JP2006104952A - Swirling flow preventive device of fluid machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a swirling flow preventive device of a fluid machine for restraining self-exciting vibration causing a swirling flow caused by a swirling component of fluid. <P>SOLUTION: In this swirling flow preventive device of the fluid machine, a guide vane 26 is arranged on a diaphragm 25 for supporting a nozzle 17 on the upstream side facing a labyrinth seal 23. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a swirl flow of a fluid machine that effectively suppresses self-excited vibration generated by a swirl flow induced from a labyrinth seal used for preventing internal fluid leakage in a fluid machine such as a steam turbine, a gas turbine, or an air compressor. Regarding prevention.

  In ultra-large fluid machines such as steam turbines and gas turbines, recently, the technology for improving reliability has been reviewed and strengthened, and one of them is suppression of self-excited vibration.

  This self-excited vibration is known to be generated not only by the bearing oil whip and oil whirl but also by the labyrinth seal swirl flow.

  FIG. 18 is an example of a steam turbine provided with a labyrinth seal.

  In FIG. 18, a rotating part (turbine rotor) 1 is provided with a large number of moving blades 2 along the circumferential direction, and these moving blades 2 are provided with a shroud 3 at the tip and adjacent to the moving blades. Connected to.

  Moreover, the nozzle 4 is arrange | positioned inside the casing 6 so that the moving blade 2 may be faced through the nozzle diaphragms 5a and 5b.

  A large number of these moving blades 2 and nozzles 4 are arranged in the axial direction to form a paragraph, and when steam passes through the paragraph, the enthalpy of the steam falls for each paragraph, and this fall is converted into power.

  As described above, in order to reduce the pressure and temperature of steam in each paragraph and effectively convert the enthalpy difference into power, it is necessary that the steam leakage between each paragraph is completely shut off. .

  However, in reality, the steam leaks to the low pressure side through the nozzle diaphragms 5a and 5b and the rotating part 1 or between the shroud 3 and the casing 6, and the rotating part 1 is further connected to the casing. Steam may also leak to the low pressure side from the ground portions 7a and 7b, which are portions that penetrate through 6.

  Such a leak causes a decrease in turbine efficiency, and hence it is necessary to further suppress the steam leakage. For this reason, as shown in FIG. 19, the labyrinth seal 11 is provided between the above-mentioned members to prevent leakage of steam to the outside.

  The labyrinth seal 11 includes an annular labyrinth fin (tooth) 8 that protrudes from the seal main body toward the rotating portion side to a portion that is extremely close to the rotating portion surface. The labyrinth fin 8 is disposed so as to surround the rotating portion 1, and the throttle portion 9 and the chamber 10 are formed by the labyrinth fin 8 and the outer peripheral portion of the rotating portion 1. The steam expands in the chamber 10 and is squeezed by the throttle portion 9, and the repetition of this process prevents the steam from leaking out.

In the labyrinth seal 11, for example, techniques for suppressing the rotation shaft from being unstable are disclosed in, for example, Japanese Patent Application Laid-Open No. 58-222902 (Patent Document 1) and Japanese Patent Application No. 58-149366 (Akira Akai). 60-56863) is disclosed (Patent Document 2).
JP 58-222902 A Microfilm of Japanese Utility Model No. 58-149366 (Japanese Utility Model Application No. 60-56863)

  Since the labyrinth seal 11 has the above-described configuration, it effectively suppresses steam leakage.

  However, although recent fluid machines have improved the prevention of steam leakage, it has been pointed out that the rotating part is a place where self-excited vibration occurs.

  Self-excited vibration has been known to date as steam whirl, but it has become more prominent as the steam pressure increases.

  When the occurrence of this self-excited vibration is investigated, the labyrinth seal 11 has a swirling component in the flowing steam, and this swirling component causes the pressure distribution in the circumferential direction in the chamber 10 of the labyrinth seal 11 to be uneven. It is considered that the vibration of the rotating part 1 is promoted.

  FIG. 20 shows the inside of the chamber 10 provided in the labyrinth seal 11 when the rotating part (turbine rotor) 1 is swinging, that is, when the rotating shaft center 12a of the rotating part 1 is different from the actual swinging center 12b. The pressure distribution 13 is shown.

