Sealing device and rotating machinery

Abstract

The sealing device of at least one embodiment includes three or more arc-shaped fins arranged axially. The arc-shaped fins include: a first fin, which is one of the two outermost fins located on the outermost side axially; a second fin, which is arranged adjacent to the first fin axially; and at least one third fin, which is arranged axially on the side opposite to the first fin with the second fin therebetween. The third fin is preferably arranged to be inclined with respect to the radial direction such that the front end portion is located on the side closer to the first fin than the base end portion axially, and has a larger inclination angle with respect to the radial direction than the first fin or the second fin.

Description

Technical Field

[0001] The present invention relates to a sealing device and a rotating machine.

[0002] This application claims priority based on Japanese Patent Application No. 2020-079332 filed with the Japan Patent Office on April 28, 2020, and incorporates its content herein. Background Art

[0003] Rotating machines such as steam turbines and gas turbines for power generation equipment are known. The rotating machine has moving blades supported on a turbine rotor (hereinafter simply referred to as a rotor) that rotates freely relative to a housing, and stationary blades supported on the housing, and is configured to convert the energy of a working fluid flowing from the upstream to the downstream in the axial direction of the rotor into rotational energy of the rotor.

[0004] In the above-mentioned rotating machine, in a sealing portion that seals between the rotor or the moving blade and the housing, a working fluid deviating from the main flow path flows in a state having a swirling flow component imparted when passing through a nozzle, thereby generating a swirling flow (so-called eddy current) in the circumferential direction of the rotor. Due to the eddy current, when the rotor is eccentric, a periodic pressure distribution having a peak in a direction different from the eccentric direction of the rotor is generated in the circumferential direction of the rotor. For example, when the eddy current increases with high-output operation, it sometimes causes self-excited vibration of the rotor. Therefore, various structures for suppressing eddy currents in the sealing portion have been proposed.

[0005] For example, the sealing device disclosed in Patent Document 1 includes a plurality of sealing fins arranged in the axial direction on the inner circumferential surface of the housing, and a plurality of eddy current breakers that connect a first sealing fin located on the most axial direction side among the plurality of sealing fins and a second sealing fin disposed adjacent to the other side in the axial direction of the first sealing fin, and are arranged at intervals in the circumferential direction. A through-hole that penetrates the first sealing fin in the axial direction is formed in the first sealing fin (see Patent Document 1).

[0006] Prior Art Documents

[0007] Patent Documents

[0008] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2017-155859 Summary of the Invention

[0009] Problems to be Solved by the Invention

[0010] In recent years, in rotating machines such as steam turbines and gas turbines, further improvement of turbine efficiency has been sought. Therefore, it is desired to suppress the leakage flow rate, that is, the flow rate of the working fluid that deviates from the main flow path and passes through the sealing portion. However, if the leakage flow rate is suppressed, the exciting force of the above-mentioned self-excited vibration may increase.

[0011] In view of the above, an object of at least one embodiment of the present invention is to suppress the flow rate of the working fluid through the seal portion and to suppress the generation of self-excited vibration in a rotating machine.

[0012] Solution to the problem

[0013] (1) The seal device according to at least one embodiment of the present invention includes three or more arc-shaped fins arranged axially with a gap therebetween and extending circumferentially respectively.

[0014] The arc-shaped fins include:

[0015] A first fin, which is one of the two outermost fins located on the outermost side in the axial direction.

[0016] A second fin, which is arranged adjacent to the first fin in the axial direction; and

[0017] At least one third fin, which is arranged on the side opposite to the first fin with the second fin therebetween in the axial direction.

[0018] The third fin satisfies at least one of the following conditions (a) and (b).

[0019] (a) The third fin is arranged inclined with respect to the radial direction such that the front end portion is located closer to the first fin side than the base end portion in the axial direction, and the third fin has a larger inclination angle with respect to the radial direction than the first fin or the second fin.

[0020] (b) The third fin has a larger radial dimension than the first fin or the second fin so as to form a smaller seal gap than the first fin or the second fin.

[0021] (2) The rotating machine according to at least one embodiment of the present invention includes:

[0022] The seal device having the structure of (1) above;

[0023] A housing;

[0024] A rotor main body that rotates around an axis in the housing;

[0025] A plurality of moving blade main bodies that are installed so as to extend radially from the rotor main body; and

[0026] A shroud that is connected to the front end portion of each of the plurality of moving blade main bodies.

[0027] The third fin is located on the downstream side in the axial direction of the rotor main body with respect to the first fin.

[0028] Advantages of the Invention

[0029] According to at least one embodiment of the present invention, the flow rate of the working fluid passing through the seal portion can be suppressed, and the generation of self-excited vibration in the rotary machine can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 FIG. is a diagram for explaining a steam turbine as an example of a rotary machine equipped with a seal device having several embodiments.

[0031] Figure 2A FIG. is a diagram for explaining a seal device having several embodiments.

[0032] Figure 2B FIG. is a diagram for explaining a seal device having several embodiments.

[0033] Figure 2C FIG. is a diagram for explaining a seal device having several embodiments.

[0034] Figure 3A FIG. is a diagram for explaining a seal device having several embodiments.

[0035] Figure 3B FIG. is a diagram for explaining a seal device having several embodiments.

[0036] Figure 3C FIG. is a diagram for explaining a seal device having several embodiments.

[0037] Figure 4A FIG. is a diagram for explaining a seal device having several embodiments.

[0038] Figure 4B FIG. is a diagram for explaining a seal device having several embodiments.

[0039] Figure 4C FIG. is a diagram for explaining a seal device having several embodiments.

[0040] Figure 5A FIG. is a diagram for explaining a seal device having several embodiments.

[0041] Figure 5B FIG. is a diagram for explaining a seal device having several embodiments.

[0042] Figure 5C FIG. is a diagram for explaining a seal device having several embodiments.

