Method of optimizing a honeycomb of a turbomachine, honeycomb and expander

Abstract

A method of optimizing a honeycomb (100, 200) of a turbomachine disposed in a seal system (105, 205) between a stator part (N) and a rotor part (102, 202) of rotating equipment comprises: cutting the honeycomb (100, 200) by means of a processing machine to integrate a swirl breaker (110, 210) in the honeycomb (100, 200), and removing material from a surface of the honeycomb (100, 200) to obtain the swirl breaker (110, 210) integrated in the honeycomb (100, 200). A honeycomb (100, 200) is obtained by the method of optimizing. An expander comprises at least a seal system (105, 205) provided with the honeycomb (100, 200) with the integrated swirl breaker (110, 210).

Description

TITLETHE HONEYCOMBS WITH INTEGRATED SWIRL BREAKERS AND OPTIMIZING METHODS.DESCRIPTIONTECHNICAL FIELD

[0001] The subject-matter disclosed herein relates to a turbine or expander comprising a honeycomb with integrated swirl breaker to reduce fluid swirl at the inlet of the seal system. The subject matter disclosed relates to a method of optimizing a honeycomb design with integrated swirl breaker.BACKGROUND ART

[0002] Interstage seals in gas turbines are essential for minimizing fluid leakage between different sections of the turbines, which helps maintaining thermodynamic efficiency and preventing energy losses. There are various types of seals, including labyrinth seals, brush seals, and honeycomb seals, each with unique benefits in reducing leakage and resisting wear. Labyrinth seals create a complex path for the fluid, reducing its pressure and velocity, while brush seals use flexible bristles to adapt to rotor variations, ensuring a good seal even when worn. Regular maintenance of these seals is crucial to ensure they remain effective, as wear and damage can significantly impact turbine efficiency.

[0003] As known a leakage flow may have a certain swirl at the inlet of a seal, as resulting from the upstream flow path features. For instance in interstage seals a certain swirl may exist at trailing edge of upstream blade row: then, moving from the flow path to the interstage sea, the swirl tends to increase since the flow is moving from an outer radius to an inner radius and becauseof the presence of a rotor surface of a shank and the angel wings of the blade or to decrease due to drag of statoric components. The higher the swirl at the inlet of the labyrinth seal of an interstage seal, the higher is the negative impact on the rotordynamic stability of the rotor.

[0004] Typical features used to reduce the fluid swirl in compressors and turboexpanders are: axial swirl breakers, i.e. statoric blade-like shape components, that reduce the tangential velocity of the fluid approaching a labyrinth seal, Pocket dumper seal, i.e. statoric pocket created between the teeth of the labyrinth seal. Above features are commonly used in balancing drum labyrinth seal, or in region of the engine where there is either enough available room to insert the axial swirl breaker, or enough number of labyrinth seal teeth for the pocket dumper.

[0005] Known from the prior art are the following patent documents: US2022275731; US2017198597; US2013156553; US2012183388; EP3147460.

[0006] However, it is desirable to shape a honeycomb in an innovative way that increases the drag to the flow, thus reducing the swirl, improving the effectiveness of a sealing system, enhancing rotodynamic effects, and achieving a honeycomb with swirl brakes in positions where it is difficult to insert them.SUMMARY

[0007] According to a first aspect, the subject-matter disclosed herein relates to an innovative method of optimizing a honeycomb of a turbomachine, wherein the honeycomb is disposed in a seal system between a stator part (N) and a rotor part of rotating equipment, wherein the method comprising: cutting the honeycomb by means of a processing machine to integrate a swirl breaker in the honeycomb, and removing material from a surface of the honeycomb to obtain the swirl breaker integrated in the honeycomb.

[0008] According to a second aspect, the subject-matter disclosed herein relates to an honeycomb obtained from the innovative method of optimizing seal system.

