Cooling medium path structure for gas turbine blade

A cooling medium path structure for cooling a gas turbine blade. The structure includes 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 therebetween. 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. Thus, the sealing property of the contact portions of the structure is secured so as to allow a cooling medium to be supplied without leaking from the cooling medium paths. The heat of the cooling medium, generated as a result of cooling the high-temperature portion of the gas turbine, can be recovered so as to make the best use of the heated medium.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a cooling medium path structure of a root 
portion of a gas turbine blade. 
2. Description of the Related Art 
The structure of a conventional cooling medium path of the above type will 
be described with reference to FIGS. 11 through 13. 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. 
Each 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. 
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 path 9 for allowing a cooling medium 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 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 l 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 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 that gaps will be 
left unoccupied in some places even after assembly. 
In FIGS. 11 and 13, 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 from the gap around the cooling 
medium 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 of recovering and using the cooling medium heated 
to a high temperature after being 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 abovedescribed 
disadvantages of the conventional cooling medium path structure and to 
provide a cooling medium path structure which is simple and which is 
capable of preventing the leakage of a cooling medium and facilitating 
supply and collection of the cooling medium. 
The cooling medium path structure for a gas turbine blade according to the 
present invention comprises a disk-side cooling medium path provided in a 
turbine disk, a blade-side cooling medium 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 path, and a delivery block 
disposed between the disk-side cooling medium path and the elbow-shaped 
projection so as to establish communication between them. 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 path. And, the cooling medium paths of the 
present invention are intended to realize that the delivery of a cooling 
medium between the disk-side cooling medium paths and the blade-side 
cooling medium 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 path so that leakage of the cooling medium is 
prevented to secure the sealing performance of the cooling medium 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 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. 
Also 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 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 path and a plurality of 
ring-shaped members inscribing the outer surface of the delivery block are 
laid one above another, respectively. Also the ring-shaped members which 
come into contact with the inner surface of each of the cooling medium 
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. 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 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 at least one of the elbow-shaped 
projection and the disk-side cooling medium 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. 
A further feature of the present invention resides in that where the 
disk-side cooling medium path and the blade-side cooling medium path are 
connected to each other through the elbow-shaped delivery block, an E-type 
seal or a C-type seal is inserted into each of the connection portions of 
the delivery block and the two cooling medium paths so that the sealing 
property of the connected portions is improved by making the best use of 
the elastic force of the seals.

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. 11 through 13 
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 also having the shape of an inverted 
Christmas tree and formed in a turbine disk 2. The turbine disk 2 is 
provided with a plurality of radial directional cooling medium paths 10 
for guiding a cooling medium. Further, in the root portion of the turbine 
blade 1 there is provided a cooling medium 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 elbowshaped 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 path 10 and 
the blade-side cooling medium 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 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 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 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 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 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 paths 5 and 10 or against a 
possible movement due to 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 path 10 and then the upper end thereof is inserted into the 
blade-side cooling medium 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 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 of the case where a 
cooling medium is supplied from the disc-side cooling medium path 10 
toward the blade-side cooling medium path 5. However, there is also 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 collection system is substantially the same in structure, function 
and effect as the supply system, the present invention will be described 
in this specification by stressing that the cooling medium supply system 
also covers 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 path 5 to be integrated therewith by seal weld 3b. 
Thus, by so forming the elbow-shaped projection 3a, it is possible to 
construct this portion in a more simplified manner. 
It should be noted that the remaining structure and function of the 
delivery block 4 and other associated structure 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 path 10. These 
ring-shaped members 7a-7i have different inner and outer diameters between 
adjacent ring-shaped members alternately in the vertical direction and are 
made of materials having different coefficients 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 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 maintains 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-7i 
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 paths 5 and 10 and a like slight gap "b" from 
the delivery block 4 and also keep a like gap "c" between member which are 
adjacent to one another in the vertical direction. However, 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-7i in the 
above manner, the sealing property of the structure id both the radial and 
vertical directions is secured by the close contact of the ring-shaped 
members with the cooling medium paths 5 and 10, the delivery block 4 or 
among themselves. 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 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 placed in a predetermined position as 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 locate the delivery block 4 
in the predetermined position shown in the figure. 