[0043] Figure 6 FIG. is a diagram for explaining a seal device having several embodiments.

[0044] Figure 7A FIG. is a graph for explaining the flow constriction effect based on the third fin.

[0045] Figure 7B It is a chart for explaining the differential pressure in each fin.

[0046] Figure 7C It is a chart for explaining the exciting force generated in each cavity. Specific Embodiments

[0047] Hereinafter, several embodiments of the present invention will be described with reference to the accompanying drawings. Among them, the dimensions, materials, shapes, relative arrangements, etc. of the constituent parts described in the embodiments or shown in the drawings are not intended to limit the scope of the present invention thereto, but are merely illustrative examples.

[0048] For example, expressions indicating relative or absolute arrangements such as "in a certain direction", "along a certain direction", "parallel", "orthogonal", "center", "concentric", or "coaxial" not only represent such arrangements in a strict sense, but also represent a state of relative displacement with tolerances, or at an angle and distance that can achieve the same function.

[0049] For example, expressions indicating a state of equality of things such as "same", "equal", and "homogeneous" not only represent a strictly equal state, but also represent a state with tolerances or differences that can achieve the same function.

[0050] For example, expressions indicating shapes such as a quadrilateral shape and a cylindrical shape not only represent shapes such as a quadrilateral shape and a cylindrical shape in a strictly geometric sense, but also represent shapes including concave and convex portions, chamfered portions, etc. within a range where the same effect can be obtained.

[0051] On the other hand, expressions such as "comprising", "containing", "equipped with", "including", or "having" a constituent element are not exclusive expressions that exclude the existence of other constituent elements.

[0052] (Regarding the structure of the steam turbine 1)

[0053] Figure 1 It is a diagram for explaining a steam turbine as an example of a rotary machine having a sealing device with several embodiments.

[0054] As Figure 1 shown, the steam turbine device 10 includes a steam turbine 1 as an axial flow rotary machine, a steam supply pipe 12 for supplying steam S as a working fluid from a steam supply source (not shown) to the steam turbine 1, and a steam discharge pipe 13 connected to the downstream side of the steam turbine 1 and discharging steam.

[0055] As Figure 1As shown, the steam turbine 1 of several embodiments includes a casing 2, a rotor main body 11 that rotates around an axis AX within the casing 2, a rotor 3 connected to the rotor main body 11, and a bearing portion 4 that supports the rotor main body 11 so as to be rotatable around the axis AX. Additionally, Figure 1 the steam turbine 1 of several embodiments shown includes a sealing device 100 which will be described in detail later.

[0056] The rotor 3 includes a rotor main body 11 and turbine moving blades 30. The turbine moving blades 30 are a moving blade row having a plurality of moving blade bodies 31 and shrouds (tip shrouds) 34, and are arranged in multiple rows at constant intervals in the direction of the axis AX.

[0057] The plurality of moving blade bodies 31 are each installed so as to extend radially from the rotor main body 11 that rotates around the axis AX within the casing 2, and are arranged at intervals in the circumferential direction of the rotor main body 11. The plurality of moving blade bodies 31 are each a member having an airfoil-shaped cross section when viewed radially.

[0058] The shroud 34 is an annular tip shroud that is connected to the front end portions (radially outer end portions) of the plurality of moving blade bodies 31 and connects the respective front end portions.

[0059] The casing 2 is a substantially cylindrical member provided so as to cover the rotor 3 from the outer peripheral side. A plurality of stationary blade bodies 21 are installed on the casing 2 so as to extend radially inward toward the rotor main body 11. The plurality of stationary blade bodies 21 are arranged in the circumferential direction and the axis AX direction along the inner circumferential surface 25 of the casing 2. A stator vane ring 23 is installed on the plurality of stationary blade bodies 21 and is connected to the front end portions of the plurality of stationary blade bodies 21.

[0060] Inside the casing 2, a region where the stationary blade bodies 21 and the moving blade bodies 31 are arranged forms a main flow path 20 through which steam S as a working fluid flows.

[0061] Moreover, a space is formed between the inner circumferential surface 25 of the casing 2 and the tip shroud 34, and this space is referred to as a cavity 50. It should be noted that in the following description, the inner side surface of the casing 2 facing the space inside the casing 2 is referred to as the inner surface 250. Therefore, the inner circumferential surface 25 of the casing 2 is a part of the inner surface 250.

[0062] Figures 2A to 2C It is a diagram for explaining the sealing device of several embodiments, and schematically shows the vicinity of the tip shroud 34 as viewed in the circumferential direction.

[0063] Figures 3A to 3C It is a diagram for explaining the sealing device of several embodiments, and schematically shows the vicinity of the tip shroud 34 as viewed in the circumferential direction.

[0064] Figures 4A to 4CIt is a diagram of a sealing device for explaining several embodiments, schematically showing the vicinity of the blade tip shroud 34 as viewed circumferentially.

[0065] Figures 5A to 5C It is a diagram of a sealing device for explaining several embodiments, schematically showing the vicinity of the blade tip shroud 34 as viewed circumferentially.

[0066] Figure 6 It is a diagram of a sealing device for explaining several embodiments, schematically showing an enlarged view of the vicinity of the blade tip shroud 34 and the front end portion of the fin as viewed circumferentially.

[0067] As Figures 2A to 2C 、 Figures 3A to 3C 、 Figures 4A to 4C 、 Figures 5A to 5C and Figure 6 As shown, a sealing device 100 is provided in the cavity 50 of several embodiments. The sealing device 100 of the embodiments includes arc-shaped fins (sealing fins) 40, and three or more of these arc-shaped fins 40 are arranged axially with gaps therebetween and extend circumferentially respectively. That is, the fins 40 of several embodiments are sealing members provided in a plurality along the axial direction in an annular gap (cavity 50) between a rotating member (shroud 34) and a stationary member (housing 2).

