JP5494972B2 - Axial-flow turbomachine and its modification method - Google Patents

Description

  The present invention relates to a stationary blade structure of an axial flow turbomachine.

  An axial-flow turbomachine has a paragraph structure consisting of a stationary blade and a moving blade disposed downstream of the stationary blade in the working fluid flow direction.

  Generally, on the downstream side of a stationary blade of an axial-flow turbomachine, the flow characteristics such as the flow velocity of the working fluid are different between the portion where the stationary blade is present and the portion where the stationary blade is not present, and the portion where the stationary blade is present upstream. The flow is called wake. Since the rotating rotor blade arranged downstream of the stationary blade repeatedly passes through the wake, the stationary blade wake frequency (Nozzle Passing) represented by the product of the rotational frequency of the moving blade and the number of stationary blades. It is vibrated by a fluid exciting force of Frequency (hereinafter NPF). When the stationary blade wake frequency and the natural frequency of the moving blade coincide with each other, excessive fluctuation stress is generated in the moving blade due to resonance, and the moving blade may be fatigued. Conventionally, in order to prevent the fatigue failure of the moving blade, a design is made to detune the stationary blade wake frequency at the rated rotational speed and the natural frequency of the moving blade.

  However, in an axial flow turbomachine that employs a multi-paragraph structure, moving blades with different blade lengths are adopted from the first stage to the last stage of the stage, and therefore it is very difficult to design a detuned natural frequency for all moving blades. Not only is it time consuming, but the number of stationary blades is limited, which is an issue when designing a paragraph.

  As a prior art in this technical field, there is JP-A-2001-27103 (Patent Document 1). This publication discloses a turbomachine having a half blade that hangs from the outer periphery toward the axial centerline side in the middle of each stationary blade at the outlet of a stationary blade row installed upstream of the moving blade row of the axial flow turbomachine. A stationary blade structure is described.

  Moreover, there exists Unexamined-Japanese-Patent No. 2004-1000055 (patent document 2). This publication has a rotating shaft extending from the outer end face of each stationary blade and an arm extending laterally from the rotating shaft, and each arm is rotated by a link to change the mounting angle of each stationary blade. A stationary blade structure of a rotating machine is described.

JP 2001-27103 A Japanese Patent Laid-Open No. 2004-1000055

  As described above, Patent Document 1 discloses a half blade that hangs down from the outer periphery toward the axial center line between each stationary blade at the outlet of the stationary blade row installed upstream of the moving blade row of the axial flow turbomachine. The stationary blade structure of the turbomachine provided is described.

  However, in the stationary blade structure of Patent Document 1, for example, when a circumferentially curved stationary blade employed in a steam turbine or the like is targeted, a half blade that hangs down from the outer periphery toward the axial centerline side is used. With the structure used, the distance between the vane blade surface and the half vane is shortened on the tip side of the half vane, and the wake of the half vane and the wake of the vane add to each other, resulting in a large excitation force acting on the rotor blade. There is a possibility.

  Patent Document 1 describes that the blade width of the half blade is preferably 1/3 to 1/2. For example, an axial-flow turbomachine in which a stationary blade throat portion such as a steam turbine is located near the blade trailing edge. Then, if the blade width of the half blade is 1/3 to 1/2, the half blade overlaps the stationary blade throat, making it difficult to demonstrate the original performance of the stationary blade, such as accelerating the working fluid. May be reduced.

  Furthermore, in FIG. 1 of Patent Document 1, since the half blade does not have a shape along the stationary blade chord line, the stationary blade outflow angle determined by the design of the stationary blade alone is maintained by installing the half blade. It may not be possible.

  Patent Document 2 describes that a stationary blade structure of a rotating machine that can easily change and adjust an asymmetric stationary blade structure that reduces cascade interference excitation force with a simple configuration is described.

  However, in the embodiment shown in Patent Document 2, since the flap that rotationally drives the arm by the link is used, for example, when using a stationary blade that is curved in the circumferential direction that is employed in a steam turbine or the like, In the flap structure that rotates around the rotation axis, there is a possibility that a curved flap cannot be used.

  For this reason, when the flap structure that rotates about the rotation axis described in Patent Document 2 is applied to a curved stationary blade, there is a region where the distance between the flap and the stationary blade surface is shortened, There is a possibility that the excitation force acting on the moving blades will increase due to the addition of the flow and the wake of the stationary blade.

  Furthermore, in FIG. 5 of Patent Document 2, the flap overlaps the stationary blade throat portion, and the inherent performance of the stationary blade, such as accelerating the working fluid, cannot be exhibited, and the efficiency may be reduced. .

  When additional structures such as half blades or flaps are added to the stationary blade row, it is necessary to consider the relative relationship between the structure and the shape and installation position of the stationary blade so as not to impair the original performance of the stationary blade. However, this point is not taken into consideration in the above prior art.

