JP2005214051A - Axial-flow turbine stage and axial-flow turbine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high performance axial-flow turbine capable of reducing the loss of interference occurring when steam leaks through a clearance between a labyrinth packing and a rotating shaft and the steam is mixed, at the outlet of a stationary blade, with a steam in a passage part. <P>SOLUTION: The inside wall section inner diameter of a disk part 11 at the inlet part of the moving blade 5 is formed smaller than the outlet inner diameter of a stationary blade inner ring 2, the inside wall part inner diameter ϕx of the disk part 11 observed from a meridian plane is formed larger continuously toward the downstream side, and a disk section fin 10 for converting a rotating shaft radial speed component of steam leaked from a labyrinth fin 8 to a rotating shaft axial flow velocity component is fitted to the inlet part of the moving blade. Also, as required, the steam from the outlet part of the stationary blade 3 to the inlet part of the moving blade 5, and a stationary blade inner ring fin 9 for converting the rotating shaft radial velocity component to the rotating shaft axial velocity component of the steam leaked from the labyrinth fin 8 is fitted to the outlet part of the stationary blade 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an axial-flow turbine stage and an axial-flow turbine composed of stationary blades and moving blades.

  In general, an axial turbine has a turbine stage composed of stationary blades and moving blades, and fluid in the turbine stage mainly flows parallel to the rotation axis. For example, a steam turbine that is an axial turbine is configured as shown in FIG. A plurality of stationary blades 3 are fixed between the stationary blade outer ring 1 and the stationary blade inner ring 2, and a plurality of moving blades 5 are fixed to the rotating shaft 4. A shroud 6 is installed at the blade top of the moving blade 5, and a turbine stage is formed by the stationary blade 3 and the moving blade 5.

  Fins 7 are implanted in the stationary blade outer ring 1 in order to prevent steam leaking from the gap between the shroud 6 and the stationary blade outer ring 1. Further, a labyrinth fin 8 is implanted in the stator blade inner ring 2 in order to reduce the leaked steam passing through the gap between the stator blade inner ring 2 and the rotating shaft 4.

  A steam turbine is configured by combining such turbine stages in a single stage or a plurality of stages in the axial direction of the rotating shaft 4. The steam in the steam turbine passage is expanded and accelerated in the stationary blade 3, and the accelerated steam is turned by the moving blade 5 to give a rotating force to the moving blade 5.

  In this case, loss occurs in the turbine passage. The loss generated in the passage is roughly divided into an airfoil loss, a secondary loss, and a leakage loss. That is, the airfoil loss due to the blade shapes of the stationary blade 3 and the moving blade 5, the secondary loss generated in the inner and outer end wall portions of the stationary blade 3 and the moving blade 5, and the gap between the fin 7 and the shroud 6 There are a tip leakage loss that occurs because more steam leaks, and a labyrinth leakage loss that occurs because steam leaks from the gap between the labyrinth fin 8 and the rotating shaft 4 implanted in the stator blade inner ring 2.

As a thing aiming at the reduction of the secondary loss which generate | occur | produces in the inner and outer end wall part of the stationary blade 3 and the moving blade 5, there exists a three-dimensional design blade (for example, refer patent document 1, 2). In order to suppress the secondary flow vortex generated on the inner and outer walls of the passage part, the blades are inclined to the inner and outer end wall surfaces, and the pressure difference (Mach number difference) on the blade surface, which is the driving force of the secondary flow vortex. By reducing this, the development of the secondary flow vortex is suppressed, the secondary flow loss is reduced, and the performance is improved. Various seal structures have also been proposed for the purpose of reducing leakage loss such as chip leakage loss and labyrinth leakage loss.
JP-A-6-212902 Japanese Patent Publication No. 4-78803

  However, the labyrinth leaking steam mixes with the steam flowing out from the stationary blade 3, the steam outflow angle of the stationary blade 3 deviates from the design angle, the inflow angle to the moving blade 5 changes, and the loss in the moving blade 5 increases. Furthermore, since the mixing is performed at right angles to the steam flowing out from the stationary blade 3, the radial velocity component of the leaked steam is lost, and mixing loss occurs.