[0068] For the sake of convenience in explanation, three fins 40 shown in each figure are arranged axially with gaps therebetween, but there may be four or more. In addition, for the sake of convenience in explanation, for the fins 40 shown in each figure, they are sequentially referred to as the first fin 41, the second fin 42, and the third fin 43 from the upstream side in the axial direction.

[0069] Figure 1 The steam turbine 1 of the several embodiments shown in includes the sealing device 100 described in detail later, so that the flow rate of the leakage steam flow SL through the sealing portion (sealing device 100) can be suppressed, and the generation of self-excited vibration in the steam turbine 1 can be suppressed.

[0070] The fins 40 shown in each figure include the first fin 41 which is one of the two outermost fins located on the outermost side in the axial direction, the second fin 42 arranged adjacent to the first fin 41 in the axial direction, and at least one third fin 43 arranged on the side opposite to the first fin 41 with the second fin 42 interposed therebetween in the axial direction.

[0071] It should be noted that the third fin 43 may also be the other of the two outermost fins located axially on the outermost side. When there are four or more fins 40 arranged axially with gaps between them in several embodiments, it is preferable to arrange at least the fin 40 closest to the downstream side in the axial direction as the third fin 43 to satisfy at least one of the following conditions (a) and (b). That is, the third fin 43 preferably includes the other outermost fin of the two outermost fins.

[0072] The fin 40 shown in each figure is a member that extends radially from the base end portion 40a toward the front end portion 40b and has a partial arc shape extending circumferentially as described above. More specifically, the fin 40 is formed in a shape where the thickness in the direction of the axis AX gradually decreases as it extends from the base end portion 40a toward the front end portion 40b.

[0073] For example, as shown in Figure 2A , Figure 3A , Figure 4A , Figure 5A and Figure 6 , the fin 40 shown in each figure may also be arranged axially with fins protruding from the inner peripheral surface 25 of the housing 2 toward the shroud 34 (e.g., the first fin 41 and the third fin 43) and fins protruding from the shroud 34 toward the inner peripheral surface 25 of the housing 2 (e.g., the second fin 42) arranged alternately.

[0074] In addition, for example, as shown in Figure 2B , Figure 3B , Figure 4B and Figure 5B , the fin 40 shown in each figure may also be arranged to protrude from the inner peripheral surface 25 of the housing 2 toward the shroud 34.

[0075] For example, as shown in Figure 2C , Figure 3C , Figure 4C and Figure 5C , the fin 40 shown in each figure may also be arranged to protrude from the shroud 34 toward the inner peripheral surface 25 of the housing 2.

[0076] In several embodiments shown in each figure, a minute gap (sealing gap) m is formed between the front end portion 40b of the fin 40 and the outer surface 35 of the shroud 34 opposed to the front end portion 40b, or between the front end portion 40b of the fin 40 and the inner peripheral surface 25 of the housing 2. Regarding the size of the gap m in the radial direction, it is determined within the range where the front end portion 40b of the fin 40 does not contact the member on the opposite side opposed to the front end portion 40b, considering the thermal expansion amount of the housing 2 and the moving blade body 31, the centrifugal elongation amount of the moving blade body 31, etc.

[0077] Among the cavities 50 of several embodiments shown in the respective figures, the region on the upstream side of the first fin 41 is referred to as the first cavity 51, the region defined between the first fin 41 and the second fin 42 is referred to as the second cavity 52, the region defined between the second fin 42 and the third fin 43 is referred to as the third cavity 53, and the region on the downstream side of the third fin 43 is referred to as the fourth cavity 54.

[0078] In the steam turbine device 10 of several embodiments, steam S from a steam supply source is supplied to the steam turbine 1 via a steam supply pipe 12.

[0079] The steam S supplied to the steam turbine 1 reaches the main flow path 20. The steam S reaching the main flow path 20 expands repeatedly and changes the direction of flow as it flows through the main flow path 20, while flowing toward the downstream side. Since the moving blade body 31 has an airfoil cross-section, the steam S collides with the moving blade body 31, or a reaction force during steam expansion is also applied inside the inter-blade flow path formed between the moving blade bodies 31 adjacent in the circumferential direction, whereby the rotor 3 rotates. Thus, the energy possessed by the steam S is obtained as the rotational power of the steam turbine 1.

[0080] In the above process, the steam S flowing through the main flow path 20 also flows into the aforementioned cavity 50. That is, the steam S flowing into the main flow path 20 is divided into a main steam flow SM and a leakage steam flow SL after passing through the stationary blade body 21. The main steam flow SM is introduced into the turbine moving blades 30 without leakage.

[0081] The leakage steam flow SL flows into the cavity 50 between the shroud 34 and the housing 2. Here, the steam S becomes a state in which the eddy current component (circumferential velocity component) increases after passing through the stationary blade body 21, and a part of the steam S separates and flows into the cavity 50 as the leakage steam flow SL. Therefore, the leakage steam flow SL also contains an eddy current component like the steam S.

[0082] (Regarding self-excited vibration in the steam turbine 1)

[0083] As described above, it is known that in a rotating machine such as the steam turbine 1, in a sealing portion that seals between the rotor or the moving blade and the housing, the working fluid deviating from the main flow path flows in a state having a swirling flow component imparted when passing through the nozzle, thereby generating a swirling flow (so-called eddy current) in the circumferential direction of the rotor. Due to the eddy current, when the rotor is eccentric, a periodic pressure distribution having a peak in a direction different from the eccentric direction of the rotor is generated in the circumferential direction of the rotor. For example, when the eddy current increases during high-output operation, it sometimes causes self-excited vibration of the rotor. Therefore, various structures for suppressing the eddy current in the sealing portion have been proposed.