  Accordingly, an object of the present invention is to provide an axial-flow turbomachine that can reduce the excitation force acting on the moving blade with the primary component of the stationary blade wake frequency with a simple structure while suppressing a decrease in efficiency. .

  In order to solve the above-described problems, the present invention provides an axial flow turbomachine having a paragraph structure in which a stationary blade row and a moving blade row are combined, and the stationary blades constituting the stationary blade row installed on the upstream side of the moving blade row. A wake-forming object is installed in between, and the wake-forming object has a cross section at each position in the turbine radial direction that is downstream from the narrowest stationary blade throat in the working fluid flow path formed between the stationary blades. The cross-sectional shape of the wake forming object at each position in the radial direction of the turbine is set so as to be positioned upstream of the leading edge line of the moving blade row installed downstream of the stationary blade row. It is characterized by a streamline shape along the vane chord parallel line parallel to the chord line of the vane cross section at the same position.

  According to the present invention, the performance of accelerating the original working fluid of a stationary blade by installing a simple structure without making a significant change in the stationary blade structure and the stationary blade outflow angle determined at the time of designing the stationary blade alone Thus, the reduction in efficiency can be suppressed, and the exciting force at the primary component of the stationary blade wake frequency acting on the moving blade installed downstream of the stationary blade row can be reduced.

It is an example of the paragraph structure of a steam turbine. It is an example of the stationary blade row structure of a general steam turbine. It is an Example (Example 1) which applied this invention to the radial direction whole cross section of a stationary blade. It is sectional drawing which showed the example (Example 1) of the stationary blade row | line | column structure of the steam turbine which concerns on this invention. It is the example which compared the fluctuation speed distribution in the stationary blade downstream of this invention and the conventional stationary blade structure. It is the example which showed the fluctuation speed distribution in the downstream of a stationary blade with respect to the magnitude | size of a wake formation body. It is the Example (Example 2) which applied this invention only to the front-end | tip vicinity of a stationary blade. It is the Example (Example 3) which applied this invention to the curved stationary blade. It is the Example (Example 4) which changed the magnitude | size of the wake formation object in each cross section of radial direction. It is an Example (Example 5) at the time of making a wake formation object into a circular shape.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, although the Example described below is an example which applied this invention to the steam turbine as an example of an axial-flow turbomachine, this invention is applicable not only to a steam turbine but to a gas turbine.

  A first embodiment of the present invention will be described. First, an example of a steam turbine to which the present invention is applied will be described.

FIG. 1 is an example of a paragraph structure of a steam turbine that is an example of an axial-flow turbomachine.
In FIG. 1, 1 is a diaphragm inner ring, 2 is a diaphragm outer ring, 3 is a stationary blade row, 4 is a moving blade row, 5 is a rotor, 6 is a casing, 7 is a shroud cover, and an arrow indicated by 20 is a steam that is a working fluid. The flow direction of each is shown.

  The stationary blade row 3 is formed by fixing a plurality of stationary blades in the circumferential direction between the diaphragm inner ring 1 and the diaphragm outer ring 2 assembled in an annular shape. The moving blade row 4 is formed by fixing a plurality of moving blades in the circumferential direction on the disk portion of the rotor 5 which is a rotating body. The outer peripheral side of the moving blade row 4 is generally connected and fixed by a shroud cover 7.

  The stage structure of the steam turbine includes a stationary blade row 3 that forms an annular flow path between a diaphragm inner ring 1 and a diaphragm outer ring 2, and a moving blade row 4 that is installed downstream of the stationary blade row 3 in the flow direction of the working fluid 20. Are combined one by one to form one paragraph. A general steam turbine has a multi-stage structure in which a plurality of stages in which the stationary blade row 3 and the moving blade row 4 are combined are provided in the turbine axial direction. The number of paragraphs is determined by design conditions.

  FIG. 2 is a diagram illustrating an example of a stationary blade row structure of a general steam turbine. FIG. 2 shows a space between one stationary blade among a plurality of stationary blades formed by the stationary blades 8 constituting the stationary blade row 3, and an annular ring formed by the diaphragm inner ring 1 and the diaphragm outer ring 2. The stator blade row 3 is configured by arranging a predetermined number of stator blades 8 over the entire circumference of 360 °.

  As shown in FIG. 2, the stationary blade row structure of the steam turbine has a structure in which the stationary blade 8 is fixed to the diaphragm inner ring 1 and the diaphragm outer ring 2, and is therefore adjacent to the diaphragm outer ring 2 from the diaphragm inner ring 1. The distance between the blades of the stationary blade 8 is increased.

  Here, as the role of the stationary blade 8, it plays the role of accelerating the inflowing working fluid 20. The energy of the working fluid 20 accelerated by the stationary blade 8 is converted into rotational energy by the moving blade row 4, and the rotor 5. Rotate. The rotor 5 is connected to a generator (not shown), and generates electricity by the rotation of the rotor 5.

