JP4822924B2 - Turbine blade and steam turbine provided with the same - Google Patents

Description

  The present invention relates to a turbine blade, and more particularly to a turbine blade that further improves blade efficiency and a steam turbine including the turbine blade.

  Recently, steam turbines applied to power plants have been reviewed to ensure reliability and to enhance efficiency from the viewpoint of environmental problems and energy savings. Is targeted.

  As shown in FIG. 3, the axial flow type steam turbine is sandwiched and supported by a stationary blade outer ring 11 and a stationary blade inner ring 12, and is implanted in a disk 15 of a stationary blade 13 and a rotating shaft 14 arranged in an annular row. The turbine blade 18 and the shroud 17 installed on the blade top side of the blade 16 constitute a turbine stage 18, and the turbine stage 18 is arranged in a plurality of stages toward the axial direction of the rotary shaft 14. .

  In addition, the axial flow type steam turbine has fins 19 installed in the stationary blade outer ring 11 for preventing the flow of steam leaking from the gap between the shroud 17 and the stationary blade outer ring 11. A labyrinth fin 20 for preventing the flow of steam leaking from the gap is implanted in the stator blade inner ring 12.

  In the axial flow type steam turbine having such a configuration, the steam is expanded in the stationary blade 13 to increase the speed, and the increased steam flow is redirected by the moving blade 16. A rotational force is applied, and a generator (not shown) is driven by the rotational force to generate power.

  By the way, of at least one of the stationary blades 13 and the moving blades 16 applied to the axial flow type, as a part of measures for improving aerodynamic performance, the blade surface roughness is made finer and smoothly applied and managed. However, a technique for reducing the friction loss on the blade surface is adopted.

  Under such blade surface management, recent turbine blades cover the entire blade surface, and the blade surface roughness Ry value (JIS notation: maximum roughness height, unit micron) is 20 or less on the design and production drawings. The construction management of the blade surface roughness is performed.

  It is reported in Non-Patent Document 1 by Forster et al. That turbine blades improve aerodynamic performance when the blade surface roughness is managed.

  In addition, in other aerodynamic performance improvement measures, for example, as seen in Patent Document 1, a slit tube extending toward the span direction of the blade trailing edge is provided, and shock waves generated on the blade back side are buffered, Reducing pressure loss is disclosed.

  Although different from turbine blades, compressor blades have rough blade surfaces to improve blade efficiency and prevent surge tolerance reduction based on suppression of laminar separation vortices and turbulent boundary layer development in the low Reynolds number region. For example, Japanese Patent Application Laid-Open No. 2004-133620 discloses management for making the thickness fine and performing smooth construction.

  For turbine blades, for example, Patent Document 3 discloses a technique for increasing the roughness of the leading edge surface as a turbulent transition promotion measure at the leading edge of the moving blade.

  Here, the degree of influence of the blade surface roughness and blade surface speed on the friction loss in the turbine blade will be considered.

  In general, the boundary layer thickness defined by the excluded thickness δ and the momentum thickness θ is a characteristic value of the boundary layer formed on the blade surface. That is, the momentum deficit per unit time formed near the blade surface is equivalent to the momentum passing through the portion of the momentum thickness θ described above. For this reason, as seen in Non-Patent Document 2, momentum deficiency is directly related to blade surface shear stress, object drag, and pressure loss.

  As shown in FIG. 4, it is reported in Non-Patent Document 3 that the momentum thickness θ increases as the absolute value of the blade surface velocity increases.

Further, as shown in FIG. 5, it is reported in Non-Patent Document 4 that the momentum thickness θ increases as the blade surface speed increases.
Japanese Patent Laid-Open No. 2002-21502 JP 2002-317797 A JP 2000-104501 A Proc Instn Mech Engrs 1966_67 Vol 181 Pt 1 N0 18 Shirakura, Fluid Dynamics (2) pp66,67 Corona By JHHORLOCK Axial Flow Turbines pp98,99 K. Bammert, Trans.ASME Power OCT.1980, Vol.102 pp.978_98

  By the way, the internal loss of the axial flow type steam turbine is roughly classified into blade profile loss, secondary flow loss, and leakage loss. Among these, reducing the secondary flow loss is an important priority item in improving aerodynamic performance.

