JP2018105297A - Turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce leakage quantity of fluid which leaks from a gap produced between a rotation part and a stationary part of a turbine.SOLUTION: A turbine having a fin on a rotation part or a stationary part as a shroud having a rotation part or a stationary part opposite to the fin includes: a contact surface part with which fluid caused to flow into the turbine is brought into contact; and a recessed part which is formed in a depth d on the contact surface part facing the upstream side in the axial direction of the turbine as a part of the contact surface part facing the upstream side on the axial direction of the turbine, of the contact surface part. Therein, the recessed part is provided on an outer circumference of the shroud and the rotation part or the stationary part and, when a distance with the tip of the fin closest to the recessed part, of the fin provided on the downstream side in a leakage flow direction from the recessed part is a first distance s, a first ratio d/s as a ratio of the depth d to the first distance s is larger than 0.0 and is less than 1.0.SELECTED DRAWING: Figure 2

Description

  The present invention relates to shrouds and turbines.

  Conventionally, a turbine for generating power is installed in a power plant. The turbine includes a moving blade provided in a turbine rotating portion for rotating a generator shaft and a stationary blade provided in a stationary portion. Furthermore, in order to reduce fluid leakage from a gap formed between the rotating part and the stationary part, a method of installing a shroud and a seal fin on the tip of the blade and the opposite surface is known. ing.

  Specifically, in this method, first, a plurality of flat portions having different outer diameter dimensions are formed on the outer peripheral surface of the shroud. In this method, the projecting fins are provided on the flat part and the surface of the stationary part facing the flat part. If it does in this way, the fluid which leaks will collide with the side surface of a seal fin part. Thus, a method for improving the sealing effect is known (for example, Patent Document 1).

  Further, a method of reducing the amount of fluid leakage in a turbine including a blade and a structure that rotates relative to the blade is known. Specifically, in this method, first, a seal fin is formed from one of the blade and the structure toward the other. Moreover, in this method, the flow collision surface where the fluid collides is provided upstream of the seal fin. Further, in this method, an opposing surface is provided opposite the flow collision surface. In this method, a cavity is formed by the seal fin, the flow collision surface, the facing surface, and the like. Subsequently, in this method, a convex portion for dividing the cavity is provided. In this way, the step portion having a step formed on the convex portion and the blade generates the main vortex, the first separation vortex, and the second separation vortex. Thus, a method of reducing the amount of vapor leakage is known (for example, Patent Document 2).

  In addition, in a turbine including a blade and a structure that rotates relative to the blade, a method for reducing the amount of fluid leakage is known. Specifically, in this method, a step portion is provided on one of the tip portion or the structure of the blade. Next, in this method, a seal fin is provided on the other side. A minute gap H is formed between the seal fin and the step portion. In this method, it is assumed that the distance L is between the seal fin and the edge of the step portion, and 0.7 × small gap H ≦ L. Alternatively, 1.25 × small gap H ≦ L ≦ 2.75 × small gap H. Thus, a method for reducing the amount of leakage is known (for example, Patent Document 3).

JP 2006-291967 A Japanese Patent No. 5518032 JP 2013-64370 A

  However, in the conventional method, there is a large amount of fluid leaking from a gap formed between the rotating part and the stationary part of the turbine, and the reduction of the leakage amount may be insufficient.

  One aspect of the present invention has been made in view of such problems, and aims to reduce the amount of fluid leaking from a gap formed between a rotating part and a stationary part of a turbine. To do.

In order to solve the above-described problems and achieve the object, a turbine having fins in a rotating part or a stationary part in one embodiment of the present invention has a shroud in a rotating part or a stationary part facing the fins.
A contact surface portion in contact with fluid flowing into the turbine;
Among the contact surface portions, a contact surface portion facing the upstream side in the axial direction of the turbine is formed with a depth d, and a depression portion is formed as a part of the contact surface portion facing the upstream side in the axial direction of the turbine. And
The depression is
Out of the fins that are installed on the outer periphery of the shroud and on the downstream side in the leakage flow direction with respect to the recessed portion and installed on the rotating portion or the stationary portion, the tip of the fin closest to the recessed portion If the distance is the first distance s,
A first ratio d / s, which is a ratio between the depth d and the first distance s, is greater than 0.0 and less than 1.0.