[0009] According to a third aspect, the subject-matter disclosed herein relates to an expander comprising at least a seal system provided with honeycomb with an integrated swirl breaker, seal system.BRIEF DESCRIPTION OF THE DRAWINGS

[0010] A more complete appreciation of the disclosed embodiments of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:Fig. 1 shows a section view of a turbomachine with a first embodiment of an innovative honeycomb with an integrated swirl breaker arranged at the forward side of the honeycomb.Fig. 2 shows a section view of a turbomachine with a first embodiment of the innovative honeycomb with an integrated swirl breaker arranged at the forward side of honeycomb of Fig.1 wherein a flow path is highlighted.Fig. 3 shows a perspective section view of an innovative honeycomb with a integrated swirl breaker arranged at the forward side of honeycomb of Fig.1.Fig.3A shows a detailed cross-sectional view of a swirl breaker of the honeycomb of Fig. 1 arranged at the forward side of honeycomb.Fig. 4 shows a section view of a portion of the innovative honeycomb of Fig.1, arranged at the forward side of the honeycomb.Fig. 5, 6, and 7 show a detailed cross-sectional view of a swirl breaker of the honeycomb of Fig. 1, arranged at the forward side of the honeycomb.Fig. 8 shows a section view of the portion of the innovative honeycomb of Fig.l, arranged at the forward side of the honeycomb.Fig. 9 shows a section view of a second embodiment of an honeycomb with an integrated forward swirl breaker arranged at the forward side of the honeycomb.Fig.10 shows a section view of a honeycomb with an integrated full axial passing swirl breaker of the honeycomb of Fig.9, arranged at the forward side of the honeycomb.Fig.11 shows a section view of a honeycomb with an integrated swirl breaker arranged at the aft side of the honeycomb of Fig.9 arranged at the aft side of the honeycomb.Fig.12 shows a section view of a honeycomb of Fig.9 with a first integrated swirl breaker arranged at the forward side of the honeycomb and a second integrated swirl breaker arranged at the aft side of the honeycomb.Fig.13 shows a section view of a honeycomb of Fig.9 with a first integrated swirl breaker arranged at the forward side of the honeycomb and a third integrated swirl breaker arranged at the forward side of the honeycomb.Fig.lOA shows a section view of a honeycomb with an integrated full axial passing swirl breaker of the honeycomb of Fig.l, arranged at the forward side of forward side.Fig.11 A shows a section view of a honeycomb with an integrated swirl breaker arranged at the aft side of the honeycomb of Fig.l arranged at the aft side of the honeycomb.Fig.l2A shows a section view of a honeycomb of Fig.1 with a first integrated swirl breaker arranged at the forward side of the honeycomb and a second integrated swirl breaker arranged at the aft side of the honeycomb.Fig.13 A shows a section view of a honeycomb of Fig.9 with a first integrated swirl breaker arranged at the forward side of the honeycomb and a third integrated swirl breaker arranged at the forward side of the honeycomb.DETAILED DESCRIPTION OF EMBODIMENTS

[0011] The subject-matter disclosed herein relates to an innovative honeycomb with an integrated swirl breaker in a turbine or expander, positioned in a seal system between a stator part and a rotor part. This swirl breaker creates a passage for the leakage flow, reducing the swirl of the leakage flow at the inlet of the seal system. This helps to improve the efficiency of the sealing system by reducing energy losses due to vortices.

[0012] By extending the swirl breaker radially in the extreme portion of the honeycomb, corresponding to the forward side of the seal system, further reduction of the leakage flow swirl is achieved. This compact design contributes to maintaining a more effective seal between the stator and rotor parts, enhancing the overall performance and rotordynamic stability of the turbine or expander with no significant complication of the manufacturing cycle.

[0013] Additionally, the swirl breaker is equipped on the surface that encounters the flow with a plurality of grooves, preferably radial, but not limited to that, to create stator pockets that increase the drag on the leakage flow. This additional design feature further helps to reduce the leakage flow and improve the system's efficiency.

