CA1113865A - Turbine blade - Google Patents
Turbine bladeInfo
- Publication number
- CA1113865A CA1113865A CA322,118A CA322118A CA1113865A CA 1113865 A CA1113865 A CA 1113865A CA 322118 A CA322118 A CA 322118A CA 1113865 A CA1113865 A CA 1113865A
- Authority
- CA
- Canada
- Prior art keywords
- passage section
- blade
- wall
- rib
- root
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
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- Turbine Rotor Nozzle Sealing (AREA)
Abstract
TURBINE BLADE
ABSTRACT OF THE DISCLOSURE
A convectively cooled turbine blade has a three-pass cooling air passageway. Air enters the blade at its root end, travels along a reversing path through the passageway and is emitted through an array of slots in the blade trailing edge generally configured in the form of a Venetian blind. Pedestals or turning vanes located in the turning areas of the passageway control separation of flow to prevent development of local hot spots. Pedestals located in a midchord portion of the passageway prevent sidewall panel vibration and enhance cooling efficiency.
A root metering plate governs magnitude of cooling flow through the turbine blade.
ABSTRACT OF THE DISCLOSURE
A convectively cooled turbine blade has a three-pass cooling air passageway. Air enters the blade at its root end, travels along a reversing path through the passageway and is emitted through an array of slots in the blade trailing edge generally configured in the form of a Venetian blind. Pedestals or turning vanes located in the turning areas of the passageway control separation of flow to prevent development of local hot spots. Pedestals located in a midchord portion of the passageway prevent sidewall panel vibration and enhance cooling efficiency.
A root metering plate governs magnitude of cooling flow through the turbine blade.
Description
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1 1113~i65 ¦ TURBINE BLADE
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I BACKGROUND OF T~IE INVEN~ION
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This invention relates in general to turbine blades and deals more particularly with an improved convectively cooled turbine blade particularly adapted for use in the second stage of an industrial gas turbine engine.
In gas turbine engines and the like a turbine operated by burning gases drives a blower or compressor which furnishes air to a burner. Such turbine engines operate at relatively high temperatures. The capacity of such an engine is limited to a large extent by the ability of the material from which the turbine blades are made to withstand thermal stresses which develop at such relatively high operating temperatures. The problem may be . ' ' ':
3~65 ¦particularly ~evere in an industrial engine because oi the rela-¦tively large slze and ~as~ oi englne parts. To enable higher ¦operatin~ temperatures nnd lncreased engine eiiiciency ~thout ¦rlsk of blade ia~lure, hollow convectively cooled tur~ine blades ¦are irequently utilized. Such blades generally have intricate ¦interior paqsageway~ which provlde torturou~ flow paths to as~ure ¦efficient cooling whereby all portlon~ oi the blades may be main-talned at relatively unliorm te~perature. However, such blades are dii~lcult and expen~ive to ~anuiacture. The present inven-¦ tlon i9 concerned with thls proble~, and lt is the general aim ¦ of this invention to provlde an i~proved convectively cooled turblne blade ~hlch ~atlsfie~ requirod de~lgn crlteria and whlcb ¦ ~ay be ~anuiactured ~t relatlvely low co~t and up-rated for in-I crea~ed cooling without expensive reoperation or redesign.
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;¦ UMUARY 0~ THE INVENTION -~
In accordance wlth the present invention an i~proved convectlvely cooled turbine blade has a three-pa~s cooling passage-; way which include~ an inlet openlng at the root end o~ the turbine and a plurality of connected pn~saee ~ections whlch define a )reversing flow path through its blnde portion to an array of out-let ~lot~ ~hlch e~tend along lts tralllng edge. Pede~tal~ or turnin~ vane~ are located at turnin~ area~ w~thin the passa~eway control separation o~ flow to prevent localized hot ~pot~. Ad-itlonal pede~tals extend between the ~ldewalls ln a ~idchord iortlon oi the pa~sageway to prevent sidewall vibration and en-ance cooling eiflciency. A ~eterlng plate attached to the root nd of the blade governs ~agnltude oi coollng ilow through the urbine blade.
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1 1113~i65 ¦ TURBINE BLADE
I .
I BACKGROUND OF T~IE INVEN~ION
I .
This invention relates in general to turbine blades and deals more particularly with an improved convectively cooled turbine blade particularly adapted for use in the second stage of an industrial gas turbine engine.