  In a stationary blade structure of a general axial-flow turbomachine, including a steam turbine, specified by the throat / pitch at each section in the turbine radial direction according to the shape and design conditions of the moving blade installed downstream of the stationary blade 8 The stationary blade outflow angle is determined. Therefore, for example, the vane chord line 10 in each section in the turbine radial direction cross section on the diaphragm inner ring 1 side, the intermediate cross section, and the diaphragm outer ring 2 side shown in FIG.

Next, the stationary blade row structure of the steam turbine according to the present embodiment will be described.
FIG. 3 is a diagram showing the stationary blade row structure of the present embodiment. FIG. 3 shows a space between one stationary blade among a plurality of stationary blades formed by each stationary blade 8 constituting the stationary blade row 3, and an annular ring formed by the diaphragm inner ring 1 and the diaphragm outer ring 2. The stator blade row 3 is configured by arranging a predetermined number of stator blades 8 over the entire circumference of 360 °.

  In FIG. 3, a wake forming object 11 is installed between the stationary blades 8 constituting the stationary blade row 3 that forms an annular flow path between the diaphragm inner ring 1 and the diaphragm outer ring 2. The wake forming object 11 has a both-ends support structure in which ends in the turbine radial direction are fixed to the diaphragm inner ring 1 and the diaphragm outer ring 2.

  FIG. 4 is a cross-sectional view of a stage structure in which the stationary blade row 3 and the moving blade row 4 are combined at a certain position in the turbine radial direction when the wake forming object 11 shown in FIG. 3 is installed between the stationary blades. FIG.

  The cross-sectional view shown in FIG. 4 is applied over the entire circumference 360 ° of the stationary blade row 3 forming an annular flow path between the diaphragm inner ring 1 and the diaphragm outer ring 2, and the stationary blade structure shown in FIG. In the above, the present invention is applied to each section in the turbine radial direction where the wake forming object 11 is installed.

  In this embodiment, the installation position of the wake forming object 11 in the flow direction of the working fluid 20 is downstream of the stationary blade throat portion 12, which is the narrowest portion of the working fluid flow path formed between the stationary blades 8. In addition, it is located upstream of the moving blade row leading edge line 13 of each moving blade 9 constituting the moving blade row 4.

  For example, in an axial flow turbomachine that accelerates the working fluid with the stationary blade throat portion 12 such as a steam turbine, if the wake forming object 11 is installed in the stationary blade throat portion 12, The area changes from the design value, and the original role of the stationary blade, such as accelerating the working fluid, may be hindered, and the turbine efficiency may be reduced.

  In this embodiment, the wake forming object 11 is installed downstream of the stationary blade throat portion 12 and upstream of the moving blade row leading edge line 13 of each moving blade 9 constituting the moving blade row 4. The acceleration of the working fluid is not hindered, and the decrease in turbine efficiency can be suppressed.

  Further, the shape of the wake forming object 11 is a cross section at each position in the turbine radial direction, and the stationary blades at the same position in the turbine radial direction of the stationary blade 8 that forms a flow path between the stationary blades where the wake forming object 11 is installed. It is necessary to make the streamline shape along the stationary blade chord parallel line 14 parallel to the chord line 10.

  The reason for this is that the stationary blade outflow angle of the axial flow turbomachine is determined by the shape of the stationary blade chord line 10 of the stationary blade 8 on the downstream side from the vicinity of the stationary blade throat portion 12. If an object having a shape different from the shape along the stationary blade chord line 10 is installed, the working fluid 20 flows out at an angle different from the stationary blade outflow angle determined in the stationary blade single unit design, and the turbine efficiency decreases. It is because it will do.

  In the present embodiment, the wake forming object 11 is formed in a streamline shape along a stationary blade chord parallel line 14 parallel to the stationary blade chord line 10 at a cross section at each position in the turbine radial direction. It is possible to maintain the determined stationary blade outflow angle of the working fluid, and to suppress a decrease in turbine efficiency.

  In this embodiment, as shown in FIG. 4, one wake forming object 11 is installed between each stationary blade 8, and the circumferential installation position of the wake forming object 11 is between each stationary blade 8. It is desirable to be installed in the middle part.

  This is because the wake forming object 11 is installed in the middle portion of each stationary blade 8, and the phase of the speed fluctuation period due to the wake of the stationary blade 8 and the speed fluctuation period due to the wake of the wake forming object 11 This is because is reversed.

  When the wake forming object 11 is installed in the middle part of each stationary blade 8 and the phase of fluctuation of the speed due to the wake is reversed, the wake forming object is smaller than the case where it is installed in a place other than the intermediate part. This is because the fluctuation width of the wake velocity with the primary component of the stationary blade wake frequency in the object 11 can be reduced, and the friction loss due to the size of the wake forming object 11 can be further reduced.

