JP2000073704A - Turbine nozzle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the efficiency of a turbine by reducing the loss of kinetic energy given to a moving blade to the utmost. SOLUTION: In a turbine nozzle in which plural nozzle pieces 4 formed integrally a streamline shape nozzle blade 3 in which the upper streamside of a vapour flow is thick and its down streamside is thin are arranged in a ring shape between an inner wheel side base plate 1 and an outer wheel side base plate 2 and the flow passage of the vapour is constituted by joining these inner wheel side base plate 1 and outer wheel side base plate 2 to an inner wheel diaphragm 5 and outer wheel diaphragm 6 by welding, respective nozzle pieces 4 are constituted so that one side end surface of the inner wheel side base plate 1 and outer wheel side base plate 2 is formed on the continuous vertical surface with the same shape as the curve shape of the back surface of the nozzle blade 3 and the belly side end surface of the other nozzle blade of the inner wheel side base plate 1 and outer wheel side base plate 2 is formed on the vertical surface with the same curve shape as the back surface of the nozzle blade 3 of the adjacent nozzle pieces.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a turbine nozzle through which high-temperature, high-pressure steam flowing into a steam turbine passes as a high-speed steam flow.

[0002]

2. Description of the Related Art A steam turbine is a motor that generates mechanical output by converting thermal energy of steam into kinetic energy. In power generation turbines, high-temperature, high-pressure steam that has flowed into the turbine casing from the boiler passes through a paragraph section composed of nozzles installed in the casing and rotor blades that are implanted on the rotating shaft, thereby generating high temperature, By expanding the high-pressure steam and rotating the rotating shaft, a generator connected to the steam turbine is driven to obtain electric power.

As shown in FIG. 8, an outer ring diaphragm 81 and an inner ring diaphragm 82 are used as nozzles for passing a high-speed steam flow in the course of expansion, as shown in FIG. And a number of nozzle blades 83 disposed therebetween.

The inner ring diaphragm 82 and the outer ring diaphragm 81 support the nozzle blades 83 and also serve to separate steam having different pressures before and after the nozzle blades. It is positioned upstream or downstream of the blade steam flow.

Further, as shown in FIG. 9, the nozzle blade 83 has a streamline shape in which the thickness on the upstream side of the steam is large and the thickness decreases toward the downstream side. In addition, the flow path formed between the adjacent nozzle blades 83 gradually decreases toward the downstream, and has a minimum area near the outlet.

As described above, the nozzle blade and the inner and outer ring diaphragms constituting the nozzle are separately joined to each other by welding, mechanically assembled with bolts or the like, or formed into an integral structure by a high steam temperature. The structure is such that it can mechanically withstand the force caused by the pressure difference of steam under the above environment.

Accordingly, in the turbine nozzle having the above-described structure, the steam passing through the nozzle blades has a low speed on the inlet side, but the speed is increased as the flow path becomes narrower, and a high-speed steam flow is formed near the nozzle blade outlet. The rotating blades sprayed on the shaft give a rotating force.

Here, when the pressure distribution on the surface of two adjacent nozzle blades is examined in detail, the pressure of the concave portion (hereinafter referred to as the ventral side) along the flow of steam of the nozzle blades is changed to the convexity on the opposite side. Pressure (hereinafter referred to as the back side). Therefore, as shown in FIG. 10, in addition to the flow of the steam flowing in the outlet direction, there is also a flow flowing in the circumferential direction from the ventral side of the nozzle blade toward the back side of the adjacent nozzle blade. At this time, when this steam flow collides with the back of the adjacent nozzle blade, a flow rising in the direction of the nozzle blade and a flow flowing in the outlet direction generate a vortex, and the energy of the flow in the outlet direction is consumed Happens. This is generally referred to as a secondary loss, which is a loss of kinetic energy given to the rotor blade, and how to suppress this loss is important for improving the efficiency of the turbine.

[0009]

However, as shown in FIG. 10, the conventional sandwall-integrated turbine nozzle has a steam flow between the inner ring-side substrate 101, the not-shown outer ring-side substrate, and the central portion between these two substrates. A predetermined number of nozzle pieces 103 integrally formed with a streamlined nozzle blade 102 having a large upstream blade thickness and a small downstream blade thickness are combined in a ring shape to form an inner ring-side substrate and an outer ring-side substrate. The inner ring diaphragm and the outer ring diaphragm are welded and integrated. In this case, in each of the nozzle pieces 103, a connection portion between the inner ring-side substrate and the outer ring-side substrate formed integrally with the nozzle blade 102 is rounded with a radius of about 3 mm due to processing restrictions.

