Rotating machine

Abstract

The present invention comprises: a rotor; an annular sealing body part that includes the inner peripheral surface which is a static wall surface facing the outer peripheral surface of the rotor and a plurality of holes which are formed in the inner peripheral surface; a plurality of static fin parts that are disposed on the inner peripheral surface at intervals in the axial direction of the rotor; and at least one first rotor fin part that is disposed on the outer peripheral surface of the rotor. Each of the plurality of static fin parts extends along the circumferential direction of the rotor and protrudes toward the outer peripheral surface of the rotor from the inner peripheral surface, and each of the at least one first rotor fin part extends along the circumferential direction and protrudes toward the hole from the outer peripheral surface of the rotor.

Description

Rotating Machinery

[0001] This application claims priority to Japanese Patent Application No. 2023-099099, filed on June 16, 2023, with the Japan Patent Office, the contents of which are incorporated herein by reference.

[0002] For example, unstable vibrations such as low-frequency vibrations may occur in rotary machines such as turbines. When the rotor of a rotary machine is displaced, a swirl (rotating flow) that flows through the gap (seal portion) between the outer circumferential surface of the rotor and the stationary wall surface generates an uneven pressure distribution in the gap. This fluid force acts on the rotor in a direction perpendicular to the direction of the rotor displacement, which has the effect of promoting rotor whirling. This fluid force is called seal excitation force, and the generation of seal excitation force reduces the axial stability of the rotor (stability of the shaft system). For this reason, reducing seal excitation force is important from the perspective of rotor axial stability.

[0003] Damper seals such as pocket damper seals, hole pattern seals, and honeycomb seals (see, for example, Patent Document 1) are seal structures that can reduce this seal excitation force. When a damper seal is provided, the swirl is reduced by introducing fluid into holes (recesses) provided on the stationary wall surface, and the vibration damping effect (squeeze film effect) that occurs in the narrow part of the gap between the stationary wall surface and the rotor, thereby reducing the seal excitation force.

[0004] Japanese Patent Application Laid-Open No. 2016-153654

[0005] In the damper seal described in Patent Document 1, the contact area between the rotor and the stationary wall surface tends to increase when the rotor is displaced, increasing the risk of thermal bending of the rotor due to frictional heat between the rotor and the stationary wall surface (hereinafter, sometimes referred to as the "risk of contact between the rotor and the stationary wall surface"). On the other hand, simply increasing the gap between the outer circumferential surface of the rotor and the stationary wall surface in order to reduce the risk of contact between the rotor and the stationary wall surface weakens the squeeze film effect, and the effect of reducing the seal excitation force is weakened. For this reason, there is a problem in that it is difficult to simultaneously reduce the risk of contact between the rotor and the stationary wall surface and achieve high axial stability of the rotor.

[0006] In view of the above circumstances, at least one embodiment of the present disclosure aims to provide a rotary machine that can achieve high axial stability of the rotor while reducing the risk of contact between the rotor and a stationary wall surface.

[0007] In order to achieve the above object, a rotary machine according to at least one embodiment of the present disclosure comprises: a rotor; an annular seal body including an inner peripheral surface which is a stationary wall surface facing the outer peripheral surface of the rotor and a plurality of holes formed on the inner peripheral surface; a plurality of stationary fin portions provided on the inner peripheral surface at intervals in the axial direction of the rotor; and at least one first rotor fin portion provided on the outer peripheral surface of the rotor, wherein each of the plurality of stationary fin portions extends along the circumferential direction of the rotor and protrudes from the inner peripheral surface toward the outer peripheral surface of the rotor, and each of the at least one first rotor fin portion extends along the circumferential direction and protrudes from the outer peripheral surface of the rotor toward the hole.

[0008] At least one embodiment of the present disclosure provides a seal system for a rotary machine that can achieve high axial stability of the rotor while reducing the risk of contact between the outer surface of the rotor and a stationary wall surface, and a rotary machine equipped with the same.