In gas turbine engines and the like a turbine operated by burning gases drives a blower or compressor which furnishes air to a burner. Such turbine engines operate at relatively high temperatures. The capacity of such an engine is limited to a large extent by the ability of the material from which the turbine blades are made to withstand thermal stresses which develop at such relatively high operating temperatures. The problem may be . ' ' ':
3~65 ¦particularly ~evere in an industrial engine because oi the rela-¦tively large slze and ~as~ oi englne parts. To enable higher ¦operatin~ temperatures nnd lncreased engine eiiiciency ~thout ¦rlsk of blade ia~lure, hollow convectively cooled tur~ine blades ¦are irequently utilized. Such blades generally have intricate ¦interior paqsageway~ which provlde torturou~ flow paths to as~ure ¦efficient cooling whereby all portlon~ oi the blades may be main-talned at relatively unliorm te~perature. However, such blades are dii~lcult and expen~ive to ~anuiacture. The present inven-¦ tlon i9 concerned with thls proble~, and lt is the general aim ¦ of this invention to provlde an i~proved convectively cooled turblne blade ~hlch ~atlsfie~ requirod de~lgn crlteria and whlcb ¦ ~ay be ~anuiactured ~t relatlvely low co~t and up-rated for in-I crea~ed cooling without expensive reoperation or redesign.
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;¦ UMUARY 0~ THE INVENTION -~
In accordance wlth the present invention an i~proved convectlvely cooled turbine blade has a three-pa~s cooling passage-; way which include~ an inlet openlng at the root end o~ the turbine and a plurality of connected pn~saee ~ections whlch define a )reversing flow path through its blnde portion to an array of out-let ~lot~ ~hlch e~tend along lts tralllng edge. Pede~tal~ or turnin~ vane~ are located at turnin~ area~ w~thin the passa~eway control separation o~ flow to prevent localized hot ~pot~. Ad-itlonal pede~tals extend between the ~ldewalls ln a ~idchord iortlon oi the pa~sageway to prevent sidewall vibration and en-ance cooling eiflciency. A ~eterlng plate attached to the root nd of the blade governs ~agnltude oi coollng ilow through the urbine blade.
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In accordance with a particular embodiment of the invention there is provided a turbine blade having a hollow elongated body including longitudinally extending leading and trailing edges and having a root portion at its inner end and : a blade portion extending from said root portion and terminat-ing at a closed tip at its outer end, said body having walls defining a triple-pass fluid passageway including three series connected passage sections providing a reversing fluid flow path through said body from said inner end to said trailing edge, said walls including a leading edge wall defining said leading edge, opposing side walls extending between said leading and trailing edges, and rib walls connected to and extending transversely between said side walls, said rib walls including : a forward rib wall spaced rearwardly from said leading edge _ wall and extending in a generally longitudinally inclined :
; direction within said blade portion from said inner end toward said leading edge wall and in the direction of said outer end, said forward rib wall having a terminal end longitudinally spaced from said closed tip, said leading edge wall and said forward rib wall partially defining a forward passage section therebetween opening through said inner end and extending . :
through said root portion and into said blade portion in the region of said leading edge and terminating within said blade :
portion at an outer turning region proximate said closed tip, one part of said leading edge wall defining the portion of said forward passage section within said blade portion having an abrupt forward offset relative to another part of said leading edge wall defining 'che portion of said forward passage section ` within said root portion, said forward offset occurring prox-30 imate the junction of said root and blade portions, said ~ ~ forward passage section having an abruptly enlarged cross-:
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sectional area at the junction of said root and blade portions and generally converging within said blade portion and toward said outer turning region, said rib walls including a rear .
rib wall spaced rearwardly from said forward rib wall and : extending in a generally longitudinally inclined direction from -:.
said closed tip toward said forward rib wall and in the general ~
direction of said inner end, said rear rib wall having a ter- -minal end proximate the junction of said root and blade portions, : said forward rib wall and said rear rib wall partially defining a midchord passage section communicating with said forward passage section at said outer turning region between the terminal end of said forward rib wall and said closed tip, said midchOrd passage section converging within said blade portion and in the direction of said inner end, said rear wall rib and said trailing edge partially defining a rear passage section within said blade portion in the region of said trail- .
.l ing edge and terminating at said closed tip, said rear passage section communicating with said midchord passage section at an inner end, said rear passage section converging within said body portion and in the direction of said closed tip, said body including a longitudinally spaced series of partitions conn-ected to and extending between said side walls generally ad-jacent.said trailing edge and defining a longitudinal series of slots opening through said trailing edge and communicating ;, with said rear passage section, said body having a plurality of pedestal members connected to and extending between said side walls within said forward passage section and proximate the junction of said root and blade portions.
