JP6986426B2 - Turbine - Google Patents

Description

The present invention relates to turbines.

A steam turbine comprises a rotor that rotates about an axis, multiple blades attached to the rotor, a casing that covers the rotor and blades from the outside, and multiple stationary blades that are attached to the inner surface of the casing. There is. Energy is added to the rotor blades by the inflow of high-temperature and high-pressure steam from one side in the axial direction, and the rotating shaft rotates. This rotational energy drives a generator or the like connected to the steam turbine.

Here, in a steam turbine as described above, in order to realize smooth rotation of the rotor, a certain clearance is generally provided between the tip of the rotor blade (shroud) and the inner peripheral surface of the casing. It is a target. However, since the steam flowing through the clearance flows away to the downstream side without colliding with the moving blades and the stationary blades, there is no contribution to the rotational drive of the rotor. In addition, the vapor flowing through the clearance contains a swirl component (velocity component in the circumferential direction). Such swirl components can cause non-uniform pressure distribution within the clearance, resulting in vibrations in the rotor. Therefore, a technique capable of reducing the swirl component is desired.

As an example of such a technique, for example, the apparatus described in Patent Document 1 below is known. Patent Document 1 describes a configuration in which a swirl prevention plate for blocking a swirl flow (swirl flow) is provided at the upstream end of the shroud cover.

Japanese Patent No. 5147885

However, in the configuration described in Patent Document 1, although the swirl component on the upstream side of the shroud cover can be reduced, steam leakage flows still in the clearance between the outer peripheral surface of the shroud cover and the inner peripheral surface of the casing. It will flow in. As a result, this leak flow may form a swirl flow again. That is, there is room for improvement in the apparatus described in Patent Document 1.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a turbine capable of suppressing shaft vibration by further reducing the swirl component.

According to the first aspect of the present invention, the turbine has a rotating shaft that rotates about an axis, a blade body extending radially outward from the rotating shaft, and a shroud provided at the tip of the blade body. A moving wing, a casing that surrounds the rotary shaft and the moving wing from the outer peripheral side, and a seal portion provided on the inner surface of the casing and facing the outer peripheral surface of the shroud are provided, and the outer peripheral surface of the shroud is provided. The seal portions are arranged from the upstream side of the facing seal facing region to the inside of the sealing facing region, and a plurality of groove portions extending toward the rear side in the rotation direction of the rotating shaft are formed from the upstream side to the downstream side. and a groove forming region, wherein is disposed on the downstream side of the groove forming region in the sealing face region, have a, a smooth region that forms a and a cylindrical surface shape centered on said axis, said smooth region in the sealing face region It has a guide groove forming region which is arranged on the downstream side and has a plurality of guide groove portions extending toward the rear side in the rotation direction of the rotation axis from the upstream side to the downstream side, and the seal portion is the casing. It has a honeycomb seal provided in a region of the inner surface facing the groove forming region and the smoothing region, and a seal fin provided in a region facing the induction groove forming region .

According to this configuration, the groove portion formed in the groove forming region can convert the fluid flowing from the upstream side. Here, the fluid flowing from the upstream side contains a swirl component that goes from the front side to the rear side in the rotation direction of the rotation axis from the upstream side to the downstream side. On the other hand, the groove portion extends from the front side in the rotation direction of the rotation shaft toward the rear side from the upstream side to the downstream side. Therefore, the swirl component that has flowed into the groove is guided by the groove and turned. As a result, the swirl component is reduced, and the bias of the pressure distribution on the outer peripheral surface of the shroud can be reduced.
Further, according to this configuration, an induction groove forming region is formed on the downstream side of the smooth region. This makes it possible to divert the fluid flowing from the upstream side through the smooth region. In particular, the guide groove portion extends from the front side to the rear side in the rotation direction of the rotation axis from the upstream side to the downstream side. Therefore, the fluid that has passed through the guide groove portion will flow along the flow of the fluid that flows on the blade body side. This makes it possible to reduce the mixing loss near the outlet of the rotor blade.
In addition, according to this configuration, a honeycomb seal is provided in the region of the inner surface of the casing facing the groove forming region and the smooth region, and a seal fin is provided in the region facing the guide groove forming region. .. Thereby, the swirl flow can be efficiently reduced in the region facing the groove forming region and the smooth region. On the other hand, in the region facing the guide groove forming region, the circumferential flow is generated in a direction different from the initial swirl flow by being turned by the groove portion on the upstream side. In the region facing the guide groove forming region, the seal fins are provided instead of the honeycomb seals, so that the circumferential flow flows toward the outlet of the rotor blade without being suppressed. As a result, the mixing loss near the outlet of the rotor blade can be positively reduced.