  However, the installation position in the circumferential direction of the wake forming object 11 is not necessarily limited to being installed in the intermediate portion, and even when the wake forming object 11 is installed in a position other than the intermediate portion, the wake velocity fluctuation with the primary component of the stationary blade wake frequency. The width can be reduced. Therefore, if the wake forming object 11 and the stationary blade surface are kept at a predetermined distance so that the wake of the stationary blade 8 and the wake forming object 11 do not overlap, they can be installed at a place other than the middle part. good.

  Further, the number of the wake forming objects 11 may be set between the stationary blades as long as the wake of the stationary blade 8 and the wake of the wake forming object 11 do not overlap. The reason for this is that if the wake of the stationary blade 8 and the wake of the wake forming object 11 overlap, the fluctuation speed on the downstream side of the stationary blade increases due to the superposition of both of the wakes. This is because the excitation force acting on the moving blade 9 is increased.

  Furthermore, the wake forming object 11 does not necessarily need to be installed between all the stationary blades. For example, even if the wake forming object 11 is installed between every two stationary blades, the excitation force acting on the moving blades can be reduced.

  Next, the effect of the present embodiment will be described. FIG. 5 shows the fluctuation velocity distribution of the stationary blade 8 alone, the fluctuation velocity distribution of the wake forming object 11 alone, and the wake forming object 11 between the stationary blades 8 at the downstream position of the stationary blade in this embodiment. It is the example which compared the fluctuation speed distribution in this execution example where this is installed. The fluctuation speed indicates only the primary component of the stationary blade wake frequency. In addition, the maximum value of the fluctuation speed of the stationary vane 8 alone is set to 1 to make it dimensionless.

  From FIG. 5, the wake velocity fluctuation cycle of the wake forming object 11 alone and the wake velocity fluctuation cycle of the stationary blade 8 alone are in opposite phases, so that the wake flow is formed between the stationary blades 8. It can be seen that the amplitude of the fluctuation speed in this embodiment in which the object 11 is installed becomes small.

  Here, the smaller the speed fluctuation width downstream of the stationary blade row 3, the smaller the excitation force acting on the moving blade 9 installed on the downstream side of the stationary blade row 3, so that this embodiment acts on the moving blade. The excitation force can be reduced.

  Furthermore, the effect of the present embodiment will be added. FIG. 6 shows the stationary blade wake frequency primary component of the changing speed at the downstream side position of the stationary blade 8 when the strength of the wake generated from the wake forming object 11 is changed. The horizontal axis in the figure indicates the ratio of the wake strength of the wake forming object 11 to the wake strength of the stationary blade 8. The wake strength described here is the width and depth of the velocity deficit region of the wake.

  From FIG. 6, it can be confirmed that the velocity fluctuation value decreases as the wake strength of the wake forming object 11 approaches the stationary blade. Therefore, it is desirable that the wake forming object 11 has the same wake strength as the wake strength of the wake forming object 11 and the wake strength of the stationary blade 8. It is determined from the viewpoint of an increase in friction loss due to an increase in the size of the wake forming object 11 and a desire to reduce the excitation force acting on the rotor blade.

  According to the present embodiment, by installing a wake forming object between the stationary blades, the design value of the stationary blade outflow angle is maintained without impairing the performance of accelerating the working fluid that is the original role of the stationary blade. There is an effect that it is possible to reduce the excitation force at the primary component of the stationary blade wake frequency acting on the moving blade while minimizing the decrease in turbine efficiency.

  Further, in this embodiment, the wake forming object 11 has a both-ends support structure, so that the stationary blade wake frequency primary component acting on the moving blade in all cross sections from the moving blade root portion to the moving blade tip portion is obtained. Since the excitation force can be reduced, there is an advantage that resonance in a vibration mode in which the excitation force of the entire moving blade is a problem can be avoided.

  Moreover, since the shape of the cross section of the wake forming object 11 at each position in the turbine radial direction is a streamline shape along the stationary blade chord parallel line 14, for example, the stationary blade shape or attachment of each section in the turbine radial direction Even when the angles are different, the wake forming object 11 can be installed while maintaining the stationary blade outflow angle determined by the design in each cross section.

  Next, a second embodiment of the present invention will be described. FIG. 7 is a view showing the stationary blade structure of the present embodiment in which the stationary blade structure shown in the first embodiment is applied only to the vicinity of the stationary blade tip on the outer peripheral side in the turbine radial direction. FIG. 7 shows a space between one stationary blade among a plurality of stationary blades formed by each stationary blade 8 constituting the stationary blade row 3, and a circle formed by the diaphragm inner ring 1 and the diaphragm outer ring 2. The stator blade row 3 is configured by arranging a predetermined number of stator blades 8 over the entire 360 ° circumference of the ring.