However, if the connection between the nozzle blade and the inner ring-side substrate and the outer ring-side substrate is round as described above, when steam flows from the ventral side of the nozzle blade to the adjacent nozzle back surface, the secondary The eddy current that causes the loss easily grows, which leads to an increase in energy loss applied to the blade side.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a turbine nozzle capable of improving the efficiency of a turbine by minimizing the loss of kinetic energy applied to a rotor blade. And

[0012]

According to the present invention, a turbine nozzle is constituted by the following means to achieve the above object. The invention corresponding to claim 1 is that a plurality of nozzle pieces are integrally arranged in a ring shape between a substrate on the inner ring side and a substrate on the outer ring side, in which streamline nozzle wings having a thicker upstream stream and a thinner downstream stream are integrally formed. The inner ring-side substrate and the outer ring-side substrate are joined to the inner ring diaphragm and the outer ring diaphragm by welding to form a steam flow path, wherein each of the nozzle pieces includes the inner ring-side substrate and the outer ring-side substrate. Is formed in a continuous vertical surface having the same shape as the curved surface of the back surface of the nozzle blade, and the other end surface of the inner ring side substrate and the outer ring side substrate on the side of the nozzle blade is adjacent to the nozzle piece. A streamlined nozzle blade with a thicker wing width on the upstream side and a smaller wing width on the downstream side between the inner ring side substrate and the outer ring side substrate formed on the same curved vertical surface as the back surface of the blade. Formed integrally A.

According to the turbine nozzle of the invention corresponding to the first aspect, one end face of each nozzle piece is formed on a vertical face continuous with the back face of the nozzle blade, and the other end face is formed with the back face of the adjacent nozzle blade. Since the inner ring side substrate and the outer ring side substrate formed on the same curved vertical surface are sequentially combined, a joining surface is formed between the back surface of each nozzle blade and the inner ring side substrate and the outer ring side substrate. Therefore, even when steam flows from the ventral side of the nozzle blade of one nozzle piece toward the rear face of the nozzle blade of the adjacent nozzle piece and collides, the vortex that generates secondary loss grows. It is difficult to reduce the secondary loss, and the efficiency of the turbine can be improved.

According to a second aspect of the present invention, in the turbine nozzle according to the first aspect of the present invention, a strip is provided on each surface of each of the nozzle pieces in contact with the inner ring diaphragm and the outer ring diaphragm of the inner ring side substrate and the outer ring side substrate. And annular grooves into which the projections provided on the inner ring-side substrate and the outer ring-side substrate are fitted, respectively, on the inner ring diaphragm and the outer ring diaphragm.

According to the turbine nozzle according to the second aspect of the present invention, in addition to the same effect as the first aspect of the invention, each nozzle piece is combined with the inner ring diaphragm and the outer ring diaphragm. In this case, the positioning is easy, and only the bolts need to be tightened and fixed, so that the assembling work can be greatly reduced.

According to a third aspect of the present invention, in the turbine nozzle according to the first aspect of the present invention, a ring-shaped inner ring-side band plate and an outer ring-side band plate provided on the side in contact with the inner ring diaphragm and the outer ring diaphragm, respectively. Providing through holes through which the inner ring side substrate and the outer ring side substrate of each nozzle piece can be inserted at intervals, and inserting the inner ring side substrate and the outer ring side substrate into these through holes to form the inner ring diaphragm and the outer ring diaphragm. It is intended to be incorporated.

According to the turbine nozzle according to the third aspect of the present invention, in addition to obtaining the same operation and effect as the first aspect of the invention, the inner ring-side substrate and the outer ring-side substrate of each nozzle piece are formed. By simply inserting the nozzle pieces into the through-holes provided in the inner ring-side band plate and the outer ring-side band plate, the positioning of each nozzle piece can be performed, thereby improving workability.

According to a fourth aspect of the present invention, a plurality of streamlined nozzle blades are arranged in a ring shape in which the upstream side of the steam flow is thick and the downstream side is thin, and the inner ring diaphragm provided on the inner diameter side and the outer ring side are provided on the outer diameter side. In a turbine nozzle joined by welding to an outer ring diaphragm to form a steam flow path, an inner ring piece forming the inner ring diaphragm, an outer ring piece forming the outer ring diaphragm, and a nozzle blade provided therebetween are integrally formed. Into a plurality of rings and integrally joined by welding or bolts. One end face of the inner ring piece and the outer ring piece is a continuous shape having the same shape as the curved shape of the back surface of the nozzle blade. The other end surface on the ventral side of the nozzle blade is formed on the vertical surface having the same curved shape as the back surface of the adjacent nozzle blade.