Further, a smooth region is formed on the downstream side of the groove forming region. As a result, the clearance between the outer peripheral surface of the shroud and the seal portion in the smooth region can be reduced. Therefore, the flow of fluid in the axial direction through the clearance can be reduced. Therefore, the performance of the turbine can be improved.

According to the second aspect of the present invention, the depth of the groove portion may be larger than the separation dimension between the seal portion and the outer peripheral surface of the shroud.

According to this configuration, since the depth of the groove portion is larger than the distance between the seal portion and the outer peripheral surface of the shroud, most of the fluid flowing from the upstream side is the outer peripheral surface of the seal portion and the shroud. It flows into the groove, not between. As a result, the leak flow can be reduced and the swirl component can be efficiently reduced by the groove portion.

According to the third aspect of the present invention, the depth of the groove may gradually decrease from the upstream side to the downstream side.

According to this configuration, the depth of the groove gradually decreases from the upstream side to the downstream side. That is, on the upstream side, the swirl component that has flowed into the groove is turned by being guided by the groove, so that reduction of the swirl component can be expected, and on the downstream side of the groove, the depth of the groove is constant as compared with the case where the depth is constant. Since the depth of the groove is shallow, the flow of fluid through the groove can be reduced. This makes it possible to further improve the performance of the turbine.

According to the fourth aspect of the present invention, the seal fins may extend from the inner surface of the casing toward the outer peripheral surface of the shroud, and a plurality of the seal fins may be arranged at intervals in the axial direction.

According to this configuration, the sealing performance as a sealing portion can be improved by using the sealing fins. In particular, since the plurality of seal fins are arranged at intervals in the axial direction, the leakage flow of the fluid in the axial direction can be further reduced.

According to the fifth aspect of the present invention, the honeycomb seal may be provided on the inner surface of the casing and may have a plurality of holes extending in the radial direction with respect to the axis.

According to this configuration, the sealing performance as a sealing portion can be improved by using the honeycomb seal. In particular, since the fluid can be efficiently captured by the plurality of holes formed in the honeycomb seal, the leakage flow of the fluid in the axial direction can be further reduced.

According to the sixth aspect of the present invention, the depth of the guide groove portion may be gradually increased from the upstream side to the downstream side.

According to this configuration, the depth of the guide groove portion gradually increases from the upstream side to the downstream side. That is, the possibility that the fluid stays in the guide groove can be reduced as compared with the case where the depth of the groove is constant. This makes it possible to further improve the performance of the turbine.

According to the seventh aspect of the present invention, the angle formed by the guide groove portion with respect to the axis line may be different from the angle formed by the groove portion with respect to the axis line when viewed in the radial direction with respect to the axis line.

According to this configuration, the angle formed by the groove portion and the guide groove portion with respect to the axis can be appropriately set according to the shape of the blade body and the direction of the swirl flow. This makes it possible to efficiently reduce the swirl flow.

According to the eighth aspect of the present invention, the seal portion faces the honeycomb seal provided in the region of the inner surface of the casing facing the groove forming region and the smooth region, and the guide groove forming region. It may have a seal fin provided in the area to be used.

According to this configuration, a honeycomb seal is provided in the region of the inner surface of the casing facing the groove forming region and the smooth region, and a seal fin is provided in the region facing the guide groove forming region. Thereby, the swirl flow can be efficiently reduced in the region facing the groove forming region and the smooth region. On the other hand, in the region facing the guide groove forming region, the circumferential flow is generated in a direction different from the initial swirl flow by being turned by the groove portion on the upstream side. In the region facing the guide groove forming region, the seal fins are provided instead of the honeycomb seals, so that the circumferential flow flows toward the outlet of the rotor blade without being suppressed. As a result, the mixing loss near the outlet of the rotor blade can be positively reduced.