  According to the present invention, it is possible to reduce the amount of fluid leaking from a gap formed between the rotating part of the turbine and the stationary part.

It is sectional drawing which shows an example of the turbine in one Embodiment of this invention. It is an enlarged view which shows an example of the shroud in one Embodiment of this invention. It is an enlarged view which shows an example of the effect in one Embodiment of this invention. It is an enlarged view which shows an example of the hollow part in one Embodiment of this invention. Example of analysis results of (A) first ratio d / s and fluid leakage (%), (B) second ratio w / s and fluid leakage (%) of stepped shroud in one embodiment of the present invention FIG. Example of analysis results of (A) first ratio d / s and fluid leakage (%), (B) second ratio w / s and fluid leakage (%) of concave-convex shroud in one embodiment of the present invention FIG. It is an enlarged view which shows a 1st comparative example. It is an enlarged view which shows the vortex in a 1st comparative example. It is an enlarged view which shows a 2nd comparative example. It is an enlarged view which shows a 3rd comparative example. It is sectional drawing which shows the modification of the turbine in one Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

  For example, the turbine according to the embodiment of the present invention is used in a plant that generates power by thermal power generation or the like. In the plant, a fluid such as steam is caused to flow inside the turbine. As described above, when a fluid is caused to flow inside the turbine, a rotating portion such as a moving blade of the turbine rotates, and rotational energy is generated. The turbine used in this way has, for example, the following structure.

  FIG. 1 is a cross-sectional view illustrating an example of a turbine according to an embodiment of the present invention. As shown in the figure, first, the turbine 10 has a rotor that rotates about a rotation axis AX. The size of the rotor, that is, the diameter is set in advance.

  In the illustrated example, the fluid that has flowed into the turbine 10 flows in the first direction DR1 inside the turbine 10. Note that the first direction DR1 is from left to right in the illustrated example. A direction orthogonal to the first direction DR1 is defined as a second direction DR2. On the other hand, the second direction DR2 is the vertical direction in the figure.

  In the figure, the axial direction is the left-right direction, and the upstream is the left side in the figure.

  And a rotor has a moving blade used as an example of a rotation part. Hereinafter, as shown in the drawing, the first moving blade RB1 and the second moving blade RB2 will be described as an example. Further, the turbine 10 has a stationary blade that is an example of a stationary portion with respect to the rotor. The rotating part and the stationary part are not limited to the number, size, position and arrangement as shown in the figure.

  Further, for example, a first shroud SHD1, a second shroud SHD2, a third shroud SHD3, and a fourth shroud SHD4 are installed in the first moving blade RB1, the second moving blade RB2, and the stationary blade, for example. Hereinafter, an example in which the first shroud SHD1, the second shroud SHD2, the third shroud SHD3, and the fourth shroud SHD4 have different shapes will be described. The first shroud SHD1, the second shroud SHD2, the third shroud SHD3, and the fourth shroud SHD4 may have the same combination. Further, the shrouds may be installed in an order different from the order shown.

  In the example shown in the figure, the first shroud SHD1 and the second shroud SHD2 are examples of shrouds (hereinafter, referred to as “concave-type shrouds”) in which irregularities are formed in the first direction DR1. On the other hand, the third shroud SHD3 and the fourth shroud SHD4 are examples of shrouds (hereinafter referred to as “stepped shrouds”) in which steps are formed in the first direction DR1. Note that the concave and convex shrouds and the stepped shrouds are not limited to the illustrated shapes.

  Hereinafter, a part including the part of the illustrated second shroud SHD2 and a part of the stationary blade (hereinafter referred to as “part A”) will be described in an enlarged manner.