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BRIEF-DEscRIprIoN OF TlilE D~AWING
Fig. 1 19 a longitudinal ~ectional view oi an airfoil ¦shaped turbine blade embodying the pre~ent inventlon.
¦ Fig. 2 is a ~omewbat enlar~ed ~rag~entary sectio~al ¦view taken along the line 2-2 oi Fig. 1.
~: ¦ ~ig. 3 i9 a ~ragmeutary lo~gitudinal sectional view ¦si~ilar to Flg. l a~d shows a modified iorm o~ the turbine blade ¦ oi Fig. 1.
I DETA~LED, DESCRIPTION~OF .PREFERn~D EUBODI~ENT
) I Turning no~ to the dra~lng, the lnvention is lllustrated . -:
: I and described wlth r~erence to an air cooled turbine blade, de-¦ signated generally by the numieral 10, and partlcularly adapted ior u~e ln the ~econd fitage of an axial ~low ga~ turbine engine ...
o~ an lndu~tsial type (not ~ho~n) wbiich hias a plurality of alr-~i I ~oil shaped turbine rotox blades mounted in an~ularly ~paced re- : :
¦ lation on a rotor disc. The turbine blade 10 has a more or le~s .
: I conYentional outer confi6uration and comprlseæ a hollow elo~igatQd body, lndicated generally at 12, which i~cludes a concave inner ¦ ~lde ~all 14 and an oppo~ing convex outer sidewall 16. The slde-~) ¦ wall8 terminate at longitudlnally extendlng leading and trailing ..
edgee lndlcated, re6pectlvely at 18 a~id 20. The body 12 further lnclude~ a root portion 22 at one end and elongated blade portion ¦ 24 whlch extends iro~ the root portlon and termlnates at a tlp I 2ff, whlch 1~ clo~ed by a separately ln~erted sealing plate 28. : :
S A platiorm 30 extendY outwardly ~rom the body at the ju~iction ~ :, between the root and blade portloDi. The root portion i8 pre- .
; ~erablg provlded with attach~ient ~houlders (not ~howni) whlch may ~
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~ 8 have a conventionnl fir tree configuration for mounting the tur-b1ne blade 10 in complementary ~lot~ in a rotor disc.
In accordance wlth the present invention, a three-pass ~eries ~lo~ cooling pas~a~eway sys~;rS is provided ~or con-vectively cooling the blade 10 and lndicated generally by the nu~eral 3~. The passageway system 32 oompri~es three ~eries connected passage sections 34, 36 and 38 which generall~ deiine a rever~lng fluid ~low path between the inner or root end o~
the turbine blade 10 and a lollgltudinally spaced ~erie~ of out-let passage~ or ~lots 40, 40 ~ormed in the trailing edge 20. The pa~sageway system 32 further includes two blind passage sectlons 42 and 44 whl¢h are rormed ~ithln the root portion 22 and which merge wlth the pas~age ~ection~ 36 and 38 proximate the junction o~ the latter sectlons.
The pa~age ~ection 34 i~ de~ined, in part, by the i~ner wall of the leading edge }8, the latter wall being designed by the numeral 46. It will be noted that the part o~ the wall 46 which deilnes the portlon o~ the passage sectlon 34 withln ;~ the leading ed~e of the blade portion 20 i~ ~orwardly o~set ~rom the part of the wall 46 whlch derine8 the portion o~ the passage ~ectlon 36 within the root portlon 22~ Thi~ of~et o¢curs pro-xi~ate the Junction between tbe root and blade portions. The pa~sageway 34 i~ rurther de~ined by a wall rib 48 which extends txan~versely between the ~idewaIls 14 and 16 and is spaced rear-
In accordance with a particular embodiment of the invention there is provided a turbine blade having a hollow elongated body including longitudinally extending leading and trailing edges and having a root portion at its inner end and : a blade portion extending from said root portion and terminat-ing at a closed tip at its outer end, said body having walls defining a triple-pass fluid passageway including three series connected passage sections providing a reversing fluid flow path through said body from said inner end to said trailing edge, said walls including a leading edge wall defining said leading edge, opposing side walls extending between said leading and trailing edges, and rib walls connected to and extending transversely between said side walls, said rib walls including : a forward rib wall spaced rearwardly from said leading edge _ wall and extending in a generally longitudinally inclined :
; direction within said blade portion from said inner end toward said leading edge wall and in the direction of said outer end, said forward rib wall having a terminal end longitudinally spaced from said closed tip, said leading edge wall and said forward rib wall partially defining a forward passage section therebetween opening through said inner end and extending . :
through said root portion and into said blade portion in the region of said leading edge and terminating within said blade :
portion at an outer turning region proximate said closed tip, one part of said leading edge wall defining the portion of said forward passage section within said blade portion having an abrupt forward offset relative to another part of said leading edge wall defining 'che portion of said forward passage section ` within said root portion, said forward offset occurring prox-30 imate the junction of said root and blade portions, said ~ ~ forward passage section having an abruptly enlarged cross-:
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sectional area at the junction of said root and blade portions and generally converging within said blade portion and toward said outer turning region, said rib walls including a rear .