According to the tenth aspect of the present invention, the turbine may have a rail portion provided in the smooth region, extending in the circumferential direction with respect to the axis line, and protruding from the smooth region toward the honeycomb seal. ..

According to this configuration, since the rail portion protrudes toward the honeycomb seal, the gap between the outer peripheral surface of the shroud and the honeycomb seal can be further reduced. This makes it possible to further reduce the leakage flow in the axial direction.

According to the present invention, it is possible to provide a turbine capable of suppressing shaft vibration by further reducing the swirl component.

It is a figure which shows the structure of the steam turbine which concerns on 1st Embodiment of this invention. It is an enlarged view of the main part of the steam turbine which concerns on 1st Embodiment of this invention. It is a figure which looked at the shroud which concerns on 1st Embodiment of this invention from the outside in the radial direction. It is an enlarged view of the main part of the steam turbine which concerns on the 2nd Embodiment of this invention. It is a figure which looked at the shroud which concerns on the 2nd Embodiment of this invention from the outside in the radial direction. It is an enlarged view of the main part of the steam turbine which concerns on the 3rd Embodiment of this invention. It is a figure which looked at the shroud which concerns on the 3rd Embodiment of this invention from the outside in the radial direction. It is an enlarged view of the main part of the steam turbine which concerns on 4th Embodiment of this invention. It is an enlarged view of the main part which shows the modification of the steam turbine which concerns on each embodiment of this invention.

[First Embodiment]
The first embodiment of the present invention will be described with reference to FIGS. 1 to 3. As shown in FIG. 1, the steam turbine 100 (turbine) according to the present embodiment has a rotary shaft 1 that rotates around an axis O, a plurality of blades 2 attached to the rotary shaft 1, a rotary shaft 1, and a moving blade. It includes a casing 3 that covers the blades 2 from the outer peripheral side, and a sealing portion 4 (see FIG. 2) provided on the inner peripheral surface (inner surface) of the casing 3.

The rotating shaft 1 has a columnar shape extending along the axis O. Of the entire region of the rotating shaft 1 in the axis O direction, the portion covered by the casing 3 has a larger diameter than the other portions. The shaft end of the rotating shaft 1 is supported by a journal bearing 5 and a thrust bearing 6. The journal bearing 5 supports a radial load on the axis O on the rotating shaft 1. The journal bearing 5 is provided at both ends of the rotary shaft 1 one by one. The thrust bearing 6 supports a load in the axis O direction on the rotating shaft 1. Only one thrust bearing 6 is provided on one side of the rotating shaft 1 in the O-direction of the axis.

A plurality of blade rows 20 are provided on the outer peripheral surface of the rotating shaft 1 at intervals in the axis O direction. Each blade row 20 has a plurality of blades 2 arranged in the circumferential direction with respect to the axis O. The rotor blade 2 projects radially outward from the platform 21 provided on the outer peripheral surface of the rotating shaft 1. The rotor blade 2 has a blade body 22 having a blade-shaped cross-sectional shape, and a rotor blade shroud 23 (shroud) attached to the tip (diametrically outer end) of the blade body 22.

The casing 3 has a substantially cylindrical shape centered on the axis O. A steam supply pipe 31 for taking in a working fluid (steam S) supplied from the outside is provided at one end of the casing 3 on one side in the axis O direction. A steam discharge pipe 32 for discharging steam S is provided at the end of the casing 3 on the other side in the axis O direction. In the following description, the side where the steam supply pipe 31 is located when viewed from the steam discharge pipe 32 is referred to as an upstream side, and the side where the steam discharge pipe 32 is located when viewed from the steam supply pipe 31 is referred to as a downstream side.

A plurality of stationary blade rows 33 are provided on the inner peripheral surface of the casing 3 at intervals in the axis O direction. The above-mentioned rotor blade rows 20 and stationary blade rows 33 are arranged alternately in the axis O direction. In other words, each rotor blade row 20 is arranged so as to be inserted between a pair of stationary blade rows 33 adjacent to each other. Each stationary blade row 33 has a plurality of stationary blades 34 arranged in the circumferential direction with respect to the axis O. Each stationary blade 34 has an airfoil cross section extending in a direction different from that of the moving blade 2. A stationary blade shroud 35 is provided at the radial inner end of the stationary blade 34.