  FIG. 6 is a schematic diagram showing secondary flow loss that occurs when steam flows between the blades. When the steam accompanied by the boundary layer flows to the leading edge of the wing 21, it becomes a horseshoe-shaped vertical vortex 22 and grows by being divided into the dorsal side and the ventral side. On the back side, the vapor flowing along the blade surface becomes the counter vortex 23, whereas on the ventral side, the vapor flows as a separation vortex when facing the back side of the adjacent blade 21. When the separation vortex reaches the adjacent back side, the separation vortex grows large in the blade height direction, becomes a passage vortex 24, and overlaps the counter vortex 23.

  When this phenomenon is verified by performing a cascade test, during the cascade loss, the counter vortex 23 and the passage vortex 24 are the causes of the secondary flow loss, and the wake (wake) from the trailing edge of the blade ) It was found that a velocity deficit of 25 was a major factor in blade profile loss.

  FIG. 7 is an average blade row loss distribution diagram in the blade row pitch direction from the blade end surface to the blade height (span) direction. From this diagram, the blade height direction ranges from 7 to 18%. It was found that the passage vortex 24 appeared.

  A velocity defect based on the boundary layer formed on the blade tip surface and the counter vortex 23 appears within 5% of the blade height direction of the blade tip.

  However, although this velocity deficit has a large pressure loss locally, the region is extremely small.

  For this reason, it is more important to reduce the secondary flow loss while leaving the velocity deficit as it is and suppressing the spread of the passage vortex 24 in the blade height (span) direction.

  As described above, in order to reduce the secondary flow loss, it is important to manage the blade surface roughness so that the passage vortex 24 does not progress in the blade height direction.

  In addition, the recent turbine blades adopt a high reaction type airfoil, and considering the fact that the blade row pitch is larger, there is a need to further manage the blade surface roughness and suppress the secondary flow loss. It was sought after.

  The present invention has been made based on such circumstances, and maintains the turbine blade roughness with high accuracy and manages the turbine blade, and further suppresses the secondary flow device output based on the passage vortex, and the turbine blade. It aims at providing a steam turbine provided with.

In order to achieve the above object, a turbine blade according to the present invention has a cylindrical inner peripheral wall and an outer peripheral wall formed coaxially, a front edge on the fluid inflow side, and a fluid as described in claim 1. The curved surface is formed between two curved surfaces, a ventral curved surface and a dorsal curved surface, formed between the rear edge of the outlet side, and the front edge and the rear edge are sandwiched between the inner peripheral wall and the outer peripheral wall. In the turbine blade provided with the blade body arranged as described above, from the blade body to the rear edge from an intermediate position between the front edge and the rear edge of each of the ventral curved surface and the back curved surface. The blade surface is used as a blade surface roughness management region, and at least one of the inner peripheral wall and the outer peripheral wall at both ends of the blade body is used as a blade endwall surface roughness management region, and the blade surface roughness management region And in the blade endwall surface roughness management area Kicking is obtained by setting the value of each surface roughness different predetermined value, respectively.

Turbine blade according to the present invention, in order to achieve the above object, as described in claim 2, in the turbine blade according to claim 1, wherein the wing body is a nozzle vanes, the inner circumferential wall and outer circumferential wall each The nozzle diaphragm inner ring and the nozzle diaphragm outer ring sandwich the blade body.

For turbine blades according to the present invention, to achieve the object described above, as described in claim 3, in the turbine blade according to claim 1, blade element body is a turbine blade, the outer peripheral wall the turbine It is a shroud provided at the outer peripheral end of the rotor blade.

In order to achieve the above-described object, the turbine blade according to the present invention has a surface roughness value of the blade surface roughness management region of A as described in claim 4 and the blade endwall surface roughness. When the surface roughness value of the management region is B, the blade height is H, the blade cord length is L, and the aspect ratio is H / L, the aspect ratio H / L is a boundary value. The relational expressions of the surface roughness A and B are made different from each other.