  Here, if there is a swirl component in the steam flow, the pressure peak is located in the delay direction with respect to the swinging direction of the rotating unit 1. The force that the non-uniformly distributed pressure acts on the rotating part 1 can be decomposed into a force Fx in the swinging direction of the rotating part 1 and a force Fg in a direction orthogonal to the force Fx in the swinging direction. .

  When such a pressure peak occurs, the rotating part 1 is always pressed with a force of Fx in the swinging direction, and therefore, the swinging of the rotating part 1 is promoted and self-excited vibration is generated.

  It is known from experience and model tests that the swirl flow component at the labyrinth seal inlet has a great influence on the destabilizing force, and that the destabilizing force increases as swirl flow increases, and self-excited vibration is likely to occur. It was done.

  With the recent progress of computers and fluid analysis programs, the relationship between swirling flow and destabilizing force under actual machine conditions can be grasped quantitatively as shown in FIG.

  FIG. 21 is a destabilizing force diagram representing the swirling flow component and the destabilizing force at the labyrinth seal inlet determined by calculation. From this diagram, the destabilizing force increases as the swirling flow increases. I understood it. Specifically, the destabilizing force when the peripheral speed ratio of the rotating part (turbine rotor) is 120% is 5 times or more when the peripheral speed ratio of the rotating part is 50%.

  In the steam turbine, the swirl flow component at the outlet of the nozzle 4 is as large as 120% to 150% of the peripheral speed of the rotating portion (turbine rotor) 1. For this reason, even at the inlet of the labyrinth seal 11 provided at the tip of the moving blade 2 into which the steam that has exited the nozzle 4 flows, the swirl flow component is large, and the destabilizing force generated in the labyrinth seal 11 also causes the nozzle 4 to It is larger than the labyrinth seal provided on the diaphragms 5a and 5b to be supported and the labyrinth seal provided on the ground portions 7a and 7b.

  Reduction of such a large swirl component generated in the labyrinth seal 11 provided at the tip of the moving blade 2 leads to suppression of self-excited vibration.

  As seen in Patent Document 2, the means for reducing the swirling flow component is provided with a hole in the chamber in the labyrinth seal that communicates with the high pressure side in the direction opposite to the rotation, and the fluid is ejected in the direction opposite to the swirling flow. As disclosed in Japanese Patent Application Laid-Open No. 2004-133620 and Patent Document 1, it is disclosed that a guide vane is provided at the labyrinth seal inlet.

  However, the former has a small pressure difference between the high-pressure side of the labyrinth seal and the inside of the chamber, and the flow velocity of the ejected steam is not high, so there is little advantage of suppressing the swirling flow. There are inconveniences and inconveniences such as few.

  In the latter case, since the steam flow near the labyrinth inlet at the tip of the moving blade is complicated, it is difficult to provide guide vanes at appropriate positions.

  The present invention has been made in consideration of such circumstances, and an object of the present invention is to provide a swirl flow prevention device for a fluid machine that effectively suppresses self-excited vibration accompanying swirl flow caused by swirl components of fluid. And

  In order to achieve the above object, a swirl flow prevention device for a fluid machine according to the present invention comprises a moving blade and a nozzle as described in claim 1 and surrounds the tip of the moving blade, and A fluid machine having a labyrinth seal between the diaphragm supporting the nozzle and the tip of the moving blade, wherein the diaphragm supporting the nozzle is provided with guide vanes on the upstream side facing the labyrinth seal. It is.

  Further, in order to achieve the above-mentioned object, the swirl flow preventing device for a fluid machine according to the present invention is characterized in that the guide vane rotates in a rotational direction with respect to a radial line passing through the center of the turbine rotor. And provided at a position inclined at an angle in the opposite direction.

  In order to achieve the above-mentioned object, the swirl flow preventing device for a fluid machine according to the present invention comprises a moving blade and a nozzle and surrounds the tip of the moving blade as described in claim 3. In addition, a fluid machine having a labyrinth seal between the diaphragm supporting the nozzle and the tip of the moving blade is an upstream side facing the labyrinth seal and provided with a groove in the diaphragm supporting the nozzle It is.

  Further, in order to achieve the above object, the swirl flow preventing device for a fluid machine according to the present invention is such that the groove is provided in the corner portion of the diaphragm.

  Further, in order to achieve the above-mentioned object, the swirl flow preventing device for a fluid machine according to the present invention is characterized in that, as described in claim 5, the groove has a rotational direction with respect to a radial line passing through the center of the turbine rotor. It is provided at a position inclined at an angle in the reverse direction.

