Connector for the transfer of a cooling fluid from a rotor disc to a turbomachine blade

Abstract: An improved cooling medium path structure for cooling a gas turbine blade comprising a disk-side cooling medium path, a blade-side cooling medium path formed at the root portion of the blade and a delivery block disposed between the two cooling medium paths so as to establish communication between them. The delivery block is provided with an elastic engaging section which comes into elastic and line- contact with the disk-side cooling medium path and the blade-side cooling medium path whereby the sealing property of the contact portions of the structure is secured to allow a cooling medium to be supplied without leaking from the cooling medium paths and the heat of the cooling medium generated as a result of cooling the high-temperature portion of the gas turbine can be taken out so as to make the best use of it for other purposes.

Description: BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a cooling medium flow path structure of a root portion of a gas turbine blade. Prior Art The structure of a conventional cooling medium flow path of the above type will be described with reference to Figs. 10 through 12. In the outer periphery of a turbine disk 2 there are formed in the axial direction a plurality of inverted Christmas tree-shaped blade grooves 7 at equal intervals in the circumferential direction so as to correspond in number to turbine blades 1 fitted in the respective stages. At the same time, in a root portion of the turbine blade 1, there are provided inverted Christmas tree-shaped portions 8 which can be assembled into the above-mentioned inverted Christmas tree-shaped grooves 7 with a very small gap therebetween. The turbine blade 1 is inserted to be assembled into the respective groove of the turbine disk 2 one by one in the axial direction so that during the operation of the turbine, the turbine disk 2 bears the centrifugal force and the vibrating force through a teeth engagement of the inverted Christmas tree-shaped groove 7 and the same-shaped portion 8, such an arrangement is disclosed in the document GB-A-2 224 082. Further, once the turbine blade 1 is so assembled into the turbine disk 2, then it is so designed that the shapes of the blade groove 7 of the turbine disk 2 and the mating portion 8 at the root portion of the turbine blade 1 secure a cooling medium flow path 9 for allowing a cooling medium to flow in the bottom portion of the blade 1. The cooling medium (usually a compressed air) for cooling the turbine blades 1 passes through radial directional holes 10, which are the same in number as the blades of the respective stage and which are formed on the side of entrance of the turbine disk 2 and is introduced into a space 14 surrounded by sealing blocks 12 and 13. After that, the cooling medium is introduced into the cooling medium flow path 9 formed at the bottom portion of the inverted Christmas tree-shaped portion 8, enters a passage (not shown) formed at the root portion of the turbine blade 1 and flows into the interior of the blade 1 thereby cooling the whole of the blade. The cooling medium having thus cooled the blade 1 is discharged into a subsequent gas path. In the mentioned course of a series of flows of the cooling medium, the cooling medium flow path 9, which is formed between the blade groove 7 and the portion 8 formed at the root portion of the turbine blade 1, defines the space 14 surrounded by the sealing blocks 12 and 13 at the entrance of the disk 2 located on the upstream side of the above-mentioned gas path while it is defined by a sealing piece 15 and a fixing piece 16 at the exit of the disk 2 located on the downstream side of the gas path. Normally, the upstream side sealing block 12 and the downstream side sealing piece 15 are provided for every two blades 1 and the upstream side sealing block 13 and the downstream side fixing piece 16 are provided for each blade 1 and all of these parts are assembled at their proper positions, respectively. Accordingly, in order to assemble these parts and the other parts associated therewith, it becomes necessary to provide suitable spaces for receiving them in position so that it is unavoidable to allow gaps to be left unoccupied in some places even after they have been assembled. In Figs. 10 and 12, reference numeral 17 designates a sealing plate for covering a small gap formed between the inverted Christmas tree-shaped groove 7 and the mating portion 8 of the same shape and since this plate 17 is usually used for each of the blades 1, there is left a space required for assembling it. As described above, it has been usual with the conventional cooling medium path structure that there exist, in the structure, various kinds of spaces or gaps left intentionally or resultantly for the convenience of designing, manufacturing and