CA1159371A - Metering water to turbine bucket cooling passages by flow resistance devices - Google Patents
Metering water to turbine bucket cooling passages by flow resistance devicesInfo
- Publication number
- CA1159371A CA1159371A CA000381075A CA381075A CA1159371A CA 1159371 A CA1159371 A CA 1159371A CA 000381075 A CA000381075 A CA 000381075A CA 381075 A CA381075 A CA 381075A CA 1159371 A CA1159371 A CA 1159371A
- Authority
- CA
- Canada
- Prior art keywords
- flow
- resistance devices
- coolant
- flow resistance
- liquid
- 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
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D5/00—Blades; Blade-carrying members; Heating, heat-insulating, cooling or antivibration means on the blades or the members
- F01D5/12—Blades
- F01D5/14—Form or construction
- F01D5/18—Hollow blades, i.e. blades with cooling or heating channels or cavities; Heating, heat-insulating or cooling means on blades
- F01D5/185—Liquid cooling
-
- Y—GENERAL 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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T50/00—Aeronautics or air transport
- Y02T50/60—Efficient propulsion technologies, e.g. for aircraft
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Turbine Rotor Nozzle Sealing (AREA)
Abstract
METERING WATER TO TURBINE BUCKET COOLING
PASSAGES BY FLOW RESISTANCE DEVICES
ABSTRACT OF THE DISCLOSURE
An improved cooling system utilizes flow resistant devices to distributing liquid coolane to air foil coolant channels in a bucket of a turbine.
A separate flow resistance device associated with each of the air foil coolant channels resists the flow of liquid coolant into the coolant channels whereby a fluid head is developed in a standpipe upstream of the flow resistance devices. The fluid head, together with the outward radial acceleration meters the flow of fluid through each flow resistance device according to the head. In the disclosed embodiments, the flow resistant devices alternately take the form of a tortuous passage, an orifice and a plurality of vortex flow chambers.
PASSAGES BY FLOW RESISTANCE DEVICES
ABSTRACT OF THE DISCLOSURE
An improved cooling system utilizes flow resistant devices to distributing liquid coolane to air foil coolant channels in a bucket of a turbine.
A separate flow resistance device associated with each of the air foil coolant channels resists the flow of liquid coolant into the coolant channels whereby a fluid head is developed in a standpipe upstream of the flow resistance devices. The fluid head, together with the outward radial acceleration meters the flow of fluid through each flow resistance device according to the head. In the disclosed embodiments, the flow resistant devices alternately take the form of a tortuous passage, an orifice and a plurality of vortex flow chambers.
Description
33 ~ ~L
METERING W~TER TO TURBINE BUCKET COOLING
PAS'SAGES BY FLOW RESI'STAN OE DEVICE'S
BACKGROUND OF THE' INVENTI'ON
.
The present invention is directed towards an improved cooling system for a gas turbine. More parti-cularly, the present invention is directed towards an improved cooling system which employs flow-resistance devices to meter coolant into a plurality of platform and air foil coolant channels located in the buckets of the gas turbine.
The cooling system of the present invention is utilized in connection with a gas turbine of the type including a turbine disk mounted on a shaft rotatably supported in a casing and a plurality of turbine buckets extending radially outward from the disk. Each of the buckets includes a root portion mounted in the disk, a shank portion extending radially outwarcl Erom the root portion to a platform portion, and an air foil extending radially outward from the pla-tform portion. During operation, the buckets receive a driving force from hot flu.id moving in a direction generally parallel to the axis of the shaft and convert this driving force to rotational motion which i.s trans-mitted to the ~haft via the turbine clisk. ~s -the result o the relatively high temperatures of -the hot ~lLI:id, a ~i significant amount of heat is transferred to the turbine buckets. In order to remove this heat from the bucket structure, the prior art has developed a larye variety of open-liquid coolin~ systems. Exemplary of such systems are U.S. Patent No. 3,658,439, issued April 25, 1972 - Kydd; U.S. Patent No. 3,804,551, issued April 16, 1974 - Moore; U.S. Patent No.
4,017,210, issued April 12, 1977 - ~arrow; and U.S.
Patent No. 4,244,67~ issued January 13, 1981 - Grondahl et al.
Open circuit liquid cooling systems are particularly important because they make it feasible to increase -the turbine inlet temperature to an operating range of from 2500F to at least 3500F, thereby obtaining an increase in power output ranging from about 100%-200% and an increase in -thermal efficiency ranging to as high as 50%. A primary requirement of open circuit liquid cooling systems is that the liquid coolant be evenly distributed to the several platform and air foil coolant channels formed in the bucket.
Such a distribution is difficult to obtain as a result of the extremely high bucket tip speeds employed, resulting in centrifugal fields of the order of 2S,000 G.
To obtain an even flow o~ coolant liqu.id throughout the several coolant channels, the prior art systems, as exempli~ied by U.S. Patents Nos. 3,804,551 and 4,017,210, su~ra,.utiliæe weir structures which meter the amount o~ coolant liquid supplied to each individual channel from pools of coolant liquid formed in the plat~orm portion o~ the bucket. Particularly, these s~ste~s introduced liq~id coolant into each end o.~ a trou~h ~ormed in the plat~orm portion o~ th~ bucket such that l:iquid coolant flows in a direction parallel to the a~is of rotation o~ the turbine disk Erom each 'O ~
end of the trough. The liquld coolant flows over the top of an elongated weir which performs the metering for each channel.
In order to perform satisfactorily, it is ~i 5 critical that the ~ of these weirs~ parallel to -~ . the axis of rotation of the turbine within a tolerance of several mils. If this relationship is not maintained, all of the coolant liquid will flow over the low end of the weir and, consequently, some of the coolant channels formed in the platform and air foil of ~he bucket will be starved for coolant.
