Blades for fluid flow machines

June 29, 1965

Filed Feb. 14, 1963

F. B. POWELL ETAL 3,191,908

BLADES FOR FLUID FLOW MACHINES

Sheets-Sheet 1

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FIG.2.

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June 29, 1965

Filed Feb. 14, 1963

F. B. POWELL ETAL 3,191,908

BLADES FOR FLUID FLOW MACHINES 4 Sheets-Sheet 2

<img file="US3191908A_D0003.tif" />

June 29, 1965

F. B. POWELL ETAL

3,191,908

BLADES FOR FLUID FLOW MACHINES

Filed Feb. 14, 1963

Sheets-Sheet 3

F/G4.

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Attorneys

June 29, 1965

Filed Feb. 14, 1963

F. B. POWELL ETAL

BLADES FOR FLUID FLOW MACHINES

3,191,908

Sheets-Sheet 4

FfG.5.

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United States Patent Office' ₄,³¹⁹¹’⁹⁰⁸

Patented' June 29, 1965

3,191,908

BLADES FOR FLUID FLOW MACHINES Frederick -Bowen Powell,' Haihern, near LougSiborough, and James Alexander Peirie, Littleover, Derby, England, assignors to Rolls-Royce Limited, Derby, England, a company of Great Britain

Filed Feb. 14,1963, Ser. No. 258,445

Claims. (Cl. 253—39.15)

This invention concerns blades for fluid flow machines e.g. turbine rotor blades -for gas turbine engines.

The term “blade” is used in this specification in a broad sense to include blade-like members such as nozzle guide vanes.

According to the present invention, there is provided a blade adapted for use in a fluid flow machine and having formed therein a fluid conduit, said fluid conduit having an inlet through which a blade cooling fluid may be introduced into said fluid conduit and a sinuous fluid passageway which is formed in -said blade and which is adapted to be supplied with a blade cooling fluid, the sinuous fluid passageway extending substantially completely around the fluid -conduit and being so formed that blade cooling fluid flowing therethrough effects substantial heat-shielding of the blade cooling fluid flowing through the fluid conduit.

Preferably the sinuous fluid passageway is such that blade cooling fluid on entering the lattter first flows through leading and trailing portions of the blade and thereafter flows through the central portion of the blade. It will be appreciated that in such an arrangement the leading and trailing portions, i.e. the hottest portions of the blade will be cooled by the blade cooling fluid when the latter is at its coldest while the central portion of the blade, which does not require as much cooling, is cooled by the blade cooling fluid after the latter has picked up heat from the said leading and trailing portions.

.Preferably the sinuous fluid passageway communicates with the fluid conduit so as to be supplied with blade cooling fluid therefrom.

Preferably the fluid conduit extends from substantially the root to the tip of the blade and the sinuous fluid passageway comprises a series of spaced fluid passages which also extend substantially from the root to the tip of the blade, said fluid passages being connected together by fluid paths which are alternatively arranged adjacent to the root and tip of the blade, one of the fluid passages communicating with the fluid conduit and another of the fluid passages having an outlet through which blade cooling fluid may pass out of the blade, whereby blade cooling fluid which has been introduced into the fluid conduit through said inlet will flow through adjacent fluid passages in opposite directions and will finally pass out of the blade through -said outlet.

The said inlet is preferably disposed at the root of the blade, the said outlet being disposed at the tip of the blade.

One of the fluid passages is preferably disposed adjacent the leading or trailing edge of the blade and communicates with the fluid conduit by way of a drilling which is disposed adjacent the mid-height of the blade whereby blade cooling fluid passing through said drilling forms a jet wnich cools the said leading or trailing edge adjacent the mid-height of the latter.

: The blade is preferably formed with two fluid conduits each of which is surrounded by a sinuous fluid passageway, the two -sinuous fluid passageways, respectively comprising fluid passages which are disposed adjacent the leading and bailing edges of the blade and which communicate with their respective fluid conduits by way of drilling disposed adjacent the mid-height of the blade.

. The invention also comprises a gas turbine engine provided with a blade as set forth above.

The invention is illustrated, merely by way of example, in the accompanying drawings in which:

FIGURE 1 is a diagrammatic section through a gas turbine engine,

FIGURE 2 is a diagrammatic elevation of a turbine blade of the engine of FIGURE 1,

FIGURE 3 is a section taken on the line 3—3 of FIG10 URE 2, and

FIGURES 4 and 5 are sections taken respectively on the lines 4—4 and 5—5 of FIGURE 3.

In the following description, air which flows within the blade and towards the root thereof is, for ease of 15 explanation, referred to as passing “downwardly” in the blade, while air which flows within the blade towards the tip thereof is referred to as passing “upwardly” in the blade.

Referring to the drawings, a gas turbine engine 10 com20 prises in flow series a compressor 11, combustion equipment 12, and a turbine 13, the turbine 13 driving the compressor 11 through a shaft 14.

The turbine 13 has turbine rotor blades 15 each of which has a “fir-tree” root 16 which is formed with air 25 inlets 17, 18 through which cooling air may be introduced into the blade 15.

The air inlets 17, 18 lead respectively to fluid conduits 20, 21 which are formed within and extend longitudinally of the blade 15 from the root 16 to the tip 22 thereof. 30 The fluid conduits 20, 21 are blanked off at the tip of the blade, but are of course supplied at the root of the blade with cooling air from the air inlets 17, 18.