[0009] 1 is a schematic diagram showing an example of a cross section perpendicular to the axial direction of a rotary machine 2 according to an embodiment. FIG. 2 is a schematic diagram showing an example of a cross section along the axial direction of the rotary machine 2 shown in FIG. 1. FIG. 3 is a schematic diagram for explaining the flow of swirl in the cross section shown in FIG. 2. FIG. 4 is a schematic diagram for explaining the flow of swirl in a part of the cross section A-A in FIG. 3. FIG. 5 is a diagram showing the relationship between the leakage flow rate and the effective damping of axial vibration of the rotor 4 for the embodiment described using FIGS. 1 to 4 and Comparative Forms 1 to 4. FIG. 6 is a diagram showing the relationship between the axial position in the gap g between the outer circumferential surface 4a of the rotor 4 and the inner circumferential surface 12a of the seal main body 12 and the swirl ratio for each of the embodiment described using FIGS. 1 to 4 and Comparative Form 1. FIG. 7 is a schematic diagram showing another example of a cross section along the axial direction of a rotary machine 2 according to an embodiment. FIG. 8 is a schematic cross-sectional diagram for explaining the effective cross-sectional area of ​​the leakage flow when the stationary fin portion 18 is not inclined with respect to the radial direction. FIG. 9 is a schematic cross-sectional diagram for explaining the effective cross-sectional area of ​​the leakage flow when the stationary fin portion 18 is inclined so as to move toward the upstream side in the axial direction as it moves inward in the radial direction. FIG. 10 is a schematic diagram for explaining the flow of swirl in the cross section shown in FIG. 8 is a diagram illustrating the leakage flow rate and the effective damping of the axial vibration of the rotor 4 in the embodiment shown in FIG. 7 in comparison with the above-described comparative embodiments 1 to 4. FIG. 9 is a schematic diagram illustrating another example of a cross section along the axial direction of the rotary machine 2 according to one embodiment.

[0010] Several embodiments of the present disclosure will be described below with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the invention. For example, expressions expressing relative or absolute arrangements, such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial," not only strictly express such arrangements, but also express relative displacements with a tolerance or angle or distance to the extent that the same function is achieved. For example, expressions expressing the equality of things, such as "same," "equal," and "homogeneous," not only express strict equality, but also express tolerance or differences to the extent that the same function is achieved. For example, expressions expressing shapes such as a square or cylindrical shape not only express shapes such as a square or cylindrical shape in the strict geometric sense, but also express shapes including concave and convex portions, chamfered portions, etc., to the extent that the same effect is achieved. On the other hand, the expressions "comprise," "include," "have," "includes," or "have" of one element are not exclusive expressions that exclude the presence of other elements.

[0011] Fig. 1 is a schematic diagram showing an example of a cross section perpendicular to an axial direction of a rotary machine 2 according to one embodiment. The rotary machine 2 may be, for example, a turbine such as a steam turbine or a compressor. As shown in Fig. 1, the rotary machine 2 includes a rotor 4 and a casing 6 that houses the rotor 4. The casing 6 includes a casing main body 8 that houses the rotor 4 and a seal device 10 (seal device for a rotary machine).

[0012] In this specification, unless otherwise specified, "axial direction" means the axial direction of the rotor 4, "circumferential direction" means the circumferential direction of the rotor 4, and "radial direction" means the radial direction of the rotor 4, unless otherwise specified. Furthermore, the upstream side in the axial direction means the upstream side of the axial flow of fluid in the gap g between the rotor 4 and the casing 6 (the gap between the rotor 4 and the inner circumferential surface 12a of the seal main body 12 described below), i.e., the high-pressure side in the axial direction of the gap g, and the downstream side in the axial direction means the downstream side of the axial flow of fluid in the gap g, i.e., the low-pressure side in the axial direction of the gap g.

[0013] 1 , the seal device 10 includes a seal body 12 and a plurality of stationary fin portions 18. In the illustrated exemplary embodiment, the seal body 12 is formed in an annular (e.g., cylindrical) shape and is held on the inner surface 8a of the casing body 8. The seal body 12 includes an inner circumferential surface 12a, which is a stationary wall surface facing the outer circumferential surface 4a of the rotor 4, and an outer circumferential surface 12b fixed to the inner surface 8a of the casing body 8.

[0014] A plurality of holes 16 (recesses) are formed in the inner peripheral surface 12a of the seal body 12. In the cross section shown in Figure 1, the plurality of holes 16 formed in the inner peripheral surface 12a of the seal body 12 include a plurality of holes 16 arranged at intervals in the circumferential direction.

[0015] Fig. 2 is a schematic diagram showing an example of a cross section taken along the axial direction of the rotary machine 2 shown in Fig. 1. In the cross section shown in Fig. 2, the multiple holes 16 formed in the inner circumferential surface 12a of the seal main body 12 include multiple holes 16 arranged at intervals in the axial direction. In the exemplary embodiment shown in Fig. 2, the shape of a cross section perpendicular to the radial direction of each of the multiple holes 16 formed in the inner circumferential surface 12a of the seal main body 12 may be circular. That is, in the exemplary embodiment shown in Fig. 2, each of the multiple holes 16 formed in the inner circumferential surface 12a of the seal main body 12 may be a bottomed recess that forms a cylindrical cavity.

[0016] 2 , the seal device 10 includes a plurality of stationary fin portions 18 provided at intervals in the axial direction on the inner peripheral surface 12a of the seal body 12. Each of the plurality of stationary fin portions 18 extends along the circumferential direction and protrudes radially inward from the inner peripheral surface 12a of the seal body 12 toward the outer peripheral surface 4a of the rotor 4. Each of the plurality of stationary fin portions 18 may be formed in an annular shape centered on the rotational axis of the rotor 4.