  That is, the labyrinth leakage loss, which is one of the leakage losses, causes steam to leak from the gap between the labyrinth fin 8 and the rotating shaft 4 as shown in FIG. Occurs for not. The labyrinth leakage loss can be expressed by a ratio GL / G of the steam flow rate G that performs effective work in the passage portion and the leakage steam flow rate GL. The leaked steam passing through the labyrinth fin 8 flows through the gap between the stationary blade inner ring 2 and the rotating shaft 4 into the moving blade 5 and flows out downstream.

  The leaked steam is mixed with the steam flowing out from the stationary blade 3 when flowing into the moving blade 5. The steam flowing out from the stationary blade 3 is controlled by the stationary blade 3 so as to have a predetermined flow velocity and flow angle, but the leaked steam flowing out from the labyrinth fin 8 (arrow A in the figure) has a radial velocity component. The mixing is caused by the loss of the radial velocity component of the leaked steam due to mixing at right angles with the steam flowing out from the stationary blade 3 (arrow B in the figure). Furthermore, since the steam outflow angle deviates from the design angle by mixing the leaked steam with the steam flowing out from the stationary blade 3, the inflow angle to the moving blade 5 changes and the loss in the moving blade 5 increases.

  FIG. 9 shows the relationship between the leakage steam flow rate measured by the test turbine and the paragraph performance. The vertical axis represents the paragraph efficiency, and the horizontal axis represents the ratio (GL / G) between the leakage steam flow rate GL and the passage portion flow rate G. The hatched portion in the figure indicates the leakage loss (GL / G) defined above. The mixing loss due to the leaked steam and the loss increase in the moving blade 5 (hereinafter referred to as interference loss) are the part surrounded by the hatched part and the solid line indicating the paragraph efficiency.

  FIG. 10 shows the relationship between the interference loss, the ratio (GL / G) of the leakage steam flow rate GL and the passage portion flow rate G. Interference loss increases with increasing leaked steam. This is because the loss in the moving blade 5 increases because the mixing loss with the steam flowing out from the stationary blade 3 increases due to an increase in the leaked steam, and the change in flow velocity and outflow angle due to the influence increases. It is.

  In recent years, axial turbines used in power plants have become important issues in terms of ensuring reliability and increasing efficiency from the viewpoint of environmental problems and energy saving, and it is required to reduce this interference loss. It has become.

  An object of the present invention is to provide a high-performance axial turbine capable of reducing interference loss that occurs when steam leaks from a gap between a labyrinth packing and a rotating shaft and mixes with steam in a passage at a stationary blade outlet. It is to provide a paragraph and axial turbine.

  In the axial turbine stage of the present invention, the inner wall inlet diameter of the disk portion at the inlet portion of the moving blade is formed smaller than the outlet inner diameter of the stationary blade inner ring, and the inner wall inlet diameter of the disk portion observed from the meridian plane is set. A disk fin that is formed continuously large toward the downstream side and converts the radial velocity component of the rotating shaft of the leaked steam from the labyrinth fin into the axial velocity component is provided at the inlet portion of the moving blade. Further, if necessary, the vane for guiding the steam from the outlet of the stationary blade to the inlet of the moving blade and converting the radial velocity component of the rotating shaft of the leaked vapor from the labyrinth fin into the axial velocity component An inner ring fin is provided at the outlet portion of the stationary blade, and a fillet continuously connected to the inner wall portion of the disk portion is provided at the inlet portion of the moving blade. As a result, the steam leaks from the gap between the labyrinth packing and the rotating shaft, and the interference loss that occurs when mixing with the steam in the passage at the stationary blade outlet is reduced.

  According to the present invention, the leaked steam from the labyrinth fin flows into the moving blade by converting the radial velocity component of the rotating shaft of the leaking steam into the axial flow velocity component by the disk portion fin or the stationary blade inner ring fin, Flows along the inner wall of the blade to the blade outlet where the minimum pressure is reached. Therefore, mixing loss due to loss of radial velocity component generated when mixing with steam flowing out from the stator blade outlet is reduced, and interference loss generated when mixing with steam in the passage at the stator blade outlet is reduced. Can be reduced.

