface protrusions of the blade wall by spot welding, soldering or gluing, which achieves the stability of the outer shape of the blade, and at the same time stiffens the graphite foil. The cooling channels are coated in the manner described in Figure 1.

Način primjene izuma Method of application of the invention

Ovaj izum prvenstveno je namijenjen za poboljšanje uvjeta hlađenja lopatica plinskih turbina. Lopatice plinskih turbina motora zrakoplova sa poboljšanom jednolikošću temperature bile bi manje osjetljive na nagla povećanja i smanjenja snage motora, pa bi imale dulji radni vijek. This invention is primarily intended to improve the cooling conditions of gas turbine blades. Aircraft engine gas turbine blades with improved temperature uniformity would be less sensitive to sudden increases and decreases in engine power, and thus would have a longer service life.

Claims (8)

1. Turbinska lopatica plinske turbine, naznačena time, da je unutarnja površina rashladnih kanala u lopatici, ili dio površine rashladnih kanala u lopatici, pokriven s tankim slojem grafitne folije koja ima usmjerenu toplinsku vodljivost, tako da je toplinska vodljivost navedene grafitne folije veća u smjeru usporednom s navedenom površinom rashladnih kanala nego u smjeru okomitom na navedenu površinu, pri čemu se spoj navedene grafitne folije s površinom navedenih rashladnih kanala ostvaruje pokrivanjem navedene grafitne folije s metalnom folijom, uz uprešavanje i/ili isisavanje uzduha iz prostora između navedene metalne folije, navedene grafitne folije i navedene površine rashladnih kanala, te plinotijesno spajanje navedene metalne folije sa stijenkom navedene turbinske lopatice, tako da metalna folija štiti grafitnu foliju od oksidacije na visokim temperaturama.1. Turbine blade of a gas turbine, characterized by the fact that the inner surface of the cooling channels in the blade, or part of the surface of the cooling channels in the blade, is covered with a thin layer of graphite foil that has directional thermal conductivity, so that the thermal conductivity of said graphite foil is greater in the direction parallel to the specified surface of the cooling channels rather than in the direction perpendicular to the specified surface, whereby the connection of the specified graphite foil with the surface of the specified cooling channels is achieved by covering the specified graphite foil with a metal foil, while pressing and/or extracting air from the space between the specified metal foil, the specified graphite foil and the specified surface of the cooling channels, and the gas-tight connection of the specified metal foil with the wall of the specified turbine blade, so that the metal foil protects the graphite foil from oxidation at high temperatures. 2. Turbinska lopatica prema zahtjevu 1, naznačena time, da je grafitna folija ojačana vlaknima od čvrstog, toplinski dobro vodljivog materijala.2. Turbine blade according to claim 1, characterized in that the graphite foil is reinforced with fibers of a solid, thermally conductive material. 3. Turbinska lopatica prema zahtjevu 1 ili 2, naznačena time, da su navedena grafitna folija i navedena zaštitna metalna folija postavljene na vanjsku površinu ili dio vanjske površine navedene turbinske lopatice.3. Turbine blade according to claim 1 or 2, characterized in that said graphite foil and said protective metal foil are placed on the outer surface or part of the outer surface of said turbine blade. 4. Turbinska lopatica prema zahtjevu 1 ili 2 ili 3, naznačena time, da se spoj navedene grafitne folije sa stijenkom lopatice i navedenom zaštitnom metalnom folijom postiže lijepljenjem uz pomoć ljepila velike toplinske vodljivosti, otpornog na visoke temperature.4. Turbine blade according to claim 1 or 2 or 3, characterized in that the connection of the said graphite foil with the wall of the blade and the said protective metal foil is achieved by gluing with the help of an adhesive of high thermal conductivity, resistant to high temperatures. 5. Turbinska lopatica prema zahtjevu 1 ili 2 ili 3 ili 4, naznačena time, da navedena grafitna folija nije pokrivena navedenom metalnom folijom, nego sama površina navedene grafitne folije sadrži sloj koji je štiti od oksidacije.5. Turbine blade according to claim 1 or 2 or 3 or 4, characterized in that said graphite foil is not covered with said metal foil, but the surface of said graphite foil contains a layer that protects it from oxidation. 6. Turbinska lopatica prema zahtjevu 1 ili 2 ili 4 ili 5, naznačena time, da je površina navedenih rashladnih kanala umjetno ohrapavljena, tako da navedena grafitna folija, zahvaljujući svojoj mekoći i savitljivosti, slijedi oblik površine navedenih rashladnih kanala, pri čemu umjetna hrapavost površine navedenih rashladnih kanala, osim što kod rotorskih i statorskih lopatica turbine služi za pojačavanje prijelaza topline, kod rotorskih lopatica ujedno sprečava izvijanje grafitne folije pod djelovanjem masenih sila.6. Turbine blade according to claim 1 or 2 or 4 or 5, indicated by the fact that the surface of the said cooling channels is artificially roughened, so that the said graphite foil, thanks to its softness and flexibility, follows the shape of the surface of the said cooling channels, whereby the artificial roughness of the surface of the mentioned cooling channels, in addition to the rotor and stator blades of the turbine, it serves to increase the transfer of heat, in the case of the rotor blades, it also prevents the graphite foil from buckling under the action of mass forces. 7. Turbinska lopatica prema zahtjevu 6, naznačena time, da elementi navedene umjetne hrapavosti, koji se sastoje od izbočina navedene površine rashladnih kanala, prolaze kroz otvore u navedenoj grafitnoj foliji, tako da su navedeni otvori svojim oblikom i veličinom prilagođeni navedenim elementima umjetne hrapavosti, pri čemu se zaštita površine navedene grafitne folije od oksidacije može izvesti na način prema zahtjevu 5, ili uz pomoć metalne folije na način prema zahtjevu 1.7. Turbine blade according to claim 6, indicated by the fact that the elements of the said artificial roughness, which consist of the protrusions of the said surface of the cooling channels, pass through the openings in the said graphite foil, so that the said openings are adjusted in their shape and size to the said elements of the artificial roughness, whereby the protection of the surface of said graphite foil from oxidation can be carried out in the manner according to claim 5, or with the help of a metal foil in the manner according to claim 1. 8. Turbinska lopatica prema zahtjevu 3, naznačena time, da navedena vanjska površina turbinske lopatice sadrži bradavičaste ili rebraste izbočine, visine jednake debljini navedene grafitne folije, tako da navedene izbočine prolaze kroz navedenu grafitnu foliju, a navedena zaštitna metalna folija je zavarivanjem ili lemljenjem ili lijepljenjem spojena s navedenim izbočinama.8. Turbine blade according to claim 3, characterized by the fact that said external surface of the turbine blade contains warty or ribbed protrusions, the height equal to the thickness of said graphite foil, so that said protrusions pass through said graphite foil, and said protective metal foil is welded or soldered or glued together with the said protrusions.
HR20000077A 2000-02-10 2000-02-10 Improved cooling of turbine blade HRP20000077A2 (en)