Inside the casing 3, the region where the stationary blade 34 and the moving blade 2 are arranged forms the main flow path F1 through which the steam S flows. Further, a space is formed between the inner peripheral surface of the casing 3 and the rotor blade shroud 23, and this space is referred to as a cavity 50. The steam S is supplied to the steam turbine 100 configured as described above via the steam supply pipe 31 on the upstream side. After that, as the rotary shaft 1 rotates, it passes through the rows of the stationary blade 34 and the moving blade 2, and is eventually discharged toward the subsequent device (not shown) through the steam discharge pipe 32 on the downstream side. Here, when passing through the row of the stationary blade 34 and the moving blade 2, the steam S also flows into the above-mentioned cavity 50.

The seal portion 4 is provided to reduce the flow of steam flowing into the cavity 50. As shown in FIG. 2, the seal portion 4 according to the present embodiment is a plurality of seal fins 41 protruding inward in the radial direction from the inner peripheral surface of the casing 3. The seal fin 41 has a plate shape in which the plate surface faces the axis O direction. In the cavity 50, a plurality of seal fins 41 are arranged at intervals in the axis O direction. Each seal fin 41 faces the outer peripheral surface of the rotor blade shroud 23 with a slight gap (clearance). Of the outer peripheral surface of the rotor blade shroud 23, the region facing the seal fin 41 is defined as the seal facing region A1.

Next, the detailed configuration of the moving blade 2 according to the present embodiment will be described with reference to FIGS. 2 and 3. As shown in FIG. 2, the blade body 22 of the moving blade 2 is supported by a platform 21 provided on the outer peripheral surface of the rotating shaft 1. The blade body 22 is exposed on the above-mentioned main flow path F1. As shown in FIG. 3, the wing body 22 has a wing-shaped cross-sectional shape when viewed from the radial direction. The wing body 22 is curved in a curved surface so as to project toward the front side of the rotation direction R of the rotation axis 1 when viewed from the outside in the radial direction. More specifically, the portion including the end portion on the upstream side (leading edge 2L side) of the blade body 22 extends from the rear side in the rotation direction R of the rotation shaft 1 toward the front side from the upstream side to the downstream side. ing. On the other hand, the portion including the end portion on the downstream side (trailing edge 2T side) of the blade body 22 extends from the front side in the rotation direction R of the rotation axis 1 toward the rear side from the upstream side to the downstream side. ..

The rotor blade shroud 23 is attached to the radial outer end of the blade body 22. The rotor blade shroud 23 has, for example, a parallel quadrilateral shape when viewed from the outside in the radial direction. The rotor blade shroud 23 is housed in the cavity 50 described above. The cavity 50 has a substantially rectangular cross-sectional shape when viewed from the circumferential direction with respect to the axis O. The upstream surface (cavity upstream surface 51) in the cavity 50 faces the upstream surface (shroud upstream surface 231) of the rotor blade shroud 23 with a gap in the axis O direction. The radial outer surface (cavity bottom surface 52) in the cavity 50 faces the outer peripheral surface (shroud outer peripheral surface 232) of the rotor blade shroud 23 via the seal fin 41 described above. The downstream surface (cavity downstream surface 53) in the cavity 50 faces the downstream surface (shroud downstream surface 233) of the blade shroud 23 with a gap.

The shroud outer peripheral surface 232 has a groove forming region A2 and a smoothing region A3 arranged in order from the upstream side to the downstream side. As shown in FIG. 3, a plurality of groove portions 60 are formed in the groove forming region A2. The plurality of groove portions 60 are arranged at intervals in a direction orthogonal to the extending direction of the groove portions 60 themselves. The groove forming region A2 is arranged from the upstream end of the shroud outer peripheral surface 232 to the inside of the seal facing region A1. In FIG. 3, the dimension of the groove forming region A2 in the axis O direction is shown to be smaller than the dimension of the smooth region A3 in the axis O direction, but it may be larger than the dimension of the smooth region A3 in the axis O direction.

