Tip clearance adjustment structure and method

Abstract

The present application relates to the technical field of turbine structure design, and particularly relates to a tip clearance adjusting structure and method. The adjusting structure comprises an outer casing of a low-pressure turbine guide vane, a plurality of replacement blocks are mounted in the inner ring of the outer casing; the plurality of replacement blocks are spliced to form a complete spliced ring; the inner circumferential surface of the spliced ring is a sawtooth surface with a sawtooth shape in axial section. The adjusting method comprises the following steps: S1, preparing new replacement blocks, and the lower surface of the new replacement blocks is initially a plane with a margin; S2, when the tip clearance between the blade tip on the turbine rotor and the sawtooth surface of the spliced ring formed by the plurality of replacement blocks is too large, all the replacement blocks on the outer casing are removed, and the new replacement blocks prepared in the step S1 are replaced; after all the new replacement blocks are spliced to form a complete spliced ring, the inner surface of the spliced ring is processed to form a sawtooth surface according to the large outer diameter of the turbine rotor, and the clearance between the sawtooth surface and the blade tip is ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of turbine structure design, in particular to a tip clearance adjusting structure and method. BACKGROUND

[0002] In the field use of an aero-engine, the rotor components are affected by thermal stress and centrifugal stress, which leads to the contact wear between the casing and the turbine blade tip, resulting in the change of the tip clearance. When the turbine works at the designed speed, the turbine inlet total temperature and the fuel consumption rate will increase with the increase of the turbine tip clearance size. According to statistics, when the tip clearance increases by 1%, the turbine efficiency decreases by about 3.5%. When the engine is shipped, the engine performance meets the standard, but as the field use time increases, the tip clearance increases, and the turbine efficiency decreases.

[0003] When the turbine efficiency decreases, the most commonly used method is to use the engine regulator to increase the turbine front temperature to improve the turbine power, but this will increase the engine fuel consumption rate, that is, the decrease of the turbine working efficiency will lead to the decrease of the engine working efficiency and the deterioration of the engine economy, and the increase of the fuel consumption rate. This method of adjusting the engine control law is feasible when the turbine power decreases to a certain extent, but when the tip clearance increases to the extent that the turbine efficiency decreases extremely and the engine control law cannot guarantee the performance, there is no particularly good method to restore the engine performance. Generally, the method of replacing new blades or increasing the height of the blades through 3D printing technology is adopted. However, the cost of replacing blades is high, the operation of 3D printing technology to increase the height of blades is complicated, and the 3D printing technology to increase the height of blades cannot guarantee the strength of the blades. SUMMARY

[0004] The main purpose of the present application is to provide a tip clearance adjusting structure and method, which aims to solve the above technical problems.

[0005] To achieve the above purpose, on the one hand, the present application provides a tip clearance adjusting structure, which comprises an outer casing of a low-pressure turbine guide vane, a plurality of replacement blocks are installed in the inner ring of the outer casing; the plurality of replacement blocks are spliced to form a complete spliced ring; the inner circumferential surface of the spliced ring is a sawtooth surface with a sawtooth shape in axial section.

[0006] Preferably, the adjustment structure further includes a retaining ring, and an arc-shaped groove is provided on the end face of the retaining ring, with an outer ring portion formed on the outer side and an inner ring portion formed on the inner side; a first ring groove and a second ring groove are provided on the inner ring of the outer casing, with a first ring body formed on the inner side of the first ring groove and a second ring body formed on the inner side of the second ring groove; the replacement block includes an arc-shaped plate and a first arc-shaped retaining strip and a second arc-shaped retaining strip integrally formed on the outer peripheral surface of the arc-shaped plate; a first retaining groove is formed between the first arc-shaped retaining strip and the outer peripheral surface of the arc-shaped plate; a second retaining groove is formed between the second arc-shaped retaining strip and the outer peripheral surface of the arc-shaped plate; the second arc-shaped retaining strip on the replacement block is inserted into the second ring groove of the outer casing, and the second ring body of the outer casing is inserted into the second retaining groove of the replacement block; the first ring body and the first arc-shaped retaining strip are both inserted into the arc-shaped groove of the retaining ring, and the outer ring portion of the retaining ring is inserted into the first ring groove of the outer casing, and the inner ring portion of the retaining ring is inserted into the first retaining groove of the replacement block.