In an effort to overcome the foregoing pro-blem, the invention described in U.S. Patent No.
4,2~4,676 utilizes V-shaped notched weirs which are less sensitive to variations in the orientation in the metering channels than the prior art weirs. While this invention represents an improvement over the prior art weir structures, all weir metering devices depend upon a uniform depth of water above the crest of each weir to ensure an equal supply of cooling water to the individual bucket cooling channels. While the V-shaped notched weirs make the accuracy of flow metering less sensitive to manufacturing tolerances and in-service distortion, it is still affected by waves on the surface of the water in the reservoir supplying the weirs. Such waves have been found to occur as a result of oscillations in the flow rate of water to the metering device and may also result from rotor vibra-tions.
30 B~ E~_DES'CR;IPTION OF ~HE 'INVENTION
In order to overcome the foreqoLng drawbacks of the prior art meter:Lng struc-twre~, the present invention wtili~es resistance ~low devices -to meter water in-to each ~uclcet cooling channel. Such clevices are not dependent upon a stahle, uniEo~n water surface 3~
for accurate metering. Thus~ while flow through a reslstance flow device is typically proportional -to the square root of the pressure head (i.e., Hl/~), weir flow rates are at best about proportional to the pressure head and may be as sensitive as H5/2.
In accordance with the foregoing, the li~uid coolan-t distribution system of the present invention includes:
a plurality of shank coolant channels located in the shank portion of a turbine bucket and extending to platform cooling channels located in the platform portion of a turbine bucket that extend into foil cooling channels located in the air foil of the turbine bucket;
and metering means for receiving coolant from a source of liquid coolant and for distributing the coolant evenly into each of the platform coolant supply channels, the metering means including a plurality of resistance flow devices.
BRIEF DESCRIPTION OF THE DRA~INGS
For the purpose of illustrating the invention, there are shown in the drawings several forms which are presently preferred, it being understood, however, that this invention is not limited to the precise arrange ments and instrumentalities shown.
Figure l is a perspective view of a first embcdiment o~ the improved cooling system of the present invention.
Figure 2 is a side plan view of a single turbine bucket and dlstrihution channel Eormed in accordance with the present invention.
3`~
Figure 3 is an exploded view of a distri-bution channel forming part of the cooling system of Figure 1.
Figure 4 illustrates the interrelationship between the distribution channel inner member of Figure 3 and certain coolant channels formed in the distribution channel outer housing of Figure 2.
Figure 5 is a cross-sectional view taken alony lineb~- ~ of Figure 4 illustrating a first embodi-ment of a flow resistance device which may be used inaccordance with the principles of the present invention.
Figure 6 is a cross-sectional view taken along line ~-~ of Figure 4 illustrating a second flow resistance device which may be used in accordance with the principles of the present invention.
b Figure 7 is a cross-sectional view taken along line ~-~ of Figure 4 illustrating a third flow resistance device which may be used in accordance with the principles of the present invention.
Figure 8 is a cross-sectional view taken along line 8-8 of Figure 7.
Figure 9 is a cross-sectional view illustrating internal passages of the flow resistance device of Figure 7.
Figure 10 is a cross-sectional view ta~en along line lU-10 of Figure 7.
DE'rAILED DESCRIPTION OF THE INVENTION
Referring now to the drawings, wherein like numerals indicate like elements, there is shown ln Figure 1 a turbine bucket constructed in accordance with the principles oE -the present invention and desigrlated generally as 10. Bucket 10 includes a root por~ion 12, a ~hank portion 1~, a platform portion 16 and an air foil 18. Root portion 12 is e}nbedded in a turb:Lne rotor ~:Lslc 20 which is mounted on a shaft (not 5~
shown) rotatably supported in a casing (not shown). As will be recognized by those skilled in the art, an actual turbine will include a plurality of buckets 10 located about the entire periphery of the rotor disk 20.
As noted above, the present invention is directed towards an improved cooling sys-tem for use with gas turbines of the general type illustrated in Figure 1. A water delivery system, such as described in U.S.
Patent No. 4,184,797 issued January 22, 1980 - Anderson et al, distributes the coolant to passage 94 and thereby to individual buckets 10. Passage 94 directs the coolant liquid to stand pipe 96, which is integral with distribution channel 28 located beneath the root portion 12 of bucket 10. The structure of distribution 15 channel 28 is illustrated in Figures 2-10 and is described in detail below. The coolant liquid supplied by passage 94 collects in stand pipe 96 of distribution channel 28 and is thereafter metered into a plurality of shank coolant channels 78 formed in the shank 14.
As best shown in Figure 4, a plurality of trap seàls 98 are interposed in shank coolant channels 78 (preferably at the bottom thereof) to permit the passage of liquid coolant from distribution channel 28 to coolant channels 78 but prevent the passage of coolant vapor from coolant channel 78 to distribution channel 28. The structure of these coolant channels is described in detail in U.S. Patent 4,244,676.
As best illu~trated in Figure 1, shan]c coolant channels 78 extend from distribution channel 28 to a plu.rality of platform coolant channels 30 (only two o~ whic~ are shown) .Eormed in platform 16 that in turn lead to ;eoil coolant channels 32 formed in the .~oil 18.
rrhe ~oil coolant channels 32 extend in a generally radial direction throughout the oute.r perimeter o~
! 35 air ;Eoil 18 and ser~e to cool the foil, 3~
As shown in Figure 1, the distribution channel 28 has a flattened top 22 which mates with a flattened bottom 62 of the turbine bucket 10 when the bucket and distribution channel are placed in the dovetail opening formed in rotor disk 20. Both surfaces 62, 22 are machined flat and parallel with the convolutions of the dovetail slot so that the centri-fugal force applied to distribution channel 28 when the turbine is rotating ensures parallelism between these surfaces and the dovetail slots.
