US 3010696 A
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Nov. 28, 1961 Filed Sept. 10, 1956 A. B. EV ETT BLADED OR TH MEA TO SUPPLY FLUID FA GES IN THE BLADES 4 Sheets-Sheet 1 Nov. 28, 1961 BLADED lgT Filed Sept. I 10, 1956 I I I Hi 1. j 56 A. B. EVERET OR WITH MEANS PASSAGES IN T su Y FLUID BLA 4 Sheets-Sheet 2 Nov. 28, 1961 A. B. EVERETT 3,010,696
- BLADED OR WITH MEANS SUPPLY FLUID PASSAGES IN T BLADES Filed Sept. 10, 1956 4 Sheets-Sheet 3 Nov. 28, 1961 A. B. EVERETT 3,
BLADED ROTOR WITH MEANS SUPPLY FLUID TO PASSAGES IN T BLADES Filed Sept. 10, 1956 4 Sheets-Sheet 4 United States Patent 3,010,696 BLADED ROTOR WITH MEANS T0 SUPPLY FLUID TO PASSAGES IN THE BLADES Anthony Bernard Everett, Littleover, England, assignor to Rolls-Royce Limited, Derby, England, a British comp y Filed Sept. 10, 1956, Ser. No. 608,897 Claims priority, application Great Britain Sept. 26, 1955 6 Claims. (Cl. 253-3915) This invention relates to axial-flow fluid machines, such for instance as axial-flow turbines or compressors as used in gas-turbine engines, of the class which has a rotor comprising a rotor disc and a ring of blades mounted on the periphery of the disc by means of extended blade roots which include shouldered attachment portions engaging in the disc and outwardly-extending portions defining a series of axially-extending spaces radially inwards of the working fluid passage of the machine. Such a bladed rotor will be referred to as a bladed rotor as set forth.
It is often desirable, for instance for the purpose of cooling turbine rotor blades, to deliver a fluid to passages formed within the blades, and this invention has for an object to provide improved means for supplying a fluid to such passages.
According to the present invention, a bladed rotor as set forth is provided with blades which have fluid flow passage means therein, at least one end of the passage means in each blade opening to one of the axiallyextending spaces between its root and the roots of the adjacent blades, and with an annular plate which is mounted on the rotor disc in spaced relation to the disc periphery to define an annular manifold space which communicates with the passage means, and which defines with the disc a path for the supply of fluid to the manifold space from a point at lesser radius than the manifold space.
In one preferred construction according to this invention, each blade also has another end of the flow passage means opening through an axially-facing surface of the root portion to the manifold space to receive fluid therefrom, the fluid flowing from the passages at said one end thereof into said axially-extending spaces which are blanked ofl from the manifold space.
In another preferred construction according to this invention, said one end of the passage means in each blade opens to the axially-extending space to one side of the root of the blade and the other end of the passage means opens to the axially-extending space on the opposite side of the root, one of said spaces being open to the manifold space and the other being blanked-off from the manifold space.
According to a feature of this invention applicable to either of the preferred constructions just set forth, the bladed rotor may comprise a further annular plate mounted on the rotor disc between the manifold-spaceforming plate and the disc periphery and in contact with the disc periphery and blade roots to cover the adjacent ends of the axially-extending spaces, there being holes in the further annular plate, which holes in the first-mentioned preferred construction register with the ends of the passage means where they open to the axially-facing surfaces of the blade roots and which holes in the second preferred arrangement are aligned with alternate ones of the axially-extending spaces between the blade roots so that some of the spaces serve to feed fiuid to the passage means in the blades and others serve to receive the fluid after it has flowed through the blades. The further plate may be flexible so that where fluid under high pressure is supplied to the manifold spaces this plate is loaded firmly into contact with the rotor disc periphery and the blade roots.
According to another feature of this invention applicable to the preferred arrangements above set forth, there may be provided an annular sealing plate mounted on the periphery of the rotor disc to close the ends of the axially-extending spaces between the roots which are remote from the manifold space.
According to yet another feature of this invention, the rnanifold-space-defining plate may be provided at a radius less than that of its outer periphery with a part aifordin'g the rotating element of a labyrinth seal which part'is adapte d to co-operate with stationary structure of the fluid machine to define a closed chamber from which pressurefluid is fed to the path between the manifoldspace-defining plate and the rotor disc.
Two preferred embodiments of this invention will now b described in which cooling air is Supplied under pressure to the rotor blades of a turbine of a gas-turbine engine. The description refers to the accompanying draw.- ings in which.