Each groove portion 60 is, for example, a square groove recessed inward in the radial direction from the outer peripheral surface of the shroud 232. The groove shape does not have to be a square groove, and the same effect can be obtained with a U-shaped groove or a V-shaped groove. Each groove portion 60 extends linearly from the front side to the rear side in the rotation direction R of the rotation axis 1 from the upstream side to the downstream side. The angle formed by the groove 60 with respect to the axis O is appropriately set within the range of 90 ° to 180 ° according to the flow direction of the swirl flow (described later) actually formed. In the present embodiment, the depth of the groove portion 60 (the dimension of the groove portion 60 in the radial direction with respect to the axis O) is constant from the upstream side to the downstream side. Further, the depth of the groove portion 60 is larger than the distance between the tip of the seal fin 41 (the end portion on the inner side in the radial direction) and the outer peripheral surface of the shroud 232.

A smooth region A3 is formed on the downstream side of the groove forming region A2. The smooth region A3 has a cylindrical surface shape centered on the axis O. No protrusions, steps, or the like are formed on the smooth region A3. The smooth region A3 forms a part of the seal facing region A1 by facing the seal fin 41 with a gap.

Next, the operation of the steam turbine 100 according to the present embodiment will be described. In driving the steam turbine 100, steam S is first supplied into the casing 3 from an external steam supply source (not shown) through the steam supply pipe 31 described above. The steam S supplied into the casing 3 alternately collides with the moving blades 2 and the stationary blades 34 while passing through the main flow path F1 to rotate the rotating shaft 1. The rotational energy of the rotating shaft 1 is taken out by a generator or the like (not shown) connected to the shaft end.

Here, a part of the steam S that has flowed into the casing 3 flows into the cavity 50 instead of the main flow path F1. Hereinafter, the steam flowing into the main flow path F1 is referred to as a main flow S1, and the steam flowing into the cavity 50 is referred to as a side flow S2. The side flow S2 that has flowed into the cavity 50 contains a swirl component (circumferential velocity component) that accompanies the rotation of the rotation shaft 1. Specifically, the side flow S2 flows from the rear side to the front side in the rotation direction R of the rotation axis 1 from the upstream side to the downstream side. When such a swirl component is predominant, the pressure distribution in the circumferential direction in the casing 3 becomes biased. Vibration may occur in the rotating shaft 1 due to the bias of the pressure distribution.

However, in the present embodiment, the groove forming region A2 is formed in the rotor blade shroud 23. As described above, the groove portion 60 of the groove forming region A2 extends from the front side to the rear side in the rotation direction R from the upstream side to the downstream side. That is, the groove portion 60 extends in a direction that cancels the swirl component in the sidestream S2. Therefore, the side flow S2 is turned by flowing into the groove portion 60, and flows from the front side to the rear side in the rotation direction R from the upstream side to the downstream side. As a result, the swirl component is reduced, and the possibility of vibration in the rotating shaft 1 is reduced. Further, the sidestream S2 converted by passing through the groove 60 heads toward the smoothing region A3 on the downstream side. The smoothing region A3 faces the plurality of seal fins 41. Therefore, the sidestream S2 is dammed by the seal fin 41. As a result, the flow rate itself of the side flow S2 is reduced, and the performance of the steam turbine 100 can be improved.

As described above, according to the above configuration, the groove portion 60 formed in the groove forming region A2 can convert the fluid flowing from the upstream side. Here, the fluid flowing from the upstream side contains a swirl component from the front side to the rear side in the rotation direction R of the rotation axis 1 from the upstream side to the downstream side. On the other hand, the groove portion 60 extends from the front side in the rotation direction of the rotation shaft 1 toward the rear side from the upstream side to the downstream side. Therefore, the swirl component that has flowed into the groove 60 is guided by the groove 60 and turned. As a result, the swirl component is reduced, and the bias of the pressure distribution on the outer peripheral surface of the shroud 232 can be reduced.

Further, a smooth region A3 is formed on the downstream side of the groove forming region A2. As a result, the clearance between the shroud outer peripheral surface 232 and the seal portion 4 in the smooth region A3 can be reduced. Therefore, the flow of fluid in the axis O direction through the clearance can be reduced. Therefore, the performance of the turbine can be improved.