[0084] In recent years, in rotating machines such as steam turbines and gas turbines, there has been a pursuit to further improve the turbine efficiency. Therefore, there has been a pursuit to suppress the leakage flow rate, that is, the flow rate of the working fluid that deviates from the main flow path and passes through the seal portion. However, if the leakage flow rate is suppressed, the exciting force of the above-mentioned self-excited vibration may increase.

[0085] For this reason, in several embodiments, the flow rate of the leakage steam flow SL passing through the seal device 100 is suppressed as described below, and the generation of self-excited vibration in the steam turbine 1 is suppressed. Hereinafter, a detailed description will be given.

[0086] (Regarding the specific structure for suppressing the leakage steam flow and suppressing self-excited vibration)

[0087] For example, as Figures 2A to 2C , Figures 4A to 4C , Figures 5A to 5C and Figure 6 shown, in the seal device 100 of several embodiments, the third fin 43 preferably satisfies at least one of the following conditions (a) and (b).

[0088] (a) The third fin 43 is disposed inclined with respect to the radial direction such that the front end portion 40b is located on the first fin 41 side with respect to the base end portion 40a in the axial direction, and has an inclination angle θ3 larger than that of the first fin 41 or the second fin 42 with respect to the radial direction.

[0089] (b) The third fin 43 has a radial dimension Hr larger than that of the first fin 41 or the second fin 42 so as to form a seal gap m smaller than that of the first fin 41 or the second fin 42.

[0090] (Regarding the case where the above condition (a) is satisfied)

[0091] As shown in the respective figures, the seal device 100 of several embodiments is configured such that the third fin 43 is located on the downstream side in the axial direction with respect to the first fin 41. And, the leakage steam flow SL passes through the seal gap m, which is the gap between the front end portions 40b of the first fin 41, the second fin 42, and the third fin 43 and the surface of the member facing the front end portions 40b in the radial direction.

[0092] For example, consider the following case: The third fin 43 is configured to satisfy the above condition (a), and in the third cavity 53 facing the side surface 43u on the upstream side in the axial direction of the third fin, as Figure 2A , Figure 2B , Figure 4A , Figure 4B , Figure 5A , Figure 5B and Figure 6As shown, the radial flow SLr of the leakage vapor flow SL flows along this side surface 43u from the base end portion 40a side of the third fin 43 toward the front end portion 40b side.

[0093] In this case, compared with the case where the third fin 43 does not satisfy the above-mentioned condition (a), the radial flow SLr flowing along this side surface 43u can impart a flow contraction effect that causes the flow to contract in the radial direction to the leakage vapor flow SL flowing in the above-mentioned sealing gap m more.

[0094] Figure 7A It is a diagram for explaining the above-mentioned flow contraction effect brought about by the third fin 43 that satisfies the above-mentioned condition (a), and shows the flow coefficient in the sealing gap m formed by each fin 40. In Figure 7A Among them, the data described as an example is the flow coefficient of the sealing device 100 having the third fin 43 that satisfies the above-mentioned condition (a), and the data described as a comparative example is the flow coefficient of the sealing device in which the third fin 43 has the same inclination angle θ3 as the first fin 41 or the second fin 42.

[0095] As Figure 7A shown, by satisfying the above-mentioned condition (a), the flow coefficient in the sealing gap m formed by the third fin 43 can be reduced.

[0096] In this way, in Figure 2A 、 Figure 2B 、 Figure 4A 、 Figure 4B 、 Figure 5A 、 Figure 5B and Figure 6 shown in the sealing device 100, the working fluid is not easily passed through the sealing gap m, which is the gap between the front end portion 40b of the third fin 43 and the outer surface 35 of the member facing the front end portion 40b in the radial direction, that is, the outer surface of the shroud 34.

[0097] Therefore, in Figure 2A 、 Figure 2B 、 Figure 4A 、 Figure 4B 、 Figure 5A 、 Figure 5B and Figure 6 shown in the sealing device 100, the differential pressure between the third cavity 53 of the cavity 50 on the upstream side of the third fin 43 and the fourth cavity 54 of the cavity 50 on the downstream side can be increased.

[0098] Here, if the first fin 41 and the third fin 43 are the outermost fins located on the outermost sides in the axial direction respectively, the pressure difference between the first cavity 51 of the cavity 50 on the upstream side of the first fin 41 and the fourth cavity 54 of the cavity 50 on the downstream side of the third fin 43, that is, the differential pressure before and after the sealing device 100, is substantially equal to the pressure difference between the inlet side and the outlet side of the moving blade main body 31. Therefore, if the differential pressure between the third cavity 53 and the fourth cavity 54, that is, the differential pressure before and after the third fin 43, increases, the differential pressure between the first cavity 51 and the second cavity 52 of the cavity 50 on the downstream side of the first fin 41, that is, the differential pressure before and after the first fin 41, decreases.

[0099] Figure 7B is a diagram for explaining the differential pressure in each fin 40, showing the expansion ratio of the leakage steam flow SL before and after passing through each fin 40. In Figure 7B the data described as an example is the expansion ratio of the sealing device 100 having the third fin 43 that satisfies the above condition (a), and the data described as a comparative example is the expansion ratio of the sealing device in which the third fin 43 has the same inclination angle θ3 as the first fin 41 or the second fin 42.

[0100] As Figure 7B shown, by satisfying the above condition (a), the differential pressure before and after the third fin 43 increases, so the expansion ratio of the leakage steam flow SL before and after passing through the third fin 43 becomes larger. In addition, since the differential pressure before and after the third fin 43 increases and the differential pressure before and after the first fin 41 decreases, the expansion ratio of the leakage steam flow SL before and after passing through the first fin 41 becomes smaller.

[0101] Generally, the greater the circumferential swirling speed of the working fluid in the sealing portion (sealing device 100), the easier it is to generate the above-mentioned self-excited vibration. In addition, generally, for the circumferential swirling speed of the working fluid in the sealing portion, the upstream side is larger than the downstream side. Generally, by suppressing the differential pressure before and after the sealing fin, the exciting force caused by the working fluid in the cavity on the downstream side of the sealing fin can be suppressed.