[0017] For example, as shown in Fig. 2 , each of the multiple stationary fin portions 18 may be provided between two axially adjacent holes 16 on the inner circumferential surface 12a of the seal body 12. In the cross section shown in Fig. 2 , the holes 16 and the stationary fin portions 18 are arranged alternately in the axial direction. As shown in Fig. 2 , in order to reduce the contact area with the rotor 4 when the rotor 4 is displaced, the tip portion of each of the stationary fin portions 18 may have a tapered shape (a shape in which the thickness decreases radially inward). In this case, in order to suppress an increase in leakage flow through the gap g, the tip end surface 18t of each of the stationary fin portions 18 may include an inclined surface 18t1 that is inclined radially inward and axially upstream.

[0018] For example, as shown in FIG. 2 , the rotary machine 2 includes a plurality of rotor fin portions 20 (a plurality of first rotor fin portions) provided on the outer peripheral surface 4 a of the rotor 4. Each of the plurality of rotor fin portions 20 extends along the circumferential direction and protrudes from the outer peripheral surface 4 a of the rotor 4 toward the corresponding hole 16. In the cross section shown in FIG. 2 , each of the rotor fin portions 20 is formed at a position facing the bottom surface 16 s of each hole 16, and is provided at a center position Pc of the hole 16 in the axial direction. In the exemplary embodiment shown in FIG. 2 , each of the rotor fin portions 20 is provided between two axially adjacent stationary fin portions 18 among the plurality of stationary fin portions 18. The axial thickness t of each of the rotor fin portions 20 is smaller than the axial dimension w of each of the holes 16, and may satisfy, for example, t<0.3w. Furthermore, in order to reduce the contact area with the seal main body 12 when the rotor 4 is displaced, the tip end of each rotor fin portion 20 may have a tapered shape (a shape in which the thickness decreases as it moves radially outward), and in this case, the tip end face 20t of each rotor fin portion 20 may include an inclined surface 20t1 that slopes toward the upstream axial direction as it moves radially outward, in order to suppress an increase in leakage flow through the gap g.

[0019] The rotary machine 2 described above includes a plurality of stationary fin portions 18 and a plurality of rotor fin portions 20, and therefore can reduce the contact area between the outer peripheral surface 4 a of the rotor 4 and the inner peripheral surface 12 a of the seal main body 12 when the rotor 4 is displaced in a direction perpendicular to the axial direction, compared to a rotary machine not including a plurality of stationary fin portions 18 and a plurality of rotor fin portions 20. This reduces the risk of contact between the rotor 4 and a stationary wall surface, i.e., the risk of thermal bending of the rotor 4 caused by frictional heat between the outer peripheral surface 4 a of the rotor 4 and the inner peripheral surface 12 a of the seal main body 12.

[0020] Furthermore, as indicated by arrow F1 in Figure 3, a swirl (leakage flow) flowing through the gap g between the outer peripheral surface 4a of the rotor 4 and the inner peripheral surface 12a of the seal body 12 is more likely to flow along the rotor fin portion 20 into the holes 16 in the inner peripheral surface 12a of the seal body 12. Then, as indicated by arrow F2 in Figure 4 (a schematic diagram showing a portion of the A-A cross section of Figure 3), the swirl turns within the holes 16, becomes a reverse swirl flowing in the opposite direction to the rotation direction r of the rotor 4, and exits the holes 16, thereby reducing the swirl. This reduces the excitation force component (component perpendicular to the axial direction) of the fluid force acting on the outer peripheral surface 4a of the rotor 4, thereby improving the damping effect of axial vibration of the rotor 4 and achieving high axial stability of the rotor 4.

[0021] 5 is a diagram illustrating the flow rate of leakage flow through the gap g (hereinafter referred to as the "leakage flow rate") and the effective damping of axial vibration of the rotor 4 for the rotary machine 2 according to the embodiment described with reference to FIGS. 1 to 4, in comparison with Comparative Examples 1 to 4. Here, Comparative Example 1 corresponds to a configuration in which the plurality of stationary fin portions 18 and the plurality of rotor fin portions 20 are removed from the rotary machine 2, Comparative Example 2 corresponds to a configuration in which the height of the inner circumferential surface 12a of the seal main body 12 from the outer circumferential surface 4a of the rotor 4 is lower than in Comparative Example 1, Comparative Example 3 corresponds to a configuration in which the height of the inner circumferential surface 12a of the seal main body 12 from the outer circumferential surface 4a of the rotor 4 is lower than in Comparative Example 2, and Comparative Example 4 corresponds to a configuration in which the height of the inner circumferential surface 12a of the seal main body 12 from the outer circumferential surface 4a of the rotor 4 is lower than in Comparative Example 3. In addition, the height of the inner surface 12a of the seal main body 12 from the outer surface 4a of the rotor 4 in the above embodiment is the same as the height of the inner surface 12a of the seal main body 12 from the outer surface 4a of the rotor 4 in comparative embodiment 1.