FIGURE *1 is an axial view of one form of turbine rotor with parts broken away to show details of con a c on,
FIGURE 2 is a section on the line 2-2 of FIGURE 1,
7 FIGURE. 3 is a view in the direction of arrow 3 on FIGURE 2,
FIGURE4 is a section on the line 44 of FIGURE 3,
FIGURE 5 is an axial section t rough the second embodiment,
FIGURE 6 is. asection on the line 66 of FIGURE 5,
Each blade 11 comprises an operative portion 11;;-
which extends radially across the working fluid passage of the turbine, a tip shroud 12 at the radially-outer end of the operative portion 11a, and a root portion at the.
radiallydnner end of the blade. The root portion comprises a shouldered attachment portion 13 which occupies a correspondingly-shaped groove in the disc periphery to retain the blade radially in position, a platform portion 14 from which the operative portion 11a of the blade projects and which with the platform portions of the remaining blades forms an annular part of the wall of the working fluid passage of the turbine, and a stem 15 by which the platform portion '14 is connected to the attachment portion 13. The stem is ciroumferentially narrower than either the attachment portion 13 or the platform portion 14, and so when the blades are mounted: in the disc periphery axially-extending spaces are leftv between the stems 15. The blades 11 are prevented from becoming detached from the disc by rearward axial displacement by being provided at one end with t-angs' 1'6 which bear against one axially-facing surface of the disc 10 and are retained against forward displacement by a retaining plate :17 which lies against the other axiallyfacing surface of the disc 10 and against the adjacent ends of the rootrportions of the blades 11. The retaining plate 17 also serves to close oft the downstream ends of the axially-extending spaces between the stems 15.
Each blade is provided internally with passages for conveying cooling fluid, In the arrangement illustrated each blade 11 has a first passage 18 adjacent its leading edge, a second passage 19 adjacent its trailing edge, and I a third passage 20 at its mid-section, these passages extend- Patented Nov. 28, 19st FIGURE 7 is a view on the line 7-7 of FIGURE 5,,
3. ing lengthwise of the operative portion 11a of the blade. The passages 18, 19 and 20 are joined together adjacent the tip of the blade by a cross passage 21. The passages 18 and 19 have extensions 18a, 19a in the stern of the root portion and these extensions meet in a port 22 formed in the upstream axially-facing surface of the stem 15. The passage 20 also extends into the stem and opens through a port 23 to one of the circumferentially-facing surfaces of the stem 15. In operation, cooling air is fed to the blade through the port 22 and flows outwardly through the passages 18 and 19 and then flows inwardly through the passage 20 and out through the port 23 into the axially-extending space between a pair of stems 15. Thence the cooling air passes outward into the working fluid passage of the turbine through small circumferential gaps between adjacent platforms 14, thus preventing the inflow of heated working fluid into the axially-extending spaces.
The cooling air is fed to the blades in the following.
There is provided on the upstream face of the turbine disc means affording a manifold which is supplied with air under high pressure and which is in communication with the ports 22 in the stems of the blades 11.
This means comprises a first annular plate 24 of flat annular form which is adapted to lie against the upstream axially-facing surface of the periphery of the rotor" disc 10 and the adjacent end surfaces of the root portions of the blades 11. The plate 24 is provided with a continuous axial flange 25 at its outer radius, with a ring of holes 26 (FIGURE 1) one to register with each of the ports 22, with a series of radially-extending slots 27 which extend from the radially-inner edge of the plate 24 and which when the plate is in position engage over the tangs 16, and with a series of ciroumferentiallyspaced axial tongues 28 which extend away from the surface of the disc. 1
The manifold-affording means also comprises a second annular plate 29 which is of substantially greater radial extent than the plate 24. The radially-outer edge of the plate 29 is formed with a peripheral bead 30 which is offset from the plane of the plate 29 so that when the plate is'in position on the disc the bead 30 fits outside the axial flange 25 at the outer edge of the plate 24 and also engages behind radially inwardly-projectin-g flanges 31 on the upstream edges of the platform portions 14. When the plate 29'is in position the flange 25 and the tongues 28 hold the outer portion of the plate 29 away from the main body of the plate 24.
At about its mid-radius, the plate 29 is provided with a number of circumferentially-spaced lands 32 which provide seats for the heads of retaining bolts 33 which pass through the plate 29 and engage in nuts 34 trapped in the structure of the rotor disc 10. The nuts 34 are of T-section in planes axially of the disc 10 (see FIGURE 2) and they are received in correspondingly-shaped grooves in axial projections 35 outstanding from the upstream surface of the rotor disc 10. The plate 29 is also provided with an annular axially-directed flange 36 to engage the radially-inner surfaces of the axial projections 35.
At its inner radius the plate 29 is provided with a second series of lands 37 through which project stems of a second series of bolts 38 to engage in T-section nuts 39 trapped in a second series of circumferentiallyspaced axial projections 40, the lands 37 abutting against the projections 40.