  In order to achieve the above object, a swirling flow preventing device for a fluid machine according to the present invention comprises a moving blade and a nozzle and surrounds the tip of the moving blade as described in claim 6. In the fluid machine having a labyrinth seal between the diaphragm supporting the nozzle and the tip of the moving blade, the diaphragm supporting the nozzle is provided on the upstream side facing the labyrinth seal. Is.

  In order to achieve the above object, the swirling flow preventing device for a fluid machine according to the present invention comprises a moving blade and a nozzle and surrounds the tip of the moving blade as described in claim 7. In addition, in the fluid machine having a labyrinth seal between the diaphragm supporting the nozzle and the tip of the moving blade, a wear resistance portion is provided on the upstream side facing the labyrinth seal and supporting the nozzle. It is a thing.

  Further, in order to achieve the above object, the swirling flow preventing device for a fluid machine according to the present invention is configured such that the frictional resistance portion has a rough surface roughness as described in claim 8. .

  Further, in order to achieve the above-mentioned object, the swirl flow prevention device for a fluid machine according to the present invention is such that the frictional resistance portion is constituted by a jagged portion.

  Moreover, in order to achieve the above-mentioned object, the swirl flow prevention device for a fluid machine according to the present invention is such that the frictional resistance portion is constituted by a brush.

  Further, in order to achieve the above object, the swirling flow preventing device for a fluid machine according to the present invention is such that the frictional resistance portion is constituted by a protruding piece.

  Moreover, in order to achieve the above-mentioned object, the swirl flow preventing device for a fluid machine according to the present invention is characterized in that the projecting piece is a polyhedral pyramid. .

  Further, in order to achieve the above object, the swirl flow preventing device for a fluid machine according to the present invention is characterized in that the projecting piece is a cone.

  Moreover, in order to achieve the above-mentioned object, the swirl flow prevention device for a fluid machine according to the present invention is the projection piece, which is one of a cylindrical body and a prismatic body, as described in claim 14. It is characterized by that.

  Moreover, in order to achieve the above-mentioned object, the swirl flow prevention device for a fluid machine according to the present invention is such that the frictional resistance portion is formed by a recess.

  The swirling flow preventing device for a fluid machine according to the present invention is provided on the upstream side facing the labyrinth seal, provided with guide vanes in the diaphragm supporting the nozzle, and the swirling flow of the fluid leaking toward the labyrinth seals by the guide vanes. Since it has a structure that cancels and removes, it is possible to make the leaking fluid a uniform flow without turbulence, to suppress the self-excited vibration associated with the fluid flowing into the labyrinth seal, and to allow the turbine rotor to perform stable operation. .

  Hereinafter, an embodiment of an exemplary steam turbine incorporating a swirl flow prevention device for a fluid machine according to the present invention will be described with reference to the drawings and reference numerals attached to the drawings.

  1 to 4 are conceptual diagrams showing a first embodiment of an exemplary steam turbine incorporating a swirl prevention device for a fluid machine according to the present invention. In addition, in the figure, FIG. 1 is the conceptual diagram which extracted some paragraphs among the paragraphs comprised with a nozzle and a moving blade, FIG. 2 is cut | disconnected sectional drawing seen from the AA arrow direction of FIG. FIG. 3 is a view showing the behavior of the fluid flowing into the labyrinth seal provided at the tip of the rotor blade in the swirling flow preventing device for a fluid machine according to the present invention, and FIG. 4 is a swirling of the fluid machine according to the present invention. It is a figure which shows the attachment apparatus of a guide blade in a flow prevention apparatus.

  As shown in FIG. 1, the steam turbine includes a set of a stationary part 15 incorporating a nozzle (static blade) 17 upstream of the steam flow SF and a rotating part 16 incorporating a downstream moving blade 18. A paragraph 19 is provided, and the paragraph 19 is arranged in a plurality of stages along the axial direction of the turbine rotor 20.

  A shroud 21 is fixed to the tip of the moving blade 18. A labyrinth seal 23 is provided between the shroud 21 and the casing 22 to prevent steam leakage.

  The labyrinth seal 23 includes seal fins with different lengths arranged in the axial direction, and these seal fins 24 are implanted in a diaphragm 25 that supports a nozzle (static blade) 17.

  As shown in FIGS. 1 and 2, the diaphragm 25 is provided with guide vanes 26 along the nozzles 17 arranged in an annular row on the side surface of the diaphragm 25 at a position facing the inlet side of the seal fin 24. ing.