[0022] 5, in Comparative Examples 1 to 4, when the height of the inner peripheral surface 12a of the seal main body 12 from the outer peripheral surface 4a of the rotor 4 is increased in order to reduce the risk of contact between the rotor 4 and the inner peripheral surface 12a of the seal main body 12 (i.e., when moving from Comparative Example 4 to Comparative Example 1), the leakage flow rate increases and the effective damping of axial vibration decreases. Therefore, in Comparative Examples 1 to 4, it is difficult to simultaneously reduce the risk of contact between the rotor 4 and the inner peripheral surface 12a of the seal main body 12 and increase the damping effect of axial vibration.

[0023] In contrast, in the rotary machine 2 according to the above embodiment, even though the height of the inner peripheral surface 12a of the seal main body 12 from the outer peripheral surface 4a of the rotor 4 is the same as that of Comparative Example 1, which has the highest height among Comparative Examples 1 to 4, it is possible to achieve high effective damping while significantly reducing the leakage flow rate compared to each of Comparative Examples 1 to 4. Therefore, it is possible to achieve high axial stability of the rotor 4 while reducing the risk of contact between the rotor 4 and the inner peripheral surface 12a of the seal main body 12.

[0024] 6 is a diagram showing the relationship between the axial position and the dimensionless circumferential velocity of the swirl (leakage flow) in the gap g between the outer circumferential surface 4 a of the rotor 4 and the inner circumferential surface 12 a of the seal body 12 for each of the above embodiment and comparative embodiment 1. Here, the dimensionless circumferential velocity is the value obtained by dividing the circumferential velocity at each position by the circumferential velocity at the 0 mm position in the axial direction.

[0025] As shown in FIG. 6, according to the above embodiment, the swirl ratio can be reduced in the axial range where the holes 16 are formed, compared to Comparative Example 1, and therefore the axial vibration of the rotor 4 can be effectively damped.

[0026] Fig. 7 is a schematic diagram showing another example of a cross section along the axial direction of the rotary machine 2 according to one embodiment. In the rotary machine 2 shown in Fig. 7, the same reference numerals as those in Fig. 2 indicate the same components as those in Fig. 2 unless otherwise specified, and descriptions thereof will be omitted.

[0027] In some embodiments, as shown in FIG. 7 , for example, each of the multiple stationary fin portions 18 may be inclined toward the upstream side in the axial direction as it extends radially inward. Furthermore, each of the multiple rotor fin portions 20 may be inclined toward the upstream side in the axial direction as it extends radially outward. In the illustrated exemplary embodiment, each of the rotor fin portions 20 protrudes toward the upstream wall surface 16a1 of the inner surface 16a of the corresponding hole 16. Specifically, as shown in FIG. 7 , when a line L connects the base end of the rotor fin portion 20 (the axial upstream end at the base end of the rotor fin portion 20 in the illustrated example) and the tip of the rotor fin portion 20 in a cross section along the axial direction, each of the rotor fin portions 20 may be formed such that the line L intersects with the upstream wall surface 16a1 of the inner surface 16a of the hole 16 corresponding to the rotor fin portion 20.

[0028] The configuration shown in Fig. 7 enhances the flow contraction effect of the stationary fin portion 18 and the rotor fin portion 20, thereby effectively reducing the leakage flow rate in the gap g between the outer peripheral surface 4a of the rotor 4 and the inner peripheral surface 12a of the seal body 12. For example, compared to a case in which the stationary fin portion 18 is not inclined radially as shown in Fig. 8A, when the stationary fin portion 18 is inclined radially inward and axially upstream as shown in Fig. 8B, the flow bends near the tip of the stationary fin portion 18, and the downward velocity component becomes stronger. This increases the backflow area near the tip of the stationary fin portion 18, thereby reducing the effective cross-sectional area of ​​the leakage flow. Furthermore, as shown by arrow F3 in Fig. 8C, in the axial cross section, the axial leakage flow in the gap g is redirected by the rotor fin portion 20 and circulates within the hole 16, effectively reducing the leakage flow rate.

[0029] 9 is a diagram comparing the leakage flow rate and effective damping of axial vibration of the rotor 4 in the embodiment shown in FIG. 7 with the embodiment shown in FIG. 2 and the above-described comparative embodiments 1 to 4. As shown in FIG. 9, the embodiment shown in FIG. 7 can also achieve significant effective damping while significantly reducing the leakage flow rate compared to each of comparative embodiments 1 to 4, thereby achieving both a reduced risk of contact between the rotor 4 and the inner circumferential surface 12a of the seal main body 12 and an increased damping effect on axial vibration of the rotor 4. Furthermore, compared to the embodiment shown in FIG. 2 (see FIG. 5), the effect of reducing the leakage flow rate is even greater.