In addition, according to the above configuration, since the depth of the groove portion 60 is larger than the separation dimension between the seal portion 4 and the shroud outer peripheral surface 232, most of the fluid flowing from the upstream side is sealed. It flows into the groove 60, not between the portion 4 and the shroud outer peripheral surface 232. As a result, the leakage flow can be reduced, and the swirl component can be efficiently reduced by the groove portion 60.

Furthermore, according to the above configuration, the sealing performance of the sealing portion 4 can be improved by using the sealing fin 41. In particular, since the plurality of seal fins 41 are arranged at intervals in the axis O direction, the side flow S2 of steam in the axis O direction can be further reduced.

The first embodiment of the present invention has been described above with reference to the drawings. It should be noted that various changes and modifications can be made to the above configuration as long as the gist of the present invention is not deviated.

[Second Embodiment]
Subsequently, the second embodiment of the present invention will be described with reference to FIGS. 4 and 5. The same components as those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. As shown in FIG. 4, in the present embodiment, the honeycomb seal 42 is provided as the seal portion 4 in place of the seal fin 41 described above. The honeycomb seal 42 is arranged along the bottom surface 52 of the cavity. The honeycomb seal 42 is a porous member having a plurality of holes extending in the radial direction with respect to the axis O. The honeycomb seal 42 is integrally formed of a material having relatively good machinability, such as ceramics.

Further, in the present embodiment, a rail portion 70 projecting from the smoothed area A3 toward the honeycomb seal 42 is provided on the smoothed area A3 on the outer peripheral surface of the shroud 232. The rail portion 70 has a substantially rectangular cross-sectional shape when viewed from the circumferential direction with respect to the axis O. As shown in FIG. 5, the rail portion 70 extends in the circumferential direction with respect to the axis O. The rail portion 70 is provided on the outer peripheral surface 232 of the shroud at a substantially central portion in the axis O direction. The radial outer surface (rail outer peripheral surface 71) of the rail portion 70 has no gap with respect to the radial inner surface (seal inner peripheral surface 421) of the honeycomb seal 42 in the state immediately after assembling the steam turbine 100. They are facing each other. When the steam turbine 100 is driven, the outer peripheral surface 71 of the rail portion and the inner peripheral surface 421 of the seal rub against each other, and the inner peripheral surface 421 of the seal is slightly scraped. That is, a minimum gap is formed between the outer peripheral surface 71 of the rail portion and the inner peripheral surface 421 of the seal as long as the rotation of the rotor blade shroud 23 (rotating shaft 1) is not hindered.

According to the above configuration, the sealing performance of the sealing portion 4 can be improved by using the honeycomb seal 42. In particular, since the side flow S2 can be efficiently captured by the plurality of holes formed in the honeycomb seal 42, the leakage flow of steam in the axis O direction can be further reduced.

Further, according to the above configuration, since the rail portion 70 projects toward the honeycomb seal 42, the gap between the outer peripheral surface of the shroud and the honeycomb seal 42 can be further reduced. As a result, the leakage flow in the axis O direction can be further reduced.

The second embodiment of the present invention has been described above with reference to the drawings. It should be noted that various changes and modifications can be made to the above configuration as long as the gist of the present invention is not deviated.

[Third Embodiment]
Next, the third embodiment of the present invention will be described with reference to FIGS. 6 and 7. The same components as those of the above embodiments are designated by the same reference numerals, and detailed description thereof will be omitted. As shown in FIG. 6, in the present embodiment, the guide groove forming region A4 is provided on the downstream side of the smooth region A3 described above. A plurality of guide groove portions 80 are formed in the guide groove forming region A4.

Each guide groove portion 80 is a square groove recessed inward in the radial direction from the outer peripheral surface of the shroud 232. The groove shape does not have to be a square groove, and the same effect can be obtained with a U-shaped groove or a V-shaped groove. As shown in FIG. 7, each guide groove portion 80 extends linearly from the front side to the rear side in the rotation direction R of the rotation axis 1 from the upstream side to the downstream side. The angle formed by the guide groove 80 with respect to the axis O is 90 ° to 180 depending on the outlet angle of the blade body 22 described above (that is, the angle formed by the trailing edge 2T of the blade body 22 with respect to the axis O). It is set appropriately within the range up to °. In other words, the angle formed by the guide groove 80 with respect to the axis O is substantially equal to the exit angle of the blade body 22 and substantially equal to the inlet angle of the subsequent stationary blade row 33. In particular, the angle formed by the guide groove 80 with respect to the axis O may be different from the angle formed by the groove 60 with respect to the axis O.