  FIG. 1 is a side sectional view of an axial turbine stage according to the first embodiment of the present invention as seen from the meridian plane. A plurality of stationary blades 3 are fixedly provided by the stationary blade outer ring 1 and the stationary blade inner ring 2, and a plurality of moving blades 5 are fixedly provided on the rotating shaft 4 via the disk portion 12. FIG. 1 shows one stationary blade 3 and one moving blade 5. A shroud 6 is installed at the blade top of the moving blade 5, and a turbine stage is formed by the stationary blade 3 and the moving blade 5. Further, fins 7 are implanted in the stationary blade outer ring 1 in order to prevent steam leaking from the gap between the shroud 6 and the stationary blade outer ring 1, and the stationary blade inner ring 2 includes the stationary blade inner ring 2, the rotating shaft 4, and the like. Labyrinth fins 8 are implanted in order to reduce the leaked steam passing through the gap.

  The disk portion 12 has an inlet inner diameter φ1 smaller than an outlet inner diameter φ2 of the stationary blade inner ring 2. Further, the diameter φx of the inner wall portion 13 of the disk portion 12 is configured to continuously increase from the inlet portion of the rotor blade 5 toward the downstream side. That is, the diameter φx of the inner wall portion 13 of the disk portion 12 observed from the meridian plane is continuously increased toward the downstream side (right side in FIG. 1).

  Further, a stationary blade inner ring fin 9 is provided in the axial direction toward the inlet portion of the moving blade 5 at the outlet portion of the stationary blade 2, and the disk portion is directed toward the outlet portion of the stationary blade 3 from the inlet portion of the moving blade 5. Fins 10 are provided. That is, the stator blade inner ring fin 9 is provided in the stator blade inner ring 2 at the outlet portion of the stator blade 3, guides the steam from the outlet portion of the stator blade 3 to the inlet portion of the moving blade 5, and leaks from the labyrinth fin 8. The radial velocity component of the rotating shaft of steam is converted into the axial velocity component. The disk fin 10 is provided in the disk 12 at the inlet of the rotor blade 5 and converts the radial velocity component of the rotating shaft of the leaked steam from the labyrinth fin 8 into an axial flow velocity component.

  The steam leaking from the labyrinth fin 8 flows downstream as indicated by an arrow A in FIG. 1 along the flow path formed by the stator blade inner ring fin 9 and the disk portion fin 10. On the other hand, steam from the passage portion flowing out from the stationary blade 3 flows into the moving blade 5 as indicated by an arrow B. Since the steam flows out toward a lower pressure field, the leaked steam flows along the inner wall portion 13 of the disk portion 12 to the outlet portion of the moving blade 5 where the minimum pressure is generated in the moving blade 5, and the outlet of the stationary blade 3. The steam that has flowed out from the section also flows out toward the outlet of the moving blade 5.

  At this time, the leaked steam is mixed with the steam flowing out from the stationary blade 3 in the passage portion of the moving blade 5 and flows out. However, since the leaked steam flows along the inner wall portion 13 of the disk portion 12, the radial velocity of the leaked steam has. The component is converted into an axial velocity component. Therefore, since the mixing loss due to the loss of the radial velocity component generated when mixing with the steam flowing out from the stationary blade 3 is reduced, the interference loss is also reduced.

  FIG. 2 is a graph showing the relationship between the interference loss according to the first embodiment of the present invention and the ratio (GL / G) between the leakage steam flow rate GL and the passage portion flow rate G. The solid line in FIG. 2 shows the loss due to the conventional example, and the broken line shows the loss according to the first embodiment of the present invention. In the figure, the range indicated by the solid line and the broken line describes the range of the leaked steam generated in the axial turbine stage, and generally the range is about 0.004 to 0.04. As shown in FIG. 2, according to the first embodiment of the present invention, the interference loss is reduced when GL / G is in the range of 0.005 to 0.04, and the performance of the axial turbine stage is reduced. It can be seen that it has improved.

  According to the first embodiment, the leaked steam from the labyrinth fin 8 is guided to the inlet portion of the moving blade 5 so as to flow along the inner wall portion of the disk portion 12 by the stationary blade inner ring fin 9 and the disk portion fin 10. Therefore, the radial velocity component is lost when mixing with the steam flowing out from the outlet of the stationary blade 3. Accordingly, the mixing loss is reduced, and the interference loss that occurs when mixing with the steam in the passage portion at the exit portion of the stationary blade 3 can be reduced.