[0030] Fig. 10 is a schematic diagram showing another example of a cross section along the axial direction of the rotary machine 2 according to one embodiment. In the rotary machine 2 shown in Fig. 10, reference numerals that are common to the components shown in Fig. 2 indicate the same components as those shown in Fig. 2 unless otherwise specified, and descriptions thereof will be omitted.

[0031] 10 , the multiple stationary fin portions 18 formed on the inner peripheral surface 12a of the seal main body 12 are referred to as stationary fin portions 18a, 18b, 18c, 18d, and 18e in order from the upstream side in the axial direction, and the multiple rotor fin portions 20 formed on the outer peripheral surface 4a of the rotor 4 are referred to as rotor fin portions 20a, 20b, 20c, and 20d in order from the upstream side in the axial direction. Therefore, stationary fin portion 18b is located downstream in the axial direction from stationary fin portion 18a, stationary fin portion 18c is located downstream in the axial direction from stationary fin portion 18b, stationary fin portion 18d is located downstream in the axial direction from stationary fin portion 18c, and stationary fin portion 18e is located downstream in the axial direction from stationary fin portion 18d. In addition, rotor fin portion 20a is located between stationary fin portion 18a and stationary fin portion 18b, rotor fin portion 20b is located between stationary fin portion 18b and stationary fin portion 18c, rotor fin portion 20c is located between stationary fin portion 18c and stationary fin portion 18d, and rotor fin portion 20d is located between stationary fin portion 18d and stationary fin portion 18e.

[0032] 10, the multiple holes 16 formed in the inner circumferential surface 12a of the seal body 12 include a hole 161 formed in the range between stationary fin portion 18a and stationary fin portion 18b in the axial direction and a hole 162 formed in the range between stationary fin portion 18b and stationary fin portion 18cb in the axial direction. Also, in the cross section shown in Fig. 10, the inner circumferential surface 12a of the seal body 12 includes a hole-free region 12a1 where no holes 16 are formed between stationary fin portion 18c and stationary fin portion 18d in the axial direction, and a hole-free region 12a2 where no holes 16 are formed between stationary fin portion 18d and stationary fin portion 18e in the axial direction.

[0033] 10 , rotor fin portion 20a is provided at the center of hole 161 in the axial direction and protrudes toward bottom surface 16s of hole 161. Rotor fin portion 20b is provided at the center of hole 16i in the axial direction and protrudes toward bottom surface 16s of hole 162. Rotor fin portion 20c is provided at the center of hole-free region 12a1 in the axial direction and protrudes toward hole-free region 12a1. Rotor fin portion 20d is provided at the center of hole-free region 12a2 in the axial direction and protrudes toward hole-free region 12a2. 10 , if the distance between inner circumferential surface 12a of seal main body 12 and rotor fin portion 20a is d1, the distance between inner circumferential surface 12a of seal main body 12 and rotor fin portion 20b is d2, the distance between inner circumferential surface 12a of seal main body 12 and rotor fin portion 20c is d3, and the distance between inner circumferential surface 12a of seal main body 12 and rotor fin portion 20d is d4, then d1 = d2, d2 < d3, and d3 = d4 are satisfied. Note that distance d1 corresponds to the distance between bottom surface 16s of hole 161 and rotor fin portion 20a, distance d2 corresponds to the distance between bottom surface 16s of hole 162 and rotor fin portion 20b, distance d3 corresponds to the distance between hole-free region 12a1 and rotor fin portion 20c, and distance d4 corresponds to the distance between hole-free region 12a2 and rotor fin portion 20d.

[0034] 10 , compared to when holes 16 are formed between all of the stationary fin portions 18 in the axial direction on the inner peripheral surface 12a of the seal body 12, by providing the hole-free regions 12a1, 12a2 and providing the rotor fin portions 20c, 20d that protrude toward the hole-free regions 12a1, 12a2, respectively, it is possible to reduce the leakage flow rate in the gap g between the outer peripheral surface 4a of the rotor 4 and the inner peripheral surface 12a of the seal body 12. Furthermore, compared to when holes 16 are not present, it is possible to improve the damping effect of axial vibration of the rotor 4 and achieve high axial stability of the rotor 4.

[0035] The present disclosure is not limited to the above-described embodiments, but also includes modifications to the above-described embodiments and appropriate combinations of these modifications.