[0102] Therefore, by suppressing the differential pressure before and after the first fin 41 as described above, the exciting force caused by the leakage steam flow SL in the second cavity 52 can be suppressed, and thus the generation of the above-mentioned self-excited vibration can be suppressed.

[0103] In addition, as described above, since the differential pressure before and after the third fin 43 can be increased, the flow rate of the working fluid passing through the sealing device 100 can be suppressed.

[0104] Figure 7C is a diagram for explaining the exciting force generated in each cavity 50. In Figure 7CAmong them, the data recorded as an example is the exciting force of the sealing device 100 having the third fin 43 that satisfies the above condition (a), and the data recorded as a comparative example is the exciting force of the sealing device in which the third fin 43 has the same inclination angle θ3 as the first fin 41 or the second fin 42.

[0105] As Figure 7C shown, by satisfying the above condition (a), the exciting force in the second cavity 52 and the third cavity 53 can be suppressed. In addition, by satisfying the above condition (a), the exciting force in the second cavity 52 can be further suppressed compared with the exciting force in the third cavity 53.

[0106] For example, consider the following situation: The third fin 43 is configured to satisfy the above condition (a). In the third cavity 53 facing the axially upstream side surface 43u of the third fin 43, as Figure 2C , Figure 4C and Figure 5C shown, the radial flow SLr flows along this side surface 43u from the front end portion 40b side to the base end portion 40a side of the third fin 43.

[0107] In this case, compared with the case where the third fin 43 is not configured to satisfy the above condition (a), the radial flow SLr easily flows from the front end portion 40b side to the base end portion 40a side of the third fin 43 along this side surface. Therefore, the leakage steam flow SL flowing from the second fin 42 side to the third fin 43 side is not likely to flow to the downstream side of the third fin 43, so that the pressure difference between the front and rear of the third fin 43 can be increased. Thereby, the pressure difference between the front and rear of the first fin 41 can be suppressed, and thus the generation of the above self-excited vibration can be suppressed.

[0108] In addition, since the pressure difference between the front and rear of the third fin 43 can be increased, the flow rate of the leakage steam flow SL passing through the sealing device 100 can be suppressed.

[0109] (Regarding the case of satisfying the above condition (b))

[0110] Similar to the description of the above condition (a), the sealing devices 100 of several embodiments are arranged such that the third fin 43 is located on the axially downstream side of the first fin 41. Moreover, the leakage steam flow SL passes through the sealing gap m, which is the gap between the front end portions 40b of the first fin 41, the second fin 42, and the third fin 43 and the surface of the member facing the front end portions 40b in the radial direction.

[0111] For example, the third fin 43 is configured to satisfy the above condition (b).

[0112] In this case, compared with the case where the third fin 43 does not satisfy the above condition (b), the pressure difference between the front and rear of the third fin 43 can be increased. As a result, the pressure difference between the front and rear of the first fin 41 can be suppressed, and thus the generation of the above-mentioned self-excited vibration can be suppressed.

[0113] In addition, since the pressure difference between the front and rear of the third fin 43 can be increased, the flow rate of the leakage steam flow SL through the sealing device 100 can be suppressed.

[0114] It should be noted that when four or more fins 40 are arranged axially with gaps between them in several embodiments, it is preferable that at least the fin 40 disposed closest to the downstream side in the axial direction be configured as the third fin 43 to satisfy at least one of the above conditions (a) and (b). That is, the third fin 43 preferably includes the other outermost fin among the two outermost fins.

[0115] By configuring at least the fin 40 disposed closest to the downstream side in the axial direction as the third fin 43 to satisfy at least one of the above conditions (a) and (b), as described above, the pressure difference between the front and rear of the first fin 41 can be suppressed to suppress the generation of self-excited vibration, and the pressure difference between the front and rear of the third fin 43 can be increased to suppress the flow rate of the leakage steam flow SL through the sealing device 100.

[0116] For example, like the sealing device 100 shown in Figure 2B , Figure 2C , Figure 4B , Figure 4C , Figure 5B and Figure 5C , other fins 40 may have the same shape except for the other outermost fin serving as the third fin 43.

[0117] Assuming that other fins 40 other than the other outermost fin are configured to satisfy at least one of the above conditions (a) and (b), although the flow rate of the leakage steam flow SL can be further suppressed, the possibility of generating self-excited vibration becomes higher. Therefore, like the sealing device 100 shown in Figure 2B , Figure 2C , Figure 4B , Figure 4C , Figure 5B and Figure 5C , by configuring other fins 40 to have the same shape except for the other outermost fin serving as the third fin 43, the generation of self-excited vibration can be suppressed.

[0118] (Regarding the curved concave surface 430)

[0119] Like Figures 4A to 4CAs shown, in the sealing device 100 of several embodiments, on the base end portion 40a side of the third fin 43, the side surface 43u of the third fin 43 facing the first fin 41 side in the axial direction may have a curved concave surface 430.

[0120] In Figure 4A and Figure 4B In the sealing device 100 shown, the curved concave surface 430 is a curved surface that smoothly connects the surface of the inner peripheral surface 25 of the housing 2 on the upstream side in the axial direction with respect to the side surface 43u to the side surface 43u of the third fin 43, and has a center of curvature O at a position on the upstream side in the axial direction with respect to the side surface 43u.

[0121] In Figure 4C In the sealing device 100 shown, the curved concave surface 430 is a curved surface that smoothly connects the surface of the outer surface 35 of the shroud 34 on the upstream side in the axial direction with respect to the side surface 43u to the side surface 43u of the third fin 43, and has a center of curvature O at a position on the upstream side in the axial direction with respect to the side surface 43u.

