GB2054046A

GB2054046A - Cooling turbine rotors

Info

Publication number: GB2054046A
Application number: GB7924364A
Authority: GB
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 1979-07-12
Filing date: 1979-07-12
Publication date: 1981-02-11

Abstract

A cooling fluid feed structure of a gas turbine engine comprises a stationary annular nozzle structure (28, 29, 30) arranged to direct cooling fluid to an entry passage (39) on the adjacent turbine rotor (16, 17). The nozzle structure comprises boundary defining sheet members (28, 29) and an annular corrugated strip (30) fastened thereto, the side portions of the corrugations being angled to the axis of the structure to impart a required degree of swirl to the cooling fluid. <IMAGE>

Description

SPECIFICATION Cooling fluid feed structure for the turbine rotor of a gas turbine engine This invention relates to a cooling fluid feed structure for the turbine rotor of a gas turbine engine.

In gas turbine engines various parts of the turbine, and in particular the turbine rotor blades, need to be provided with cooling fluid to enable them to withstand the high temperature environment in which they operate. In order to supply this cooling fluid to the rotor blades, stationary nozzle structure is provided adjacent the rotor, the nozzle structure being adapted to impart a circumferential swirl to the cooling fluid in the same direction as the rotation of the rotor.

The present invention provides a cooling fluid feed structure which includes these nozzles and which is cheap, simple and light In weight.

According to the present invention, a cooling fluid feed structure for the turbine rotor of a gas turbine engine comprises a stationary annular nozzle structure adapted to direct cooling fluid to an adjacent turbine rotor, and cooling fluid entry means on the rotor adapted to receive the fluid, the annular nozzle structure comprising sheet members defining the inner and outer annular boundaries of the nozzle structure and an annular corrugated strip extending between the sheet members, the inner and outer peaks of the corrugations lying against and being fastened to the sheet members and the side portion of the corrugations being angled to the axis of the structure to form flow directing means which give a required degree of swirl to the cooling fluid.

Preferably the corrugated strip is castellated and the inner and outer circumferentially extending portions of the castellations lie against the sheet members.

The corrugated strip may be welded, brazed or diffusion brazed to the sheet members.

The invention will now be particularly described, merely by way of example, with reference to the accompanying drawings in which Figure 1 is a partly broken-away view of a gas turbine engine having a cooling fluid feed structure in accordance with the invention, Figure 2 is an enlarged cross-section of the cooling fluid feed structure of Figure 1, Figure 3 is a further enlarged section on the line 3-3 of Figure 2 and, Figure 4 is a section on the line 4 4 of Figure 3.

In Figure 1 there is shown a gas turbine engine comprising a casing 10 within which are mounted in flow series a compressor 1 1 combustion chamber 12 and turbine 13 The casing forms at Its downstream extremity a propulsion nozzle 14.

Operation of the engine Is in general conventional, and is not therefore described herein However. In the turbine region which Is visible in Figure 2 it will be seen that the hot gases from the -:ombustion chamber 1 2 are directed oy the nozzle guide vanes 1 5 on to the rotor blades 1 6 of the turbine. These blades are carried from a rotor disc 1 7 and drive, via a shaft 18, the compressor 12 of the engine. Because the blades 16 operate in the very hot gases from the combustion chamber, they have to be supplied with coolant, and in Figure 2 can be seen the structure which carries this out.

It will be seen that the vanes 1 5 are connected, via mounting flanges 19, with a sheet metal cone 20 which serves to define the downstream extremity of a plenum chamber Indicated at 21.

The engagement of the cone with the flanges 19 is made through a channel section ring 21 which is welded to the cone 20 and which also has a projecting annular flange 22 which in conjunction with the extensions 23 of the inner platforms 24 of the vanes 1 5 provides a sealing channel. Into this channel further projections 25 from the platforms 26 of the blades 16 extend to form a seal which prevents high pressure air from inside the seal escaping into the hot gas flow annulus of the engine.

The high pressure air contained within the plenum 21, which is derived from a bleed arrangement (not shown) from the compressor 11, is required for use in cooling the blades 1 6.

Apertures 27 in the cone 20 therefore allow this air to flow into a nozzle structure comprising inner and outer annular sheet members 28 and 29 respectively and a corrugated annular strip 30.

The sheet member 28 is rivetted to the cone 20 at 31. and curves away from the cone so that its right hand portion, as shown in the drawings, provides the inner boundary of the nozzle structure.

The outer sheet member 29 is again rivetted to the cone 20 at 32, and it curves away from the core so that its right hand portion, as shown in the drawings, provides the outer boundary of the nozzle structure. The members 28 and 29 converge and therefore form a convergent nozzle boundary.

The actual nozzles themselves are formed, as can best be seen from Figures 3 and 4, by the corrugated strip 30 It will be seen than in this case the corrugations take the form of rectangular castellations, and that the castellations are not parallel with the axis of the structure but are at an angle to the axis. The rectangular castellations are formed so that there are inner and outer circumferentially extending portions 33 and 34 respectively which lie against the inner and outer sheet members 28 and 29, and radially extending portions 35 which form the flow-directing means of the nozzle The circumferentially extending portions are affixed to the respective one of the members 28 and 29 against which they lie, in the present case by welds such as those shown at 36 and 27 but of course other methods such as brazing or diffusion brazing could be used.

It will therefore be understood that the air from the plenum 21 will pass through the holes 27 and Into the nozzle structure, where the convergence of the sheet members 28 and 29 will speed up the airflow and the portions 34 of the strip 30 will give the air a predetermined degree of swirl in the direction of rotation of the rotor 17.

In order to allow the air to pass to the blades 16, underneath the root 38 of each of the blades 16 and inlet passage 39 is left between the disc and the blade. These passages are aligned with the nozzle structure so that the air blown through the nozzle structure mainly enters the passage 39.

From these passages, ducts 40 in the blades allow the cooling air to flow to the interior of the aerofoil of each blade where a cooling passage configuration, which may be one of many known to those skilled in the art, enables the air to provide effective cooling of the aerofoil.

It will be seen that the embodiment described provides a relatively cheap and simple form of nozzle structure which may also be relatively light.

There are of course a number of alterations which could be made to the structure described; thus in particular it would be possible to use corrugations other than rectangular castellations, and the auxiliary structure such as the cone 20 could well be altered.

Claims

1. A cooling fluid feed structure for the turbine rotor of a gas turbine comprising a stationary annular nozzle structure adapted to direct cooling fluid to an adjacent turbine rotor, and cooling fluid entry means on the rotor adapted to receive the fluid, the annular nozzle structure comprising sheet members defining the inner and outer annular boundaries of the nozzle structure and an annular corrugated strip extending between the sheet members, the inner and outer peaks of the corrugations lying against and being fastened to the sheet members and the side portions of the corrugations being angled to the axis of the structure to form flow directing means which give a required degree of swirl to the cooling fluid.

2. A cooling fluid feed structure as claimed in claim 1 and in which said corrugated strip is castellated.

3. A cooling fluid feed structure as claimed in claim 2 and in which the inner and outer circumferentially extending portions of the castellations lie against the sheet members.

4. A cooling fluid feed structure as claimed in any of the preceding claims and in which said annular corrugated strip is welded, brazed or diffusion brazed to the sheet members.

5. A cooling fluid feed structure substantially as hereinbefore described with reference to the accompanying drawings.

6. A gas turbine engine having a cooling fluid feed structure for its turbine rotor as claimed in any of the preceding claims.