  FIG. 2 is an enlarged view showing an example of a shroud in one embodiment of the present invention. FIG. 2 is an enlarged view of a portion A in FIG. In addition, the same code | symbol is attached | subjected to the structure similar to FIG. 1, and it demonstrates below.

  First, the fin FIN is formed in the stationary part. The fin FIN shown in the figure is installed in the stationary part, and is located downstream (in the drawing, in the right-and-left direction) from the recess part DE on the downstream side (in the drawing, on the right side). Among these, it is an example of the fin nearest to the hollow part DE.

  The fin FIN is formed to reduce the amount of fluid leakage. On the other hand, the fin FIN is formed in a position and a size where a certain gap is formed between the fin FIN and the shroud so that the rotation of the rotating portion is not hindered. In the illustrated example, a gap is formed between the outer periphery OUR of the second shroud SHD2 and the tip of the fin FIN. Further, the width of the gap, that is, the distance between the outer periphery OUR of the second shroud SHD2 and the tip of the fin FIN (hereinafter referred to as “first distance”) is “s”.

  In the example shown in the drawing, the fluid that flows between the gaps among the inflowing fluids is a fluid that leaks.

  On the other hand, the second shroud SHD2 has a contact surface portion TA. In the illustrated example, the contact surface TA is a surface that receives the fluid flowing in the first direction DR1 and contacts the fluid. The contact surface TA is formed with, for example, a recess DE that faces the upstream side in the axial direction of the turbine, as shown in the figure. Further, the depth of the depression DE is “d”. Furthermore, the ratio (hereinafter referred to as “first ratio”) between the depth d of the depression DE and the first distance s is referred to as “d / s”.

The depression DE is formed such that the first ratio d / s is greater than 0.0 and less than 1.0. In other words, the first ratio d / s is in the condition of the following formula (1).

0.0 <d / s <1.0 (1)

When the first ratio d / s is larger than 0.0 and smaller than 1.0 as expressed by the above formula (1), the following effects are obtained.

  FIG. 3 is a diagram illustrating an example of the effect in one embodiment of the present invention. This figure shows an example in which vortex WH1, leakage flow FL and vortex WH2 are formed. As shown in the drawing, when there is a recess portion DE, the leakage flow FL has an inertia toward the upper left in the figure. Thereby, there is no hollow part DE like the conventional type, that is, compared with the case of the first ratio d / s = 0, when there is the hollow part DE, the vortex WH2 having a nearly circular shape and high vorticity is formed. Can be made. The vorticity is an amount indicating the state of rotation of the flow. Further, when the vortex WH2 is formed by the depression DE, the vortex WH2 has an effect of narrowing the flow path of the leakage flow FL and reducing the leakage flow FL.

  On the other hand, when the first ratio d / s is 1.0 or more, the inertia is further increased. Therefore, the leakage flow FL is meandering so as to flow clockwise along the stationary part and the fin FIN after passing through the space occupied by the vortex WH1 and moving to the upper left. The large clockwise vortex is excited and the vortex WH2 disappears.

  The vortex WH2 has an effect of reducing the flow path of the leakage flow FL generated in the gap between the fin and the shroud. When the vortex WH2 having a high vorticity is generated, the amount of leakage is reduced by the leakage flow FL. Further, the vorticity of the vortex WH2 is influenced by the first ratio d / s. Therefore, when the first ratio d / s shown in the above equation (1) is used, as shown in the drawing, a vortex WH2 having a higher vorticity is formed, and the amount of fluid leakage can be reduced.

In the case of a step-type shroud, the first ratio d / s is desirably larger than 0.0 and smaller than 1.0 as in the above equation (1).

0.0 <d / s <1.0 (1)

More preferably, in the case of a stepped shroud, the first ratio d / s is preferably greater than 0.0 and less than 0.5, as shown in the following equation (2).