The detailed structure of distribution channel 28 will now be described with reference to Figures 2-10.
As shown in Figure 3, distribution channel 28 comprises two parts: an outer casing 68, and a cylindrical member 48. Outer casing 68 fits under the bottommost convolution of the dovetail slot in rotor disk 20. A cylindrical bore 74 is formed in outer casing 68 and receives member 48 in interference fit therewith.
A plurality of coolant channels 76 are formed in the top of casing 68 and each extends from bore 74 to flattened top 22. Coolant channels 76 are equal in number to the number of platform coolant channels 30 and are each connected to a respective platform coolant channel 30 by one of the shank coolant channels 78.
Member 48 has a hollow cylindrical central section 80, a threaded extension section 82, a coolant supply receiving section 84 and a side cover 50 which may, if desired, be formed integrally with member ~8.
The outer diameter of central section 80 is substantially identical to -the inner diameter of bore 7~ to ensure an in-terference ~it when central section 80 is placecl in bore 7~. ~he leng-th of central sectlon 80 is equal -to -khe leng-th o~ bore 7~ such -tha-t sec-tions 82 and 8 extencl beyond opposi-te encls of outer casing 68.
Whell clistribution channel 28 has been placecl ,;
in its positi,on within the dovetail slot formed in rotor disk 20 (see Figure 1), threaded extension section 82 extends through an opening 90 in ring 34. In the preferred embodiment, the external threads on extension seetion 82 engage a retaining nut 92 which serves to lock a ring 34 to rotor disk 20.
Coolant supply receiving section 84 of member 48 extends out the opposite side of casing 68. Coolant fluid enters a plenum 64 through stand pipe 96 which communicates with passage 94 formed in ring 34.
A plurality of grooves 56 are formed around the outer perimeter of central section 80 at spaced intervals eorresponding to the spacing of eoolant channels 76 formed in outer casing 68 such that eaeh ].5 groove 56 cooperates with a different shank coolant ehannel 78. Licluid eoolant supplied to supply plenum 64 exits member 48 via individual exit openings 58 formed in eaeh of the grooves 56. A respeetive flow resistance device 66 (see Figures 5-10) is located between supply plenum 64 and each exit opening 58 and meters the flow of liquid eoolant into its respeetive opening 58.
The manner in which liquid eoolant is supplied to coolant channels 76 by distribution channel 2~ can best be understood with referenee to Figure 4. Figure 4 depiets the righ-t-hand portion of distribu~ion ehannel 28 after it has been plaeed in position within the dove-tail slot formed in rotor 20, beneath root portion 12 of bueket 10. As the hueket rotates about the eentral axis of the turhine, the eoolant fluid is foreed in a radial outward direetion by eentrifugal foree. As such, the eoolant flows through stand pipe 96 l:nto -the suppl.y plenum 64 where i-t eolleets on the radially outwarcl wa,ll of plenum 6~. Th~ eoolan-t dis-tribu-tes -throughout the dlstribution channel 28 and builds up ln heigh~:
3~
until it passes through the flow resistance device 66 and flows through the opening 58 and into the groove 56.
The so metered coolant ~lows into its associated outer ~R~ J D /q~/ 7~
; ~ casing ~ channel 76 and thereafter to a cor-responding shank coolant channel 78, platform coolant channel 30 and foil coolant channel 32.
Three separate embodiments of flow resistance devices which may be utilized in connection with the present invention are illustrated in Figures 5-lO.
While these structures represent the preferred flow resistance devices, it should be recognized that a large number of different flow resistance devices can be used without departing from the spirit and scope of the present invention as long as such devices meter a liquid coolant into the individual coolant channels 76 in such a manner that the flow of coolant through such devices does not depend upon a stable, uniform water surface ~or accurate metering.
Referring now to Figure 5, a first embodiment of a flow resistance device 66 is illustrated. In this embodiment, the flow resistance device 66 comprises a tortuous path 88 comprising a series of bends. In order to operate properly, it is essential that these passages be filled with liquid in order to generate the requisite losses. This is ensured when the liquid coolant flows radially inward against the "G" field, as shown. Head losses at each bend contribute to the total resistance of the passage. Passages of relatively large size are possible. For example, passages having a minimum cross-sec~ion dimension of 0.025 inches have been found tooperate satisfactorily.
rrhe relationship between ~low and pressure drop as a ~unction o~ t}le si~e and shape oE constltuent bend elements oE the tor1uous path may be Eound in the "~landboo~ o~ HydrauLic Re~istance" au-thored by 3 ~'~
I.E. Idel'Chik. Since the particular size and shape of the tortuous path does not make up part of the present invention, a further discussion of the manner in which these parameters affect flow characteristics will not be set forth herein.
While the tortuous path 88 may be formed in any desired manner, one simple process :is to form the path by laminating a plurality of wafer--like plates 70 each of which has been formed with an opening at the location corresponding to the tortuous path 88. These openings may be formed, for example, by using known photo-etchiny technology similar to that used in producing fluidic devices.
The operation of flow resistance device 66, as illustrated in Figure 5, is as follows. As the buckets 10 are rotated about the axis of rotor disk 20, the artificially generated "G" field causes the liquid coolant to flow through supply plenum 64 pressing against the radially outward wall thereof. The height of the liquid coolant builds up and passes through a "last chance" strainer 72 located adjacent plenum 64.
A separate strainer 72 is provided for each flow resis-tance device 66. The height of the liquid coolant con-tinues to flow through the tortuous path 88 until it flows out the opening 58 into the groove 56 formed in the distribution channel 28. This liquid then flows into the coolant channel 76 and through its associated bucket coolant channel.