  Here, the same components as those described in the first embodiment are denoted by the same reference numerals, description thereof is omitted, and portions different from those in the first embodiment are mainly described.

  In FIG. 7, a wake forming object 11 is installed between the stationary blades 8 constituting the stationary blade row 3 that forms an annular flow path between the diaphragm inner ring 1 and the diaphragm outer ring 2. One end of the wake forming object 11 in the turbine radial direction is fixed to the diaphragm outer ring 2, and the non-fixed end extends from the diaphragm outer ring 2 toward the diaphragm inner ring 1 into the flow path formed by each stationary blade 8. It has a cantilever support structure.

  By adopting a cantilever support structure fixed to the diaphragm outer ring 2, the excitation force in the primary component of the stationary blade wake frequency acting near the tip of the moving blade can be reduced, so the excitation force near the tip of the moving blade becomes a problem. There is an advantage that resonance in the vibration mode can be avoided.

  Here, as described in the first embodiment, the cross-sectional shape of the wake forming object 11 at each position in the turbine radial direction is parallel to the stationary blade chord parallel to the chord line of the stationary blade section at the same position in the turbine radial direction. It has a streamline shape along the line 14. Therefore, for example, even when the shape or mounting angle of the stationary blade cross section at each position in the turbine radial direction is different, the wake forming object 11 can be installed while maintaining the stationary blade outflow angle design value of each turbine radial direction cross section. .

  Furthermore, as described in the first embodiment, the installation position of the cross section at each position in the turbine radial direction of the wake forming object 11 in FIG. 7 is the narrowest portion of the working fluid flow path formed by each stationary blade 8. It must be installed downstream of the stationary blade throat portion 12 in the working fluid flow direction and upstream of the moving blade row leading edge line 13 of each moving blade 9 constituting the moving blade row 4 in the working fluid flow direction. .

  Further, as described in the first embodiment, the installation position of the wake forming object 11 in the turbine circumferential direction is preferably an intermediate portion between the stationary blades 8 in each section in the turbine radial direction. As long as the wake forming object 11 and the stationary blade surface are kept at a predetermined distance so that the wake and the wake forming object 11 do not overlap with each other, the intermediate part is not necessarily required.

  Furthermore, as described in the first embodiment, the number of the wake forming objects 11 may be set between the stationary blades as long as the wake of the stationary blade 8 and the wake forming object 11 do not overlap. May be installed.

  Further, as described in the first embodiment, the wake forming object 11 is not necessarily installed between all the stationary blades. For example, even if the wake forming object 11 is installed between every two stationary blades, the exciting force acting on the moving blades Can be reduced.

  According to the present embodiment, as in the first embodiment, the reduction in turbine efficiency is minimized while maintaining the design value of the stationary blade outflow angle without impairing the performance of accelerating the working fluid, which is the original role of the stationary blade. There is an effect that the excitation force in the primary component of the stationary blade wake frequency acting on the tip portion of the moving blade can be reduced.

  In FIG. 7 of the present embodiment, the stationary blade structure is applied when the excitation force near the tip of the moving blade becomes a problem. For example, when the excitation force near the root of the moving blade becomes a problem, , The wake forming object 11 is fixed to the diaphragm inner ring 1, and the unfixed end is slid into a cantilever support structure that extends from the diaphragm inner ring 1 toward the diaphragm outer ring 2 into the flow path formed by each stationary blade 8. Thus, the excitation force acting on the rotor blade root can be reduced, and the same effect as in this embodiment can be obtained.

  In addition, the structure of the present embodiment can reduce the area of the wake forming object 11, reduce the loss caused by the wake forming object 11 itself, and can be manufactured at a lower cost than the dual support structure. Can do.

Next, a third embodiment of the present invention will be described.
FIG. 8 is a diagram showing an embodiment in which the present invention is applied to a stationary blade structure having a stationary blade curved in the circumferential direction. FIG. 8 shows a space between one stationary blade among a plurality of stationary blades formed by the stationary blades 8 constituting the stationary blade row 3, and an annular ring formed by the diaphragm inner ring 1 and the diaphragm outer ring 2. The stator blade row 3 is configured by arranging a predetermined number of stator blades 8 over the entire circumference of 360 °.

  Here, the same components as those described in the first embodiment are denoted by the same reference numerals, description thereof is omitted, and portions different from those in the first embodiment are mainly described.

  In FIG. 8, a wake forming object 11 is installed between the stationary blades 8 constituting the stationary blade row 3 that forms an annular flow path between the diaphragm inner ring 1 and the diaphragm outer ring 2. The wake forming object 11 has a both-ends support structure in which ends in the turbine radial direction are fixed to the diaphragm inner ring 1 and the diaphragm outer ring 2.