0.0 <d / s <0.5 (2)

Or, more desirably, in the case of a stepped shroud, the first ratio d / s is greater than 0.0 and less than 1.0 as shown in the following equation (3), and from the fin FIN: A ratio (hereinafter referred to as “second ratio”) w / s between the distance w (hereinafter referred to as “second distance”) to the end portion EG (see FIG. 2) of the contact surface portion TA and the first distance s, It is desirable to be greater than 0.8 and less than 3.0.

0.0 <d / s <1.0 and 0.8 <w / s <3.0 (3)

On the other hand, in the case of a concavo-convex shroud, the first ratio d / s is desirably 0.8 or less as shown in the following equation (4).

0.0 <d / s ≦ 0.8 (4)

More desirably, in the case of a concavo-convex shroud, the first ratio d / s is preferably greater than 0.0 and less than 0.3, as shown in the following equation (5).

0.0 <d / s <0.3 (5)

Or, more desirably, in the case of a concavo-convex shroud, the first ratio d / s is greater than 0.0 and less than 0.4 and the second ratio, as in the following formula (6): It is desirable that w / s is 1.0 or more and less than 2.0.

0.0 <d / s <0.4 and 1.0 ≦ w / s <2.0 (6)

In the above equation (6), “w” (see FIG. 2) indicates the second distance. “W / s” indicates the second ratio. The same applies hereinafter.

Or, more desirably, in the case of a concavo-convex shroud, the first ratio d / s is greater than 0.0 and less than 0.7 and the second ratio, as in the following equation (7): It is desirable that w / s is 0.8 or more and 1.5 or less.

0.0 <d / s <0.7 and 0.8 ≦ w / s ≦ 1.5 (7)

The vortex WH2 having a higher vorticity can be created when the depression is in the above condition. That is, a strong contraction effect can be generated by the depression DE.

  In addition, as shown in the drawing, a circular or elliptical vortex WH2 that can reduce the amount of fluid leakage can be created by the depression DE.

  In addition, the hollow part DE is not restricted to the shape as shown in figure, For example, the following shapes may be sufficient.

  FIG. 4 is an enlarged view showing an example of a recess in one embodiment of the present invention. The depression DE shown in FIG. 2 may have the shape shown in FIGS. 4 (A) to 4 (F), for example.

  As shown in FIGS. 4A, 4 </ b> B, 4 </ b> E, and 4 </ b> F, the hollow portion may have a curvature (indicated by “r” in the drawing). Moreover, as shown in FIG.4 (F), in addition to a curvature, the hollow part may further have the linear part ST. On the other hand, the recess may have a slope as shown in FIG. Furthermore, the dent may have a right angle, as shown in FIG. Further, as shown in FIGS. 4E and 4F, a shape in which an arc and a straight line are tangent may be provided. In particular, FIGS. 4B, 4C, 4E, and 4F are shapes in which a vortex WH2 having a high vorticity is likely to be generated.

  That is, as shown in FIG. 3, the recess is not limited to the shape shown in the figure as long as it can form a vortex WH <b> 2 having a high effect of reducing the amount of fluid leakage and having a high vorticity.

(Experimental result)
FIG. 5 shows (A) the first ratio d / s and the amount of fluid leakage (%), (B) the second ratio w / s and the amount of fluid leakage (%) of the step type shroud according to the embodiment of the present invention. It is a figure which shows the example of an analysis result.

  From FIG. 5A, when 0 <d / s <0.5, the amount of fluid leakage is 3.9% or less. Here, the reference value of 3.9% of the fluid leakage amount is a value set from the design conditions of the shroud, and the reference value of the fluid leakage amount also changes depending on the shroud shape.

  As shown in the figure, when the first ratio d / s is larger than 0.0 and less than 1.0, it is compared with the case where the first ratio d / s as in the first point D1 is 1.0 or more. As a result, the amount of fluid leakage decreases. On the other hand, if the first ratio d / s is 0.0, that is, if there is no depression, the amount of fluid leakage increases as in the second point D2.