[0007] Preferably, the first arc-shaped retaining strip and the second arc-shaped retaining strip each have multiple anti-cracks, and an anti-crack hole is provided at the root of each anti-crack.

[0008] Preferably, a steel wire is inserted into the two opposite anti-crack holes of the first arc-shaped retaining strip and the second arc-shaped retaining strip.

[0009] Preferably, the adjustment structure further includes a cover plate; one side of the cover plate is sandwiched between the first arc-shaped retaining strip and the first ring body; the other side of the cover plate is sandwiched between the second arc-shaped retaining strip and the groove wall of the second ring groove; a groove is formed between the first arc-shaped retaining strip and the second arc-shaped retaining strip; the cover plate and the groove together form a cooling cavity; and multiple ventilation holes are provided on the cover plate.

[0010] Preferably, support blocks are welded to both ends of the groove to support the cover plate.

[0011] Preferably, the cover plate and the replacement block are offset in the circumferential direction, so that one end of the cover plate forms a cantilever end for overlapping the adjacent replacement block.

[0012] Preferably, a first U-shaped notch is provided on the cover plate; a second U-shaped notch is provided on the second arc-shaped retaining strip; the positions of the first U-shaped notch and the second U-shaped notch correspond to each other to form an axial limiting notch; a positioning pin is provided on the outer casing, and the positioning pin is inserted into the circumferential limiting notch formed by the first U-shaped notch and the second U-shaped notch.

[0013] Preferably, the retaining ring is provided with a slit.

[0014] On the other hand, the present invention also proposes a method for adjusting the blade tip clearance, which adopts the aforementioned adjustment structure and includes the following steps:

[0015] S1, a new replacement block is prepared, and the lower surface of the new replacement block is initially flat and has a margin;

[0016] S2, when the tip of the blade on the turbine rotor is too large from the serrated surface gap of the joint ring formed by the joint of the plurality of replacement blocks, all the replacement blocks on the outer casing are removed, and the new replacement blocks prepared in the step S1 are replaced; after all the new replacement blocks are jointed to form a complete joint ring, the inner surface of the joint ring is processed to form a serrated surface according to the large outer diameter of the turbine rotor, and the gap between the serrated surface and the tip is ensured.

[0017] Due to the adoption of the above technical scheme, the beneficial effects of the present application are as follows:

[0018] (1) In the present application, the tip gap is adjusted by using the structure of the replacement block. When the tip of the blade on the turbine rotor is too large from the serrated surface gap of the joint ring formed by the joint of the plurality of replacement blocks, the new replacement blocks are replaced, and the inner surface of the joint ring formed by the new replacement blocks is processed to form a serrated surface according to the large outer diameter of the turbine rotor, and the gap between the serrated surface and the tip is ensured. Therefore, the replacement block is used to adjust the tip gap, and the new blade does not need to be replaced, thereby reducing the cost.

[0019] (2) In the present application, since the inner circumferential surface of the complete joint ring formed by the joint of all the replacement blocks is a serrated surface, the contact area with the tip can be prevented from being too large, thereby preventing the tip from being worn too quickly and causing cracks and excessive wear.

[0020] (3) In the present application, the cooling cavity is formed by the cover plate and the groove of the replacement block, a plurality of air holes are formed on the cover plate for introducing the cold air introduced by the turbine into the cooling cavity, which plays a role of cooling the replacement block, carries away part of the heat generated by the contact and friction between the tip and the replacement block during work, controls the temperature of the tip, prevents the blade from being overburned, and plays a role of protecting the blade.

[0021] (4) The tip gap adjustment structure and method provided by the present application greatly reduces the cost and time of restoring the efficiency of the engine turbine. Only the replacement block needs to be added to the original structure, and the tip gap is adjusted by replacing the replacement block, thereby restoring the efficiency of the engine turbine. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the drawings shown.

[0023] Figure 1 schematic diagram of the adjusting structure provided by the present application;

[0024] Figure 2 schematic diagram of the structure of the replacement block in the present application;

[0025] Figure 3 schematic diagram of the replacement block in the present application in cooperation with the cover plate;

[0026] Figure 4 schematic diagram of the partial structure of the clasp in the present application;

[0027] Figure 5 schematic diagram of the structure of the support block in the present application;

[0028] Figure 6 schematic diagram of the structure of the cover plate in the present application;

[0029] Figure 7 schematic diagram of the steel wire in the present application.