In operation, debris which is heavier than the liquid coolant is centrifuged away from strainer 72 to the bottom 54 of plenum 64. As a result, the openings formed in stxainer 72 need only be smaller in diameter than the minimum dimension Oe. tortuous path 88. In the pre:eerred embodiment, strainer 72 is a metallic plate having a plurality o~ openin~s formed therein.
3 ~
A second flow .resistance device 66 which may be used in connection with the present invention is illustrated in Figure 6. In this embodiment, an orifice 46 is used to create -the desired head. losses. While a single orifice 46 is illustrated, a plurality of orifices may be used. As in the embodiment of Figure 6, the flow resistance device of Figure 6 includes a strainer 72 adapted to prevent small debris from flowing into, and thereby clogging, orifice 46. Water builds up in the standpipe 96 to a water head H (see Figure 4) radially inward of exit opening 58. In comparative tests, it has been found that bucket channel flow will vary as a function of the square root of the water head H (see Figure 4) when using an orifice such as that illustrated in Figure 6. In comparison, the channel flow varies as a function of H5/2 using a "V" shaped notched weir such as that described in aforementioned U.S. Patent No. ~,244,676.
In the illustrated embodiment, orifice 46 is formed as a projection in a cylindrical flow path 58. Other orifices
METERING W~TER TO TURBINE BUCKET COOLING
PAS'SAGES BY FLOW RESI'STAN OE DEVICE'S
BACKGROUND OF THE' INVENTI'ON
.
The present invention is directed towards an improved cooling system for a gas turbine. More parti-cularly, the present invention is directed towards an improved cooling system which employs flow-resistance devices to meter coolant into a plurality of platform and air foil coolant channels located in the buckets of the gas turbine.
The cooling system of the present invention is utilized in connection with a gas turbine of the type including a turbine disk mounted on a shaft rotatably supported in a casing and a plurality of turbine buckets extending radially outward from the disk. Each of the buckets includes a root portion mounted in the disk, a shank portion extending radially outwarcl Erom the root portion to a platform portion, and an air foil extending radially outward from the pla-tform portion. During operation, the buckets receive a driving force from hot flu.id moving in a direction generally parallel to the axis of the shaft and convert this driving force to rotational motion which i.s trans-mitted to the ~haft via the turbine clisk. ~s -the result o the relatively high temperatures of -the hot ~lLI:id, a ~i significant amount of heat is transferred to the turbine buckets. In order to remove this heat from the bucket structure, the prior art has developed a larye variety of open-liquid coolin~ systems. Exemplary of such systems are U.S. Patent No. 3,658,439, issued April 25, 1972 - Kydd; U.S. Patent No. 3,804,551, issued April 16, 1974 - Moore; U.S. Patent No.
4,017,210, issued April 12, 1977 - ~arrow; and U.S.
Patent No. 4,244,67~ issued January 13, 1981 - Grondahl et al.
Open circuit liquid cooling systems are particularly important because they make it feasible to increase -the turbine inlet temperature to an operating range of from 2500F to at least 3500F, thereby obtaining an increase in power output ranging from about 100%-200% and an increase in -thermal efficiency ranging to as high as 50%. A primary requirement of open circuit liquid cooling systems is that the liquid coolant be evenly distributed to the several platform and air foil coolant channels formed in the bucket.
Such a distribution is difficult to obtain as a result of the extremely high bucket tip speeds employed, resulting in centrifugal fields of the order of 2S,000 G.
To obtain an even flow o~ coolant liqu.id throughout the several coolant channels, the prior art systems, as exempli~ied by U.S. Patents Nos. 3,804,551 and 4,017,210, su~ra,.utiliæe weir structures which meter the amount o~ coolant liquid supplied to each individual channel from pools of coolant liquid formed in the plat~orm portion o~ the bucket. Particularly, these s~ste~s introduced liq~id coolant into each end o.~ a trou~h ~ormed in the plat~orm portion o~ th~ bucket such that l:iquid coolant flows in a direction parallel to the a~is of rotation o~ the turbine disk Erom each 'O ~
end of the trough. The liquld coolant flows over the top of an elongated weir which performs the metering for each channel.
In order to perform satisfactorily, it is ~i 5 critical that the ~ of these weirs~ parallel to -~ . the axis of rotation of the turbine within a tolerance of several mils. If this relationship is not maintained, all of the coolant liquid will flow over the low end of the weir and, consequently, some of the coolant channels formed in the platform and air foil of ~he bucket will be starved for coolant.
In an effort to overcome the foregoing pro-blem, the invention described in U.S. Patent No.
4,2~4,676 utilizes V-shaped notched weirs which are less sensitive to variations in the orientation in the metering channels than the prior art weirs. While this invention represents an improvement over the prior art weir structures, all weir metering devices depend upon a uniform depth of water above the crest of each weir to ensure an equal supply of cooling water to the individual bucket cooling channels. While the V-shaped notched weirs make the accuracy of flow metering less sensitive to manufacturing tolerances and in-service distortion, it is still affected by waves on the surface of the water in the reservoir supplying the weirs. Such waves have been found to occur as a result of oscillations in the flow rate of water to the metering device and may also result from rotor vibra-tions.
30 B~ E~_DES'CR;IPTION OF ~HE 'INVENTION
In order to overcome the foreqoLng drawbacks of the prior art meter:Lng struc-twre~, the present invention wtili~es resistance ~low devices -to meter water in-to each ~uclcet cooling channel. Such clevices are not dependent upon a stahle, uniEo~n water surface 3~
for accurate metering. Thus~ while flow through a reslstance flow device is typically proportional -to the square root of the pressure head (i.e., Hl/~), weir flow rates are at best about proportional to the pressure head and may be as sensitive as H5/2.