assembling the entire structure so that even when cooling air or the like as a cooling medium is supplied through the holes drilled in the disk 2, it leaks fromthe gap around the cooling medium flow path or the sealing plate so that the cooling air or the like cannot be collected but is discharged into the gas path. Consequently, there has been a problem to take out and use of the cooling medium heated to a high temperature after used for cooling and the resultant thermal efficiency loss has been unavoidable. SUMMARY OF THE INVENTION The present invention has been made to eliminate the above-described disadvantages of the conventional cooling medium flow path structure and to provide a cooling medium flow path structure which is simple and which is capable of preventing the leakage of a cooling medium and facilitating the supply and collection of the cooling medium. The cooling medium flow path structure for a gas turbine blade according to the present invention comprises a disk-side cooling medium flow path provided in a turbine disk, a blade-side cooling medium flow path provided in a root portion of the blade, an elbow-shaped projection forming an entrance and an exit of both ends of the blade-side cooling medium flow path, and a delivery block disposed between the disk-side cooling medium flow path and the elbow-shaped projection so as to establish communication between them, wherein the delivery block is provided with an elastic engaging section capable of coming into elastic contact with at least one of the elbow-shaped projection and the disk-side cooling medium flow path, and the cooling medium flow paths of the present invention are intended to realize that the delivery of a cooling medium between the disk-side cooling medium flow paths and the blade-side cooling medium flow path is performed through the elbow-shaped projection and the delivery block such that the elastic engaging section of the delivery block comes into elastic contact with the elbow-shaped projection and the disk-side cooling medium flow path whereby the leakage of the cooling medium is prevented to secure the sealing performance of the cooling medium flow path and the flexible connection of the delivery block with the cooling medium paths is attained without giving rise to an adverse effect on the vibrating characteristic of the gas turbine blade. With the basic structure described above, another feature of the present invention resides in that the elastic engaging section of the delivery block is formed of a ring-shaped projection and a plurality of slits extending axially from the open ends of the delivery block such that the ring-shaped projection comes into line-contact with the mating cooling medium flow path so that the flexibility of the delivery block with respect to the axial deviation from each of the cooling medium paths or the movement of the vibrations etc. of the blades is secured to a sufficient degree and the presence of the slits at the open ends of the delivery block secures the spring forces of the delivery block at both of the open ends resulting in further securing the sealing performance by the line contact of each of the projections with the mating cooling medium flow path. Still another feature of the present invention resides in that the elastic engaging section of the delivery block is formed such that a plurality of ring-shaped members circumscribing the inner surface of the elbow-shaped projection or the disk-side cooling medium flow path and a plurality of ring-shaped members inscribing the outer surface of the delivery block are laid one above another, respectively, and the ring-shaped members which come into contact with the inner surface of each of the cooling medium flow paths and the ring-shaped members which come into contact with the outer surface of the delivery block share their sealing positions, respectively. Further, since the respective ring-shaped members are urged toward the blade side due to a centrifugal force, their close contactability and sealing property are secured and also since the ring-shaped members themselves are movable in the radial direction, their flexibility with respect to the axial deviation of the delivery block from the disk-side or blade-side cooling medium flow path or the movement of the vibration etc. of each of the blades can be secured. A further feature of the present invention resides in that the intermediate portion of the delivery block exposed outside the elbow-shaped projection and the disk of the turbine is covered with a spacer band so that the relative position of the elbow-shaped projection with respect to the disk of the turbine can be securely maintained. A further feature of the present invention resides in that the delivery block comes into screw-engagement with one of the elbow-shaped projection and the disk-side cooling medium flow path so that when the delivery block is set at a predetermined position, the surface pressure of the contact surfaces of the two members is increased by making use of the clamping force of the screw-engagement thereby improving the sealing property of the delivery block. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic diagram showing a structural relationship between a blade and a disk of a gas turbine according to a first embodiment of the present invention; Fig. 2 is an illustrative view , on an enlarged scale, of an A-section as an essential portion of Fig. 1; Fig. 3 is an illustrative view showing a partial modification of the structure shown in Fig. 2; Fig. 4 is a schematic diagram mainly showing a delivery block disposed between a blade and a disk of a gas turbine according to a second embodiment of the present invention; Fig. 5 is an illustrative view showing, on an enlarged scale, a state in which ring-shaped members shown in Fig. 4 are assembled; Fig. 6 is an illustrative view showing, on an enlarged scale, a state in which the ring-shaped members shown in Fig. 4 are in operation; Fig. 7 is a schematic diagram of a delivery block between a blade and a disk of a gas turbine according to a third embodiment of the present invention; Fig. 8 is a schematic diagram showing a partial modification of the delivery block shown in Fig. 7; Fig. 9 is a schematic diagram showing another partial modification of the delivery block shown in Fig. 7; Fig. 10 is a schematic diagram showing a structural relationship between a blade and a disk of a conventional gas turbine; Fig. 11 is a schematic diagram of an upstream side of the structure shown in Fig. 10 especially when viewed along the arrow-indicated XII - XII line; and Fig. 12 is a schematic diagram of a downstream side of the structure shown in Fig. 10 especially when viewed along the arrowindicated XIII - XIII line. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will now be described with reference to Fig. 1 wherein like parts are designated by like reference numerals used with respect to the structure of the conventional gas turbine described in the foregoing with reference to Figs. 10 through 12 and no redundant description of these like parts is made herein. In Fig. 1, reference numeral 1 designates a turbine blade whose root portion is in the shape of an inverted Christmas tree (not shown) and which is in engagement with a groove having the same shape of an inverted Christmas tree as the blade 1 and formed in a turbine disk 2. The turbine disk 2 is provided with a plurality of radial directional cooling medium flow paths 10 for guiding a cooling medium. Further, in the root portion of the turbine blade 1 there is provided a cooling medium flow path 5 for guiding the cooling medium to a blade cooling section (not shown). As shown in detail in Fig. 2 which is an enlarged sectional view of the A-portion shown in Fig. 1, an entrance and an exit of the cooling medium path 5 for the turbine blade 1 are formed with an elbow-shaped projection 3 where a delivery block 4 in the shape of a thin tube is disposed so as to establish communication between the disk-side cooling medium flow path 10 and the blade-side cooling medium flow path 5. The delivery block 4 has a ring-shaped projection 4a at a position near one end thereof which is fitted in the blade-side cooling medium flow path 5 and a ring-shaped projection 4b at a position near the other end thereof which is fitted in the disk-side cooling medium flow path 10, so that the surfaces of the ring-shaped projections 4a and 4b come into line-contact with the inner peripheral surfaces of the cooling medium flow paths 5 and 10, respectively. Further, the delivery block 4 is provided at both ends thereof with a plurality of slits 4c extending in the axial direction of the delivery block 4 from near the ring-shaped projections 4a and 4b up to the ends, respectively. Further, the intermediate portion of the delivery block 4, that is, the portion lying outside the cooling medium flow paths 5 and 10 is wound with a spacer band 6 around its outer peripheral surface. With the above structure, since the ring-shaped projections 4a and 4b on both sides of the delivery block 4 are in line-contact with the inner peripheral surfaces of the cooling medium flow paths 5 and 10, the flexibility of the delivery block 4 against a possible deviation of the axis thereof from the axis of each of the cooling medium flow paths 5 and 10 or against a possible movement of vibrations etc. is maintained to thereby secure the sealing property of the delivery block 4 at the line-contact portions. In addition, due to the provision of the plurality of slits 4c extending from near the projections 4a and 4b up to each end of the delivery block 4, a spring force acts on each of the projections 4a and 4b so that the line-contacts of the projections 4a and 4b with the