[0036] For example, in some of the above-described embodiments, the cross section of each of the holes 16 taken perpendicular to the radial direction has a circular shape, but the cross section of each of the holes 16 taken perpendicular to the radial direction may also have a rectangular shape. That is, each of the holes 16 may have a recess with a bottom that forms a cavity in the shape of a rectangular prism. This can promote the turning of the flow within the hole 16 and enhance the above-described effect of reducing swirl.

[0037] Furthermore, the casing body 8, the seal body 12, and the stationary fin portion 18 do not need to be configured as separate components, and any combination of these may be integrally configured as a single component.

[0038] Furthermore, each of the plurality of stationary fin portions 18 may be provided so as to straddle the plurality of holes 16. In other words, each of the plurality of stationary fin portions 18 may be provided so as to overlap at least a portion of the plurality of holes 16 when viewed in the radial direction.

[0039] Also, for example, only one of all the stationary fin portions 18 of the sealing device 10 may be provided at a position between two circumferentially adjacent holes 16 on the inner surface 12a of the seal main body portion 12, or any number of all the stationary fin portions 18 of the sealing device 10 may be provided at a position between two circumferentially adjacent holes 16 on the inner surface 12a of the seal main body portion 12.

[0040] In addition, only one of all the stationary fin portions 18 of the sealing device 10 may be inclined toward the upstream side of the rotation direction r of the rotor 4 as it moves radially inward, or any number of all the stationary fin portions 18 of the sealing device 10 may be inclined toward the upstream side of the rotation direction r of the rotor 4 as it moves radially inward.

[0041] In addition, only one of all rotor fin portions 20 of the rotary machine 2 may be inclined toward the upstream side of the rotation direction r of the rotor 4 as it moves radially outward, or any number of stationary fin portions 18 of all rotor fin portions 20 of the sealing device 10 may be inclined toward the upstream side of the rotation direction r of the rotor 4 as it moves radially outward.

[0042] Further, for example, each of the multiple stationary fin portions 18 of the sealing device 10 may be inclined toward the upstream side in the rotation direction r of the rotor 4 as it moves radially inward, and each of the multiple rotor fin portions 20 may extend along the radial direction (along a plane perpendicular to the axial direction). Further, each of the multiple stationary fin portions 18 of the sealing device 10 may be inclined toward the upstream side in the rotation direction r of the rotor 4 as it moves radially outward.

[0043] The contents described in each of the above embodiments can be understood, for example, as follows.

[0044] (1) A rotary machine (e.g., rotary machine 2) according to at least one embodiment of the present disclosure comprises: a rotor (e.g., rotor 4); an annular seal body (e.g., seal body 12) including an inner circumferential surface (e.g., inner circumferential surface 12a) that is a stationary wall surface facing an outer circumferential surface (e.g., outer circumferential surface 4a) of the rotor, and a plurality of holes (e.g., a plurality of holes 16) formed in the inner circumferential surface; a plurality of stationary fins (e.g., the above-mentioned plurality of stationary fins 18) provided on the inner circumferential surface at intervals in the axial direction of the rotor; and at least one first rotor fin (e.g., the above-mentioned plurality of rotor fins 20 or rotor fins 20a, 20b) provided on the outer circumferential surface of the rotor, wherein each of the plurality of stationary fins extends along the circumferential direction of the rotor and protrudes from the inner circumferential surface toward the outer circumferential surface of the rotor, and each of the at least one first rotor fin extends along the circumferential direction and protrudes from the outer circumferential surface of the rotor toward the hole.

[0045] According to the rotary machine described in (1) above, by including multiple stationary fins and at least one rotor fin, the contact area between the outer circumferential surface of the rotor and the stationary wall surface can be reduced when the rotor is displaced in a direction perpendicular to the axial direction, thereby reducing the risk of contact between the rotor and the stationary wall surface, i.e., the risk of thermal bending of the rotor due to frictional heat between the outer circumferential surface of the rotor and the stationary wall surface. Furthermore, swirls (leakage flows) flowing through the gap between the outer circumferential surface of the rotor and the inner circumferential surface (stationary wall surface) of the seal body are more likely to flow along the rotor fins into the holes in the inner circumferential surface of the seal body. The swirls are redirected within the holes, becoming reverse swirls flowing in the opposite direction to the rotor rotation direction before exiting the holes. This reduces the swirl and reduces the excitation force component (component perpendicular to the axial direction) of the fluid force acting on the outer circumferential surface of the rotor. This enhances the damping effect of the rotor's axial vibration, achieving high axial stability of the rotor.

[0046] (2) In some embodiments, in the rotary machine described in (1) above, the thickness of each of the plurality of stationary fin portions is smaller than the dimension of the hole in the axial direction.

[0047] According to the rotary machine described in (2) above, it is possible to reduce the risk of contact between the rotor and the stationary wall surface and achieve high axial stability of the rotor.