  As described in the first embodiment, the cross-sectional shape of the wake forming object 11 at each position in the turbine radial direction is a stationary blade chord parallel line 14 parallel to the chord line of the stationary blade section at the same position in the turbine radial direction. It has a streamline shape along. Therefore, for example, because the stationary blade is curved in the circumferential direction, the shape of the trailing edge line of the wake-forming object can be The wake forming object 11 can be installed while maintaining the stationary blade outflow angle determined by the design in each cross section in the radial direction.

  In the example of FIG. 8, the trailing edge line of the stationary blade is curved in a convex shape in the circumferential direction. Therefore, the stationary blade shape and the mounting angle of the cross section at each position in the turbine radial direction are different. On the other hand, the wake forming object 11 has a cross-sectional shape at each position in the turbine radial direction, a streamline shape along a stationary blade chord parallel line 14 parallel to the chord line of the cross section of the stationary blade at the same position in the turbine radial direction. Is formed. Therefore, the wake forming object 11 also has a shape curved in a convex shape in the circumferential direction in accordance with the trailing edge line of the stationary blade 8, and the trailing edge line of the wake forming object 11 is substantially the same as the trailing edge line of the stationary blade 8. It can be a shape. Therefore, the stationary blade outflow angle determined by the design in each cross section in the radial direction can be maintained.

  Here, as described in the first embodiment, the installation position of the cross section of the wake forming object 11 in FIG. 8 at each position in the turbine radial direction is the narrowest portion of the flow path formed by each stationary blade 8. It must be installed downstream of the throat portion 12 and upstream of the moving blade row leading edge line 13 of each moving blade 9 constituting the moving blade row 4.

  Further, as described in the first embodiment, the installation position of the wake forming object 11 in the turbine circumferential direction is preferably an intermediate portion between the stationary blades 8 of each cross section in the radial direction. There is no. For example, in the case of the curved stationary blade shown in FIG. 8, the wake forming object 11 is curved so as to have a shape close to the trailing edge line of the stationary blade 8, and the circumferential installation position is set in each radial section. If the wake forming object 11 and the stationary blade surface are arranged so as to maintain a predetermined distance with different shapes, the wake of the stationary blade 8 and the wake forming object 11 do not overlap. Therefore, it is possible to prevent an increase in fluctuation speed in the wake of the stationary blade due to the superposition of the blades, and to reduce the excitation force acting on the moving blade.

  Furthermore, as described in the first embodiment, the number of the wake forming objects 11 may be set between the stationary blades as long as the wake of the stationary blade 8 and the wake forming object 11 do not overlap. May be installed.

  Further, as described in the first embodiment, the wake forming object 11 is not necessarily installed between all the stationary blades. For example, even if the wake forming object 11 is installed between every two stationary blades, the exciting force acting on the moving blades Can be reduced.

  According to the present embodiment, in addition to the effects of the first embodiment, even when the shape of the stationary blade is a complicated shape, the wake of the stationary blade and the wake of the wake forming object do not overlap each other. There is an advantage that the excitation force at the primary component of the stationary blade wake frequency acting on the cross section can be reduced.

  Although FIG. 8 of the present embodiment shows a curved stationary blade, it is not necessarily limited to a curved stationary blade. For example, an inclined stationary blade or a stationary blade having a complicated shape of a trailing edge line is used. Even in the blade, as described in the present embodiment, the excitation force acting on the moving blade can be reduced by arranging the wake-forming object 11 in the circumferential direction so as to have different positions in each cross section in the radial direction. it can.

Next, a fourth embodiment of the present invention will be described.
FIG. 9 is an embodiment in which the stationary blade structure shown in the first embodiment is applied when the trailing edge line of the cross section at each position in the turbine radial direction of the stationary blade is changed in the axial direction. Note that FIG. 9 shows a space between one stationary blade among a plurality of stationary blades formed by each stationary blade 8 constituting the stationary blade row 3, and an annular ring formed by the diaphragm inner ring 1 and the diaphragm outer ring 2. The stator blade row 2 is configured by arranging a predetermined number of stator blades 8 over the entire circumference of 360 °.

  Here, the same components as those described in the first embodiment are denoted by the same reference numerals, description thereof is omitted, and portions different from those in the first embodiment are mainly described.

  In FIG. 9, the trailing edge line of the stationary blade 8 is curved in the axial direction, and the position of the stationary blade throat portion in the cross section at each radial height position is also changed in the axial direction accordingly.

  In the example of FIG. 9, the trailing edge line of the stationary blade 8 is curved in a convex shape toward the downstream side in the working fluid flow direction toward the blade height direction center. In this case, the position of the stationary blade throat portion also moves gradually downstream toward the central portion in the blade height direction in accordance with the trailing edge line.