[0030] Brief Description of the Drawings:

[0031] 1, outer case; 1a, first ring groove; 1b, second ring groove; 1c, first ring body; 1d, second ring body; 2, replacement block; 2a, first arc-shaped clamping strip; 2b, second arc-shaped clamping strip; 2c, first clamping groove; 2d, second clamping groove; 2e, recess; 2f, crack stopping seam; 2g, crack stopping hole; 2h, arc-shaped plate; 2j, second U-shaped notch; 3, clasp; 3a, arc-shaped groove; 3b, outer ring portion; 3c, inner ring body; 4, steel wire; 5, cover plate; 5a, air hole; 5b, first U-shaped notch; 6, support block. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0033] It should be noted that all the directionality indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present application are only used to explain the relative position relationship, movement condition, etc. between components in a certain specific posture (as shown in the drawings), and if the specific posture changes, the directionality indications also change accordingly.

[0034] In addition, the descriptions involving "first", "second" and the like in the present application are only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the same, or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second" can explicitly or implicitly include at least one of the features. In addition, the technical solutions of various embodiments can be combined with each other, but it must be based on the realization of ordinary skilled in the art, when the combination of technical solutions appears contradictory or cannot be realized, it should be considered that the combination of technical solutions does not exist, nor within the protection scope required by the present application.

[0035] In combination with the drawings, in one aspect, the present embodiment provides a tip clearance adjusting structure, which comprises an outer casing 1 of a low-pressure turbine guide vane, a plurality of replacement blocks 2 are mounted in the inner ring of the outer casing 1; the plurality of replacement blocks 2 are spliced together to form a complete spliced ring; the inner circumferential surface of the spliced ring is a sawtooth surface with a sawtooth shape in axial section.

[0036] Further, the adjusting structure further comprises a snap ring 3, and an arc-shaped groove 3a is provided on the end surface of the snap ring 3, the outer side of the arc-shaped groove 3a forms an outer ring part 3b, and the inner side forms an inner ring part 3c; a first ring groove 1a and a second ring groove 1b are provided on the inner ring of the outer casing 1, the inner side of the first ring groove 1a forms a first ring body 1c, and the inner side of the second ring groove 1b forms a second ring body 1d; the replacement block 2 comprises an arc-shaped plate 2h, and a first arc-shaped clamping strip 2a and a second arc-shaped clamping strip 2b integrally formed on the outer circumferential surface of the arc-shaped plate 2h; a first clamping groove 2c is formed between the first arc-shaped clamping strip 2a and the outer circumferential surface of the arc-shaped plate 2h; a second clamping groove 2d is formed between the second arc-shaped clamping strip 2b and the outer circumferential surface of the arc-shaped plate 2h; the second arc-shaped clamping strip 2b on the replacement block 2 is inserted into the second ring groove 1b of the outer casing 1, and the second ring body 1d of the outer casing 1 is inserted into the second clamping groove 2d of the replacement block 2; the first ring body 1c and the first arc-shaped clamping strip 2a are jointly inserted into the arc-shaped groove 3a of the snap ring 3, and the outer ring part 3b of the snap ring 3 is inserted into the first ring groove 1a of the outer casing 1, and the inner ring part 3c of the snap ring 3 is inserted into the first clamping groove 2c of the replacement block 2. By adopting the above structure, a detachable clamping structure is formed, which is convenient for disassembly and replacement of new replacement blocks 2.

[0037] In combination with the drawings, Figure 2 As shown, the first arc-shaped clamping strip 2a and the second arc-shaped clamping strip 2b are respectively provided with a plurality of crack arrest slots 2f, and a crack arrest hole 2g is provided at the root of each crack arrest slot 2f. The purpose of providing the crack arrest slot 2f is to adjust the circumferential deformation amount of the replacement block 2, prevent cracks caused by thermal deformation, and release thermal stress. The purpose of providing the crack arrest hole 2g is to avoid cracks at the root position of the crack arrest slot 2f of the replacement block 2.