In accordance with the foregoing, the li~uid coolan-t distribution system of the present invention includes:
a plurality of shank coolant channels located in the shank portion of a turbine bucket and extending to platform cooling channels located in the platform portion of a turbine bucket that extend into foil cooling channels located in the air foil of the turbine bucket;
and metering means for receiving coolant from a source of liquid coolant and for distributing the coolant evenly into each of the platform coolant supply channels, the metering means including a plurality of resistance flow devices.
BRIEF DESCRIPTION OF THE DRA~INGS
For the purpose of illustrating the invention, there are shown in the drawings several forms which are presently preferred, it being understood, however, that this invention is not limited to the precise arrange ments and instrumentalities shown.
Figure l is a perspective view of a first embcdiment o~ the improved cooling system of the present invention.
Figure 2 is a side plan view of a single turbine bucket and dlstrihution channel Eormed in accordance with the present invention.
3`~
Figure 3 is an exploded view of a distri-bution channel forming part of the cooling system of Figure 1.
Figure 4 illustrates the interrelationship between the distribution channel inner member of Figure 3 and certain coolant channels formed in the distribution channel outer housing of Figure 2.
Figure 5 is a cross-sectional view taken alony lineb~- ~ of Figure 4 illustrating a first embodi-ment of a flow resistance device which may be used inaccordance with the principles of the present invention.
Figure 6 is a cross-sectional view taken along line ~-~ of Figure 4 illustrating a second flow resistance device which may be used in accordance with the principles of the present invention.
b Figure 7 is a cross-sectional view taken along line ~-~ of Figure 4 illustrating a third flow resistance device which may be used in accordance with the principles of the present invention.
Figure 8 is a cross-sectional view taken along line 8-8 of Figure 7.
Figure 9 is a cross-sectional view illustrating internal passages of the flow resistance device of Figure 7.
Figure 10 is a cross-sectional view ta~en along line lU-10 of Figure 7.
DE'rAILED DESCRIPTION OF THE INVENTION
Referring now to the drawings, wherein like numerals indicate like elements, there is shown ln Figure 1 a turbine bucket constructed in accordance with the principles oE -the present invention and desigrlated generally as 10. Bucket 10 includes a root por~ion 12, a ~hank portion 1~, a platform portion 16 and an air foil 18. Root portion 12 is e}nbedded in a turb:Lne rotor ~:Lslc 20 which is mounted on a shaft (not 5~
shown) rotatably supported in a casing (not shown). As will be recognized by those skilled in the art, an actual turbine will include a plurality of buckets 10 located about the entire periphery of the rotor disk 20.
As noted above, the present invention is directed towards an improved cooling sys-tem for use with gas turbines of the general type illustrated in Figure 1. A water delivery system, such as described in U.S.
Patent No. 4,184,797 issued January 22, 1980 - Anderson et al, distributes the coolant to passage 94 and thereby to individual buckets 10. Passage 94 directs the coolant liquid to stand pipe 96, which is integral with distribution channel 28 located beneath the root portion 12 of bucket 10. The structure of distribution 15 channel 28 is illustrated in Figures 2-10 and is described in detail below. The coolant liquid supplied by passage 94 collects in stand pipe 96 of distribution channel 28 and is thereafter metered into a plurality of shank coolant channels 78 formed in the shank 14.
As best shown in Figure 4, a plurality of trap seàls 98 are interposed in shank coolant channels 78 (preferably at the bottom thereof) to permit the passage of liquid coolant from distribution channel 28 to coolant channels 78 but prevent the passage of coolant vapor from coolant channel 78 to distribution channel 28. The structure of these coolant channels is described in detail in U.S. Patent 4,244,676.
As best illu~trated in Figure 1, shan]c coolant channels 78 extend from distribution channel 28 to a plu.rality of platform coolant channels 30 (only two o~ whic~ are shown) .Eormed in platform 16 that in turn lead to ;eoil coolant channels 32 formed in the .~oil 18.
rrhe ~oil coolant channels 32 extend in a generally radial direction throughout the oute.r perimeter o~
! 35 air ;Eoil 18 and ser~e to cool the foil, 3~
As shown in Figure 1, the distribution channel 28 has a flattened top 22 which mates with a flattened bottom 62 of the turbine bucket 10 when the bucket and distribution channel are placed in the dovetail opening formed in rotor disk 20. Both surfaces 62, 22 are machined flat and parallel with the convolutions of the dovetail slot so that the centri-fugal force applied to distribution channel 28 when the turbine is rotating ensures parallelism between these surfaces and the dovetail slots.
The detailed structure of distribution channel 28 will now be described with reference to Figures 2-10.
As shown in Figure 3, distribution channel 28 comprises two parts: an outer casing 68, and a cylindrical member 48. Outer casing 68 fits under the bottommost convolution of the dovetail slot in rotor disk 20. A cylindrical bore 74 is formed in outer casing 68 and receives member 48 in interference fit therewith.
A plurality of coolant channels 76 are formed in the top of casing 68 and each extends from bore 74 to flattened top 22. Coolant channels 76 are equal in number to the number of platform coolant channels 30 and are each connected to a respective platform coolant channel 30 by one of the shank coolant channels 78.
Member 48 has a hollow cylindrical central section 80, a threaded extension section 82, a coolant supply receiving section 84 and a side cover 50 which may, if desired, be formed integrally with member ~8.
The outer diameter of central section 80 is substantially identical to -the inner diameter of bore 7~ to ensure an in-terference ~it when central section 80 is placecl in bore 7~. ~he leng-th of central sectlon 80 is equal -to -khe leng-th o~ bore 7~ such -tha-t sec-tions 82 and 8 extencl beyond opposi-te encls of outer casing 68.