  In such a case, the installation position of the wake forming object 11 described in the first embodiment is located downstream of the stationary blade throat portion 12 which is the narrowest portion of the working fluid flow path formed by each stationary blade 8, and When the moving blades 9 constituting the moving blade row 4 are installed so as to be located upstream of the moving blade row leading edge line 13 of the moving blade row 4, the size of the wake forming object 11 in a cross section at each radial position is constant. In this case, the wake forming object 11 has a shape that is curved convexly toward the downstream side. And the area | region where the distance of the wake forming object 11 and the moving blade 8 is near partially will be created, and the influence on the flow field by potential interference will arise. Here, the potential interference is that the pressure fields of the objects interfere with each other.

  Therefore, as shown in FIG. 9, the moving blade and the wake forming object 11 can be maintained at a predetermined distance by changing the size of the cross-sectional area of the wake forming object 11 in each cross section in the radial direction.

  In the example of FIG. 9, the trailing edge line of the stationary blade 8 is curved in the turbine axial direction, and the position of the stationary blade throat portion in the cross section at each position in the turbine radial direction is also directed toward the central portion in the blade height direction. Gradually move downstream. The wake forming object 11 is formed so that the cross-sectional area decreases toward the center in the blade height direction as the throat portion moves downstream. Therefore, the wake forming object 11 can be prevented from becoming a convexly curved shape on the downstream side, the distance between the wake forming object 11 and the moving blade 8 is kept constant, and the flow field due to potential interference is maintained. The influence on can be suppressed.

  In addition, as described in the first embodiment, the installation position of the cross section at each radial position of the wake forming object is downstream of the stationary blade throat portion 12 which is the narrowest portion of the flow path formed by each stationary blade 8. In addition, it must be installed on the upstream side of the moving blade row leading edge line 13 of each moving blade 9 constituting the moving blade row 4.

  Further, as described in the first embodiment, the cross-sectional shape of the wake forming object 11 shown in FIG. 9 at each position in the turbine radial direction is parallel to the chord line of the radial cross section of the stationary blade at the same radial position. It must be streamlined along the stationary vane chord parallel line 14.

  Further, as described in the first embodiment, the circumferential direction installation position of the wake forming object 11 is preferably an intermediate portion between the stationary blades 8 in a cross section at each position in the turbine radial direction. As long as the wake forming object 11 and the stationary blade surface are kept at a predetermined distance so that the wake and the wake forming object 11 do not overlap with each other, the intermediate part is not necessarily required.

  Further, as shown in the third embodiment, in the case of a stationary blade curved in the circumferential direction, it is curved in the circumferential direction so as to have a shape close to the trailing edge line of the stationary blade 8, and each cross section in the radial direction. The wake-forming object 11 and the stationary blade surface may be installed so as to maintain a predetermined distance in a shape having different circumferential installation positions.

  Furthermore, as described in the first embodiment, the number of the wake forming objects 11 may be set between the stationary blades as long as the wake of the stationary blade 8 and the wake forming object 11 do not overlap. May be installed.

  Further, as described in the first embodiment, the wake forming object 11 is not necessarily installed between all the stationary blades. For example, even if the wake forming object 11 is installed between every two stationary blades, the exciting force acting on the moving blades Can be reduced.

  According to the present embodiment, in addition to the effects of the first embodiment, by changing the size of the cross-sectional area of the wake forming object 11 in each radial cross section, the moving blade and the wake forming object are set at a predetermined distance. Therefore, there is an advantage that the influence of potential interference due to the moving blade and the wake forming object being too close can be prevented.

  Next, a fifth embodiment of the present invention will be described. FIG. 10 is a cross-sectional view as seen from the radial direction of the paragraph structure in which the stationary blade row 3 and the moving blade row 4 are combined when the circular wake forming object 11 is installed between the stationary blades.

  The cross-sectional view shown in FIG. 10 is applied over the entire circumference 360 ° of the stationary blade row 3 that forms an annular flow path between the diaphragm inner ring 1 and the diaphragm outer ring 2, and each radial direction in which the wake forming object is installed. Apply to the cross section.

  Here, the same components as those described in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

In this embodiment, the radial cross-sectional shape of the wake forming object 11 is circular.
Here, as described in the first embodiment, the installation position of the wake forming object 11 in the flow direction of the working fluid 20 is determined by the stationary blade throat portion 12 which is the narrowest portion of the flow path formed by each stationary blade 8. It must be installed downstream and upstream of the moving blade row leading edge line 13 of each moving blade 9 constituting the moving blade row 4.

  Furthermore, as described in the first embodiment, it is desirable that the wake forming object 11 is installed in the middle portion between the stationary blades 8, but the wake and wake formation of the stationary blades 8 are preferable. If the wake forming object 11 and the stationary blade surface are kept at a predetermined distance so that the wake of the object 11 does not overlap, it is not always necessary to be in the middle.