[0038] In combination with the drawings, Figure 3As shown, a steel wire 4 is inserted into the opposite two crack arrest holes 2g of the first arc-shaped clamping strip 2a and the second arc-shaped clamping strip 2b. The purpose of arranging the steel wire 4 is to prevent the crack arrest hole 2g from being excessively deformed after thermal deformation and cooling shrinkage.

[0039] In the embodiment, the adjusting structure further comprises a cover plate 5 which is integrated with the replacement block 4 by spot welding and does not allow the gasket to exceed the replacement block 4 on both sides. One side of the cover plate 5 is clamped between the first arc-shaped clamping strip 2a and the first ring body 1c; the other side of the cover plate 5 is clamped between the second arc-shaped clamping strip 2b and the groove wall of the second ring groove 1b; the first arc-shaped clamping strip 2a and the second arc-shaped clamping strip 2b form a groove 2e; the cover plate 5 and the groove 2e jointly form a cooling cavity; a plurality of air holes 5a are formed on the cover plate 5 for introducing the cold air introduced by the turbine into the cooling cavity, thereby cooling the replacement block, removing part of the heat generated by the contact friction between the blade tip and the replacement block during work, controlling the temperature of the blade tip, and protecting the blade.

[0040] Supporting blocks 6 are welded at both ends of the groove 2e for supporting the cover plate 5, and the end face of the supporting block 6 does not protrude from the end face of the replacement block 2, thereby avoiding interference between the adjacent two replacement blocks 2 when they are spliced.

[0041] In combination Figure 3 As shown, the cover plate 5 and the replacement block 2 are arranged in a circumferential direction, so that one end of the cover plate 5 forms a cantilever end 5b for lapping on the adjacent replacement block 2. In addition, the cantilever end 5b can cover the splicing gap between the adjacent two replacement blocks 2, thereby playing a sealing role.

[0042] In the embodiment, the materials of the supporting block 6, the cover plate 5 and the replacement block 4 are all high-temperature alloys, and the steel wire 4 is stainless steel.

[0043] In combination Figure 2 , Figure 3 and Figure 6 As shown, a first U-shaped notch 5b is arranged on the cover plate 5; a second U-shaped notch 2j is formed on the second arc-shaped clamping strip 2b; the first U-shaped notch 5b and the second U-shaped notch 2j correspond in position to jointly form an axial limiting notch; a positioning pin (not shown in the figure) is arranged on the outer casing 1 and is inserted into the circumferential limiting notch formed by the first U-shaped notch 5b and the second U-shaped notch 2j, thereby playing a circumferential limiting role.

[0044] In combination Figure 1 As shown, a split 3d is arranged on the clamping ring 3. The purpose is to adjust the circumferential deformation amount of the clamping ring 3.

[0045] On the other hand, the embodiment also proposes a method for adjusting the blade tip gap, which adopts the above adjusting structure and comprises the following steps:

[0046] S1, a new replacement block 2 is prepared, and the lower surface of the new replacement block 2 is initially flat and has a margin;

[0047] S2, when the tip of the blade on the turbine rotor is too large from the serrated surface gap of the joint ring formed by the plurality of replacement blocks 2, all the replacement blocks 2 on the outer casing 1 are removed, and the new replacement blocks 2 prepared in the step S1 are replaced; after all the new replacement blocks 2 are jointed to form a complete joint ring, the inner surface of the joint ring is processed to form a serrated surface according to the large outer diameter of the turbine rotor, and the gap between the serrated surface and the tip is ensured.

[0048] The above only describes the preferred embodiments of the present application, and does not limit the patent scope of the present application, and any equivalent structural transformation, direct / indirect application in other related technical fields within the inventive concept of the present application and the content of the specification and drawings are included in the patent protection scope of the present application.