rib wall spaced rearwardly from said forward rib wall and : extending in a generally longitudinally inclined direction from -:.
said closed tip toward said forward rib wall and in the general ~
direction of said inner end, said rear rib wall having a ter- -minal end proximate the junction of said root and blade portions, : said forward rib wall and said rear rib wall partially defining a midchord passage section communicating with said forward passage section at said outer turning region between the terminal end of said forward rib wall and said closed tip, said midchOrd passage section converging within said blade portion and in the direction of said inner end, said rear wall rib and said trailing edge partially defining a rear passage section within said blade portion in the region of said trail- .
.l ing edge and terminating at said closed tip, said rear passage section communicating with said midchord passage section at an inner end, said rear passage section converging within said body portion and in the direction of said closed tip, said body including a longitudinally spaced series of partitions conn-ected to and extending between said side walls generally ad-jacent.said trailing edge and defining a longitudinal series of slots opening through said trailing edge and communicating ;, with said rear passage section, said body having a plurality of pedestal members connected to and extending between said side walls within said forward passage section and proximate the junction of said root and blade portions.
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!
BRIEF-DEscRIprIoN OF TlilE D~AWING
Fig. 1 19 a longitudinal ~ectional view oi an airfoil ¦shaped turbine blade embodying the pre~ent inventlon.
¦ Fig. 2 is a ~omewbat enlar~ed ~rag~entary sectio~al ¦view taken along the line 2-2 oi Fig. 1.
~: ¦ ~ig. 3 i9 a ~ragmeutary lo~gitudinal sectional view ¦si~ilar to Flg. l a~d shows a modified iorm o~ the turbine blade ¦ oi Fig. 1.
I DETA~LED, DESCRIPTION~OF .PREFERn~D EUBODI~ENT
) I Turning no~ to the dra~lng, the lnvention is lllustrated . -:
: I and described wlth r~erence to an air cooled turbine blade, de-¦ signated generally by the numieral 10, and partlcularly adapted ior u~e ln the ~econd fitage of an axial ~low ga~ turbine engine ...
o~ an lndu~tsial type (not ~ho~n) wbiich hias a plurality of alr-~i I ~oil shaped turbine rotox blades mounted in an~ularly ~paced re- : :
¦ lation on a rotor disc. The turbine blade 10 has a more or le~s .
: I conYentional outer confi6uration and comprlseæ a hollow elo~igatQd body, lndicated generally at 12, which i~cludes a concave inner ¦ ~lde ~all 14 and an oppo~ing convex outer sidewall 16. The slde-~) ¦ wall8 terminate at longitudlnally extendlng leading and trailing ..
edgee lndlcated, re6pectlvely at 18 a~id 20. The body 12 further lnclude~ a root portion 22 at one end and elongated blade portion ¦ 24 whlch extends iro~ the root portlon and termlnates at a tlp I 2ff, whlch 1~ clo~ed by a separately ln~erted sealing plate 28. : :
S A platiorm 30 extendY outwardly ~rom the body at the ju~iction ~ :, between the root and blade portloDi. The root portion i8 pre- .
; ~erablg provlded with attach~ient ~houlders (not ~howni) whlch may ~
I
1, .
~ 8 have a conventionnl fir tree configuration for mounting the tur-b1ne blade 10 in complementary ~lot~ in a rotor disc.
In accordance wlth the present invention, a three-pass ~eries ~lo~ cooling pas~a~eway sys~;rS is provided ~or con-vectively cooling the blade 10 and lndicated generally by the nu~eral 3~. The passageway system 32 oompri~es three ~eries connected passage sections 34, 36 and 38 which generall~ deiine a rever~lng fluid ~low path between the inner or root end o~
the turbine blade 10 and a lollgltudinally spaced ~erie~ of out-let passage~ or ~lots 40, 40 ~ormed in the trailing edge 20. The pa~sageway system 32 further includes two blind passage sectlons 42 and 44 whl¢h are rormed ~ithln the root portion 22 and which merge wlth the pas~age ~ection~ 36 and 38 proximate the junction o~ the latter sectlons.