cooling medium paths 5 and 10 can be further secured. Further, the delivery block 4 shown by solid lines in Fig. 2 is set up at a position in such a manner that, as shown by a two-dot chain line L, the lower end of the delivery block 4 is inserted into the disk-side cooling medium flow path 10 and then the upper end thereof is inserted into the blade-side cooling medium flow path 5 in the elbow-shaped projection 3 while the lower end thereof is raised. After the above process, the outer peripheral surface of the intermediate portion of the delivery block 4 lying outside the cooling medium flow paths 5 and 10 is covered with the spacer band 6 so that the delivery block 4 is held in position and protected against any external damage. It is to be noted that the description here is made in mind with a case where a cooling medium is supplied from the disc-side cooling medium flow path 10 toward the blade-side cooling medium flow path 5, however, there is also a flow of a cooling medium collection system which is substantially right and left symmetrical and extends from the blade side to the disk side and since this collecting system is substantially the same in structure, function and effect as the supply system, the present invention will be described in this specification by laying stress on the cooling medium supply system as covering also the collecting system. Further, a partial modification of said embodiment of the present invention is shown in Fig. 3 in which the elbow-shaped projection 3a is formed not integrally with, but separately from, the blade root portion and a terminal end of the projection 3a is inserted into the blade-side cooling medium flow path 5 to be integrated therewith by a seal weld 3b. It should be noted that the remaining structure and function of the delivery block 4 and others are the same as those shown in Fig. 2 and illustration thereof is omitted. Next, a second embodiment of the present invention will be described with reference to Figs. 4 through 6 wherein like parts are designated by like reference numerals with no redundant description of the like parts. In this second embodiment, a plurality.of ring-shaped members 7a - 7e are arranged in layers at a position where the delivery block 4 is fitted into the blade-side cooling medium path 5 and a plurality of ring-shaped members 7f - 7j are arranged in layers at a position where the delivery block 4 is fitted into the disk-side cooling medium flow path 10. These ring-shaped members 7a - 7j have different inner and outer diameters between adjacent ring-shaped members alternately in the vertical direction and are made of materials having different coefficient of thermal expansion with the members of larger diameters having a larger coefficient of thermal expansion and vice versa. That is, each of the members 7a, 7c, 7e and each of the members 7f, 7h, 7j are of a larger diameter and the outer peripheral surface thereof substantially circumscribes the inner surface of each of the cooling medium flow paths 5 and 10 while the inner peripheral surface thereof keeps a sufficient gap from the outer peripheral surface of the delivery block 4. Further, each of the members 7b, 7d which are arranged alternately with the members 7a, 7c, 7e and each of the members 7g, 7i which are arranged alternately with the members 7f, 7h and 7j are of a small diameter and the outer peripheral surface thereof keeps a sufficient gap from the inner peripheral surface of each of the cooling medium paths 5 and 10 while the inner peripheral surface thereof substantially inscribe the outer peripheral surface of the delivery block 4. Further, the upper ring-shaped members 7a - 7e fitted in the blade-side cooling medium path 5 are arranged in layers substantially in close contact with one another and likewise, the lower ring-shaped members 7f - 7j are arranged in layers substantially in close contact with one another. The above conditions of the ring-shaped members are shown in Figs. 5 and 6 on an enlarged scale. That is, as shown in Fig. 5, the ring-shaped members 7a - 7j are arranged such that in order to secure a freedom of assembly, they keep a slight gap "a" (substantially equal to a contact) from the respective cooling medium flow paths 5 and 10 and a like slight gap "b" from the delivery block 4 and also keep a like gap "c" between themselves adjacent to one another in the vertical direction but when the gas turbine is in operation, the above-mentioned gaps a - c change to a' - c' due to a change in thermal expansion as shown in Fig. 6 so that the ring-shaped members are securely brought into close contact with one another so as to be in a completely gap-less state. From the above circumstance, in this specification, the gaps a - c shown in Fig. 5 with respect to the ring-shaped members are described as being substantially equal to a contact. In this embodiment of