  FIG. 3 is a side sectional view of the axial turbine stage according to the second embodiment of the present invention as seen from the meridian plane. This second embodiment is different from the first embodiment shown in FIG. 1 in that a fillet 11 continuously connected to the inner wall portion 13 of the disk portion 12 is provided at the inlet portion of the rotor blade 5. is there. The same elements as those in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted.

  In FIG. 3, the inner diameter φ1 of the disk portion 12 is smaller than the inner diameter φ2 of the stator blade inner ring 2, and the inner wall diameter φx of the disk portion 12 is continuously larger from the inlet portion of the moving blade 5 toward the downstream side. It is comprised so that it may become. Further, a stationary blade inner ring fin 9 is provided in the axial direction toward the inlet portion of the moving blade 5 at the outlet portion of the stationary blade inner ring 2, and the outlet portion of the stationary blade 3 is provided in the disk portion 12 of the inlet portion of the moving blade 5. The disk part fin 10 is provided toward the direction.

  Further, a fillet 11 is formed on the inner wall portion 13 of the disk portion 12 at the inlet portion of the moving blade 5 on the moving blade surface from the inner wall portion 13. FIG. 4 shows an enlarged view of the fillet 11 portion viewed from the inlet portion of the moving blade 5. The fillet 11 is formed with a smooth continuous curvature between the moving blade 5 and the inner wall portion 13 of the disk portion 12.

  According to the second embodiment, in addition to the effects of the first embodiment, since the fillet 11 is provided at the inlet of the moving blade 5, the area of the passage portion in the moving blade 5 is reduced, and the first Compared with the embodiment, the pressure in the passage portion of the moving blade 5 is lowered, and the leakage steam is more easily guided.

  FIG. 5 is a side sectional view of an axial turbine stage according to the third embodiment of the present invention as seen from the meridian plane. In the third embodiment, the stator blade inner ring fin 9 is omitted from the first embodiment shown in FIG.

  In FIG. 5, the inner diameter φ1 of the disk portion 12 is smaller than the outlet inner diameter φ2 of the inner ring 2 of the stationary blade, and the inner wall diameter φx of the disk portion 12 is continuously larger from the inlet portion of the moving blade 5 toward the downstream side. It is comprised so that it may become. Further, the disk part 12 at the inlet part of the moving blade 5 is provided with a disk part fin 10 toward the outlet part of the stationary blade 3. The vane inner ring fin 9 at the outlet of the vane inner ring 2 is omitted.

  According to the third embodiment, the leaked steam from the labyrinth fin 8 loses the radial velocity component of the rotating shaft of the leaked steam by the disk part fin 10 provided in the disk part 11 of the inlet part of the rotor blade 5. Since it flows into the moving blade 5 and flows along the inclined surface of the inner wall portion 13 of the disk portion 11, when there is little leakage steam, the exit of the stationary blade 3 is not required even if the stationary blade inner ring fin 9 is not provided. It is possible to reduce the interference loss that occurs when mixing with the vapor of the passage part at the part.

  FIG. 6 is a side sectional view of an axial turbine stage according to the fourth embodiment of the present invention as seen from the meridian plane. This fourth embodiment is different from the third embodiment shown in FIG. 5 in that the inlet 11 of the rotor blade 5 is provided with a fillet 11 continuously connected to the inner wall 13 of the disk portion 12. is there.

  In FIG. 6, the inner diameter φ1 of the disk portion 12 is smaller than the inner diameter φ2 of the stator blade inner ring 2, and the inner diameter φx of the disk portion 12 is continuously larger from the inlet portion of the moving blade 5 toward the downstream side. It is comprised so that it may become. A disk part fin 10 is provided on the disk part 12 at the inlet of the rotor blade 5 toward the outlet of the stationary blade 3. The vane inner ring fin 9 at the outlet of the vane inner ring 2 is omitted.

  Further, a fillet 11 is formed on the inner wall portion 13 of the disk portion 12 at the inlet portion of the moving blade 5 on the moving blade surface from the inner wall portion 13. The fillet 11 is formed with a smooth continuous curvature between the moving blade 5 and the inner wall portion 13 of the disk portion 12.