[0014] However, the honeycomb is subject to wear over time, for example,when the sealing fin on the tip of the turbine blade comes into contact with it, at the seal between the nozzles and the shaft, or between the casing and the tip of the turbine blades. This contact is designed to create a tight seal but can cause abrasion and wear of the honeycomb material. The integration of a swirl breaker in the honeycomb not only helps to reduce the swirl of the leakage flow but can also help to better distribute the contact forces, potentially reducing localized wear, and it could also be applied when the rotor is smooth, i.e., without irregularities or teeth.

[0015] Reference now will be made in detail to embodiments of the disclosure, an example of which is illustrated in the drawings. Each example is provided by way of explanation of the disclosure, not limitation of the disclosure. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present disclosure without departing from the scope or spirit of the disclosure. In the following description, similar reference numerals are used for the illustration of figures of the embodiments to indicate elements performing the same or similar functions. Moreover, for clarity of illustration, some references may not be repeated in all the figures.

[0016] In Figures 1 and 9 are schematically shown two embodiments of an innovative honeycomb. The innovative honeycomb is generally indicated with reference to a numeral 100 in Fig. 1 and 200 in Fig. 9. Fig. 2 wherein an internal flow path leakage is highlighted and applies to the flow path leakage of the embodiments of both Fig. 1 and Fig. 9.

[0017] According to first embodiment shown in Fig. 1 the honeycomb 100 of a turbine or expander, is disposed in a seal system 105 between a stator part N and a rotor part 102 of a rotating equipment, for example a turbine, an expander or a compressor, advantageously the honeycomb 100 is provided with a swirl breaker 110. In particular, the seal system 105 is an interstage seal between anozzle platform 101 of the stator N and a surface of a spacer of the rotor part 102, preferably the surface of the rotor part 102 is a toothed surface 102a.

[0018] Advantageously Fig.1, and Fig. 9 show an innovative honeycomb 100, 200 with an integrated swirl breaker 110, 210 arranged at the forward side of the honeycomb.

[0019] Typically, with non-limiting reference to Figs. 1, 3 and 7, the said swirl breaker 110 is integrated in the honeycomb 100, the swirl breaker 110, as shown in Fig. 2 is included in a passage for the flow path leakage 103, reducing the leakage flow swirl at the inlet of the seal system 105.

[0020] In particular, as shown in Figs.l, 2, 4, 8,9,10 the swirl breaker 110 extends in the radial direction in the extreme portion of the honeycomb 100 corresponding to a forward side of the seal system 105. The plurality of grooves 106 is obtained by the step of removing material from a forward surface of the honeycomb 100, 200.

[0021] Advantageously, with non-limiting reference to Figs. 3, 3 A and 5, the swirl breaker 110 is provided on the surface that encounters the flow, with a plurality of grooves 106, to create stator pockets, preferably radial or of another suitable shape, to increase the drag on the leakage flow. It should be noted that the swirl breaker 110, 210 is not a separate component but is obtained by this modification of the forward surface of the honeycomb 100, 200 through the formation of the plurality of grooves 106. Therefore, reference numerals 110, 210 indicate the entire forward surface of the honeycomb 100, 200 including the grooves 106 and the resulting protrusions 108. Preferably the plurality of grooves 106 may be entirely or partially equipped with a hexagonal-shaped honeycomb surface 109.

[0022] Considering Fig.2 the flow path leakage 103 comprises a firstsection (0-1) that extends from the stator N at the inlet of the seal system 105, and a second section (1-2) that extends along the entire length of the seal system 105.

[0023] As shown in Fig. 8, in the seal system 105, there is a gap 107 between the swirl breaker 110 of the honeycomb 100 and the surface of the rotor part 102. Advantageously, the gap 107 is such as to prevent contact between the swirl breaker 110 and the rotor part 102.

