EP1712744B1 - Arrangement in a high pressure turbine for passive tip clearance control - Google Patents

Description

The invention relates to an arrangement for internal passive clearance adjustment in a high-pressure turbine, in which arranged above the blade tips of the rotor housing segments are supported at the front and rear ends of radially movable vane segments and concentric with the vane segments arranged and acting on these inner rings are provided, the thermal Expansion and contraction behavior is matched to the elongation or contraction of the rotor according to its respective load to cause a matched to the rotor load radial movement of the housing segments for running gap control.

In aircraft gas turbine, the running gap between the blade tips of the rotor of the high-pressure turbine and the blade tips at a distance opposite, non-rotating housing parts or liners at the different flight conditions and loads should be consistently small to keep the power and fuel losses low in all flight phases and a high To ensure efficiency of the engine. On the other hand, however, the running gap must be large enough to avoid friction of the rotating blade tips on the stationary parts in the case of the different expansion or contraction behavior of the rotor occurring under transition conditions such as start, landing, acceleration or deceleration. Due to the different thermal and dynamic load of the rotor in the various operating conditions and the only thermal expansion Therefore, a corresponding control of the running gap width is required for the blade elements facing the fixed elements.

In order to keep the running gap in all phases of operation as constant and small as possible and thus to use the energy used effectively, and without contact in a phase of lower thermal and dynamic rotor load blade tips of the rotor, the adjacent stationary housing parts, in addition to the costly active gap width control by means of controlled cold air or hot gas supply also proposed a passive automatic running gap control.

For example, in the GB 20 61 396 described inside passive adjustment of the clearance gap spaced liner segments spaced above the tips of the rotor blades are supported on one side on the outer platforms of the high pressure turbine vanes and on the other side on the outer platforms of downstream further vanes of a subsequent low pressure turbine. The inner platforms of the vane segments arranged on either side of the high-pressure turbine are each connected to a ring element whose thermal expansion or contraction behavior coincides with that of the rotor of the high-pressure turbine. According to the load of the rotor and the different radial expansion or contraction of the rotor disk and the rotor blades increase or decrease in this inner passive running gap control system due to the influence of temperature and the mutual, mounted on the vane segments inner ring elements such that the guide vane segments and supported on these Liner segments are adjusted according to the expansion or contraction of the rotor radially outward or inward. That's the way it is ensures a passive automatic running gap adjustment according to the load conditions in the high-pressure turbine.

However, the application of the internal passive clearance control can not be applied to engines in which, due to the absence of a fixed structure located downstream of the rotor, the support of the inner ring connected to the radially movable vane segments is not possible. This is the case, for example, with a rotor of the high-pressure turbine which is not static downstream, but is mounted in a rotating component, since no rear static structure is available for fastening the inner ring acting on the guide vanes.

The invention has for its object to provide an arrangement for internal passive Laufspalteinstellung of the type mentioned for a high-pressure turbine with downstream not statically mounted rotor.

According to the invention the object is achieved with a trained according to the features of claim 1 arrangement. From the dependent claims, advantageous refinements and expedient embodiments of the invention.

In the inner passive control of the running gap width matched to the expansion behavior of the rotor at different load upstream and downstream arranged inner rings, which arranged on the inner circumference of the turbine housing above the blade tips on the inner circumference of the turbine housing, the running gap limiting, radially movable segments, does not exist statically, for example, on a rotating bearing ring of the low-pressure turbine mounted rotor, the basic idea of Invention in the formation of a projecting from the inner platform of the vane segments, not bound to a static structure Torsionsbox that increases or decreases according to the elongation behavior of the rotor of the high-pressure turbine and the respective temperature conditions and acts on the outer segments of the vane segments on the liner segments and the running gap automatically and passively adjusts, but is designed so that a strain compensation in the axial direction and in the circumferential direction is guaranteed to compensate for stress. The Torsionsbox has a U-shaped inner ring, which is not attached to a static structure, but with its open side to the platforms of the vane segments, and whose radial expansion is transmitted to the vane segments and thus to the gap defining segments.

The Torsionsbox formed from the U-shaped inner ring and the inner platform abstrebenden webs is in addition to the exercise in the radial direction of the housing segments acting forces also able to absorb the acting on the vanes as a result of the gas forces rolling moment and tilting moment.

The legs of the U-shaped inner ring of Torsionsbox are connected to the webs, which also form a U-profile with the inner platform of the vane segments, with releasable fastening means so that in the Torsionsbox in the axial direction and in the circumferential direction acting expansion forces are compensated.