  Further, from FIG. 5B, if the range is 0.8 <w / s <3.0, the amount of fluid leakage is 3.9% or less.

  FIG. 6 shows (A) the first ratio d / s and the amount of fluid leakage (%), (B) the second ratio w / s and the amount of fluid leakage (%) of the concavo-convex shroud according to the embodiment of the present invention. It is a figure which shows the example of an analysis result.

  From FIG. 6A, if 0 <d / s <0.3, the amount of fluid leakage is 3.9% or less.

  Further, from FIG. 6B, 0 <d / s <0.4 and 1.0 ≦ w / s <2.0, or 0 <d / s <0.7 and 0.8 ≦ w / s. If it is in the range of ≦ 1.5, the amount of fluid leakage is 3.9% or less.

  If there exists a hollow part as mentioned above, as shown in FIG. 3, the shroud can make vortex WH2 with higher vorticity. When the vortex WH2 is present, the flow path through which the fluid flows is reduced in the gap between the fin FIN and the shroud. That is, if there is the vortex WH2, the flow path of the leaking fluid can be narrowed, and the amount of fluid leaking by the leakage flow FL can be reduced.

  Therefore, with the configuration as described above, it is possible to reduce the amount of fluid leaking from a gap formed between the rotating part of the turbine and the stationary part. Further, reducing the amount of fluid leaking can improve the efficiency of the turbine.

<First comparative example>
FIG. 7 is an enlarged view showing a first comparative example. The first comparative example is a configuration that does not have the depression DE as compared to the configuration illustrated in FIG. Further, the first comparative example corresponds to the second point D2 in FIG. 5 (that is, the first ratio d / s is “0.0”).

  If the configuration has no depression as in the first comparative example, the vortex produced is different from the configuration with the depression DE as shown in FIG. As illustrated, in the first comparative example, vortices such as the vortex WH11 and the vortex WH12 are created. In particular, the shape of the vortex WH2 shown in FIG. 3 is different from that of the vortex WH12 shown in FIG.

  FIG. 8 is an enlarged view showing a vortex in the first comparative example. The vortex WH2 shown in FIG. 3 has a so-called “circle” or “ellipse” shape. On the other hand, the vortex WH12 has a so-called “kamaboko” or “semicircle” shape.

  As shown in the figure, in the shape like the vortex WH12, the flow of the vortex WH12 changes greatly particularly in the corner portions C1 and C2. Accordingly, in the corner portions C1 and C2, a part of the kinetic energy of the vortex WH12 is dissipated into thermal energy. Therefore, the vortex having a shape like the vortex WH12 is weaker in rotation and weakening the contraction effect than the shape like the vortex WH2 shown in FIG. That is, the distance between the vortex and the fin FIN (the flow path of the leakage flow FL) increases, and the amount of leakage increases.

  Further, as shown in FIG. 7, in the first comparative example, the flow path of the leakage flow FL has a width WD. On the other hand, the configuration shown in FIG. 3, that is, the vortex WH2 can narrow the width WD of the flow path of the leakage flow FL. Therefore, with the configuration shown in FIG. 3, the amount of fluid leaking can be reduced.

  As described above, when the depression DE is present, a vortex having a shape such as “circle” or “ellipse” like the vortex WH2 shown in FIG. 3 can be created, and the amount of fluid leaking can be reduced. .

<Second Comparative Example>
The second comparative example is a case where there is a hollow portion in which the first ratio d / s is equal to or greater than a predetermined value like a first point D1 shown in FIG. That is, the example shown in FIG. 5 corresponds to a configuration in which the first ratio d / s is “1.0” or more. As shown in FIG. 5, when the first ratio d / s is “1.0” or more, the amount of fluid leaking increases.

  FIG. 9 is an enlarged view showing a second comparative example. The illustrated example is different from the configuration shown in FIG. 3 in that the contact surface portion DEC has a hollow portion DE2 in which the first ratio d / s is “1.0” or more.