The pa~age ~ection 34 i~ de~ined, in part, by the i~ner wall of the leading edge }8, the latter wall being designed by the numeral 46. It will be noted that the part o~ the wall 46 which deilnes the portlon o~ the passage sectlon 34 withln ;~ the leading ed~e of the blade portion 20 i~ ~orwardly o~set ~rom the part of the wall 46 whlch derine8 the portion o~ the passage ~ectlon 36 within the root portlon 22~ Thi~ of~et o¢curs pro-xi~ate the Junction between tbe root and blade portions. The pa~sageway 34 i~ rurther de~ined by a wall rib 48 which extends txan~versely between the ~idewaIls 14 and 16 and is spaced rear-
3 wardly o~ the wall 46. The wall rib 48 extends ~rom the root : end oi the turblne blade 10 toward its tlp 26 and terminates in , -
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longitudinally spaced relation to the sealing plate 28. As shown in Fig. 1, the wall rib 48 is outwardly inclined in the direction of the leading edge 18, so that the passageway section 34 generally converges in the direction of the tip 26. ~ -The rear passageway 36, is defined in part by the wall rib 46, and is further defined by another wall rib 50 which extends from the tip end 26 and in the direction of the root end -of the turbine blade. The wall rib 50 extends between the side-walls 14 and 16 and is inclined inwardly and in the direction of the wall rib 48 relative to the longitudinal axis of the turbine blade. The wall rib 50 terminates proximate the junction be-tween the root and blade portions 22 and 24, substantially as ' shown. Another wall rib 52 extends from the root end in the direction of the tip 26 and terminates in longitudinally spaced ; relation to the wall rib 50. The wall rib 52 cooperates with the portion of the wall rib 48 to define the blind passageway 42 and also cooperates with a trailing edge wall 54 to define the other blind passage section 44.
The rear passage section 38 extends through the blade portion 24 in the region of its trailing edge and is defined in part by the wall rib 50. A plurality of partitions or elongated pedestal members 56, 56 are arranged in Venetian blind array and extend between the sidewalls 14 and 16 generally adjacent the trailing edge 20 to define the slots 40, 40 which commun-icate with the rear passage section 38.
Four generally cylindrical pedestal members 58, 58 disposed within the forward passage section 34 and extend between ~
:' ' _ 5 _ 11138~i5 the sidewalls 14 and 16 proximate the junction of the rib and -blade portions 22 and 24 at a turn in the forward passage section 34. The latter pedestals are disposed in a generally in-line arrangement inclined to the longitudinal axis of the turbine blade, substantially as shown in Fig. 1. A plurality of gener-ally cylindrical pedestal members 60, 60 are disposed within the ` midchord passageway section 36 and extend between the sidewalls 14 and 16. Two additional pedestal mernbers 62, 62, which extend between the sidewalls, are disposed at the entry end of the rear 10 passage section 38 proximate the junction between the root and blade portions and adjacent the downstream end of the inner turn in the passageway system 32.
A pair of airfoil shaped turning vanes 64 and 66 extend between the sidewalls 14 and 16 proximate the entry end of the : .
i midchord passage section 36 and generally between the terminal end of the wall rib 48 and the sealing plate 28, substantially as shown in Fig. 1. A metering plate 68 attached to the inner end of the turbine blade 10 provides closures for the blind pas-sageways 42 and 44 and has a metering orifice 70 which communi-20 cates with the passage section 34. The metering plate 68 is preferably welded or brazed to the inner end of the body 12, which is preferably made by a casting process. To facilitate casting the body 12 is made with an opening at its tip end 26. The latter opening is closed by the sealing plate 28, which, as shown, is received within a slot in the tip end of the body.
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Cooling air ~rom the blade disc (not shown) enters the forward passage section 34 through the metering orliice 70. The cross-sectional area o~ the ~orwar~ passage sectlo~ 34 increases abruptly at the junction between the root and blade portions due :
: ~o the ~orward o~fset oi the leading edge inner wall 46. The four pedestals 58, 58 prevent local flow separatio~ at this turn in the flow path by causlng turbulence in the ~low and iorcing it outwardly against the inner wall 46 and inwardly agal~t the wall ~ : :
rib 48 thereby preventing the development o~ a hot ~pot in this region o~ the blade. The cooling air ~lows the full spa~ o~ the blade through the iorward pa~sa~e section 34 until it reache~ the ., tip end ~6 where it i~ bloc~ed by the ~ealing plate as. The turning vane~ 64 and 66 a6sist iR directing the ~low o~ cooling air into the ~idchord pas~age section 36, as lndicated by the ~low arrows ln the Flg. 1, and control ~eparation o~ ~low to pre-: vent development o~ hot spots in thi~ outer turning regio~.