Whell clistribution channel 28 has been placecl ,;
in its positi,on within the dovetail slot formed in rotor disk 20 (see Figure 1), threaded extension section 82 extends through an opening 90 in ring 34. In the preferred embodiment, the external threads on extension seetion 82 engage a retaining nut 92 which serves to lock a ring 34 to rotor disk 20.
Coolant supply receiving section 84 of member 48 extends out the opposite side of casing 68. Coolant fluid enters a plenum 64 through stand pipe 96 which communicates with passage 94 formed in ring 34.
A plurality of grooves 56 are formed around the outer perimeter of central section 80 at spaced intervals eorresponding to the spacing of eoolant channels 76 formed in outer casing 68 such that eaeh ].5 groove 56 cooperates with a different shank coolant ehannel 78. Licluid eoolant supplied to supply plenum 64 exits member 48 via individual exit openings 58 formed in eaeh of the grooves 56. A respeetive flow resistance device 66 (see Figures 5-10) is located between supply plenum 64 and each exit opening 58 and meters the flow of liquid eoolant into its respeetive opening 58.
The manner in which liquid eoolant is supplied to coolant channels 76 by distribution channel 2~ can best be understood with referenee to Figure 4. Figure 4 depiets the righ-t-hand portion of distribu~ion ehannel 28 after it has been plaeed in position within the dove-tail slot formed in rotor 20, beneath root portion 12 of bueket 10. As the hueket rotates about the eentral axis of the turhine, the eoolant fluid is foreed in a radial outward direetion by eentrifugal foree. As such, the eoolant flows through stand pipe 96 l:nto -the suppl.y plenum 64 where i-t eolleets on the radially outwarcl wa,ll of plenum 6~. Th~ eoolan-t dis-tribu-tes -throughout the dlstribution channel 28 and builds up ln heigh~:
3~
until it passes through the flow resistance device 66 and flows through the opening 58 and into the groove 56.
The so metered coolant ~lows into its associated outer ~R~ J D /q~/ 7~
; ~ casing ~ channel 76 and thereafter to a cor-responding shank coolant channel 78, platform coolant channel 30 and foil coolant channel 32.
Three separate embodiments of flow resistance devices which may be utilized in connection with the present invention are illustrated in Figures 5-lO.
While these structures represent the preferred flow resistance devices, it should be recognized that a large number of different flow resistance devices can be used without departing from the spirit and scope of the present invention as long as such devices meter a liquid coolant into the individual coolant channels 76 in such a manner that the flow of coolant through such devices does not depend upon a stable, uniform water surface ~or accurate metering.
Referring now to Figure 5, a first embodiment of a flow resistance device 66 is illustrated. In this embodiment, the flow resistance device 66 comprises a tortuous path 88 comprising a series of bends. In order to operate properly, it is essential that these passages be filled with liquid in order to generate the requisite losses. This is ensured when the liquid coolant flows radially inward against the "G" field, as shown. Head losses at each bend contribute to the total resistance of the passage. Passages of relatively large size are possible. For example, passages having a minimum cross-sec~ion dimension of 0.025 inches have been found tooperate satisfactorily.
rrhe relationship between ~low and pressure drop as a ~unction o~ t}le si~e and shape oE constltuent bend elements oE the tor1uous path may be Eound in the "~landboo~ o~ HydrauLic Re~istance" au-thored by 3 ~'~
I.E. Idel'Chik. Since the particular size and shape of the tortuous path does not make up part of the present invention, a further discussion of the manner in which these parameters affect flow characteristics will not be set forth herein.
While the tortuous path 88 may be formed in any desired manner, one simple process :is to form the path by laminating a plurality of wafer--like plates 70 each of which has been formed with an opening at the location corresponding to the tortuous path 88. These openings may be formed, for example, by using known photo-etchiny technology similar to that used in producing fluidic devices.
The operation of flow resistance device 66, as illustrated in Figure 5, is as follows. As the buckets 10 are rotated about the axis of rotor disk 20, the artificially generated "G" field causes the liquid coolant to flow through supply plenum 64 pressing against the radially outward wall thereof. The height of the liquid coolant builds up and passes through a "last chance" strainer 72 located adjacent plenum 64.
A separate strainer 72 is provided for each flow resis-tance device 66. The height of the liquid coolant con-tinues to flow through the tortuous path 88 until it flows out the opening 58 into the groove 56 formed in the distribution channel 28. This liquid then flows into the coolant channel 76 and through its associated bucket coolant channel.
In operation, debris which is heavier than the liquid coolant is centrifuged away from strainer 72 to the bottom 54 of plenum 64. As a result, the openings formed in stxainer 72 need only be smaller in diameter than the minimum dimension Oe. tortuous path 88. In the pre:eerred embodiment, strainer 72 is a metallic plate having a plurality o~ openin~s formed therein.
3 ~
A second flow .resistance device 66 which may be used in connection with the present invention is illustrated in Figure 6. In this embodiment, an orifice 46 is used to create -the desired head. losses. While a single orifice 46 is illustrated, a plurality of orifices may be used. As in the embodiment of Figure 6, the flow resistance device of Figure 6 includes a strainer 72 adapted to prevent small debris from flowing into, and thereby clogging, orifice 46. Water builds up in the standpipe 96 to a water head H (see Figure 4) radially inward of exit opening 58. In comparative tests, it has been found that bucket channel flow will vary as a function of the square root of the water head H (see Figure 4) when using an orifice such as that illustrated in Figure 6. In comparison, the channel flow varies as a function of H5/2 using a "V" shaped notched weir such as that described in aforementioned U.S. Patent No. ~,244,676.