[0024] As explained above with non-limiting reference to Fig. 8, the gap 107, to prevent contact between the swirl breaker 110 and the rotor part 102, is dimensionally equal to n times the space between the rotor part 102 and the central portion of the honeycomb 100, where 0,1 < n < 5.

[0025] Advantageously, a method of optimizing a honeycomb 100, 200 of a turbomachine, wherein the honeycomb 100, 200 is disposed in a seal system 105, 205 between a stator part (N) and a rotor part 102, 202 of rotating equipment. The method 100, 200 comprising the step of cutting the honeycomb 100, 200 by means of a processing machine to integrate a swirl breaker 110, 210 in the honeycomb 100, 200, wherein the swirl breaker 110, 210 is integrated on a surface of the honeycomb 100, 200 and comprises a plurality of grooves 106.

[0026] In particular the method of optimizing a honeycomb 100, 200 provided with an integrated swirl breaker 110, 210 in the honeycomb 100, 200, wherein the swirl breaker 110, 210 is provided on the surface that encounters the flow, with a plurality of grooves 106, comprises the step of cutting the honeycomb 100, 200 through a processing machine, for example milling machine, wherein a cut at the forward side of a seal system 105, 205 which faces the incoming flow, is oriented along a direction (C) inclined respect to a rotational axis (A) with a cutting angle a preferably perpendicularto the rotational axis (A), as shown for example and without limitation in Fig.7.

[0027] It is to be noted that the optimization of swirl breaker 110, 210 depends on the ratio R1 / R2 between the higher radius R1 and the lower R2 radius of a seal system (Fig.4), as well as the ratio (Rl-R2) / R_average between the honeycomb 100, 200 radial extension and the average radius. The higher radius R1 and the lower radius R2 are calculated respect to the rotation machine axis. This optimization helps in achieving a more efficient flow control, reducing turbulence and enhancing the overall performance of the system. As shown in Figs 6 and 7 the honeycomb features are made preferably a hexagonal cell structure.

[0028] Furthermore, the plurality of grooves 106 is obtained by the step of removing material from a forward surface of the honeycomb 100, 200 through a machining process, for example milling, electrical discharge machining (EDM), or similar methods. This allows for precise control over the groove dimensions, which can significantly improve the aerodynamic properties and reduce drag. As shown in Figs.3 and 3A, the plurality of grooves 106 provides a plurality of protrusions 108 preferably with a toothed profile at the extreme portion of the honeycomb 100, 200. Advantageously to optimize the aerodynamic flow and enhance the efficiency of the swirl brake 110, 210, while reducing vibrations and improving the rotor dynamic stability of a turbomachine, preferably each of the plurality of protrusions 108 assumes a three-dimensional shape similar to an airfoil, rather than being limited to a rectangular shape. These protrusions have two-dimensional sections stacked along a straight axis, with axial stacking where the sections are aligned along the longitudinal axis of the cylinder in the direction of the main flow, or radial stacking where the sections are aligned along a radial axis relative to the cylinder, forming an angle with the central axis of the cylinder

[0029] Specifically, as shown in Figs 3A and 7, they form a leaning angle where the sections are inclined at an angle P relative to the radial axis of the cylinder, or a bowling angle where the sections are curved, creating an arcuate shape.

[0030] To further enhance overall performance, efficiency, and stability of the compressor, as shown in Fig. 5 it is advantageous to adjust the stagger angle y, which is the angle of inclination of the sections relative to the direction of the flow.

[0031] Advantageously, the step of removing material is based on the ratio 0 (27tR_average) (Fig. 5) between the length of tangential span of each groove and the length of the circumference at the average radius of the honeycomb, and the ratio d / L (Figs. 4 and 5) between the depth d and the length L of each groove. This ensures that the grooves are optimally sized to maximize the reduction of swirl and enhance the stability of the flow, leading to better efficiency and performance of the system.