  As shown in FIG. 4, the guide vanes 26 are inclined at an angle α with respect to a radial line R passing through the rotation center O in the direction opposite to the rotation direction of the turbine rotor 20 (clockwise direction). Installed.

  The operation of the swirl flow prevention device for a fluid machine according to the present embodiment having such a configuration will be described.

  As shown in FIG. 3, when the steam SF that has finished the expansion work by the nozzle 17 flows toward the moving blade 18, a part of the steam LSF is placed on the side surface of the diaphragm 25 that supports the nozzle 17 and the tip of the moving blade 18. It leaks between the provided shroud 21 and leaks toward the seal fin 24 of the labyrinth seal 23 planted in the diaphragm 25.

  At that time, the leaked vapor LSF generates a separation vortex 27 while meandering and flows, and is directly affected by the separation vortex 27 to become a swirling flow.

  However, in this embodiment, the steam LSF accompanied by the leaked swirl flow is swirled in the direction opposite to the direction of the swirl flow by the guide vanes 26 provided in the diaphragm 25, so that the swirl flow of the leaked steam LSF is offset. Thus, a uniform flow without turbulence can be obtained.

  As described above, in the present embodiment, of the steam SF that has finished the expansion work and flows from the nozzle 17 toward the moving blade 18, some of the leaked steam LSF flows to the seal fins 24 of the labyrinth seal 23 along with the swirling flow. At this time, since the guide vanes 26 for canceling out the swirl flow are provided in the diaphragm 25, the leaked steam LSF can be made a uniform flow without turbulence, and self-excited by the steam LSF flowing into the labyrinth seal 23 Vibration can be suppressed and the turbine rotor 20 can be operated stably.

  5 and 6 are conceptual diagrams showing a second embodiment of the swirling flow preventing device for a fluid machine according to the present invention. In addition, in the figure, FIG. 5 is the conceptual diagram which extracted some paragraphs among the paragraphs comprised with a nozzle and a moving blade, FIG. 6 is the cut sectional view seen from the BB arrow direction of FIG. It is.

  Moreover, the same code | symbol is attached | subjected to the same component as the component of 1st Embodiment shown in FIGS.

  The swirl flow preventing device for a fluid machine according to the present embodiment is provided with a groove 28 at a position facing the inlet side of the seal fin 24 on the side surface of the diaphragm 25.

  As shown in FIG. 6, the groove 28 is provided on a radial line R that passes through the rotation center O of the turbine rotor 20.

  In the swirl flow prevention device for a fluid machine according to the embodiment having such a configuration, a part of the steam SF that has finished the expansion work by the nozzle 17 leaks toward the moving blade 18. The leaked steam LSF passes through between the side surface of the diaphragm 25 that supports the nozzle 17 and the shroud 21 provided at the tip of the rotor blade 18 and swirls while flowing toward the seal fin 24 of the labyrinth seal 23. Accompanied by.

  The steam LSF accompanied with the swirling flow enters the groove 28 while meandering, and the swirling flow is removed here, and the steam LSF is uniformly flowed to the seal fins 24 of the labyrinth seal 23 installed in the diaphragm 25. Inflow.

  As described above, in the present embodiment, of the steam SF that has finished the expansion work and flows from the nozzle 17 toward the moving blade 18, some of the leaked steam LSF flows to the seal fins 24 of the labyrinth seal 23 along with the swirling flow. At this time, since the groove 25 for removing the swirl flow is provided in the diaphragm 25, the leaked steam LSF can be made uniform, and the self-excited vibration accompanying the steam LSF flowing into the labyrinth seal 23 is suppressed, and the turbine rotor 20. Can be operated stably.

  In the present embodiment, the swirl flow of the steam LSF generated while flowing between the diaphragm 25 and the shroud 21 is removed by the groove 28 provided on the side surface of the diaphragm 25. For example, as shown in FIGS. 7 and 8, a groove 28 may be provided in the corner portion 29 of the diaphragm 25, and for example, as shown in FIG. 9, the groove 28 is formed in the rotational direction of the turbine rotor 20. May be provided on the side surface of the diaphragm 25 so as to be inclined at an angle β with respect to the radial line R passing through the rotation center O in the opposite direction (clockwise direction).

  FIG. 10 is a conceptual diagram showing a fifth embodiment of the swirl flow preventing device for a fluid machine according to the present invention.