In the illustrated embodiment, orifice 46 is formed as a projection in a cylindrical flow path 58. Other orifices
2~ may, however, be used.
A third embodiment of a flow resistance ; device 66 constructed in accordance with the principles of the present invention is illustrated in Figures 7-10.
In this embodiment, the flow resistance device takes the form of a plura].ity of vortex chambers 81, 83, 85 and 87. Liquid coolant l.ocated in supply plenum 64 ! passes through strainer 72 and flows into a first vortex chamber 81 wherein it is agitated in the known manner (see Figures 8, 9 and 10). ~he agitated coolank leaves vortex chamber 81 via a cylindrical opening 79 into a second vortex chamber 83.
A~ bes-t illus-tratecl in Figuxes 8, 9 ancl 10, liquid coolant in vortex chamber 83 passes into vortex chamber 85 via a llnear passage 77. Liqu:id coolant leaves vortex chamber 85 via opening 75 and en-ters eourth vortex chamher 87 (see Figures 8, 9 and 10).
A third embodiment of a flow resistance ; device 66 constructed in accordance with the principles of the present invention is illustrated in Figures 7-10.
In this embodiment, the flow resistance device takes the form of a plura].ity of vortex chambers 81, 83, 85 and 87. Liquid coolant l.ocated in supply plenum 64 ! passes through strainer 72 and flows into a first vortex chamber 81 wherein it is agitated in the known manner (see Figures 8, 9 and 10). ~he agitated coolank leaves vortex chamber 81 via a cylindrical opening 79 into a second vortex chamber 83.
A~ bes-t illus-tratecl in Figuxes 8, 9 ancl 10, liquid coolant in vortex chamber 83 passes into vortex chamber 85 via a llnear passage 77. Liqu:id coolant leaves vortex chamber 85 via opening 75 and en-ters eourth vortex chamher 87 (see Figures 8, 9 and 10).
3`~
Finally, the licluid coolant leaves vortex chamber 87 via passaye 73 wherein it exits via opening 58 into groove 56.
Having described the structure and operation of the preferred flow resistance devices, the manner in which coolant flows from liquid coolant source through the entire bucket 10 will now be described. The buckets 10 receive a driviny force from a ho-t fluid moving in a direction generally parallel to the axis of rotation of rotor disk 20. The driving force of the hot fluid is transmitted to the shaft about which the rotor disk 20 is mounted via the buckets 10 and rotor disk 20 causiny the turbine to rotate about the axis of the shaft. ~he high rotational velocity of the rotor creates a substantial centrifugal force which urges the liquid coolant through the bucket in a radially outward direction. As the liquid coolant enters coolant supply passage 94, it is forced in a radially outward direction into standpipe 96 where it is collected in distribution channel 28. When the level of coolant in supply plenum 64 overflows, it passes through the individual flow resistance devices 66 into the respective platform coolant channels 76 and thereafter into the respective shank coolant channels 78. The coolant continues to advance in a generally radial direction to platform and foil coolant channels 30 and 32 to the tip of foil 18.
In the foregoillg embodiment, distribution channel 28 is located in the rim of rotor disc 20 below the 30 bucket 10. In aforementioned U.S. Patent No. 4,244,676 the manner in which a dlstrihution ahannel may be located in the platform portion 16 o:E bucke-t 10 i~ illustrated in Figures 1-4. A sirnllar arrangement may be used in connec-tion w.ith the presen-t application. ~, ~lthough ~everal preferred embodiments oE -this J~ .
' 31r^JL
inventlon have been described, many variations and modifications will now be apparent -to those skilled in the art, and it i5 therefore preferred that the lnstant invention be limited not by the specific disclosure herein, but only by the appending claims.
Finally, the licluid coolant leaves vortex chamber 87 via passaye 73 wherein it exits via opening 58 into groove 56.
Having described the structure and operation of the preferred flow resistance devices, the manner in which coolant flows from liquid coolant source through the entire bucket 10 will now be described. The buckets 10 receive a driviny force from a ho-t fluid moving in a direction generally parallel to the axis of rotation of rotor disk 20. The driving force of the hot fluid is transmitted to the shaft about which the rotor disk 20 is mounted via the buckets 10 and rotor disk 20 causiny the turbine to rotate about the axis of the shaft. ~he high rotational velocity of the rotor creates a substantial centrifugal force which urges the liquid coolant through the bucket in a radially outward direction. As the liquid coolant enters coolant supply passage 94, it is forced in a radially outward direction into standpipe 96 where it is collected in distribution channel 28. When the level of coolant in supply plenum 64 overflows, it passes through the individual flow resistance devices 66 into the respective platform coolant channels 76 and thereafter into the respective shank coolant channels 78. The coolant continues to advance in a generally radial direction to platform and foil coolant channels 30 and 32 to the tip of foil 18.
In the foregoillg embodiment, distribution channel 28 is located in the rim of rotor disc 20 below the 30 bucket 10. In aforementioned U.S. Patent No. 4,244,676 the manner in which a dlstrihution ahannel may be located in the platform portion 16 o:E bucke-t 10 i~ illustrated in Figures 1-4. A sirnllar arrangement may be used in connec-tion w.ith the presen-t application. ~, ~lthough ~everal preferred embodiments oE -this J~ .
' 31r^JL
inventlon have been described, many variations and modifications will now be apparent -to those skilled in the art, and it i5 therefore preferred that the lnstant invention be limited not by the specific disclosure herein, but only by the appending claims.