The fluid conduits 20, 21 respectively communicate with fluid passages 23, 24 by way of drillings 25, 26, the 35 passages 23, 24 being respectively blanked off at the root and tip of the blade. The drillings 25, 26 are disposed at the mid-height of the blade i.e. halfway between the root and the tip of the blade.

The fluid passages 23, 24 are respectively disposed 40 adjacent the leading edge 27 and the trailing edge 28 of the blade. Accordingly jets of cooling air are directed through the drillings 25, 26 into the fluid passages 23, 24 so as to impinge, at mid-height, on the surfaces of the latter adjacent the leading and trailing edges 27, 28. The said jets thus effect cooling of what are, in operation, the hottest parts of the blade.

Extending longitudinally within the blade 15 from the root to the^ tip thereof are spaced apart fluid passages 30-39 all of which are blanked off at the root and at the 50 ~^l7&gt;· blade. The fluid passages 30—34 are disposed adjacent the convex or upstream side 41 of the blade, while the fluid passages 35—39 are disposed adjacent the concave or downstream -side 42 of the blade.

The fluid passages 30, 39 respectively communicate 55 with the fluid passage 23 by way of drilling 43, 44 which are respectively disposed adjacent the tip and the root of the blade. The fluid passages 30, 39 also respectively communicate with the fluid passages 31, 38 by way of drillings 45, 46 which are respectively disposed adjacent ₆θ the root and the tip of the blade.

The fluid passages 31, 38 respectively communicate, by way of drillings. 47, 48, with a fluid passage 50 which extends longitudinally of the blade from the root to the tip thereof, the fluid passage 50 being blanked off at the 65 ™^{otand bein}3 °Pen at the tip of the blade. The drillings 47, 48 are respectively disposed adjacent the tip and the root of the blade.

a ^Tbeduid Passages 34, 35 respectively communicate with the fluid passage 24 by way of drillings 51, 52 which are 70 ^p,^ectlv®Jy disposed adjacent the root and the tip of the blade. The fluid passages 34, 35 also respectively communicate with the fluid passages 33, 36 by way of drill3,191,908 &lt;C5 ings 53, 54, while the fluid passages 33, 36 respectively communicate with the fluid passages 32, 37 by way of drillings 55, 56. The fluid passages 32, 37 respectively communicate, by way of drillings 57, 58, with a fluid passage 60 which extends longitudinally of the blade from the root to the tip thereof, the fluid passage 60 being blanked at the root and being open at the tip of the blade.

The drillings 51, 54, 55 and 58 are disposed adjacent the root of the blade, while the drillings 52, 53, 56, and 57 are disposed adjacent the tip of the blade.

Accordingly, the cooling air which has passed into the fluid conduit 20 and has entered the fluid passage 23 through the drilling 25 first impinges on the surface of the passage 23 at mid-height and thereafter divides into two portions which respectively flow downwardly and upwardly through the passage 23 towards the root and the tip of the blade. The air which has flowed upwardly in the passage 23 passes through the drilling 43, flows down the passage 30, passes through the drilling 45, flows up the passage 31 and passes through the drilling 47 to the “upper” end of the passage 50.

The air which has flowed downwardly in the passage 23 passes through the drilling 44, flows up the passage 39, passes through the drilling 46, flows down the passage 38, and then passes through the drillings 48 to the “lower” end of the passage 50. The cooling air which is thus supplied to the passage 50 passes out of the blade through the tip thereof.

It will thus be noted that the fluid passages 23, 30, 31, 38, 39, 50, together with the drillings 43-48, collectively constitute a sinuous fluid pasasgeway the cooling air flowing through which effects substantial heat-shielding of the cooling air flowing through the fluid conduit 20.

Similarly, the cooling air which has passed into the fluid conduit 21 and has entered the fluid passage 24 through the drilling 26, impinges on the surface of the passage 24 at mid-height, and thereafter divides into two portions which respectively flow downwardly and upwardly through the passage 24 towards the root and the tip of the blade.

The air which has flowed upwardly in the passage 24 passes through the drilling 52, flows down the passage 35, passes through the drilling 54, passes up the passage 36, passes through the drilling 56, passes down the passage 37, and passes through the drilling 58 to the “lower” end of the passage 60.

The air which has flowed downwardly in the passage 24 passes through the drilling 51, flows up the passage 34, passes through the drilling 53, flows down the passage 33, passes through the drilling 55, flows up the passage 32, and passes through the drilling 57 to the “upper” end of the passage 60. The cooling air which is thus supplied to the passage 60 passes out of the blade through the tip thereof.

The fluid passages 24, 32-37, and 60, together with the drillings 51-58, collectively constitute a sinuous fluid passageway and the cooling air flowing through this sinuous fluid passageway will effect substantial heat-shielding of the cooling air flowing through the fluid conduit 21.

The blade, which may be a close forging, which is subsequently machined by an electrolytic or spark process, may be formed in two halves which abut at the midchord line of the blade and are secured together by brazing or electron beam welding. The conduits, passages and drillings in the blade may be formed by spark machining (e.g. carbon electrode spark machining) or by an electrolytic process.

It will be appreciated that the leading and trailing edges 27, 28, which are in operation the hottest portions of the blade, will be cooled by the cooling air when the latter is at its coldest, while the central portion of the blade, which does not require as much cooling, is cooled by the cooling air when the latter is at its coldest, while the central portion of the blade, which does not require as much cooling, is cooled by the cooling air after the latter has been heated by flowing through the blade. A substantially uniform temperature is therefore achieved throughout the blade.