  In addition, the same code | symbol is attached | subjected to the same component as the component of 1st Embodiment shown in FIGS.

  The swirling flow preventing device for a fluid machine according to the present embodiment is provided with a protruding portion 30 extending toward the seal fin 24 side at a position facing the inlet side of the seal fin 24 of the labyrinth seal 23 on the side surface of the diaphragm 25. It is a thing.

  As described above, in the present embodiment, the protrusion 30 is provided to increase the surface area of the diaphragm 25, and the resistance given to the steam LSF leaking between the side surface of the diaphragm 25 and the shroud 21 provided at the tip of the rotor blade 18 is increased. Since the generation of the swirling flow of the steam LSF is reduced by the increased resistance and the increased resistance, the relatively stable uniform flow of steam LSF can be caused to flow into the seal fin 24, and the turbine rotor 20 can be stably operated. Can be performed.

  FIG. 11: is a conceptual diagram which shows 6th Embodiment of the swirl | vortex flow prevention apparatus of the fluid machine which concerns on this invention.

  In addition, the same code | symbol is attached | subjected to the same component as the component of 1st Embodiment shown in FIGS.

  The swirl flow preventing device for a fluid machine according to the present embodiment is provided with a frictional resistance portion 31 at a position facing the inlet side of the seal fin 24 of the labyrinth seal 23 on the side surface of the diaphragm 25.

  The frictional resistance portion 31 has a surface roughness SR that is roughened, or is configured as a jagged portion JZ on the side surface of the diaphragm 25 as shown in FIG.

  As described above, in this embodiment, the frictional resistance part 31 having the rough surface roughness SR or the frictional resistance part 31 having the jagged part JZ is provided on the side surface of the diaphragm 25, and the steam flows toward the seal fin 24 of the labyrinth seal 23. Since the LSF is provided with resistance so that the generation of the swirling flow of the steam LSF is reduced, the steam LSF having a relatively stable uniform flow can be caused to flow into the seal fin 24, and the turbine rotor 20 is stably operated. Can be made.

  In the present embodiment, the swirl flow of the steam LSF generated while flowing between the diaphragm 25 and the shroud 21 has a large surface roughness SR as the frictional resistance portion 31 provided on the side surface of the diaphragm 25. However, the present invention is not limited to this example. For example, as shown in FIG. 13, the friction resistance portion 31 may be a brush 32. For example, as shown in FIGS. The resistance portion 31 may be a projection piece 33 having a shape such as a polyhedral pyramid, cone, cylinder, prism, etc. For example, as shown in FIG. 16 and FIG. The recess 34 may be used. Further, the protruding piece 33 and the recess 34 as the frictional resistance portion 31 are provided on a radial line R passing through the center O of the turbine rotor 20.

The conceptual diagram which shows 1st Embodiment of the swirl | vortex flow prevention apparatus of the fluid machine which concerns on this invention. FIG. 2 is a cross-sectional view taken from the direction of arrows AA in FIG. 1. The figure which shows the behavior of the fluid which flows in into the labyrinth seal provided in the front-end | tip part of a moving blade in the swirl | vortex flow prevention apparatus of the fluid machine which concerns on this invention. The figure which shows the attachment position of a guide blade | wing in the swirl | vortex flow prevention apparatus of the fluid machine which concerns on this invention. The conceptual diagram which shows 2nd Embodiment of the swirl | vortex flow prevention apparatus of the fluid machine which concerns on this invention. FIG. 6 is a cross-sectional view taken along the line B-B in FIG. 5. The conceptual diagram which shows 3rd Embodiment of the swirl | vortex flow prevention apparatus of the fluid machine which concerns on this invention. Sectional drawing cut | disconnected seen from the CC arrow direction of FIG. The conceptual diagram which shows 4th Embodiment of the swirl | vortex flow prevention apparatus of the fluid machine which concerns on this invention. The conceptual diagram which shows 5th Embodiment of the swirl | vortex flow prevention apparatus of the fluid machine which concerns on this invention. The conceptual diagram which shows 6th Embodiment of the swirl | vortex flow prevention apparatus of the fluid machine which concerns on this invention. The conceptual diagram which shows 7th Embodiment of the swirl | vortex flow prevention apparatus of the fluid machine which concerns on this invention. The conceptual diagram which shows 8th Embodiment of the swirl | vortex flow prevention apparatus of the fluid machine which concerns on this invention. The conceptual diagram which shows 9th Embodiment of the swirl | vortex flow prevention apparatus of the fluid machine which concerns on this invention. FIG. 15 is a cross-sectional view taken along line DD in FIG. 14. The conceptual diagram which shows 10th Embodiment of the swirl | vortex flow prevention apparatus of the fluid machine which concerns on this invention. FIG. 17 is a cross-sectional view taken along the line EE in FIG. 16. The longitudinal cross-sectional view which shows the upper half part of the conventional steam turbine. The fragmentary figure which shows the labyrinth seal provided between the stationary part and the rotation part in the conventional steam turbine. The figure which shows the pressure distribution around a rotation part in the conventional steam turbine. In the conventional steam turbine, the destabilization force diagram which expressed the swirl flow component and destabilization force in a labyrinth seal inlet.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotating part 2 Moving blade 3 Shroud 4 Nozzle 5a, 5b Diaphragm 6 Casing 7a, 7b Gland part 8 Labyrinth fin 9 Restriction part 10 Chamber 11 Labyrinth seal 12a Rotating shaft center 12b Swing center 13 Pressure distribution 15 Stationary part 16 Rotating part 17 Nozzle 18 Moving blade 19 Paragraph 20 Turbine rotor 21 Shroud 22 Casing 23 Labyrinth seal 24 Seal fin 25 Diaphragm 26 Guide vane 27 Separation vortex 28 Groove 29 Corner portion 30 Protruding portion 31 Friction resistance portion 32 Brush 33 Protruding piece 34 Indentation