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HR20000077A HRP20000077A2 (en) 2000-02-10 2000-02-10 Improved cooling of turbine blade
AU33984/01A AU3398401A (en) 2000-02-10 2001-02-08 Improved cooling of turbine blades
PCT/HR2001/000007 WO2001059262A1 (en) 2000-02-10 2001-02-08 Improved cooling of turbine blades

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US8852720B2 (en) * 2009-07-17 2014-10-07 Rolls-Royce Corporation Substrate features for mitigating stress
WO2011085376A1 (en) 2010-01-11 2011-07-14 Rolls-Royce Corporation Features for mitigating thermal or mechanical stress on an environmental barrier coating
US10040094B2 (en) 2013-03-15 2018-08-07 Rolls-Royce Corporation Coating interface

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US4156582A (en) * 1976-12-13 1979-05-29 General Electric Company Liquid cooled gas turbine buckets
US4142831A (en) * 1977-06-15 1979-03-06 General Electric Company Liquid-cooled turbine bucket with enhanced heat transfer performance
GB2286229B (en) * 1977-10-04 1995-12-20 Rolls Royce Turbine aerofoil blade provided with a heat insulating coating
US6095755A (en) * 1996-11-26 2000-08-01 United Technologies Corporation Gas turbine engine airfoils having increased fatigue strength

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