JP3806373B2 - Paragraph structure of axial turbine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a paragraph structure of an axial flow turbine such as a steam turbine.
[0002]
[Prior art and problems to be solved by the invention]
As a stage structure of an axial flow turbine such as a steam turbine, for example, as shown in FIG. 4, a stationary blade 100 and a moving blade 101 are alternately arranged in multiple stages with gaps G.
[0003]
However, in such a stage structure of an axial turbine, since there is a gap (cavity) G between the cascades, the vortex generated in the gap G interferes with the main flow to increase mixing loss, There was a problem that the inlet condition of the wake (the moving blade 101) was affected and the blade performance was deteriorated.
[0004]
The present invention has been made in view of the above-described situation, and the axial structure of an axial flow turbine capable of effectively suppressing the generation of vortices in a gap between blade rows and improving blade performance by a simple blade shape. The purpose is to provide.
[0005]
[Means for Solving the Problems]
In order to achieve such an object, the axial structure of the axial turbine according to the present invention is the axial structure of the axial turbine in which the stationary blades and the moving blades are arranged in multiple stages with gaps alternately. An overhang portion is provided along a fluid flow direction at a gap inlet portion of the downstream end surface of the inner and outer platforms of the stationary blade, and a gap between the upstream end surfaces of the inner and outer platforms of the moving blade facing the overhang portion. An R portion is provided at an inlet portion, and an R portion is provided along the R portion provided on the inner and outer platforms of the moving blade on the inner surface of the stationary blade and on the back side of the outer platform. .
[0006]
In addition, the R portion is a single arc projection.
[0007]
Further, a relational expression of R / L = 0.1 to 0.5 is established between the radius of curvature R of the R portion and the gap L of the gap.
[0008]
Further, the arc of the R portion and the arc of the leading edge R portion of the downstream blade root of the rotor blade do not intersect in the blade length direction.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the paragraph structure of an axial turbine concerning the present invention is explained in detail using an example using a drawing.
[0010]
[Example]
FIG. 1 is a cross-sectional view of a main part of a steam turbine showing an embodiment of the present invention, FIG. 2 is a structural explanatory view of the hub side and the tip side, and FIG. 3 is a schematic longitudinal cross-sectional view of the steam turbine.
[0011]
As shown in FIG. 3, the steam turbine as an axial flow turbine is formed by a casing 1 and a rotor (rotating body) 2, and the rotor 2 is fixed to the turbine shaft 3 and the turbine shaft 3, and the turbine shaft 3. And a rotating blade 4 that rotates together.
[0012]
A stationary blade 5 is disposed upstream of the moving blade 4 in the flow direction of steam (fluid), and the stationary blade 5 is supported by the casing 1.
[0013]
The stationary blades 5 and the moving blades 4 are arranged in multiple stages with gaps G alternately in an enlarged flow passage 6 formed between the casing 1 and the turbine shaft 3.
[0014]
Therefore, the steam supplied to the inside of the casing 1 flows while expanding in the enlarged flow passage 6 as indicated by arrows in the figure, and the moving blade 4 is actuated by the steam ejected through the stationary blade 5, whereby the rotor 2 Will be rotated.
[0015]
In this embodiment, as shown in FIG. 1, an overhang portion 7 is provided along the steam flow direction at the gap inlet portion of the downstream end face of the inside and outside platforms 5a and 5b of the stationary blade 5, and this An R portion 8 is provided at the gap inlet portion on the upstream end face of the inner and outer platforms 4a and 4b of the rotor blade 4 facing the overhang portion 7.
[0016]
In the illustrated example, the R portion 8 is formed by one arc protrusion, but it may be a shape in which the corners of the upstream side end surfaces of the inner and outer platforms 4a and 4b are removed instead of the protrusion.
[0017]
As shown in FIG. 2, a relational expression of R / L = 0.1 to 0.5 is established between the radius of curvature R of the R portion 8 and the gap L of the gap G. .
[0018]
In the illustrated example, the relational expression R1 / L = 0.1 to 0.5 is established between the curvature radius R1 of the back surface side R portion of the overhang portion 7 and the gap L of the gap G. .
[0019]
The arc (trajectory) of the radius of curvature R of the R portion 8 and the arc (trajectory) of the radius of curvature R2 of the leading edge R portion of the root of the moving blade on the downstream side do not intersect in the blade length direction. .
[0020]
Further, the inside of the upstream stationary blade 5, the outside platforms 5a, 5b and the inside of the downstream moving blade 4, the outside platforms 4a, 4b are provided on the same straight line shown by the broken line in FIG. (Line Online). Accordingly, the overhang portion 7 and the R portion 8 are also located outside the straight line.
[0021]