[0048] (3) In some embodiments, in the rotary machine described in (1) or (2) above, at least one of the plurality of stationary fin portions is provided at a position between two of the holes adjacent in the axial direction on the inner circumferential surface of the seal main body portion.

[0049] According to the rotary machine described in (3) above, by providing the axial fin portion at a position between two axially adjacent holes on the inner surface of the seal main body, the stationary fin portion can be more firmly fixed to the seal main body than when the stationary fin portion is provided so as to straddle the holes.

[0050] (4) In some embodiments, in the rotary machine according to any one of (1) to (3) above, the first rotor fin portion is provided at a center position of the hole in the axial direction.

[0051] According to the rotary machine described in (4) above, by providing the first rotor fin portion at the center position of the hole in the axial direction, a robust structure can be achieved that can suppress deterioration of sealing performance, such as a sudden decrease in effective damping or a sudden increase in leakage flow rate, even if an axial thermal expansion difference occurs between the stationary wall surface and the rotor and the axial relative position of the first rotor fin portion with respect to the hole changes.

[0052] (5) In some embodiments, in the rotary machine according to any one of (1) to (4) above, the shape of a cross section of the hole perpendicular to the radial direction of the rotor is circular.

[0053] According to the rotary machine described in (5) above, by making the cross-sectional shape of the hole perpendicular to the radial direction of the rotor circular, the turning of the flow within the hole can be promoted, thereby enhancing the effect of reducing the swirl described in (1) above.

[0054] (6) In some embodiments, in the rotary machine according to any one of (1) to (5) above, the shape of a cross section of the hole perpendicular to the radial direction of the rotor is quadrangular.

[0055] According to the rotary machine described in (6) above, by making the cross-sectional shape of the hole perpendicular to the radial direction of the rotor square, the turning of the flow within the hole can be promoted, thereby enhancing the effect of reducing the swirl described in (1) above.

[0056] (7) In some embodiments, in the rotary machine described in any one of (1) to (6) above, at least one of the plurality of stationary fin portions is inclined toward the upstream side in the axial direction as it moves toward the inside in the radial direction of the rotor.

[0057] According to the rotary machine described in (7) above, the effect of the contracted flow by the stationary fin portion can be enhanced, and the amount of leakage flow that flows through the gap between the outer circumferential surface of the rotor and the stationary wall surface can be reduced.

[0058] (8) In some embodiments, in the rotary machine described in any one of (1) to (7) above, the first rotor fin portion is inclined toward the upstream side in the axial direction as it moves toward the outside in the radial direction of the rotor.

[0059] According to the rotary machine described in (8) above, the effect of the contracted flow by the first rotor fin portion can be enhanced, and the amount of leakage flow that flows through the gap between the outer peripheral surface of the rotor and the stationary wall surface can be reduced.

[0060] (9) In some embodiments, in the rotary machine according to any one of (1) to (8) above, the rotary machine according to claim 1, wherein a tip of the first rotor fin portion has a tapered shape.

[0061] According to the rotary machine described in (9) above, the contact area between the first rotor fin portion and the seal main body portion can be reduced when the rotor is displaced in a direction perpendicular to the axial direction, thereby reducing the risk of contact between the rotor and the stationary wall surface, i.e., the risk of thermal bending of the rotor due to frictional heat between the outer peripheral surface of the rotor and the stationary wall surface.

[0062] (10) In some embodiments, in the rotary machine described in any one of (1) to (9) above, the plurality of stationary fin portions include a first stationary fin portion (e.g., the above-described stationary fin portion 18a or the above-described stationary fin portion 18b), a second stationary fin portion (e.g., the above-described stationary fin portion 18b or the above-described stationary fin portion 18c) located downstream of the first stationary fin portion in the axial direction, a third stationary fin portion (e.g., the above-described stationary fin portion 18c or the above-described stationary fin portion 18d) located downstream of the second stationary fin portion in the axial direction, and a fourth stationary fin portion (e.g., the above-described stationary fin portion 18d or the above-described stationary fin portion 18e) located downstream of the third stationary fin portion, and the plurality of holes include holes (e.g., the above-described hole 161 or the above-described hole 162) formed in a range between the first stationary fin portion and the second stationary fin portion in the axial direction, The inner surface of the seal main body includes a hole-free region (e.g., the above-mentioned hole-free region 12a1 or hole-free region 12a2) in which no holes are formed between the third stationary fin portion and the fourth stationary fin portion in the axial direction, and the rotating machine includes a second rotor fin portion (e.g., the above-mentioned rotor fin portion 20c or rotor fin portion 20d) provided on the outer surface of the rotor at a position between the third stationary fin portion and the fourth stationary fin portion in the axial direction, and the second rotor fin portion extends along the circumferential direction and protrudes toward the hole-free region of the inner surface.