Claims

1. A blade tip clearance adjustment structure, characterized in that, The outer casing (1) includes a low-pressure turbine guide, and multiple replacement blocks (2) are installed in the inner ring of the outer casing (1); the multiple replacement blocks (2) are spliced ​​together to form a complete splicing ring; the inner circumferential surface of the splicing ring is a sawtooth surface with a serrated axial section. It also includes a retaining ring (3), and an arc groove (3a) is provided on the end face of the retaining ring (3). An outer ring portion (3b) is formed on the outer side of the arc groove (3a), and an inner ring portion (3c) is formed on the inner side. A first ring groove (1a) and a second ring groove (1b) are provided on the inner ring of the outer casing (1). A first ring body (1c) is formed on the inner side of the first ring groove (1a), and a second ring body (1d) is formed on the inner side of the second ring groove (1b). The replacement block (2) includes an arc-shaped plate (2h) and a first arc-shaped retaining strip (2a) and a second arc-shaped retaining strip (2b) integrally formed on the outer peripheral surface of the arc-shaped plate (2h); a first retaining groove (2c) is formed between the first arc-shaped retaining strip (2a) and the outer peripheral surface of the arc-shaped plate (2h); a second retaining groove (2d) is formed between the second arc-shaped retaining strip (2b) and the outer peripheral surface of the arc-shaped plate (2h). The second arc-shaped retaining strip (2b) on the replacement block (2) is inserted into the second annular groove (1b) of the outer casing (1), and the second annular body (1d) of the outer casing (1) is inserted into the second retaining groove (2d) of the replacement block (2); the first annular body (1c) and the first arc-shaped retaining strip (2a) are inserted into the arc-shaped groove (3a) of the retaining ring (3), and the outer annular part (3b) of the retaining ring (3) is inserted into the first annular groove (1a) of the outer casing (1), and the inner annular part (3c) of the retaining ring (3) is inserted into the first retaining groove (2c) of the replacement block (2); The first arc-shaped retaining strip (2a) and the second arc-shaped retaining strip (2b) are respectively provided with multiple anti-cracks (2f), and an anti-crack hole (2g) is provided at the root of each anti-crack (2f). A steel wire (4) is inserted into the two opposite crack-stopping holes (2g) of the first arc-shaped clip (2a) and the second arc-shaped clip (2b).

2. The blade tip clearance adjustment structure as described in claim 1, characterized in that, It also includes a cover plate (5); one side of the cover plate (5) is sandwiched between the first arc-shaped clip (2a) and the first ring body (1c); the other side of the cover plate (5) is sandwiched between the second arc-shaped clip (2b) and the groove wall of the second ring groove (1b); a groove (2e) is formed between the first arc-shaped clip (2a) and the second arc-shaped clip (2b); the cover plate (5) and the groove (2e) together form a cooling cavity; a plurality of vent holes (5a) are provided on the cover plate (5).

3. The blade tip clearance adjustment structure as described in claim 2, characterized in that, Support blocks (6) are welded to both ends of the groove (2e) to support the cover plate (5).

4. The blade tip clearance adjustment structure as described in claim 2, characterized in that, The cover plate (5) and the replacement block (2) are offset in the circumferential direction, so that one end of the cover plate (5) forms a cantilever end for attaching to the adjacent replacement block (2).

5. The blade tip clearance adjustment structure as described in claim 2, characterized in that, A first U-shaped notch (5b) is provided on the cover plate (5); a second U-shaped notch (2j) is provided on the second arc-shaped retaining strip (2b); the positions of the first U-shaped notch (5b) and the second U-shaped notch (2j) correspond to each other to form an axial limiting notch; a positioning pin is provided on the outer casing (1), and the positioning pin is inserted into the circumferential limiting notch formed by the first U-shaped notch (5b) and the second U-shaped notch (2j).

6. The blade tip clearance adjustment structure as described in claim 1, characterized in that, A split slit (3d) is provided on the retaining ring (3).

7. A method for adjusting blade tip clearance, characterized in that, The adjustment structure according to any one of claims 1 to 6 includes the following steps: S1. Prepare a new replacement block (2), and the lower surface of the new replacement block (2) is initially planar with a margin. S2. When the gap between the blade tip on the turbine rotor and the serrated surface of the splicing ring obtained by splicing multiple replacement blocks (2) is too large, remove all replacement blocks (2) on the outer casing (1) and replace them with new replacement blocks (2) prepared in step S1. After all the new replacement blocks (2) are spliced ​​together to form a complete splicing ring, the inner surface of the splicing ring is processed according to the large outer diameter of the turbine rotor to form a serrated surface, and the gap between the serrated surface and the blade tip is ensured.

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