The vanes are also held by a toothing on the housing in the circumferential direction and guided radially. An axial fixation takes place with the help of a retaining ring on the turbine housing.

The connection of the legs of the U-shaped inner ring with the integrally formed on the platforms and lying flat against the legs webs is carried out with a clamping sleeve which is slidably fitted on one side in bores of the leg and the web and on the opposite side by means of a in the clamping sleeve mounted bolt are pressed firmly together. While the sliding arrangement of the clamping sleeve on one side of the torsion box causes an expansion compensation in the axial direction, a circumferentially extending slot is provided for the expansion compensation in the circumferential direction for every second clamping sleeve attachment.

• Fig. 1 eine Teilansicht eines Triebwerks im Bereich der Hochdruckturbine, der stromauf statisch und stromab nicht statisch gehaltenen ist;
• Fig. 2 eine vergrößerte Darstellung eines stromab an einem als Torsionsbox ausgebildeten Dehnungsring montierten, radial beweglich am Turbinengehäuse fixierten Leitschaufelsegments; und
• Fig. 3 eine detaillierte Darstellung der Torsionsbox.

An embodiment of the invention will be explained in more detail with reference to the drawing. Show it:

• Fig. 1 a partial view of an engine in the high-pressure turbine, which is statically static and downstream not statically held upstream;
• Fig. 2 an enlarged view of a downstream of a trained as Torsionsbox expansion ring, radially fixed to the turbine housing fixed vane segment; and
• Fig. 3 a detailed view of the torsion box.

The high pressure turbine (HDT) of the engine includes a static upstream and downstream of an intermediate shaft bearing 1 (inter shaft bearing) of the following low-pressure turbine (NDT, not shown) not statically held rotor, which consists of a rotor disk 2 and the rotor blades attached to the periphery 3. The upstream of the rotor blades 3 arranged and with its outer platform 5 a radially movable on the turbine housing. 4 held turbine blades 5 of the high-pressure turbine are connected via the inner platform 5b with a fixed structure mounted on the inner ring 6 for inner passive running gap adjustment (inner passive ring) whose thermal expansion behavior is matched to that of the rotor. Downstream of the rotor blades 3 are the guide blade segments 7 of the subsequent low-pressure turbine, which are also guided radially movable on the turbine housing 4 via its outer platform 7a, while on the inner platform 7b serving as Laufspalteinstellorgan (inner passive ring) Torsionsbox 8 is formed whose thermal expansion behavior corresponds to the rotor of the high-pressure turbine. The outer platforms 5a, 7a of the vane segments 5, 7 are connected to a liner segment 9 arranged above the tips of the rotor blades 3. Due to the matching elongation properties of the rotor and the torsion box 8 and the inner ring 6, the rotor segments 2 and the rotor blades 3 are radially raised or lowered at a radial extension or contraction corresponding to the respective load conditions, so that at different heat load the formation of a consistently small tip gap is ensured and thus the power and fuel losses of the turbine can be kept low.

Since in the present case, downstream of the high-pressure turbine, there is no fixed structure for attaching an expansion ring acting on the liner segments, this is designed as a U-shaped inner ring 10, the legs 11, 12 of which are braced with webs 13 radially projecting from the inner platform 7b of the guide blade segments 7 14, which likewise form a U-profile with the platform 7b. By a firm connection of the legs 11, 12 of the U-shaped ring 10 with the webs 13, 14 is on the platform 7b, the above-mentioned torsion 8th created, which - without the connection to a fixed structure - is able to absorb the forces acting on the vane segments 7 forces. In addition, the vane segments 7 on the upper platforms 7a on the turbine housing 4 in a - Fig. 2 indicated - Cross-key teeth 15 (Hirth serration) held in the circumferential direction and guided radially and additionally axially fixed to a retaining ring 25.