the present invention, due to the arrangement of the ring-shaped members 7a - 7j in the above manner, the sealing property of the structure in both the radial and vertical directions is secured by the close contact of the ring-shaped members with the cooling medium flow paths 5 and 10, the delivery block 4 or among themselves and further, due to the sufficient gaps provided on the side opposite the contact portions of the ring-shaped members 7a - 7j, the flexibility of the structure against the axial displacement between the blade-side and disk-side cooling medium paths 5 and 10 or against the movement of vibrations etc. of the blades can be secured. Next, a third embodiment of the present invention will be described with reference to Figs. 7 through 9 wherein like parts are designated by like reference numerals used with respect to the above-described conventional structure and the structures according to the first and second embodiment of the present invention and a redundant description of these like parts is omitted. This embodiment of the present invention features that the connection of the delivery block 4 to the turbine disk 2 or the elbow-shaped projection 3 is performed through a screw-mechanism . That is, the structure shown in Fig. 7 is such that a screw-threaded ring 8 having its inner and outer surfaces screw-threaded is screwed into the turbine disk 2, the delivery block 4 is brought into engagement with the inner screw-threaded surface of the ring 8 thereby securing the sealing property of the structure through such screw-engagement surfaces. In assembly, the ring 8 is set to a predetermined position shown in Fig. 7, then the delivery block 4 is caused to sink below the ring 8 as shown by a two-dot chain line and after that, the delivery block 4 is raised upward as it is turned round to thereby set the delivery block 4 to the predetermined position shown in the figure. The sealing of the delivery block 4 with respect to the blade-side cooling medium flow path 5 is taken charge of by a flexible ring-shaped projection 4a while the sealing of the delivery block 4 with respect to the disk-side cooling medium flow path 10 is taken charge of by the sealing surfaces 8a and 8b of the screw-threaded ring 8 coming into engagement with the the disc 2 and the delivery block 4. Figs. 8 and 9 show partial modifications of the third embodiment of the present invention of which the structure shown in Fig. 8 is such that the upper end of the delivery block 4 is expanded and the inner peripheral surface of the expanded portion is screw-threaded to have a female-screw to thereby form an engagement section 4d which is clamped with a male-screw formed on the terminal end of the elbow-shaped projection 3 with a circular ring 20 interposed therebetween. Further, the structure shown in Fig. 9 is such that instead of expanding the upper end of the delivery block 4, the outer peripheral surface of the upper end of the delivery block 4 is screw-threaded to have a male-screwed engagement section 4e which is clamped with the female-screwed terminal end of the elbow-shaped projection 3 with the circular ring 20 interposed therebetween. That is, according to the structures shown in Figs. 8 and 9, the delivery block 4 and the blade-side cooling medium flow path 5 are brought into engagement with each other by the screwed engagement sections 4d and 4e through the circular ring 20 with an improved sealing property while the delivery block 4 and the disk-side cooling medium flow path 10 are connected to each other through the ring-shaped projection 4b formed on the outer peripheral surface of the delivery block 4 thereby maintaining a sufficient degree of sealing property and flexibility. As described above, the present invention provides a cooling medium path structure for the blades of a gas turbine, which comprises a disk-side cooling medium flow path, a blade-side cooling medium flow path, an elbow-shaped projection forming an entrance and an exit at both ends of the blade-side cooling medium flow path and a delivery block provided with an elastic engaging section and disposed between the disk-side cooling medium flow path and the elbow-shaped projection so as to establish communication between them with the elastic engaging section of the delivery block coming into elastic engagement with at least one of the elbow-shaped projection and the disk-side cooling medium flow path whereby the delivery of the cooling medium between the disk-side and the blade-side cooling medium flow paths is performed securely and accurately with a sufficient degree of flexibility against vibrations etc. while keeping the sealing property of the structure because of the elastic engagement structure of the delivery block. Accordingly, it has become possible with the present invention to securely collect the cooling medium heated to a high temperature