[0032] According to a second embodiment shown in Fig.9 the honeycomb 200, is disposed in a shrouded stator seal 205 between a shrouded stator part 201 and a tip of a row of rotating blades 202, advantageously the honeycomb is provided with the integrated swirl breaker 210. arranged at the forward side of the honeycomb preferably directed towards the upstream blade U of the turbomachine. It is to be noted that the swirl breaker 210 is extended in the radial direction in the extreme portion of the honeycomb 200 corresponding to a forward side of the honeycomb 200.

[0033] Analogously to the first embodiment, the swirl breaker 210 of the second embodiment is provided on the surface that encounters the flow with a plurality of grooves 106, preferably radial, to create stator pockets that increase thedrag on the leakage flow. The plurality of grooves 106 is obtained by removing material from the forward surface of the honeycomb 200.

[0034] Advantageously, in the shrouded stator seal 205 a surface of the tip of a row of rotating blades 202 is a toothed surface 202a, rendering the shrouded stator seal 205 a labyrinth seal.

[0035] According to the first and second embodiment, Fig. 10 and Fig.lOA show the innovative honeycomb 100, 200, provided with an integrated full axial passing swirl breaker 111, 211 arranged at the forward side of honeycomb and / or at the after side of honeycomb 100, 200.

[0036] Considering Fig. 11 and Fig.11 A the honeycomb 100, 200 is provided with the integrated swirl breaker 110, 210 arranged at the aft side of the honeycomb 100, 200 preferably directed towards the upstream blade U of the turbomachine.

[0037] With non limiting reference to Fig. 12 and to Fig, 12A the innovative honeycomb 100, 200 is provided with a first integrated swirl breaker 110a, 210a arranged at the forward side of the honeycomb 100, 200 preferably directed towards downstream blade D and a second integrated swirl breaker 110b,210b arranged at the aft side of the honeycomb 100, 200 preferably towards the upstream blade U of turbomachine, allowing the reduction of sealing vortices.

[0038] Furthermore, in the Fig. 13 and in the Fig.13Athe honeycomb 100,200 is provided with the first integrated swirl breaker 110a, 210a arranged at the forward side of the honeycomb 100, 200 preferably towards the downstream blade D and a third integrated swirl breaker 110c, 210c arranged at the aft side of the honeycomb 100, 200 towards the downstream blade D.

[0039] According to a third embodiment the honeycomb 100, 200 provided with an integrated swirl breaker is obtained through an additive manufacturing,or milling process, or EDM machine (Electrical Discharge Machining)

[0040] Furthermore, an expander comprising at least a seal system provided with honeycomb with an integrated swirl breaker, may be the expander is configured to expand a supercritical carbon dioxide flow.

Claims

CLAIMS1. A method of optimizing a honeycomb (100, 200) of a turbomachine, wherein the honeycomb (100, 200) is disposed in a seal system (105, 205) between a stator part (N) and a rotor part (102, 202) of rotating equipment, wherein the method comprising: cutting the honeycomb (100, 200) by means of a processing machine to integrate a swirl breaker (110, 210) in the honeycomb (100, 200), and removing material from a surface of the honey comb (100, 200) to obtain the swirl breaker (110, 210) integrated in the honeycomb (100, 200).

2. Method of claim 1, wherein the plurality of grooves (106) of the honeycomb (100, 200) is obtained by a step of removing material from a forward surface of the honeycomb (100, 200) through a machining process.

3. Method of claim 1, wherein a cut at a forward side of a seal system (105, 205) which faces the incoming flow, is oriented along a direction (C) inclined respect to a rotational axis (A) with a cutting angle a preferably perpendicular to the rotational axis (A).

4. Method of claim 1, wherein the plurality of grooves (106) provides a toothed profile at the extreme portion of the honeycomb (105, 205).

5. Method of claim 1, wherein the integrated swirl breaker (110, 210) is obtained through additive manufacturing.

6. A honeycomb (100, 200) obtained by the method according to any one of claims 1 to 5.

7. The honeycomb (100, 200) of claim 6, wherein the swirl breaker (110, 210) is arranged at the forward side of the honeycomb (100, 200).