  When the first point D1 shown in FIG. 5, that is, the first ratio d / s is equal to or greater than “1.0”, the flow of the gas flowing into the turbine is different from the case shown in FIG. Become. Specifically, as shown in the drawing, in the second comparative example, the leakage flow FL flows greatly in the clockwise direction along the stationary portion and the fin FIN after being guided to the upper left by the recess portion DE2. Since the vortex WH21 is generated by being excited by the leakage flow FL, the vortex WH21 is a vortex that occupies a wide space up to the fin FIN inlet surrounded by the leakage flow FL. Therefore, the existence region of the vortex WH2 that causes the contraction effect generated near the second shroud SHD2 at the fin FIN entrance as shown in FIG. 3 is lost, and the vortex WH2 is not formed, so that the contraction effect is impaired. Therefore, the amount of fluid leaking increases as shown by the first point D1 in FIG.

  On the other hand, as shown in FIG. 3, the configuration of the recessed portion DE in which the first ratio d / s is in a predetermined range can reduce the leakage amount of the leaked fluid by the vortex WH2.

<Third comparative example>
FIG. 10 is an enlarged view showing a third comparative example.

  The third comparative example is for the purpose of devising the cross-sectional shape of the groove as disclosed in Japanese Patent Application Laid-Open No. 2012-137006, as shown in FIG. It is a configuration. In other words, a plurality of grooves provided in the circumferential direction are made shallower toward the outer diameter portion, and the depth of the groove is “0” at the outermost diameter portion, that is, aligned with no groove. This is a configuration for generating the separation vortex stably.

  In the third comparative example, a leakage flow having a strong circumferential flow velocity component is pushed back by a plurality of grooves provided in the circumferential direction and directed in the axial direction, so that the effect is d / s <1.0. A large groove, not a small groove, is required.

<Summary>
As described above, in the configuration having the recess portion DE of the present invention, the leakage flow FL varies depending on the value of the first ratio d / s. As shown in FIG. 3, when the first ratio d / s is larger than “0.0” and smaller than “1.0”, the inertia of the leakage flow FL is relatively small. After turning toward the upper left along the contact surface TA of the two shroud SHD2, it quickly turns clockwise. In such a flow, the angle formed between the leakage flow FL and the upper surface of the second shroud SHD2 is an obtuse angle rather than a right angle. Therefore, in the configuration as shown in FIG. 3, unlike the vortex WH12 as shown in FIG. 8, the vortex excited inside the leakage flow FL tends to be a vortex having a shape close to a “circle”.

  Since the leakage flow flows between the fin FIN and the vortex WH2, when the distance between the fin FIN and the vortex WH2 is smaller than the distance s between the fin FIN and the outer periphery of the shroud, the leakage amount is Although it is defined by the distance to the vortex WH2, when a vortex having such a shape is formed, the kinetic energy is less likely to be lost than the vortex WH12, and the vortex is stronger, so the vortex is less likely to be pushed back into the leakage flow FL. . Therefore, the distance between the vortex WH2 and the fin FIN is narrower than the width WD when the vortex WH12 is formed, and the amount of leakage can be effectively reduced.

  On the other hand, when the first ratio d / s is increased, the second comparative example is obtained. In the second comparative example, as shown in FIG. 9, the leakage flow FL is first directed from the depression DE to the upper left by the depression DE. Since the inertia of the leakage flow FL is large, it proceeds as it is until it hits the stationary part in the upper left direction in the figure, and then flows clockwise along the stationary part and the fin FIN, and then between the fin FIN and the second shroud SHD2. Fluid is leaked from the gap that can be made.

  In the second comparative example, the leaking flow FL excites a large weak vortex that occupies the fin inlet in the upper right space with respect to the upper left flow. Therefore, unlike the configuration shown in FIG. 3, in the second comparative example, a vortex that causes a contraction effect is unlikely to occur at a position close to the gap formed between the fin FIN and the second shroud SHD2. Therefore, the leakage amount of the second comparative example is defined by the distance between the fin FIN and the shroud, and since the flow path of the leakage flow FL is wider than the configuration shown in FIG. 3, the leakage amount of the leaking fluid is large. Become.