In order to achieve the above-described object, the turbine blade according to the present invention has a surface roughness value of the blade surface roughness management region as A and the blade endwall surface roughness as described in claim 5. When the surface roughness value of the management region is B, the blade height is H, and the blade cord length is L, when the aspect ratio H / L is 2 or less, the surface roughness A, B is A It is set so as to satisfy the relational expression ≧ B.

In order to achieve the above-described object, the turbine blade according to the present invention has a surface roughness value of A in the blade surface roughness management region as defined in claim 6 and the blade endwall surface roughness. When the surface roughness value of the management region is B, the blade height is H, the blade cord length is L, and the aspect ratio H / L is 2 or more, the surface roughness A, B is <B is set to satisfy the relational expression B.

In order to achieve the above-mentioned object, the turbine blade according to the present invention is configured such that, as described in claim 7 , the blade endwall surface roughness management region has a maximum height Ry of the blade endwall surface roughness. And when the blade cord length is L, the blade endwall surface roughness ratio Ry / L per unit length of the blade cord satisfies the relational expression of Ry / L <0.001. It is.

In order to achieve the above-described object, the turbine blade according to the present invention is configured such that, as described in claim 8 , the blade endwall surface roughness management region has a maximum height Ry of the blade endwall surface roughness. In this case, the relational expression of Ry <50 μm is satisfied.

In order to achieve the above-mentioned object, a turbine blade according to the present invention includes the turbine blade according to any one of claims 1 to 8 , as described in claim 9 .

  The turbine blade according to the present invention provides a blade surface roughness management region from the middle position on the abdominal side and the back side of the blade body to the trailing edge, and is provided on each of the diaphragm outer inner rings that support the both ends of the blade body. Since the blade endwall surface roughness control area is provided and the fluid flow is smooth and stable, the loss and pressure loss due to the secondary flow can be further suppressed. According to the turbine, the thermal efficiency can be further improved.

  Hereinafter, embodiments of a turbine blade according to the present invention will be described with reference to the drawings and the reference numerals attached to the drawings.

  The turbine blade according to this embodiment, for example, when the stationary blade 1 is an application target, the front edge 2 positioned on the inflow side of fluid such as steam, the rear edge 3 positioned on the outflow side of fluid, and the front The wing body 6 is composed of a ventral side 4 and a dorsal side 5 which are formed by connecting the edge 2 and the rear edge 3 with two ridgelines and forming a curved surface toward the outside.

  Further, the turbine blade according to the present embodiment sandwiches and supports the tip side (blade top side) and the root side (blade root side) of the blade body 6 between the diaphragm outer ring 7 and the diaphragm inner ring 8, respectively. A blade surface roughness management region 9 located in the blade surface low pressure region or blade surface high speed region where the momentum thickness of the boundary layer is large, and blade endwall surface roughness management regions 10a and 10b surrounding the wall surface are provided.

  Of these blade surface roughness management regions 9 and blade endwall surface roughness management regions 10a and 10b, the blade surface roughness management region 9 is shown in the figure, the ventral side 4 and back of the blade body 6 surrounded by a one-dot chain line. The region from the middle position of the side 5 to the trailing edge 3, and the blade endwall surface roughness management regions 10a and 10b are the inner wall of the diaphragm outer ring 7 (fluid of fluid) sandwiching and supporting both ends of the blade body 6. This is the entire region between the passage side) and the inner wall (the fluid passage side) of the diaphragm inner ring 8.

  Thus, in the present embodiment, the blade surface roughness management region 9 and the blade end wall surface roughness management regions 10a and 10b are divided into the blade body 6 and the inner walls of the outer and inner rings 7 and 8 of the diaphragm. In addition, since it is an area where the surface roughness of these divided areas 9, 10a, 10b is controlled to a preset value, the friction loss generated in the fluid passing through the areas 9, 10a, 10b can be kept low, Secondary flow loss can be further suppressed by suppressing the secondary flow vortex (passage vortex) generated on the root side of the blade body 6 from spreading in the blade height (blade span) direction.