The connection of the front and rear webs 13, 14 of the inner platforms 7b of the guide blade segments 7 with the U-shaped inner ring 10 by means of specially trained ferrules 16 and bolts 17 with rivet nut 18. The webs 13, 14 engage over the legs 11, 12 of the U-shaped inner ring 10. In the legs or webs are - each aligned - normal (round) holes and - seen in the circumferential direction of the torsion box 8 - elongated holes formed. In the circumferential direction round holes and elongated holes are arranged alternately, that is, in the webs 13, 14 are each provided opposite a round hole and a long hole. The clamping sleeve 16 has at a distance from the front end face a collar 19 which rests against the inside of the front leg 11 of the U-shaped inner ring 10. The rear region of the clamping sleeve 16 has a straight, smooth region 20, which is inserted precisely into the aligned bores of the rear leg 12 and the rear web 14 and allows a sliding movement. With the thus formed clamping sleeve 16 and the bolt 17 with safety nut 18 of the downstream of the passive running gap setting effecting U-shaped inner ring 10 on the webs 13, 14 of the inner platform 7b firmly clamped on one side and on the opposite side - to compensate for thermal expansion in the axial direction - slidably fixed. Thermal expansions in the circumferential direction of the torsion box 8 are compensated by the partial attachment in oblong holes. In particular from Fig. 2 It can be seen that on the U-shaped inner ring 10 of the torsion box 8, a circumferential sealing web 22 for shielding the rivet nuts 18 and a reaching to the intermediate shaft bearing 1 circumferential protective shield 23 with edge and brush seal 24 are formed. By shielding the rivet nuts 18 and the bolt heads and the arrangement of the shield 23, the ventilation losses are minimized.

LIST OF REFERENCE NUMBERS

1

Intermediate shaft bearing

2

rotor disc

3

rotor blades

4

turbine housing

5

Guide vane segment (HDT)

5a

outer platform

5b

inner platform

6

Inner ring (upstream inner passive ring)

7

Guide vane segment (NDT)

7a

outer platform

7b

inner platform

8th

torsion

9

liner segment

10

U-shaped inner ring (downstream inner passive ring)

11, 12

Thighs of 10

13, 14

Footbridges from 7b

15

cross-key teeth

16

collet

17

bolt

17a

screw head

18

Rivet nut

19

Federation

20

straight area, sliding area v. 16

21

Depression v. 16

22

sealing web

23

shield

24

Edge and brush seal

25

retaining ring

Claims (8)

1. Arrangement for internal passive tip clearance control in a high-pressure turbine in which moveable casing segments (9) located above the blade tips of the rotor (2, 3) are supported at the front and rear ends at the outer platforms (5a, 7a) by radially moveable guide vane segments (5, 7) and inner rings (6, 10), which are concentrically arranged to the guide vane segments (5, 7), and acting upon them, are provided, whose thermal expansion and contraction behaviour matches the expansion or contraction of the rotor (2, 3) in dependence of its respective loading, to provide radial movement of the casing segments (9) - in accordance with the rotor loading - to control tip clearance, characterized in that, when there is no downstream static bearing of the rotor (2, 3) on struts (14, 15) forming a U-shaped profile with the inner platform (7b), a U-shaped inner ring (10) for passive tip clearance control is mounted such that a torsion box (8) is provided on the platform (7b) and in that the torsion box (8) compensates expansions in axial and in peripheral direction.
2. Arrangement in accordance with Claim 1, characterized in that, to form the torsion box (16), the one leg (11) of the inner ring (10) is firmly tightened to the adjacent struts (13) of the inner platform (7b) using a clamping sleeve (16) that comprises a collar (19) and a screw bolt (17) arranged in said clamping sleeve (16) with safety nut (18) while the even area (20) at the opposite end portion of the clamping sleeve (16) is slidingly fitted into holes of the other leg (12) and the other struts (14) for expansion compensation in axial direction, and while every other hole that receives fastening means (16, 18) in the legs (11, 12) or struts (13, 14) is an oblong hole to provide expansion compensation in peripheral direction.
3. Arrangement in accordance with Claim 2, characterized in that the clamping sleeve (16) includes an indentation (21) on its front that receives the head of the screw bolt (17) to minimize ventilation losses.
4. Arrangement in accordance with Claim 1, characterized in that the torsion box (8) is provided with an upstream circumferential sealing dam (22) directed towards the inner platform (7b) to shield the portion of the screw bolt (17) with rivet nuts (18) that protrudes from the outer surface of the torsion box (8) to minimize ventilation losses.
5. Arrangement in accordance with Claim 1, characterized in that the torsion box (8) is provided with a circumferential protective shield (23) pointing inwards with an edge and/or brush packing (24) on its free edge to minimize ventilation losses.
6. Arrangement in accordance with Claim 1, characterized in that the guide vane segments (7) equipped with the torsion box (8) are held in peripheral direction, and guided in radial direction, by a cross key serration (15) between turbine casing (4) and outer platform (7a) and in that a retainer ring (25) is provided for axial fixation of the guide vane segments (7).
7. Arrangement in accordance with Claim 1, characterized in that the casing segments located upstream of the rotor blade tips (3) are liner segments (9) that can be moved in the radial direction.
8. Arrangement in accordance with Claim 1, characterized in that the downstream bearing of the rotor of the high-pressure turbine is a non-static inter-shaft bearing (1) of the subsequent low-pressure turbine.

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