as a result of cooling the high-temperature portion of the gas turbine and to make the best use of such high-temperature cooling medium for other purposes by taking it out . Further, according to the present invention, since the elastic engaging section of the delivery block is formed in an extremely simple structure of the ring-shaped projections and a plurality of slits extending axially to both open ends of the delivery block, the sealing function and flexibility of the structure against the leakage of the cooling medium and vibrations etc. are displayed securely and it is possible to further improve the effect of collecting the heat of the gas turbine by the provision of such a cooling medium flow path structure that is excellent from economical and functional points of view. Further, according to the present invention, the elastic engaging section of the delivery block is formed by laying one above another a plurality of ring-shaped members circumscribing the inner surface of the elbow-shaped projection or the disk-side cooling medium flow path and a plurality of ring-shaped members inscribing the outer surface of the delivery block so that by making use of the phenomenon of thermal expansion of the ring-shaped members contacting the inner surface of the cooling medium flow paths and those contacting the outer surface of the delivery block and the centrifugal force acting on the overlapped ring-shaped members, it is possible to improve the sealing effect and the flexibility of the structure thereby enabling the effective delivery of the cooling medium and to make the effective use of the heat of the high temperature of the gas turbine. Still further, since the intermediate portion of the delivery block lying between the elbow-shaped projection and the turbine disk is covered with the spacer band, it is possible to accurately maintain the positional arrangement of the blade-side cooling medium flow path, the disk-side cooling medium flow path and the delivery block relative to one another and to perform the delivery of the cooling medium securely, thereby increasing the availability and reliability of the structure. According to the present invention, the delivery block is brought into screw-engagement with one of the elbow-shaped projection and the disk-side cooling medium flow path so that the surface pressure of the contact surface is increased by such a screw-engagement to enable the construction of a cooling medium delivery system having a sharply improved sealing property and it is possible to sharply enhance the possibility of realization of heat collection of the turbine through the cooling medium and the effective use of the collected heat.

Claims: A cooling medium flow path structure for a gas turbine blade, comprising: a disk-side cooling medium flow path (10) provided in a turbine disk (2); a blade-side cooling mediumflow path (5) provided in a root portion of the blade (1); characterised by an elbow-shaped projection (3) forming an entrance and an exit at both ends of the blade-side cooling medium flow path (5); and a delivery block (4) disposed between the disk-side cooling medium flow path (10.) and the elbow-shaped projection (3) so as to establish communication therebetween, wherein said delivery block (4) is provided with an elastic engaging section coming into elastic engagement with at least one of said elbow-shaped projection (3) and said disk-side cooling medium flow path (10). The cooling medium flow path structure as described in claim 1, wherein the elastic engaging section of said delivery block (4) is formed of a ring-shaped projection (4a,4b) and a plurality of slits (4c) extending axially from an open end of said delivery block (4). The cooling medium flow path structure as described in claim 1, wherein the elastic engaging section of said delivery block (4) is formed in such a manner that a plurality of ring-shaped members (7a,7c,7e,7f,7h,7j) circumscribing an inner peripheral surface of said elbow-shaped projection (3) or said disk-side cooling medium flow path (10) and a plurality of ring-shaped members (7b, 7d, 7g, 7i) inscribing an outer peripheral surface of said delivery block (4) are laid one above another, respectively. The cooling medium flow path structure as described in claim 2 or 3, wherein said delivery block (4) is covered with a spacer band (6) between said elbow-shaped projection (3) and said turbine disk (2). The cooling medium flow path structure as described in claim 1, wherein said delivery block (4) is in screw-engagement with one of said elbow-shaped projection (3) and said disk-side cooling medium flow path (10).

Inventors: MATSUO ASAHARU, MATSUO, ASAHARU, Matsuo, Asaharu, Mitsubishi Heavy Industries Ltd.
Applicants: MITSUBISHI HEAVY IND LTD, MITSUBISHI HEAVY INDUSTRIES, LTD.
Application year: 1998
Main classification: F01D5
IPC codes: F01D5, F02C7, F01D11