The sealing of the delivery block 4 with respect to the blade-side cooling 
medium path 5 is provided by a flexible ring-shaped projection 4a while 
the sealing of the delivery block 4 with respect to the disk-side cooling 
medium path 10 is provided 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 provide 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 provide 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 path 5 are brought into 
engagement with each other by the screwed engagement sections 4d and 4e 
through the circular ring 20 to provide an improved sealing property while 
the delivery block 4 and the disk-side cooling medium 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. 
Lastly, a fourth embodiment of the present invention will be described with 
reference to FIG. 10 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 through third embodiment of the 
present invention without making any redundant description of these like 
parts. 
The structure according to this embodiment is such that the blade-side 
cooling medium path 5 and the disk-side cooling medium path 10 are 
arranged so as to communicate with an elbow-shaped delivery block 9. 
That is, the elbow-shaped delivery block 9 is connected to the disk-side 
cooling medium path 10 by a bolt 24. In that case, a C-type seal 22 is 
interposed between block A and disc Z to thereby improve the sealing 
property of the flange surface. 
At the same time, the elbow-shaped delivery block 9 has an E-type of type 
seal 21 interposed between the upper end the block 9 is connected to the 
root portion of the mating blade by means of bolts and the like (not 
shown) to thereby establish its communication with the blade-side cooling 
medium path 5. 
Further, at the connection portion in which the E-type seal 21 is 
interposed, there is arranged a cover plate 23 for covering the connection 
portion. 
In the case of this fourth embodiment, the blade-side cooling medium path 5 
and the disk-side cooling medium path 10 are arranged made to communicate 
with each other by the elbow-shaped delivery block 9 in the 
above-described manner and in that case, since the C-type seal 22 and the 
E-type seal 21 are interposed therein, the sealing property of one of the 
connection portions is secured by the C-type seal 22 while the sealing 
property of the other connection portion is secured by the E-type seal 21. 
Furthermore, since the E-type seal 21 is arranged with its inner side 
directed inward as shown, a spring force generated in the E-type seal 21 
due to the difference between the pressure of the cooling medium flowing 
inside and the pressure outside the E-type seal-21 so that the sealing 
property of the E-type seal 21 is further secured and at the same time, 
since the E-type seal 21 is brought into line-contacts with the blade root 
portion and the elbow-shaped delivery block 9, the flexibility of these 
contact portions can be secured, 
It should be noted that although the present invention has been described 
with reference to several embodiments shown in the drawings, the invention 
is not limited thereto and it goes without saying that various kinds of 
modifications and changes may be made, without departing from the scope of 
the present invention. 
As described above, the present invention provides a cooling medium path 
structure for the blades of a gas turbine. The structure comprises a 
disk-side cooling medium path, a blade-side cooling medium path, an 
elbow-shaped projection forming an entrance and an exit at both ends of 
the blade-side cooling medium path and a delivery block provided with an 
elastic engaging section and disposed between the disk-side cooling medium 
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 path whereby the delivery of 
the cooling medium between the disk-side and the blade-side cooling medium 
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 recover 
the cooling medium after being 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. 
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 leakage of the cooling medium and 
vibrations etc. are reliably provided 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 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 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 
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 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 path, the disk-side cooling 
medium path and the delivery block relative to one another and to surely 
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 at least one of the elbow-shaped projection and the 
disk-side cooling medium path so that the surface pressure of the contact 
surface is increased by such a screw-engagement so as 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. 
Moreover, the cooling medium path structure according to the present 
invention comprises the disk-side cooling medium path, the blade-side 
cooling medium path and the elbow-shaped delivery block disposed between 
the entrance and exit at both ends of the blade-side cooling medium path 
and the disk-side cooling medium path so as to establish communication 
between them and wherein the delivery block is brought into elastic 
engagement with the blade-side cooling medium path and the disk-side 
cooling medium path through the E-type seals or C-type seals thereby 
forming a cooling medium path structure for the blades of a gas turbine so 
that it is possible to improve and secure the sealing property and the 
flexibility of the structure by making use of the characteristics of the 
C-type or E-type seals arranged at the connection portions of the delivery 
block with the respective cooling medium paths and to make the structure 
safe, accurate and suitable for practical use.