  In addition, although this embodiment set the stationary blade as an application object, not only this example but a moving blade can also be an application object.

  When moving blades are applied, the blade surface roughness management region is the region from the middle position of the blade body to the trailing edge, as with the stationary blades, and the blade endwall surface roughness management region is The shroud provided at the tip corresponds to this.

  On the other hand, when comparing the surface roughness of the blade surface roughness management region 9 and the blade endwall surface roughness management region 10a, 10b, the value of the blade surface management roughness of the blade surface roughness management region 9 is A, In this embodiment, the aspect ratio H / L is H / L, where B is the wall management roughness value of the blade endwall surface roughness management regions 10a, 10b, H is the blade height, and the blade cord length L is L / H. In the case of L ≦ 2, the relational expression of the surface roughness values A and B is more preferably set to A ≧ B. In other words, in the present invention, in the blade having a relatively low blade height, the wall surface management roughness of the blade endwall surface roughness management regions 10a and 10b is set to be smaller than the blade surface management roughness of the blade surface roughness management region 9. Or set it to roughly the same roughness and manage it strictly.

  In the prior art, since the blade endwall surface roughness management region is not provided, the wall surface management roughness of the blade endwall surface roughness management regions 10a and 10b is set to the blade surface management of the blade surface roughness management region 9 in the present invention. Even if the roughness is set to be approximately the same as the roughness, the secondary flow loss can be suppressed lower than that of the conventional blade, but the relationship between the surface roughness values A and B is further set to A ≧ B. Greater effect can be expected.

  Further, when the aspect ratio H / L is H / L> 2, in the present embodiment, the relational expression of the surface roughness values A and B is set to A <B or the blade endwall surface roughness management regions 10a and 10b are set. Set to unmanaged area. Thus, in the present embodiment, when the aspect ratio H / L is H / L ≦ 2, the relational expression of the surface roughness A and B is A ≧ B or the blade endwall surface roughness management regions 10a and 10b. The surface roughness is set to a level equivalent to the blade surface roughness of the blade surface roughness management region 9 and the fluid flow is smooth and stabilized, so that the secondary flow loss can be further reduced. .

  In the present embodiment, when the aspect ratio H / L is H / L> 2, the relational expression of the surface roughness A and B is A <B or the blade endwall surface roughness management regions 10a and 10b are not managed. Therefore, roughness management can be performed at low cost.

  By the way, in the turbine blade according to the present embodiment, of the blade end wall surface roughness, when the maximum height is Ry (JIS notation maximum roughness) and the blade cord length is L, the unit length of the blade cord As shown in FIG. 2, it was confirmed by experiment that when the blade blade end wall surface roughness ratio Ry / L was controlled to Ry / L <0.001, the pressure loss was further reduced.

  That is, FIG. 2 shows that in the blade endwall surface roughness management regions 10a and 10b, the blade endwall surface roughness is set to the blade endwall surface roughness ratio Ry / L <0.001 per unit length of the blade cord. Furthermore, it is the diagram which compared the degree which reduced the pressure loss when the ratio shall be Ry / L> 0.001.

  From this diagram, the ratio Ry / L <0.001 is lower by the cascade loss δζ than the ratio Ry / L> 0.001, and is also reduced by the secondary flow vortex region δy. I understood it.

  As described above, in this embodiment, the blade endwall surface roughness is set so that the blade endwall surface roughness ratio Ry / L per unit length of the blade cord satisfies the relational expression of Ry / L <0.001. Since the management areas 10a and 10b are managed, the pressure loss and the secondary flow vortex area can be further reduced.

  In this embodiment, the blade endwall surface roughness management regions 10a and 10b are set so as to satisfy the relational expression of Ry / L <0.001, but the present invention is not limited to this example, and the blade endwall surface roughness is not limited to this example. Ry may be Ry <50.