: The pedestal ~embers 60, 60 in the midchord pa~sage ~ ;
section 36 preveut sidewall vlbration and cause turbulent ~lou within the pa~sage ~ectlon 36 which re9ults in n scrubblng action D on the wall~ o~ the passa~e ~ection ~or more ei~lcient coollng.
~ter ~lowlng through the ~idchord pas~age section 36 the CooliR~
air rounds the inner end o~ the wall rib 50 at a~ inner turning region and passes over the pedestal members 62, 62 and into the : .
reax passage ~ectlon 38 where it emlts irom the slots 40-4C.at .5 the inner end o~ the rear passage ~ection 38 generally ad~acent .
the lnner turnlng reglon, lndlcated by the ~low arrow in Flg. 1.
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The pedestal members 62, 62 prevent flow separation and cause flow to emit from the trailing edge slots 40-40 near the inner end of the blade portion 20, thereby preventing development of a hot spot in this region.
The metering plate 60 governs the magnitude of cooling flow through the turbine blade 10 and permits future modification of the blade cooling system, such as an up-rating of the cooling system, without expensive alteration or blade redesign. Present-ly, .5% engine air is used to cool the turbine blade 10. How-ever, the criteria in determining the amount of cooling air whichmust flow through the blade is determined by the maximum temp-erature to which the blade will be subjected. A 1500 F max-imum blade temperature is thought to be desirable to prevent fuel products deposits from sticking to the blade.
~ In Fig. 3 there is shown a turbine blade lOa for a ;j "first generation" gas turbine engine. The hollow body 12a of the blade lOa is substantially identical to the body 12 of the previously described blade 10. However, the separate plate 68a, which is attached to the inner end of the body 12a serves only as a closure for the blind passage section 42a and 44a. The passage section 34a which opens through the inner end of the body allows maximum cooling air flow through the passage system 32a.
It will now be apparent that the magnitude of cooling flow through the turbine blade may be altered by attaching to the inner end of the body a separate metering plate having a metering orifice of appropriate size. Thus, the rating of the cooling system ~ay be changed without altering the body of the turbine blade.
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longitudinally spaced relation to the sealing plate 28. As shown in Fig. 1, the wall rib 48 is outwardly inclined in the direction of the leading edge 18, so that the passageway section 34 generally converges in the direction of the tip 26. ~ -The rear passageway 36, is defined in part by the wall rib 46, and is further defined by another wall rib 50 which extends from the tip end 26 and in the direction of the root end -of the turbine blade. The wall rib 50 extends between the side-walls 14 and 16 and is inclined inwardly and in the direction of the wall rib 48 relative to the longitudinal axis of the turbine blade. The wall rib 50 terminates proximate the junction be-tween the root and blade portions 22 and 24, substantially as ' shown. Another wall rib 52 extends from the root end in the direction of the tip 26 and terminates in longitudinally spaced ; relation to the wall rib 50. The wall rib 52 cooperates with the portion of the wall rib 48 to define the blind passageway 42 and also cooperates with a trailing edge wall 54 to define the other blind passage section 44.
The rear passage section 38 extends through the blade portion 24 in the region of its trailing edge and is defined in part by the wall rib 50. A plurality of partitions or elongated pedestal members 56, 56 are arranged in Venetian blind array and extend between the sidewalls 14 and 16 generally adjacent the trailing edge 20 to define the slots 40, 40 which commun-icate with the rear passage section 38.
Four generally cylindrical pedestal members 58, 58 disposed within the forward passage section 34 and extend between ~
:' ' _ 5 _ 11138~i5 the sidewalls 14 and 16 proximate the junction of the rib and -blade portions 22 and 24 at a turn in the forward passage section 34. The latter pedestals are disposed in a generally in-line arrangement inclined to the longitudinal axis of the turbine blade, substantially as shown in Fig. 1. A plurality of gener-ally cylindrical pedestal members 60, 60 are disposed within the ` midchord passageway section 36 and extend between the sidewalls 14 and 16. Two additional pedestal mernbers 62, 62, which extend between the sidewalls, are disposed at the entry end of the rear 10 passage section 38 proximate the junction between the root and blade portions and adjacent the downstream end of the inner turn in the passageway system 32.