  Accordingly, when the first ratio d / s is set to a range greater than “0.0” and less than “1.0” as in the configuration shown in FIG. Can be reduced. Furthermore, it is desirable that the second ratio w / s is greater than 0.8 and less than 3.0. As shown in FIG. 5A, when the second ratio w / s is greater than 0.8 and less than 3.0, the amount of fluid leaking can be reduced.

<Modification>
FIG. 11 is a cross-sectional view showing a modification of the turbine in one embodiment of the present invention. As shown in the drawing, the turbine 10 preferably has a shroud having a stepped portion 11 having a plurality of shapes serving as the depressions DE.

  However, the shroud may have an uneven portion 12 as shown.

  As shown in the drawing, when the depressions DE are present at a plurality of locations, the effects shown in FIG. 3 are produced at each location. Therefore, if it is a shroud like illustration, the amount of leakage of the fluid which leaks can be decreased.

  Further, the shroud as shown in the figure has a shape that is easy to insert and can be easily manufactured as compared with the concavo-convex shroud such as a tool such as a cutting tool used for cutting.

  The shroud is more preferably a step type shroud like the third shroud SHD3 and the fourth shroud SHD4 shown in FIG. The step type shroud has an effect that it is easier to manufacture than other shapes.

  The shroud desirably has a plurality of shapes described in FIGS. Specifically, it is more desirable that the second and subsequent steps and irregularities from the upstream also have the shape described with reference to FIGS.

  The turbine may be a turbine that handles a fluid other than a liquid, such as a gas turbine, in addition to a steam turbine.

  The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the above-described embodiments, and various modifications or changes can be made within the scope of the gist of the present invention described in the claims. Is possible.

10 turbine TA contact surface part DE hollow part DR1 1st direction DR2 2nd direction EG end part OUR outer periphery

The present invention relates to a turbine .

To solve the above problems and achieve an object, according to an embodiment of the present invention, have a fin to the rotating portion or the stationary portion, and, in a turbine having a shroud the rotating part or stationary part facing the fin Is
The shroud configured with a cross-sectional shape with the rotation axis as the rotation center is,
A contact surface portion in contact with fluid flowing into the turbine;
Of the contact surface portions, the contact surface portion facing the upstream side in the axial direction of the turbine is formed with a depth d, and the cross-sectional shape is a part of the contact surface portion facing the upstream side in the axial direction of the turbine. A depression ,
Have,
The recessed portion is recessed upstream of the contact surface portion and downstream of the blade-side end .

Claims (6)

A turbine having fins in the rotating part or stationary part is a shroud in the rotating part or stationary part facing the fins,
A contact surface portion in contact with fluid flowing into the turbine;
Among the contact surface portions, a contact surface portion facing the upstream side in the axial direction of the turbine is formed with a depth d, and a depression portion is formed as a part of the contact surface portion facing the upstream side in the axial direction of the turbine. And
The depression is
Out of the fins that are installed on the outer periphery of the shroud and on the downstream side in the leakage flow direction with respect to the recessed portion and installed on the rotating portion or the stationary portion, the tip of the fin closest to the recessed portion If the distance is the first distance s,
A shroud in which a first ratio d / s, which is a ratio between the depth d and the first distance s, is greater than 0.0 and less than 1.0.   The shroud according to claim 1, wherein a step is formed on an outer periphery of the shroud in a direction in which the fluid flows.   The shroud according to claim 2, wherein the first ratio d / s is greater than 0.0 and less than 0.5.   The second ratio w / s, which is the ratio of the second distance w from the fin to the end of the contact surface portion and the first distance s, is greater than 0.8 and less than 3.0. The shroud according to 2.   A shroud having a plurality of shapes according to claim 1.   A turbine having the shroud according to any one of claims 1 to 5.

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