At its inner edge the disc 29 is provided with an axiallyprojeoting flange 41 having on its radially-outer surface a series of axially-spaced ribs 42 so as to provide the rotating element of a labyrinth seal, the stationary element of which is formed by a part of the stator structure 43. The labyrinth seal is employed to prevent excessive leakage of high-pressure air fed to the chamber 44 formed between the radially inner portion of the upstream surface of the rotor disc 10 and adjacent stator structure, and it will be appreciated that since the labyrinth seal is at a relatively small radius from the axis of rotation the leakage area through it for a given clearance between the ribs 42 and the stator structure 43 is correspondingly reduced.
In operation, pressure air flows from the chamber 44 outwardly, circumferentially between the projections 49 and the projections 35, into the fluid supply manifold space 45 formed between the plate 24 and the outer portion of the plate 29. The pressure air then flows through the holes 26 and ports 22 into the passages 18 and 19 in the blades and thence through passages 20 and ports 23 into the axially-extending spaces between the stems 15. The cooling air leaks from these spaces through the circumferential clearances between the platform portions 14 into the working fluid passage of the turbine and thus prevents hot gas from flowing inwardly into these spaces.
Preferably the plate 24 is made flexible so that it is loaded by the high-pressure air within the manifold space 45 firmly into contact with the adjacent surfaces of the turbine'disc 10 and blade roots, thus preventing leakage ofcooling air direct from the holes 26 into the axiallyextending spaces between the stems 15.
The projections 3-5 and 40 are conveniently formed on the rotor disc 10 by providing a continuous rib on the disc 10, milling a groove of appropriate T-section in the rib and then machining away the rib at intervals to leave the projections.
Referring now to FIGURES 3 and 4, there is illustrated a convenient way of closing off the radially-outer ends of the passages 18, 19 and 20 after formation of the cross passage 21. For this purpose the cross passage 21 is formed by milling a slot in the tip shroud 12, and by forming the shroud with a dovetail groove extending across it above the passage 21 to receive a closure plate 46. The closure plate 46 is slid into position along the dovetail groove 21 and is tack-welded in position. It will be seen that the tip shroud is provided with features afiording tip seals to co-operate with stator structure, and it will be understood that the cover plate 46 will have its external surface correspondingly shaped.
Referring now to FIGURES 5 to 8, there is shown a turbine rotor disc 50 having blades 51 mounted at its periphery. Each blade has an operative portion 51a, a tip shroud 52 and a root portion which comprises an attachment portion 53, a blade platform 54 and a stem 55 joining the attachment portion 53 and platform 54. The stems are circumferentially narrower than the platforms and attachment portions and so a series of axiallyextending spaces 56 are formed between them.
Each blade 51 has internal passages extending lengthwise through it, there being a passage 57 at its upstream edge, a passage 58 at its downstream edge, and a passage 59 at its mid chord. The passages 57, 58, 59 are joined at the tip of the blade by a transverse passage 60, and at their inner ends, the passages 57, 58 open into the space 56 to one side of the stem 55 and the passage 59 opens to the space 56 on the other side of the stem. It is arranged that passages 57, 58 open to alternate spaces 56 and that the passages 59 open to the remaining spaces 56.
Each blade 51 has a tang 62 at one end of its attachment portion to abut the disc rim and prevent detachment in one direction and an annular plate 63 is mounted on the downstream surface of the rotor to retain the blades against detachment in the opposite sense. The plate 63 closes the downstream ends of the spaces 56.
Cooling air is supplied to the blades in the following way. A first annular plate 64 is mounted on the upstream face of the rotor. This plate has a continuous axially-narrow flange 65 at its radially outer edge, a
' series of holes 66 which open into the upstream ends and at its inner edge a series of radial tongues 67 each of which projects between a pair of the tangs 62. Each of the tongues 67 has at its free ends an axially thickened portion 68 with a central projecting rib 69, the majority of which portions 68 are radially narrow but a diametrically-opposite pair of which 68a are radially of greater extent.
A second annular plate 70 of substantially greater radial dimension than plate 64 is mounted on the rotor to form with the plate 64 a cooling air distribution manifold. The plate 70 has at its outer edge a peripheral head 71 which is offset from the plane of plate 70 so as to fit outside the flange 65 of plate 64 and behind radially-inwardly-projecting flanges 72 on the platforms 54. At a position radially within the tangs 62, the plate 70 is provided with a ring of circumterentially-spaced hooked, axially projections 73 which engage behind corresponding projections 74 on the turbine disc 70. At its inner radius, the plate 70 has a thickened portion 79a and bears against cireumferentially-spaced pairs of projections 75 on the disc 50. Dowel pins 76 pass through the portion 70a of the plate 70 and each pin 76 engages between a pair of the projections 75. Each pin 76 has a tongue 77 at its outer end which projects into a corresponding notch 78 in bead 79 formed around the portion 70a of the plate 70, and the bead has an inwardly-facing channel receiving a spring retaining ring 80 which overlies the tongues 77 to retain the dowel pins in position. The portion 70a also has circumferentially-spaced radially-inwardly projecting dogs 81 which engage behind correspondingly-spaced hooked projections 82 on the turbine disc 50.