A pair of airfoil shaped turning vanes 64 and 66 extend between the sidewalls 14 and 16 proximate the entry end of the : .
i midchord passage section 36 and generally between the terminal end of the wall rib 48 and the sealing plate 28, substantially as shown in Fig. 1. A metering plate 68 attached to the inner end of the turbine blade 10 provides closures for the blind pas-sageways 42 and 44 and has a metering orifice 70 which communi-20 cates with the passage section 34. The metering plate 68 is preferably welded or brazed to the inner end of the body 12, which is preferably made by a casting process. To facilitate casting the body 12 is made with an opening at its tip end 26. The latter opening is closed by the sealing plate 28, which, as shown, is received within a slot in the tip end of the body.
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Cooling air ~rom the blade disc (not shown) enters the forward passage section 34 through the metering orliice 70. The cross-sectional area o~ the ~orwar~ passage sectlo~ 34 increases abruptly at the junction between the root and blade portions due :
: ~o the ~orward o~fset oi the leading edge inner wall 46. The four pedestals 58, 58 prevent local flow separatio~ at this turn in the flow path by causlng turbulence in the ~low and iorcing it outwardly against the inner wall 46 and inwardly agal~t the wall ~ : :
rib 48 thereby preventing the development o~ a hot ~pot in this region o~ the blade. The cooling air ~lows the full spa~ o~ the blade through the iorward pa~sa~e section 34 until it reache~ the ., tip end ~6 where it i~ bloc~ed by the ~ealing plate as. The turning vane~ 64 and 66 a6sist iR directing the ~low o~ cooling air into the ~idchord pas~age section 36, as lndicated by the ~low arrows ln the Flg. 1, and control ~eparation o~ ~low to pre-: vent development o~ hot spots in thi~ outer turning regio~.
: The pedestal ~embers 60, 60 in the midchord pa~sage ~ ;
section 36 preveut sidewall vlbration and cause turbulent ~lou within the pa~sage ~ectlon 36 which re9ults in n scrubblng action D on the wall~ o~ the passa~e ~ection ~or more ei~lcient coollng.
~ter ~lowlng through the ~idchord pas~age section 36 the CooliR~
air rounds the inner end o~ the wall rib 50 at a~ inner turning region and passes over the pedestal members 62, 62 and into the : .
reax passage ~ectlon 38 where it emlts irom the slots 40-4C.at .5 the inner end o~ the rear passage ~ection 38 generally ad~acent .
the lnner turnlng reglon, lndlcated by the ~low arrow in Flg. 1.
':' .
' ?
~13~
The pedestal members 62, 62 prevent flow separation and cause flow to emit from the trailing edge slots 40-40 near the inner end of the blade portion 20, thereby preventing development of a hot spot in this region.
The metering plate 60 governs the magnitude of cooling flow through the turbine blade 10 and permits future modification of the blade cooling system, such as an up-rating of the cooling system, without expensive alteration or blade redesign. Present-ly, .5% engine air is used to cool the turbine blade 10. How-ever, the criteria in determining the amount of cooling air whichmust flow through the blade is determined by the maximum temp-erature to which the blade will be subjected. A 1500 F max-imum blade temperature is thought to be desirable to prevent fuel products deposits from sticking to the blade.
~ In Fig. 3 there is shown a turbine blade lOa for a ;j "first generation" gas turbine engine. The hollow body 12a of the blade lOa is substantially identical to the body 12 of the previously described blade 10. However, the separate plate 68a, which is attached to the inner end of the body 12a serves only as a closure for the blind passage section 42a and 44a. The passage section 34a which opens through the inner end of the body allows maximum cooling air flow through the passage system 32a.
It will now be apparent that the magnitude of cooling flow through the turbine blade may be altered by attaching to the inner end of the body a separate metering plate having a metering orifice of appropriate size. Thus, the rating of the cooling system ~ay be changed without altering the body of the turbine blade.
.~. ...