[0122] Thus, the flow of the radial flow SLr of the leakage steam flow SL in the cavity 50 (the third cavity 53) facing the side surface 43u of the third fin 43 is guided by the curved concave surface 430 and flows easily.

[0123] Thus, as Figure 4A and Figure 4B shown, in the third cavity 53, when the radial flow SLr flows along the side surface 43u from the base end portion 40a side of the third fin 43 toward the front end portion 40b side, the radial flow SLr flowing along the side surface 43u can impart a greater constriction effect to the leakage steam flow SL flowing in the sealing gap m. Thus, the pressure difference between the front and rear of the third fin 43 can be increased.

[0124] In addition, as Figure 4C shown, when the radial flow SLr flows along the side surface 43u from the front end portion 40b side of the third fin 43 toward the base end portion 40a side, the radial flow SLr easily flows along the side surface 43u from the front end portion 40b side of the third fin 43 toward the base end portion 40a side. Therefore, the leakage steam flow SL is not likely to flow toward the downstream side with respect to the third fin 43, and thus the pressure difference between the front and rear of the third fin 43 can be increased.

[0125] (Regarding the expansion portion 541 of the fourth cavity 54)

[0126] As Figure 5A and Figure 5BAs shown, the steam turbine 1 of several embodiments includes a cavity 50 (fourth cavity 54) defined by a third fin 43 which is the outermost fin 40 and an inner surface 250 of the housing 2 that is downstream of the outermost fin 40 (third fin 43) in the axial direction. Further, the fourth cavity 54 may have an expansion portion (housing-side expansion portion) 541 that expands radially outward or axially downstream on the inner surface 250.

[0127] As Figure 5A and Figure 5B shown, in the steam turbine 1 of several embodiments, at least a part of the radially outer surface of the expansion portion 541 may also be defined by an inner peripheral surface 251 that is radially outside the inner peripheral surface 25 facing the third cavity 53. Additionally, as Figure 5A and Figure 5B shown, in the steam turbine 1 of several embodiments, at least a part of the axially downstream surface of the expansion portion 541 may also be defined by the following annular inner wall surface 253 for the radially outer surface. It should be noted that the annular inner wall surface 253 is connected to the inner peripheral surface 25A of the housing 2 that defines the main flow path 20, for example, downstream of the moving blade main body 31 in the axial direction, and faces the upstream in the axial direction at a position downstream of the inner wall surface 25B. The inner wall surface 25B is the inner surface 250 that faces the upstream in the axial direction at the upstream position of the inner peripheral surface 25A.

[0128] If the fourth cavity 54 has the expansion portion 541, compared with the case where the fourth cavity 54 does not have the expansion portion 541, the leakage steam flow SL after passing through the sealing gap m expands, so that the pressure difference across the third fin 43 can be increased. The sealing gap m is the gap between the front end portion 40b of the third fin 43 and the surface of the member facing the front end portion 40b in the radial direction (for example, the outer surface 35 of the shroud 34).

[0129] It should be noted that, as Figure 5C shown, the expansion portion (shroud-side expansion portion) 543 may also be provided by making a cut from the radial outside to the region of the shroud 34 that is downstream of the third fin 43. Additionally, in the steam turbine 1 of several embodiments, the housing-side expansion portion 541 and the shroud-side expansion portion 543 may also be provided.

[0130] (Regarding the shape of the front end portion 40b of the third fin 43)

[0131] In the sealing device 100 of several embodiments, as Figure 6As shown, the radius of curvature ru of the corner 431 between the side surface 43uu and the front end surface 43t of the third fin 43 facing the first fin 41 side in the axial direction is preferably smaller than the radius of curvature ru of the corner 421 between the side surface 42u and the front end surface 42t of the second fin 42 facing the first fin 41 side in the axial direction.

[0132] Thus, in the third cavity, when the radial flow SLr flows along the side surface 43u of the third fin 43 from the base end portion 40a side toward the front end portion 40b side of the third fin 43, the radial flow SLr is likely to peel off from the side surface 43u at the front end portion 40b side. Therefore, the radial flow SLr flowing along the side surface 43u can impart a constriction effect to the leakage vapor flow SL flowing in the seal gap m more than the radial flow SLr flowing along the side surface 42u. As a result, the pressure difference between the front and rear of the third fin 43 can be increased.

[0133] It should be noted that in the seal device 100 of several embodiments, as Figure 6 shown, the radius of curvature rd of the corner 433 between the side surface 43d and the front end surface 43t of the third fin 43 facing the downstream side in the axial direction may also be the same as the radius of curvature ru of the corner 431. In addition, the radius of curvature rd of the corner 423 between the side surface 42d and the front end surface 42t of the second fin 42 facing the downstream side in the axial direction may also be the same as the radius of curvature ru of the corner 421.

[0134] The present invention is not limited to the above-described embodiments, and also includes forms in which the above-described embodiments are modified and forms in which these forms are appropriately combined.

[0135] For example, the third fin 43 of the above-described embodiment may also be configured to satisfy both of the above conditions (a) and (b).

[0136] In addition, in Figures 2A to 2C , Figures 3A to 3C , Figures 5A to 5C and Figure 6 shown in the seal device 100, a curved concave surface 430 may also be provided as Figures 4A to 4C shown.

[0137] In Figures 2A to 2C , Figures 3A to 3C , Figures 4A to 4C and Figure 6 shown in the steam turbine 1, at least one of a housing side expansion portion 541 and a shroud side expansion portion 543 may also be provided as Figures 5A to 5C shown.

[0138] The content described in each of the above embodiments can be understood as follows, for example.

[0139] (1) The sealing device according to at least one embodiment of the present invention includes three or more arc-shaped fins arranged axially with a gap therebetween and extending circumferentially respectively.

[0140] The arc-shaped fins include: a first fin, which is one of the two outermost fins located on the outermost side axially; a second fin, which is arranged adjacent to the first fin axially; and at least one third fin, which is arranged axially on the side opposite to the first fin with the second fin therebetween.