In the present embodiment, the depth of the guide groove portion 80 (the dimension of the groove portion 60 in the radial direction with respect to the axis O) is constant from the upstream side to the downstream side. Further, the depth of the guide groove portion 80 is larger than the distance between the tip of the seal fin 41 (the end portion on the inner side in the radial direction) and the outer peripheral surface of the shroud 232.

In the above configuration, the side flow S2 flowing from the upstream side to the downstream side along the smooth region A3 can be turned according to the extending direction of the guide groove portion 80. Specifically, the flow direction of the side flow S2 is substantially equal to the outlet angle of the blade body 22, and is substantially equal to the inlet angle of the subsequent stationary blade row 33. That is, the side flow S2 is turned in a direction substantially the same as the flow of steam flowing on the blade body 22 side (main flow S1).

As described above, according to the above configuration, the guide groove forming region A4 is formed on the downstream side of the smooth region A3. As a result, the fluid flowing from the upstream side through the smooth region A3 can be turned. In particular, the guide groove portion 80 extends from the front side in the rotation direction R of the rotation shaft 1 toward the rear side from the upstream side to the downstream side. Therefore, the fluid that has passed through the guide groove 80 will flow along the flow of steam (mainstream S1) that flows on the blade body 22 side. Thereby, the mixing loss in the vicinity of the outlet of the moving blade 2 can be reduced.

Further, according to the above configuration, the angle formed by the groove portion 60 and the guide groove portion 80 with respect to the axis O can be appropriately set according to the shape of the blade body 22 and the direction of the swirl flow. This makes it possible to efficiently reduce the swirl flow.

The third embodiment of the present invention has been described above with reference to the drawings. It should be noted that various changes and modifications can be made to the above configuration as long as the gist of the present invention is not deviated.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described with reference to FIG. The same components as those of the above embodiments are designated by the same reference numerals, and detailed description thereof will be omitted. As shown in FIG. 8, in the present embodiment, the rail portion 70 described above is provided on the smooth region A3, and a guide groove forming portion is provided on the downstream side of the smooth region A3. Further, the honeycomb seal 42 described above is provided on the bottom surface 52 of the cavity facing the groove forming region A2 and the smoothing region A3. On the other hand, a seal fin 41 is provided on the bottom surface 52 of the cavity facing the guide groove forming region A4.

According to this configuration, in the region facing the groove forming region A2 and the smoothing region A3, the swirl flow can be efficiently reduced by turning the side flow S2 by the groove portion 60. On the other hand, in the region facing the guide groove forming region A4, the circumferential flow is generated in a direction different from the initial swirl flow by being turned by the groove portion 60 on the upstream side. In the region facing the guide groove forming region A4, the seal fin 41 is provided instead of the honeycomb seal 42, so that the circumferential flow flows toward the outlet of the rotor blade 2. As a result, the mixing loss in the vicinity of the outlet of the rotor blade 2 can be positively reduced.

The embodiments of the present invention have been described above with reference to the drawings. It should be noted that various changes and modifications can be made to the above configuration as long as the gist of the present invention is not deviated. For example, in each of the above embodiments, the configuration in which the groove portion 60 and the guide groove portion 80 have a constant depth over the entire area in the axis O direction has been described as an example. However, the aspect of the groove portion 60 and the guide groove portion 80 is not limited to the above, and the configuration shown in FIG. 9 can be adopted. In the example of FIG. 9, the depth of the groove portion 60 gradually decreases from the upstream side to the downstream side. Further, the depth of the guide groove portion 80 gradually increases from the upstream side to the downstream side. According to this configuration, it is possible to reduce the possibility that the fluid stays in the groove portion 60 and the guide groove portion 80 as compared with the case where the depth of the groove portion 60 is constant. This makes it possible to further improve the performance of the turbine.