Claims (7)
1. A liquid coolant supply for use in a rotating element wherein rotation of the rota-ting element produces substantial outward-directed radial acceleration, comprising:
a plurality of coolant channels in said rotating element;
a plurality of flow-resistance devices, one per coolant channel;
means for feeding a cooling liquid to a radially outward portion of each of said flow resistance devices;
a path in each of said flow-resistance devices effective for permitting said fluid to flow radially inward to an exit opening;
means for conveying said fluid from said exit opening to its respective coolant channel; and all of said plurality of flow-resistance devices being effective to resist a fluid flow therethrough and being effective to meter a flow therethrough proportional to a function of a pressure head applied thereto.
a plurality of coolant channels in said rotating element;
a plurality of flow-resistance devices, one per coolant channel;
means for feeding a cooling liquid to a radially outward portion of each of said flow resistance devices;
a path in each of said flow-resistance devices effective for permitting said fluid to flow radially inward to an exit opening;
means for conveying said fluid from said exit opening to its respective coolant channel; and all of said plurality of flow-resistance devices being effective to resist a fluid flow therethrough and being effective to meter a flow therethrough proportional to a function of a pressure head applied thereto.
2. The liquid coolant supply of claim 1, wherein said flow resistance devices each include a tortuous path formed of a plurality of bends.
3. The liquid coolant supply of claim 1, wherein said flow resistance devices each include a flow resistant orifice.
4. The liquid coolant supply of claim 1, wherein said flow resistance devices each include a plurality of vortex flow chambers.
5. The liquid coolant supply of claim 1, 2 or 3, wherein said path includes a respective strainer located between said radially outward portion and each of said flow resistance devices.
6. The liquid coolant supply of claim 4, wherein said path includes a respective strainer located between said radially outward portion and each of said flow resistance devices.
7. The liquid coolant supply of claim 1 wherein said means for feeding a cooling liquid to a radially outward portion includes a standpipe and a plenum, said cooling liquid being urged into said plenum by said outward-directed radial acceleration.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US17660080A | 1980-08-08 | 1980-08-08 | |
| US176,600 | 1994-01-03 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1159371A true CA1159371A (en) | 1983-12-27 |
Family
ID=22645036
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000381075A Expired CA1159371A (en) | 1980-08-08 | 1981-07-03 | Metering water to turbine bucket cooling passages by flow resistance devices |
Country Status (8)
| Country | Link |
|---|---|
| JP (1) | JPS5756629A (en) |
| CA (1) | CA1159371A (en) |
| DE (1) | DE3129853A1 (en) |
| FR (1) | FR2488327A1 (en) |
| GB (1) | GB2082257B (en) |
| IT (1) | IT1138056B (en) |
| NL (1) | NL8103719A (en) |
| NO (1) | NO812670L (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5977675U (en) * | 1982-11-16 | 1984-05-25 | 前澤給装工業株式会社 | air valve |
| JPH068793U (en) * | 1991-01-29 | 1994-02-04 | 日本ドライケミカル株式会社 | Fire pump water pump |
| JP2516580Y2 (en) * | 1991-05-02 | 1996-11-06 | 敏雄 矢野 | Lever type compound air valve |
| JP2552229Y2 (en) * | 1993-06-16 | 1997-10-29 | 株式会社清水合金製作所 | Air valve |
| DE19961565A1 (en) * | 1999-12-20 | 2001-06-21 | Abb Alstom Power Ch Ag | Coolant flow at a turbine paddle is adjusted by an inserted body into an opening in the coolant channel which reduces its cross section to give the required coolant flow vol |
| US6390774B1 (en) | 2000-02-02 | 2002-05-21 | General Electric Company | Gas turbine bucket cooling circuit and related process |
| EP3287596A1 (en) * | 2016-08-25 | 2018-02-28 | Siemens Aktiengesellschaft | A platform cooling device for a blade of a turbomachine and a turbomachine arrangement |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3658439A (en) * | 1970-11-27 | 1972-04-25 | Gen Electric | Metering of liquid coolant in open-circuit liquid-cooled gas turbines |
| US3804551A (en) * | 1972-09-01 | 1974-04-16 | Gen Electric | System for the introduction of coolant into open-circuit cooled turbine buckets |
| US4017210A (en) * | 1976-02-19 | 1977-04-12 | General Electric Company | Liquid-cooled turbine bucket with integral distribution and metering system |
| US4212587A (en) * | 1978-05-30 | 1980-07-15 | General Electric Company | Cooling system for a gas turbine using V-shaped notch weirs |
| US4244676A (en) * | 1979-06-01 | 1981-01-13 | General Electric Company | Cooling system for a gas turbine using a cylindrical insert having V-shaped notch weirs |
-
1981
- 1981-06-25 GB GB8119674A patent/GB2082257B/en not_active Expired
- 1981-07-03 CA CA000381075A patent/CA1159371A/en not_active Expired
- 1981-07-15 IT IT22933/81A patent/IT1138056B/en active
- 1981-07-29 DE DE19813129853 patent/DE3129853A1/en not_active Withdrawn
- 1981-08-05 FR FR8115150A patent/FR2488327A1/en not_active Withdrawn
- 1981-08-06 NO NO812670A patent/NO812670L/en unknown
- 1981-08-06 NL NL8103719A patent/NL8103719A/en not_active Application Discontinuation
- 1981-08-07 JP JP56123155A patent/JPS5756629A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| IT1138056B (en) | 1986-09-10 |
| JPS5756629A (en) | 1982-04-05 |
| IT8122933A0 (en) | 1981-07-15 |
| GB2082257B (en) | 1984-02-15 |
| NO812670L (en) | 1982-02-09 |
| DE3129853A1 (en) | 1982-03-18 |
| GB2082257A (en) | 1982-03-03 |
| FR2488327A1 (en) | 1982-02-12 |
| NL8103719A (en) | 1982-03-01 |
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