The conceptual diagram which shows embodiment of the turbine blade which concerns on this invention. Among the turbine blades according to the present invention, the blade endwall surface roughness is set to the blade endwall surface roughness ratio Ry / L per unit length of the blade cord, and Ry / L <0.001 and Ry / L> 0. The diagram which compares a pressure loss when it is set to 001. Sectional drawing which shows the conventional axial flow type turbine. The diagram which shows the relationship between the blade surface speed and the momentum thickness of the conventional turbine blade. The diagram which shows the relationship between each of the ventral-side roughness and the back-side roughness and the momentum thickness in the conventional turbine blade. The figure explaining the behavior of the fluid which flows between blades in the conventional turbine blade. The diagram which shows the blade | wing loss based on the secondary flow of the fluid in the conventional turbine blade.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Stator blade 2 Leading edge 3 Trailing edge 4 Ventral side 5 Back side 6 Blade body 7 Diaphragm outer ring 8 Diaphragm inner ring 9 Blade surface roughness management region 10a, 10b Blade endwall surface roughness management region 11 Stator blade outer ring 12 Stator blade inner ring 13 Stator blade 14 Rotating shaft 15 Disc 16 Rotor blade 17 Shroud 18 Turbine stage 19 Fin 20 Labyrinth fin 21 Wing 22 Horseshoe-shaped vertical vortex 23 Counter vortex 24 Passage vortex 25 Wake

Claims (9)

Two curved shapes, a cylindrical inner peripheral wall and an outer peripheral wall formed coaxially, and a ventral curved surface and a back curved surface formed between a front edge on the fluid inflow side and a rear edge on the fluid outlet side. A turbine blade comprising a blade body that is formed of a curved surface and is arranged so that the front edge and the rear edge are sandwiched between the inner peripheral wall and the outer peripheral wall. Among the blade main bodies, the ventral curved surface and the back The blade surface from the intermediate position between the leading edge and the trailing edge of each of the side curved surfaces to the trailing edge is used as a blade surface roughness management region, and the inner peripheral wall and the outer periphery at both ends of the blade main body At least one surface of the wall is a blade endwall surface roughness management region, and each surface roughness value in the blade surface roughness management region and the blade endwall surface roughness management region is set to a different predetermined value. Characteristic that has been set Bottle wing. 2. The turbine blade according to claim 1, wherein the blade body is a nozzle blade, and the inner peripheral wall and the outer peripheral wall are respectively a nozzle diaphragm inner ring and a nozzle diaphragm outer ring that sandwich the blade body . 2. The turbine blade according to claim 1 , wherein the blade body is a turbine blade, and the outer peripheral wall is a shroud provided at an outer peripheral end of the turbine blade. The surface roughness value of the blade surface roughness management region is A, the surface roughness value of the blade endwall surface roughness management region is B, the blade height is H, and the blade cord length is L. 4. When the aspect ratio is H / L, the relational expressions of the surface roughnesses A and B are made different from each other with a predetermined value of the aspect ratio H / L as a boundary . The turbine blade according to any one of the preceding claims. The surface roughness value of the blade surface roughness management region is A, the surface roughness value of the blade endwall surface roughness management region is B, the blade height is H, and the blade cord length is L. The turbine blade according to claim 4 , wherein when the aspect ratio H / L is 2 or less, the surface roughnesses A and B are set so as to satisfy a relational expression of A ≧ B. The surface roughness value of the blade surface roughness management region is A, the surface roughness value of the blade endwall surface roughness management region is B, the blade height is H, and the blade cord length is L. The turbine blade according to claim 4 , wherein when the aspect ratio H / L is 2 or more, the surface roughnesses A and B are set so as to satisfy a relational expression of A <B . The blade endwall surface roughness management region is the blade endwall surface roughness per unit length of the blade cord when the maximum height of the blade endwall surface roughness is Ry and the blade cord length is L. the ratio Ry / L, Ry / L < 0.001 claims 1-3 set forth in any one turbine blade characterized by satisfying the relational expression. The blade endwall surface roughness management area, when the maximum height of the blade endwall surface roughness and Ry, either Ry <claims 1-3, characterized in that meet 50μm relation 1 The turbine blade according to the item. Steam turbine with a turbine blade according to any one of claims 1-8.

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