  According to the fourth embodiment, in addition to the effects of the third embodiment, since the fillet 11 is provided at the inlet portion of the moving blade 5, the area of the passage portion in the moving blade 5 decreases, and the third embodiment Compared with the embodiment, the pressure in the passage portion of the moving blade 5 is lowered, and the leakage steam is more easily guided.

The side sectional view which looked at the axial flow turbine paragraph concerning a 1st embodiment of the present invention from the meridian plane. The graph which shows the relationship between the interference loss by the 1st Embodiment of this invention, and ratio (GL / G) of the leakage steam flow volume GL and the channel | path part flow volume G. The sectional side view which looked at the axial-flow turbine stage concerning the 2nd Embodiment of this invention from the meridian surface. The enlarged view of the fillet part in the axial turbine stage which concerns on the 2nd Embodiment of this invention. The sectional side view which looked at the axial-flow turbine stage concerning the 3rd Embodiment of this invention from the meridian surface. The sectional side view which looked at the axial-flow turbine stage concerning the 4th Embodiment of this invention from the meridian surface. The side sectional view which looked at the conventional axial flow turbine paragraph from the meridian surface. The sectional side view seen from the meridian surface for demonstrating the loss form of the conventional axial flow turbine stage. Explanatory drawing which shows the relationship between leakage steam flow rate and paragraph efficiency. The graph which shows the relationship between leakage steam flow and interference loss.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Stator blade outer ring, 2 ... Stator blade inner ring, 3 ... Stator blade, 4 ... Rotating shaft, 5 ... Rotor blade, 6 ... Shroud, 7 ... Fin, 8 ... Labyrinth fin, 9 ... Stator blade inner ring fin, 10 ... Disc Part fin, 11 ... fillet, 12 ... disk part, 13 ... inner wall part

Claims (5)

  A stationary blade fixed between a stationary blade outer ring and a stationary blade inner ring, a moving blade fixed on a disk portion of a rotating shaft and having a shroud formed on the top of the blade, and between the stationary blade outer ring and the shroud In the axial turbine stage formed by a fin provided on the inner surface of the rotating blade to prevent steam leakage and a labyrinth fin provided between the inner ring of the stationary blade and the rotary shaft to prevent leakage of steam. An inner diameter of the inner wall portion of the disk portion at the inlet portion is formed smaller than an inner diameter of the outlet of the inner ring of the stationary blade, and an inner diameter of the inner wall portion of the disk portion observed from the meridian surface is continuously increased toward the downstream side. A vane inner ring fin for guiding the steam from the outlet part of the stationary blade to the inlet part of the moving blade and converting the radial velocity component of the rotating shaft of the leaked steam from the labyrinth fin into the axial velocity component Said stationary blade An axial flow characterized in that a disc fin is provided at the inlet portion of the moving blade for converting the radial velocity component of the rotating shaft of the leaked steam from the labyrinth fin into an axial flow velocity component provided at the outlet portion. Turbine paragraph.   2. The axial turbine stage according to claim 1, wherein a fillet that is continuously connected to an inner wall portion of the disk portion is provided at an inlet portion of the moving blade.   A stationary blade fixed between a stationary blade outer ring and a stationary blade inner ring, a moving blade fixed on a disk portion of a rotating shaft and having a shroud formed on the top of the blade, and between the stationary blade outer ring and the shroud In the axial turbine stage formed by a fin for preventing leakage of steam and a labyrinth fin provided between the inner ring of the stationary blade and the rotating shaft for preventing leakage of steam. An inner diameter of the inner wall portion of the disk portion at the inlet portion is formed smaller than an inner diameter of the outlet of the inner ring of the stationary blade, and an inner diameter of the inner wall portion of the disk portion observed from the meridian surface is continuously increased toward the downstream side. An axial flow turbine stage characterized in that a disk portion fin for converting a radial velocity component of a rotating shaft of a leaked steam from the labyrinth fin into an axial flow velocity component is provided at an inlet portion of the moving blade.   The axial turbine stage according to claim 3, wherein a fillet that is continuously connected to an inner wall portion of the disk portion is provided at an inlet portion of the moving blade. An axial-flow turbine comprising the axial-flow turbine stage according to any one of claims 1 to 4.

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