[0141] The third fin satisfies at least one of the following conditions (a) and (b).

[0142] (a) The third fin is arranged obliquely with respect to the radial direction such that the front end portion is located on the first fin side with respect to the base end portion axially, and the third fin has a larger inclination angle with respect to the radial direction than the first fin or the second fin.

[0143] (b) The third fin has a larger radial dimension than the first fin or the second fin so as to form a smaller sealing gap than the first fin or the second fin.

[0144] According to the structure of the above (1), by configuring the third fin 43 to satisfy at least one of the above conditions (a) and (b), in the steam turbine 1 which is an example of a rotating machine and has the sealing device having the structure of the above (1), the flow rate of the working fluid, i.e., the leakage steam flow SL, passing through the sealing portion (sealing device 100) can be suppressed, and the generation of self-excited vibration in the steam turbine 1 can be suppressed.

[0145] (2) In several embodiments, based on the structure of the above (1), the third fin 43 preferably includes the other outermost fin 40 of the two outermost fins 40.

[0146] By making at least the fin 40 arranged on the most downstream side axially, i.e., the third fin 43, satisfy at least one of the above conditions (a) and (b), as described above, the front-back differential pressure of the first fin 41 can be suppressed to suppress the generation of self-excited vibration, and the front-back differential pressure of the third fin 43 can be increased to suppress the flow rate of the leakage steam flow SL passing through the sealing device 100.

[0147] (3) In several embodiments, based on the structure of the above (2), except for the other outermost fin 40 as the third fin 43, the arc-shaped fins 40 may have the same shape.

[0148] Assume that other fins 40 other than the outermost fin of the other party described above are configured to satisfy at least one of the above conditions (a) and (b). Although the flow rate of the leakage steam flow SL can be further suppressed, the possibility of self-excited vibration increases. Therefore, like the sealing device 100 shown in Figure 2B , Figure 2C , Figure 4B , Figure 4C , Figure 5B and Figure 5C , except for the outermost fin of the other party that is the third fin 43, the other fins 40 are configured to have the same shape, thereby being able to suppress the generation of self-excited vibration.

[0149] (4) In several embodiments, based on any of the structures in the above (1) to (3), on the proximal end side (proximal end portion 40a side) of the third fin 43, the side surface 43u of the third fin 43 facing the first fin 41 side in the axial direction preferably has a curved concave surface 430.

[0150] According to the structure of the above (4), as described above, the front-back differential pressure of the third fin 43 can be increased.

[0151] (5) In several embodiments, based on any one of the structures in the above (1) to (4), the radius of curvature ru of the corner portion 431 between the side surface 43u and the front end surface 43t of the third fin 43 facing the first fin 41 side in the axial direction is preferably smaller than the radius of curvature ru of the corner portion 421 between the side surface 42u and the front end surface 42t of the second fin 42 facing the first fin 41 side in the axial direction.

[0152] According to the structure of the above (5), in the third cavity 53 facing the side surface 43u of the third fin 43 facing the first fin 41 side, when the radial flow SLr flows along the side surface 43u from the proximal end portion 40a side to the front end portion 40b side of the third fin 43, the radial flow SLr is likely to peel off from the side surface 43u at the front end portion 40b side. Therefore, the radial flow SLr flowing along the side surface 43u can impart a more throttling effect to the leakage steam flow SL flowing in the sealing gap m. Thereby, the front-back differential pressure of the third fin 43 can be increased.

[0153] (6) A steam turbine 1 of a rotary machine according to at least one embodiment of the present invention includes: a sealing device 100 having any one of the structures in the above (1) to (5); a housing 2; a rotor main body 11 that rotates around an axis AX in the housing 2; a plurality of moving blade main bodies 31 that are installed so as to extend radially from the rotor main body 11; and a shroud (blade tip shroud) 34 that is connected to the front end portions of the plurality of moving blade main bodies 31 respectively. The third fin 43 is located on the axial downstream side of the first fin 41 with respect to the rotor main body 11.

[0154] According to the structure of (6) above, since the sealing device 100 has any one of the structures of (1) to (5) above, the flow rate of the leakage steam flow SL passing through the sealing device 100 can be suppressed, and the generation of self-excited vibration in the steam turbine 1 can be suppressed.

[0155] (7) In several embodiments, based on the structure of (6) above, the third fin 43 includes the other outermost fin 40 among the two outermost fins 40. The steam turbine 1 as a rotating machine has a cavity 50 (fourth cavity 54), which is defined by the outermost fin 40 (third fin 43) and the inner surface 250 of the housing 2 on the downstream side of the axis relative to the outermost fin 40 (third fin 43). The fourth cavity 54 preferably has an expansion portion 541 that expands radially outward or axially downstream on the inner surface 250.

[0156] According to the structure of (7) above, compared with the case where the fourth cavity 54 does not have the expansion portion 541, the leakage steam flow SL expands after passing through the sealing gap m, so that the differential pressure before and after the third fin 43 can be increased. The sealing gap m is the gap between the front end portion 40b of the third fin 43 and the surface of the member facing the front end portion 40b in the radial direction.

[0157] (8) In several embodiments, based on the structure of (6) or (7) above, the arc-shaped fins 40 may also protrude from the inner peripheral surface 25 of the housing 2 toward the shroud 34.

[0158] According to the structure of (8) above, all the arc-shaped fins 40 of the sealing device 100 are configured to protrude from the inner peripheral surface 25 of the housing 2 toward the shroud 34. Thus, even if the axial relative position of the housing 2 and the rotor body 11 changes due to thermal expansion, the arc-shaped fins 40 will not contact each other.

[0159] (9) In several embodiments, based on the structure of (6) or (7) above, the arc-shaped fins 40 may also protrude from the shroud 34 toward the inner peripheral surface 25 of the housing 2.