The disc 70 also has an axially-projecting annular flange 83 extending from its upstream surface at a radius between its inner and outer edges, and the flange is formed with axially-spaced ribs 84. The ribs 84 cooperate with an annular member 85 which is part of the stationary structure of the turbine, to form a labyrinth seal preventing excessive leakage of pressure air from a chamber 86 formed between the inner part of plate 70 and stationary structure 87 and fed with pressure air through duct 88.
In operation air flows from chamber 86 between the pairs of projections 75 into space 89 and outwardly from the space 89 past projections 73, 74 and ribs 69 into the fluid supply manifold space 90 formed between the outer portion of plate 70 and plate 64. From the manifold space 90, the air passes through holes 66 into alternate spaces 56 and thence through passages 57, 58, passages 60 and passages 59 into the remaining spaces 56. The air leaves these latter spaces through the clearance gaps between the platforms 54.
In either of the two arrangements just described, the annular plate 17, 63 may be provided with exit passages which communicate with the exit spaces between the blade stems. I
1. A bladed rotor for an axial-flow fluid machine, which rotor comprises a rotor disc having an outer peripheral rim, a plurality of rotor blades, each blade having a root, the root of each blade comprising a shouldered attachment portion with radially-facing shoulders, a platform portion and a stem portion extending from the shouldered attachment portion to the platform portion, the said rim having therein slots extending across the rim and receiving the shouldered attachment portions, said slots having radially-facing shoulders complementary to the shoulders of the attachment portions whereby the blades are retained radially in position on the rim with their stem portions projecting radially outwards from the rim, the stem portions being circumferentially narrower than the attachment portions and defining spaces extending axially between them, the
blades having in them internal fluid passages having inlets thereto and outlets therefrom in the stem portions, at least the outlets of the passages in the blades opening into the axially-extending spaces defined by the stem portions and platform portions of the blade roots, a first annular plate mounted on the disc rim in contact therewith and in contact with the attachment portions and the stem portions and closing the adjacent ends of the axially-extending spaces into which said outlets open, and a second annular plate mounted on the disc in axially-spaced relation thereto and extending radially over the first annular plate in axially-spaced relation, the space between the annular plates forming a fluid supply manifold for cooling air, there being apertures in said first annular plate placing the manifold in communication with said inlets, and said second annular plate having a greater radial extent than the first annular plate and extending radially inwards of the first annular plate and of the rim and defining with the disc a fluid path extending radially outwards from a position at a less radius than the rim to the manifold, said platform portions having means communicating with the anally-extending spaced defined by said stem and platform portions so that the cooling air is exhausted between said platform portions.
2. A rotor according to claim 1, wherein the said outlets open into alternate ones of the axially-extending spaces and the said inlets open into the remaining axiallyextending spaces, the apertures in the first annular plate opening into the said remaining axially-extending spaces, and wherein there is provided a further plate which is mounted on the rim in contact therewith and in contact with the root attachment portions and stem portions, said further plate closing oii the ends of the axially-extending spaces remote from the first annular plate.
3. A rotor according to claim 1, wherein said apertures in the first annular plate are in portions of the plate in contact with the stem portions and the said inlets open through the stem portions in register with the apertures, the first annular plate closing 01? the adjacent ends of all the axially-extending spaces and the outlet of the fluid passage of each blade opening to the axially-extending space on one side of its stem portion.
4. A bladed rotor as claimed in claim 1, comprising radially-inwardly-projecting flanges on the blade roots adjacent the first and second annular plates, said first annular plate having a continuous axial flange at its outer edge and the second annular plate having at its outer edge a peripheral head which axially overlaps and fits outside the continuous axial flange and engages axially behind said flanges on the blade roots.
5. A bladed rotor as claimed in claim 1, wherein the second annular plate is provided at a radius less than that of its outer periphery with a part affording the rotating element of a labyrinth seal.
6. A bladed rotor as claimed in claim 1, wherein said first annular plate is flexible so that Where fluid under high pressure is supplied to the manifold space, the said further plate is loaded firmly into contact with the rotor disc periphery and the blade roots.
References Cited in the file of this patent UNITED STATES PATENTS