In addition, in each of the above embodiments, the configuration has been described by taking the moving blade 2 of the steam turbine 100 as an example. However, the application target of the present invention is not limited to the steam turbine 100, and the present invention can also be applied to the turbine portion of the gas turbine.

The groove portion 60 and the guide groove portion 80 (groove forming region A2 and guide groove forming region A4) are the most downstream rotor blade rows 20 among all the rotor blade rows 20 provided on the rotary shaft 1. It is desirable to apply it to the rotor blade row 20 excluding. As each rotor blade 2 works to divert the sidestream S2, the efficiency of each rotor blade 2 stage is slightly reduced, but according to such a configuration, the heat drop is caused by the final stage rotor blade 2. Since it can be recovered, it is possible to minimize the decrease in efficiency of the steam turbine 100 as a whole.

1 ... Rotating shaft 2 ... Moving blade 2L ... Front edge 2T ... Trailing edge 3 ... Casing 4 ... Seal part 5 ... Journal bearing 6 ... Thrust bearing 20 ... Moving blade row 21 ... Platform 22 ... Wing body 23 ... Moving blade shroud 31 ... Steam supply pipe 32 ... Steam discharge pipe 33 ... Static blade row 34 ... Static blade 35 ... Static blade shroud 41 ... Seal fin 42 ... Honeycomb seal 50 ... Cavity 51 ... Cavity upstream surface 52 ... Cavity bottom surface 53 ... Cavity downstream surface 60 ... Groove 70 ... Rail portion 71 ... Rail portion outer peripheral surface 80 ... Induction groove portion 100 ... Steam turbine 231 ... Shroud upstream surface 232 ... Shroud outer peripheral surface 233 ... Shroud downstream surface 421 ... Seal inner peripheral surface A1 ... Seal facing region A2 ... Groove forming region A3 ... Smooth region A4 ... Induction groove forming region F1 ... Main flow path O ... Axis line

Claims (8)

A rotating shaft that rotates around the axis, and
A blade body extending radially outward from the rotation axis, and a moving blade having a shroud provided at the tip of the blade body,
A casing that surrounds the rotating shaft and the moving blade from the outer peripheral side,
A sealing portion provided on the inner surface of the casing and facing the outer peripheral surface of the shroud,
Equipped with
The outer peripheral surface of the shroud
The seal portions are arranged from the upstream side of the facing seal facing region to the inside of the sealing facing region, and a plurality of groove portions extending toward the rear side in the rotation direction of the rotating shaft are formed from the upstream side to the downstream side. Groove formation area and
A smooth region having a cylindrical surface shape centered on the axis, which is arranged on the downstream side of the groove forming region in the seal facing region,
Have,
Yes said arranged downstream of the smoothing region in the seal face region, guide grooves formed region in which a plurality of induction groove is formed extending toward the rotation direction rear side of the rotary shaft according to buy direction from the upstream side to the downstream side death,
The seal portion is a turbine having a honeycomb seal provided in a region of the inner surface of the casing facing the groove forming region and the smoothing region, and a seal fin provided in a region facing the guide groove forming region. .. The turbine according to claim 1, wherein the depth of the groove portion is larger than the separation dimension between the seal portion and the outer peripheral surface of the shroud. The turbine according to claim 1 or 2, wherein the depth of the groove gradually decreases from the upstream side to the downstream side. The turbine according to any one of claims 1 to 3, wherein the seal fins extend from the inner surface of the casing toward the outer peripheral surface of the shroud, and a plurality of the seal fins are arranged at intervals in the axial direction. The turbine according to any one of claims 1 to 3, wherein the honeycomb seal is provided on the inner surface of the casing and has a plurality of holes extending in the radial direction with respect to the axis. The turbine according to any one of claims 1 to 5, wherein the depth of the guide groove portion gradually increases from the upstream side to the downstream side. The turbine according to any one of claims 1 to 6, wherein the angle formed by the guide groove with respect to the axis when viewed from the radial direction with respect to the axis is different from the angle formed by the groove with respect to the axis. .. The turbine according to any one of claims 1 to 7, which is provided in the smooth region, extends in the circumferential direction with respect to the axis, and has a rail portion protruding from the smooth region toward the honeycomb seal.

Images