  Further, as shown in the third embodiment, in the case of a curved stationary blade, it is curved so as to have a shape close to the trailing edge line of the stationary blade 8, and the circumferential installation position is different in each radial cross section. Thus, the wake forming object 11 and the stationary blade surface may be installed so as to maintain a predetermined distance.

  Further, as described in the first embodiment, the number of the wake forming objects 11 may be set between the stationary blades as long as the wake of the stationary blade 8 and the wake forming object 11 do not overlap. May be installed.

  Furthermore, as described in the first embodiment, the wake forming object 11 is not necessarily installed between all the stationary blades. For example, even if the wake forming object 11 is installed between every two stationary blades, the exciting force acting on the moving blades Can be reduced.

  According to the present embodiment, in addition to the effects of the first embodiment, since the wake forming object 11 has a circular shape, it is not necessary to consider the influence of the shape of the wake forming object 11 on the stationary blade outflow angle. Compared with the wake forming object 11 having a streamline shape, there is an advantage that the wake forming object can be installed easily and at low cost, and the excitation force acting on the moving blade can be reduced.

  As mentioned above, although the Example of this invention was described, this invention is not limited to an above-described Example, Various modifications are included. For example, the wake forming object 11 may be newly attached to a stationary blade structure of a steam turbine that has already been installed. The method of attaching the wake forming object 11 to the stationary blade structure varies depending on the stationary blade structure, such as a method of welding and fixing to the nozzle diaphragm, a method of embedding in the nozzle diaphragm, and a method of fixing with a bolt.

DESCRIPTION OF SYMBOLS 1 Diaphragm inner ring | wheel 2 Diaphragm outer ring | wheel 3 Stator blade row | line | column 4 Rotor blade row | line | column 5 Rotor 6 Casing 7 Shroud cover 8 Stator blade 9 Rotor blade 10 Stator blade chord line 11 Wake flow formation object 12 Stator blade chord parallel line 20 Working fluid

Claims (7)

An axial flow turbomachine having a paragraph structure in which a stationary blade row provided between a diaphragm outer ring and a diaphragm inner ring and a moving blade row provided on a rotor are combined,
A wake forming object is provided between the stationary blades constituting the stationary blade row provided on the upstream side of the moving blade row in the working fluid flow direction;
The installation position of the cross-section at each position in the turbine radial direction of the wake forming object is downstream of the narrowest stationary blade throat portion in the working fluid flow path formed between the stationary blades and the operation of the stationary blade rows. Located upstream of the leading edge line of the rotor blade row provided on the downstream side in the fluid flow direction,
The cross-sectional shape of the wake forming object at each position in the turbine radial direction is a streamline shape along a stationary blade chord parallel line parallel to the chord line of the stationary blade cross section at the same position in the turbine radial direction. A featured axial flow turbomachine. The axial-flow turbomachine according to claim 1,
One end of the wake forming object in the radial direction of the turbine is fixed to the outer ring of the diaphragm, and the other end of the wake forming object enters the working fluid passage formed between the stationary blades from the outer ring of the diaphragm to the diaphragm. An axial-flow turbomachine characterized by a cantilever support structure extending toward the inner ring. The axial-flow turbomachine according to claim 1,
The wake forming object has one end in the radial direction of the turbine fixed to the inner ring of the diaphragm, and the other end of the wake forming object into the working fluid flow path formed between the stationary blades. An axial-flow turbomachine characterized by a cantilever support structure extending toward the outer ring. The axial-flow turbomachine according to claim 1,
2. The axial flow turbomachine according to claim 1, wherein the wake forming object has a both-end support structure in which end portions in a turbine radial direction are fixed to the inner diaphragm ring and the outer diaphragm ring. An axial-flow turbomachine according to any one of claims 2 to 4,
The trailing edge line of the stationary blade is curved in the turbine circumferential direction,
The axial flow turbomachine according to claim 1, wherein a shape of a trailing edge line of the wake forming object is curved in a circumferential direction in accordance with a shape of a trailing edge line of the stationary blade. The axial-flow turbomachine according to claim 1,
  Instead of the streamline shape, the shape of the cross section at each position in the turbine radial direction of the wake forming object
An axial-flow turbomachine characterized by a circular shape. The stator blade row and rotor provided between the outer ring of the diaphragm and the inner ring of the diaphragm
A method for remodeling an axial-flow turbomachine having a paragraph structure combined with a moving blade row,
  The narrowest stationary blade throat portion in the flow path of the working fluid formed between the stationary blades constituting the stationary blade row
More upstream of the stationary fluid row in the working fluid flow direction and downstream of the stationary blade row in the working fluid flow direction
Disconnection at each position in the turbine radial direction upstream of the leading edge of the moving blade row in the working fluid flow direction
The shape of the surface is parallel to the vane chord line of the vane cross section at the same position in the turbine radial direction.
An axial-flow turbomachine characterized by installing a wake-forming object formed in a streamline shape along a line
How to modify the machine.

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