Claims (15)

In a fluid machine including a moving blade and a nozzle, and surrounding the tip of the moving blade and having a labyrinth seal between the tip of the moving blade of the diaphragm supporting the nozzle, the upstream facing the labyrinth seal An apparatus for preventing a swirling flow of a fluid machine, characterized in that a guide vane is provided on the diaphragm that supports the nozzle. The swirl flow prevention device for a fluid machine according to claim 1, wherein the guide vane is provided at a position inclined with respect to a radial line passing through the center of the turbine rotor at an angle opposite to the rotation direction. In a fluid machine including a moving blade and a nozzle, and surrounding the tip of the moving blade and having a labyrinth seal between the tip of the moving blade of the diaphragm supporting the nozzle, the upstream facing the labyrinth seal A swirl flow preventing device for a fluid machine, characterized in that a groove is provided on a side of the diaphragm that supports the nozzle. 4. The swirl flow prevention device for a fluid machine according to claim 3, wherein the groove is provided in a corner portion of the diaphragm. The swirl flow prevention device for a fluid machine according to claim 3, wherein the groove is provided at a position inclined with respect to a radial line passing through the center of the turbine rotor at an angle opposite to the rotation direction. In a fluid machine including a moving blade and a nozzle, and surrounding the tip of the moving blade and having a labyrinth seal between the tip of the moving blade of the diaphragm supporting the nozzle, the upstream facing the labyrinth seal A swirl flow prevention device for a fluid machine, characterized in that a projecting portion is provided on a side of the diaphragm that supports the nozzle. In a fluid machine including a moving blade and a nozzle, and surrounding the tip of the moving blade and having a labyrinth seal between the tip of the moving blade of the diaphragm supporting the nozzle, the upstream facing the labyrinth seal An anti-swirl device for a fluid machine, characterized in that a wear resistance portion is provided on a side of the diaphragm that supports the nozzle. 8. The swirl flow preventing device for a fluid machine according to claim 7, wherein the frictional resistance portion is configured to increase the surface roughness. 8. The swirl flow prevention device for a fluid machine according to claim 7, wherein the friction resistance portion is formed of a jagged portion. 8. The swirl flow prevention device for a fluid machine according to claim 7, wherein the friction resistance portion is constituted by a brush. 8. The swirl flow preventing device for a fluid machine according to claim 7, wherein the frictional resistance portion is constituted by a protruding piece. The swirl flow prevention device for a fluid machine according to claim 11, wherein the protruding piece is a polyhedral pyramid. The swirl flow prevention device for a fluid machine according to claim 11, wherein the protruding piece is a cone. The swirl flow prevention device for a fluid machine according to claim 11, wherein the protruding piece is one of a cylindrical body and a prismatic body. The swirl flow prevention device for a fluid machine according to claim 7, wherein the frictional resistance portion is formed of a recess.

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