[0160] According to the structure of (9) above, all the arc-shaped fins 40 of the sealing device 100 are configured to protrude from the shroud 34 toward the inner peripheral surface 25 of the housing 2. Thus, even if the axial relative position of the housing 2 and the rotor body 11 changes due to thermal expansion, the arc-shaped fins 40 will not contact each other.

[0161] (10) In several embodiments, based on the structure of the above (6) or (7), the arc-shaped fins 40 can also be axially alternately arranged with fins 40 protruding from the inner peripheral surface 25 of the housing 2 towards the shroud 34 and fins 40 protruding from the shroud 34 towards the inner peripheral surface 25 of the housing 2.

[0162] According to the structure of the above (10), by axially alternately arranging the fins 40 protruding from the inner peripheral surface 25 of the housing 2 towards the shroud 34 and the fins 40 protruding from the shroud 34 towards the inner peripheral surface 25 of the housing 2, the flow rate of the leakage steam flow SL through the sealing device 100 can be further suppressed.

[0163] Description of reference numerals:

[0164] 1... steam turbine;

[0165] 2... housing;

[0166] 3... rotor;

[0167] 11... rotor body;

[0168] 25... inner peripheral surface;

[0169] 30... turbine blade;

[0170] 31... blade body;

[0171] 34... shroud (tip shroud);

[0172] 40... fin (sealing fin);

[0173] 40a... base end;

[0174] 40b... tip end;

[0175] 41... first fin;

[0176] 42... second fin;

[0177] 43... third fin;

[0178] 50... cavity;

[0179] 51... first cavity;

[0180] 52... second cavity;

[0181] 53... third cavity;

[0182] 54... fourth cavity;

[0183] 100... sealing device;

[0184] 430... Curved concave surface;

[0185] 541... Expansion part (housing-side expansion part);

[0186] 543... Expansion part (shield-side expansion part).

Claims

1. A sealing device, wherein, the sealing device includes three or more arc-shaped fins arranged axially with a gap therebetween and each extending circumferentially, the arc-shaped fins include: a first fin, which is one of the two outermost fins located on the outermost side in the axial direction; a second fin, which is arranged adjacent to the first fin in the axial direction; and at least one third fin, which is arranged on the side opposite to the first fin with the second fin therebetween in the axial direction, the third fin satisfies at least one of the following conditions (a) and (b), (a) the third fin is arranged obliquely with respect to the radial direction such that the front end portion is located on the first fin side with respect to the base end portion in the axial direction, and the third fin has a larger inclination angle with respect to the radial direction than the first fin or the second fin, (b) the third fin has a larger radial dimension than the first fin or the second fin so as to form a smaller sealing gap than the first fin or the second fin, on the base end side of the third fin, the side surface of the third fin facing the first fin side in the axial direction has a curved concave surface.

2. A sealing device, wherein, the sealing device includes three or more arc-shaped fins arranged axially with a gap therebetween and each extending circumferentially, the arc-shaped fins include: a first fin, which is one of the two outermost fins located on the outermost side in the axial direction; a second fin, which is arranged adjacent to the first fin in the axial direction; and at least one third fin, which is arranged on the side opposite to the first fin with the second fin therebetween in the axial direction, the third fin is arranged obliquely with respect to the radial direction such that the front end portion is located on the first fin side with respect to the base end portion in the axial direction, and the third fin has a larger inclination angle with respect to the radial direction than the second fin, on the base end side of the third fin, the side surface of the third fin facing the first fin side in the axial direction has a curved concave surface.

3. A sealing device, wherein, the sealing device includes three or more arc-shaped fins arranged axially with a gap therebetween and each extending circumferentially, the arc-shaped fins include: a first fin, which is one of the two outermost fins located on the outermost side in the axial direction; a second fin, which is arranged adjacent to the first fin in the axial direction; and at least one third fin, which is arranged on the side opposite to the first fin with the second fin therebetween in the axial direction, the third fin has a larger radial dimension than the first fin or the second fin so as to form a smaller sealing gap than the first fin or the second fin, on the base end side of the third fin, the side surface of the third fin facing the first fin side in the axial direction has a curved concave surface.

4. The sealing device according to any one of claims 1 to 3, wherein, The radius of curvature of the corner between the side surface and the front end surface of the third fin facing the first fin side in the axial direction is smaller than the radius of curvature of the corner between the side surface and the front end surface of the second fin facing the first fin side in the axial direction.

5. The sealing device according to any one of claims 1 to 3, wherein the third fin includes the outermost fin of the other of the two outermost fins.

6. The sealing device according to claim 5, wherein except for the outermost fin of the other as the third fin, the arc-shaped fins have the same shape.

7. A rotary machine, wherein the rotary machine includes: the sealing device according to any one of claims 1 to 6; a housing; a rotor body that rotates around an axis in the housing; a plurality of moving blade bodies that are mounted so as to extend radially from the rotor body; and a shroud that is connected to the front end portion of each of the plurality of moving blade bodies, the third fin is located on the axially downstream side of the rotor body relative to the first fin.

8. The rotary machine according to claim 7, wherein the third fin includes the outermost fin of the other of the two outermost fins, the rotary machine includes a cavity defined by the outermost fin and the inner surface of the housing on the axially downstream side of the outermost fin, the cavity has a portion where the inner surface expands radially outward or axially downstream.

9. The rotary machine according to claim 7 or 8, wherein the arc-shaped fins project from the inner peripheral surface of the housing toward the shroud.

10. The rotary machine according to claim 7 or 8, wherein the arc-shaped fins project from the shroud toward the inner peripheral surface of the housing.

11. The rotary machine according to claim 7 or 8, wherein the arc-shaped fins are alternately arranged in the axial direction with fins projecting from the inner peripheral surface of the housing toward the shroud and fins projecting from the shroud toward the inner peripheral surface of the housing.

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