8. The honeycomb (100, 200) of claim 6, wherein the swirl breaker (110, 210) is included in a passage for a flow path leakage.

9. The honeycomb (100,200) of claim 6, wherein the swirl breaker (110,210) extends in a radial direction in an extreme portion of the honeycomb (100,200) corresponding to a forward side of the honeycomb (100, 200).

10. The honeycomb (100) of claim 6, wherein the seal system (105) is an interstage seal between a nozzle platform (101) of the stator (N) and a surface of a spacer of the rotor part (102).

11. The honeycomb (100, 200) of claim 6, wherein the swirl breaker (110, 210) is provided on a surface that encounters the flow, a plurality of grooves (106), preferably radial, to create stator pockets increasing the drag to the leakage flow.

12. The honeycomb (100) of claim 6, wherein there is a gap (107) in the seal system (105) between the swirl breaker (110) of the honeycomb (100) and the surface of the rotor part (102), wherein the gap (107) is such as to prevent contact between the swirl breaker (110) and the rotor part (102).

13. The honeycomb (100) of claim 12, wherein the gap (107) is dimensionally equal to n times the space between the rotor part (102) and the central portion of the honeycomb (100), where 0,1 < n < 5.

14. The honeycomb (100) of claim 6, wherein the flow path leakage (103) comprises a first section (0-1) that extends from the stator (N) at the inlet of the seal system (105), and a second section (1-2) that extends along the entire length of the seal system (105).

15. The honeycomb (100) of claim 6, wherein a surface of the rotor part (102) is a toothed surface (102a).

16. The honeycomb (100,200) of claim 6, wherein the rotating equipment is a turbine, an expander or a compressor.

17. The honeycomb (200) of claim 6, wherein the rotor part (202) is a tip of a row of rotating blades ,wherein the seal system (205) is a shrouded stator seal.

18. The honeycomb (200) of claim 17, wherein in the shrouded stator seal a surface of the tip of a row of rotating blades is a toothed surface (202a), rendering the shrouded stator seal a labyrinth seal.

19. The honeycomb (200) of claims 1 and 17, wherein the swirl breaker (210) is extended in a direction preferably radial in an extreme portion of the honeycomb (200) corresponding to a forward side of the shrouded stator seal.

20. The honeycomb (100, 200) of claim 6, wherein the honeycomb (100, 200) is provided with an integrated full axial passing swirl breaker (111, 211) arranged at a forward side of honeycomb.

21. The honeycomb (100, 200) of claim 20, wherein the integrated full axial passing swirl breaker (111, 211) is arranged at an aft side of honeycomb (100, 200).

22. The honeycomb (100, 200) of claim 6, wherein the honeycomb (100, 200) is provided with the integrated swirl breaker (110, 210) arranged at an aft side of the honeycomb (100, 200) directed towards upstream blade (U) of the turbomachine.

23. The honeycomb (100, 200) of claim 6, wherein the honeycomb (200) is provided with a first integrated swirl breaker (110a, 210a) arranged at a forward side of the honeycomb (100, 200) directed towards downstream blade (D) and a second integrated swirl breaker (110b, 210b) arranged at an aft side-15-of the honeycomb (100,200) towards the upstream blade (U) of turbomachine.

24. The honeycomb (100, 200) of claim 6, wherein the honeycomb (100, 200) is provided with a first integrated swirl breaker (110a, 210a) arranged at a forward side of the honeycomb (100, 200) directed towards downstream blade (D) and a third integrated swirl breaker (110c, 210c) arranged at an aft side of the honeycomb (100, 200) towards the downstream blade (D).

25. An expander comprising at least a seal system provided with honeycomb with an integrated swirl breaker according to any one of claims 6 to 24.

26. The expander of claim 25, wherein the expander is configured to expand a supercritical carbon dioxide flow.

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