Claims (8)
1. A turbine blade having a hollow elongated body including longitudinally extending leading and trailing edges and having a root portion at its inner end and a blade portion extending from said root portion and terminating at a closed tip at its outer end, said body having walls defining a triple-pass fluid passageway including three series connected passage sections providing a reversing fluid flow path through said body from said inner end to said trailing edge, said walls including a leading edge wall defining said leading edge, opposing side walls extending between said leading and trail-ing edges, and rib walls connected to and extending trans-versely between said side walls, said rib walls including a forward rib wall spaced rearwardly from said leading edge wall and extending in a generally longitudinally inclined direction within said blade portion from said inner end toward said leading edge wall and in the direction of said outer end, said forward rib wall having a terminal end longitudinally spaced from said closed tip, said leading edge wall and said forward rib wall partially defining a forward passage section therebetween opening through said inner end and extending through said root portion and into said blade portion in the region of said leading edge and terminating within said blade portion at an outer turning region proximate said closed tip, one part of said leading edge wall defining the portion of said forward passage section within said blade portion having an abrupt forward offset relative to another part of said leading edge wall defining the portion of said forward passage section within said root portion, said forward offset occurring proximate the junction of said root and blade portions, said forward passage section having an abruptly enlarged cross-sectional area at the junction of said root and blade portions and generally converging within said blade portion and toward said outer turning region, said rib walls including a rear rib wall spaced rearwardly from said forward rib wall and extending in a generally longitudinally inclined direction from said closed tip toward said forward rib wall and in the general direction of said inner end, said rear rib wall having a terminal end proximate the junction of said root and blade portions, said forward rib wall and said rear rib wall partially defining a midchord passage section communicating with said forward passage section at said outer turning region between the terminal end of said forward rib wall and said closed tip, said midchord passage section converging within said blade portion and in the direction of said inner end, said rear wall rib and said trailing edge partially defining a rear passage section within said blade portion in the region of said trailing edge and terminating at said closed tip, said rear passage section communicating with said midchord passage section at an inner end, said rear passage section converging within said body portion and in the direction of said closed tip, said body including a longitudinally spaced series of partitions connected to and extending between said side walls generally adjacent said trailing edge and defining a longit-udinal series of slots opening through said trailing edge and communicating with said rear passage section, said body having a plurality of pedestal members connected to and ex-tending between said side walls within said forward passage section and proximate the junction of said root and blade portions.
2. A turbine blade as set forth in claim 1 including a metering plate attached to said body at said inner end and having a metering orifice therethrough communicating with said forward passage section..
3. A turbine blade as set forth in claim 1 including another wall rib within said root portion and extending from said inner end and toward the terminal end of said rear wall rib, said other wall rib partially defining two blind passage sections within said root portion merging with said mid-chord passage section and said rear passage section at the junction between said midchord passage section and said rear passage section.
4. A turbine blade as set forth in claim 3 wherein said blind passage sections open through said inner end and including a plate attached to the inner end of said body and providing closures for the inner ends of said blind passage sections.
5. A turbine blade as set forth in claim 4 wherein said plate has a metering orifice therethrough communicating with said forward passage section.
6. A turbine blade as set forth in claim l wherein said body has a slot in its outer end and said turbine blade includes a plate received in said slot and defining a closure for said closed tip.
7. A turbine blade as set forth in claim 1 wherein said root portion has a trailing edge wall, said trailing edge of said blade portion is defined by said opposing side walls and has an abrupt rearward offset proximate the junction of said root and blade portions and relative to said trailing edge wall, and said body has a plurality of pedestal members conn-ected to and extending between said side walls within said rear passage section proximate the junction of said root and blade portions.
8. A turbine blade as set forth in claim 7 wherein said body has at least one turning vane connected to and ex-tending between said side walls in said outer turning region and a plurality of pedestals connected to and extending be-tween said sidewall within said midchord passage section.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA322,118A CA1113865A (en) | 1979-02-22 | 1979-02-22 | Turbine blade |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA322,118A CA1113865A (en) | 1979-02-22 | 1979-02-22 | Turbine blade |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1113865A true CA1113865A (en) | 1981-12-08 |
Family
ID=4113608
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA322,118A Expired CA1113865A (en) | 1979-02-22 | 1979-02-22 | Turbine blade |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1113865A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5507621A (en) * | 1995-01-30 | 1996-04-16 | Rolls-Royce Plc | Cooling air cooled gas turbine aerofoil |
| CN112943379A (en) * | 2021-02-04 | 2021-06-11 | 大连理工大学 | Turbine blade separation transverse rotation re-intersection type cooling structure |
-
1979
- 1979-02-22 CA CA322,118A patent/CA1113865A/en not_active Expired
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5507621A (en) * | 1995-01-30 | 1996-04-16 | Rolls-Royce Plc | Cooling air cooled gas turbine aerofoil |
| CN112943379A (en) * | 2021-02-04 | 2021-06-11 | 大连理工大学 | Turbine blade separation transverse rotation re-intersection type cooling structure |
| CN112943379B (en) * | 2021-02-04 | 2022-07-01 | 大连理工大学 | Turbine blade separation transverse rotation re-intersection type cooling structure |
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