In this way, in the present embodiment, the gap H between the blades is reduced as much as possible by the overhang portion 7 and the R portion 8, and the main flow of steam is positively guided from the upstream side to the downstream side. Therefore, the generation of vortices in the gap G can be suppressed and interference between the vortices and the mainstream can be reduced.
[0022]
Thereby, an increase in mixing loss (fluid loss) can be avoided and blade performance can be improved, and the performance of the entire turbine is improved.
[0023]
In addition, the R portion 8 is formed by a single arc projection, and an arc (trajectory) of the radius R of the R portion 8 and an arc (trajectory) of the curvature radius R2 of the leading edge R portion of the moving blade root on the downstream side. Since it does not intersect with the blade length direction, a relatively simple blade shape can be used, and the processing cost by a lathe can be reduced.
[0024]
Further, a relational expression of R / L = 0.1 to 0.5 is established between the radius of curvature R of the R portion 8 and the gap L of the gap G, and the back side R of the overhang portion 7. The curvature radius R1 of the portion is set so that the relational expression R1 / L = 0.1 to 0.5 is established between the gap G and the gap L of the gap G, so that the generation of vortices in the gap G is suppressed. The axial thermal expansion of the rotor 2 and the like can also be effectively absorbed.
[0025]
Needless to say, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the present invention. Further, the present invention is not limited to the steam turbine but can be applied to an axial flow turbine such as a gas turbine.
[0026]
【The invention's effect】
As described above in detail, the invention according to claim 1 of the present invention is the above-described paragraph structure of an axial-flow turbine in which the stationary blades and the moving blades are arranged in multiple stages with gaps alternately. An overhang portion is provided along a fluid flow direction at a gap inlet portion of a downstream end surface of the inner and outer platforms of the stationary blade, and a gap between the upstream end surfaces of the inner and outer platforms of the moving blade facing the overhang portion. Since the R part is provided at the inlet part and the R part is provided along the R part provided on the inner and outer platforms of the moving blades on the back surface side of the inner and outer platforms of the stationary blade , a simple blade shape This effectively suppresses the generation of vortices in the gap between the blade rows and improves blade performance.
[0027]
In the invention according to claim 2 of the present invention, since the R portion is a single arc projection, a relatively simple blade shape is sufficient, and the processing cost by a lathe can be reduced.
[0028]
In the invention according to claim 3 of the present invention, a relational expression of R / L = 0.1 to 0.5 is established between the curvature radius R of the R portion and the gap L of the gap. The thermal expansion in the axial direction of the rotor or the like can be effectively absorbed while suppressing the generation of vortices.
[0029]
In the invention according to claim 4 of the present invention, the arc of the R portion and the arc of the leading edge R portion of the moving blade root on the downstream side do not intersect in the blade length direction, so a relatively simple blade shape is sufficient. The processing cost with a lathe is small.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a main part of a steam turbine showing an embodiment of the present invention.
FIG. 2 is a structural explanatory view of the hub side and the chip side in the same manner.
FIG. 3 is a longitudinal sectional view of a schematic configuration of a steam turbine.
FIG. 4 is a cross-sectional view of a main part of a conventional steam turbine.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Casing 2 Rotor 3 Turbine shaft 4 Rotor blade 4a Inner platform 4b Outer platform 5 Stator blade 5a Inner platform 5b Outer platform 6 Expanded flow path 7 Overhang part 8 R part G Gap

Claims (4)

In the stage structure of the axial flow turbine in which the stationary blades and the moving blades are arranged in multiple stages with gaps alternately,
Providing an overhang along the fluid flow direction at the gap inlet of the downstream end face of the inner and outer platforms of the stationary blade,
An R portion is provided at the gap inlet portion of the upstream end surface of the inner and outer platforms of the rotor blade facing the overhang portion,
And the stage structure of the axial-flow turbine characterized by providing the R part which followed the said R part provided in the inner side of the said moving blade, and the outer platform on the inner surface of the said stationary blade, and the back surface side of the outer platform .   The paragraph structure of the axial-flow turbine according to claim 1, wherein the R portion is one arc projection.   The axial flow turbine according to claim 1, wherein a relational expression of R / L = 0.1 to 0.5 is established between a radius of curvature R of the R portion and a gap L of the gap. Paragraph structure.   The axial structure of the axial flow turbine according to claim 1, 2 or 3, wherein the arc of the R portion and the arc of the leading edge R portion of the root of the rotor blade on the downstream side do not intersect in the blade length direction.

Images