[0063] According to the rotary machine described in (10) above, compared to when holes are formed between all of the stationary fins in the axial direction on the inner peripheral surface of the seal body, by providing a hole-free region and providing a second rotor fin portion that protrudes toward the hole-free region, it is possible to reduce the amount of leakage flow that flows through the gap between the outer peripheral surface of the rotor and the stationary wall surface. Also, compared to when there are no holes, it is possible to improve the damping effect of axial vibration of the rotor and achieve high axial stability of the rotor.

[0064] (11) In some embodiments, in the rotary machine described in any of (1) to (10) above, each of the first rotor fin portions is formed so that, in a cross section along the axial direction, a straight line connecting the base end of the first rotor fin portion and the tip end of the first rotor fin portion intersects with the wall surface upstream in the axial direction on the inner surface of the hole corresponding to the first rotor fin portion.

[0065] According to the rotary machine described in (11) above, in a cross section along the axial direction, the axial leakage flow in the gap between the outer peripheral surface of the rotor and the inner peripheral surface of the seal main body can be redirected by the first rotor fin portion and circulated within the hole, thereby effectively reducing the flow rate of the leakage flow.

[0066] 2 Rotating machine 4 Rotor 4a Outer peripheral surface 6 Casing 8 Casing body 8a Inner surface 10 Seal device 12 Seal body portion 12a Inner peripheral surface 12a1, 12a2 Hole-free region 12b Outer peripheral surface 16 Hole 16a Inner surface 16a1 Wall surface 16s Bottom surface 18, 18a, 18b, 18c, 18d, 18e Stationary fin portion 20, 20a, 20b, 20c, 20d Rotor fin portion L Straight line Pc Position d1, d2, d3, d4 Distance g Gap r Rotation direction w Dimension

Claims

1. A rotary machine comprising: a rotor; an annular seal body including an inner circumferential surface which is a stationary wall surface facing the outer circumferential surface of the rotor and a plurality of holes formed on the inner circumferential surface; a plurality of stationary fin portions provided on the inner circumferential surface at intervals in the axial direction of the rotor; and at least one first rotor fin portion provided on the outer circumferential surface of the rotor, wherein each of the plurality of stationary fin portions extends along the circumferential direction of the rotor and protrudes from the inner circumferential surface toward the outer circumferential surface of the rotor, and each of the at least one first rotor fin portion extends along the circumferential direction and protrudes from the outer circumferential surface of the rotor towards one of the holes.

2. A rotary machine as set forth in claim 1, wherein the thickness of each of said plurality of stationary fin portions is less than the dimension of said hole in said axial direction.

3. A rotary machine as set forth in claim 1, wherein at least one of said plurality of stationary fin portions is provided at a position between two of said holes adjacent in the axial direction on said inner peripheral surface of said seal body portion.

4. A rotary machine according to claim 1, wherein the first rotor fin portion is provided at a central position of the hole in the axial direction.

5. A rotary machine according to claim 1, wherein the shape of a cross section perpendicular to the radial direction of the rotor at said hole is circular.

6. A rotary machine according to claim 1, wherein the shape of a cross section perpendicular to the radial direction of the rotor at said hole is rectangular.

7. A rotary machine according to claim 1, wherein at least one of said plurality of stationary fin portions is inclined so as to move toward the upstream side in the axial direction as it moves toward the inside in the radial direction of said rotor.

8. A rotary machine according to claim 1, wherein the first rotor fin portion is inclined toward the upstream side in the axial direction as it moves toward the outside in the radial direction of the rotor.

9. The rotary machine according to claim 1, wherein a tip of said first rotor fin portion has a tapered shape.

10. The rotating machine of claim 1, wherein the plurality of stationary fin portions include a first stationary fin portion, a second stationary fin portion located downstream in the axial direction from the first stationary fin portion, a third stationary fin portion located downstream in the axial direction from the second stationary fin portion, and a fourth stationary fin portion located downstream of the third stationary fin portion, the plurality of holes include holes formed in a range between the first stationary fin portion and the second stationary fin portion in the axial direction, the inner surface of the seal main body portion includes a hole-free region in which no holes are formed between the third stationary fin portion and the fourth stationary fin portion in the axial direction, and the rotating machine includes a second rotor fin portion provided on the outer surface of the rotor at a position between the third stationary fin portion and the fourth stationary fin portion in the axial direction, and the second rotor fin portion extends along the circumferential direction and protrudes toward the hole-free region of the inner surface.

11. A rotary machine as described in claim 1, wherein each of the first rotor fin portions is formed so that, in a cross section along the axial direction, a straight line connecting the base end of the first rotor fin portion and the tip end of the first rotor fin portion intersects with the wall surface upstream in the axial direction on the inner surface of the hole corresponding to the first rotor fin portion.