According to the turbine nozzle according to the fourth aspect of the invention, the same effect as that of the first aspect is obtained, and in addition, the nozzle piece, the inner race piece and the outer race piece are integrally formed. Since it is formed, it is not necessary to individually weld each nozzle piece to the inner ring diaphragm and the outer ring diaphragm by welding, and it is possible to improve workability.

According to a fifth aspect of the present invention, there is provided a steam flow path in which a plurality of stream-shaped nozzle blades having a thick upstream side and a thin downstream side are arranged in a ring shape, and these are joined to an inner ring diaphragm and an outer ring diaphragm. In the turbine nozzle, the outer ring piece constituting the outer ring diaphragm and the nozzle blade having the inner ring side substrate are integrally formed, and a plurality of these are arranged side by side in a ring shape and integrally formed by welding or bolts. And one end surface of the outer ring piece and the inner ring side substrate is formed as a continuous vertical surface having the same shape as the curved surface shape of the back surface of the nozzle blade, and the other end surface of the nozzle blade ventral side is adjacent It is formed on a vertical surface having the same curved shape as the back surface of the nozzle blade.

According to a sixth aspect of the present invention, there is provided a steam flow path in which a plurality of stream-shaped nozzle blades having a thicker upstream side and a thinner downstream side are arranged in a ring shape and joined to an inner ring diaphragm and an outer ring diaphragm. In the turbine nozzle, the inner ring piece constituting the inner ring diaphragm and the nozzle blade having the outer ring side substrate are integrally formed, and a plurality of these are arranged side by side in a ring shape and integrally formed by welding or bolts. One end surface of the inner ring piece and the outer ring side substrate is formed as a continuous vertical surface having the same shape as the curved surface shape of the back surface of the nozzle blade, and the other end surface of the nozzle blade ventral side is adjacent to the nozzle surface. It is formed on the vertical surface having the same curved shape as the back surface of the wing.

According to the fifth and sixth aspects of the present invention, the same effects as those of the first aspect of the invention can be obtained, and in addition, the nozzle piece and the outer ring piece, or the nozzle piece Since the inner ring piece and the inner ring piece are integrally formed, it is not necessary to individually weld each nozzle piece to the outer ring diaphragm or the inner ring diaphragm by welding, and the workability is improved accordingly.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 and FIG. 2 are perspective views of a turbine nozzle with an integrated sidewall showing a first embodiment of the present invention.

As shown in FIG. 1 and FIG.
And one end surface of the outer ring side substrate 2 is formed on a continuous vertical surface having the same shape as the curved surface shape of the back surface of the streamlined nozzle blade 3 provided between the two substrates, and the inner ring side substrate 1 and the outer ring side substrate 2 The nozzle piece 4 is formed with a vertical surface having the same curved shape as the back surface of the nozzle blade 3 adjacent to the other end face of the nozzle blade. Then, a predetermined number of nozzle pieces 4 are sequentially arranged so as to face the ventral side of each nozzle blade with respect to the flow of steam, and are combined in a ring shape, and these inner ring side substrate 2 and outer ring side substrate 1 are connected to inner ring diaphragm 5. And the outer ring diaphragm 6 to be integrally formed.

In this case, each of the nozzle pieces 4 is formed by precision casting or machining of alloy steel to machine the inner ring side substrate 1 and the outer ring side substrate 2 and the streamlined nozzle blades 3 provided therebetween. In the turbine nozzle having the above-described configuration, the one end face of each nozzle piece 4 is formed as a continuous vertical surface having the same shape as the curved shape of the back surface of the nozzle blade 3. Since the inner ring side substrate 1 and the outer ring side substrate 2 whose nozzle blade ventral end surfaces are formed in the same curved shape as the back surface of the adjacent nozzle blade 3 are sequentially combined, the back surface of each nozzle blade 3 and the inner ring side substrate 1 are combined. In addition, roundness existing between the outer ring-side substrate 2 and the outer ring-side substrate 2 can be eliminated.

Therefore, as shown in FIG. 1, even if the steam flows from the ventral side of the nozzle blade 3 of one nozzle piece 4 toward the rear surface of the nozzle blade 3 of the adjacent nozzle piece 4 and collides, the secondary loss is reduced. The generated eddy current is difficult to grow and the secondary loss can be suppressed low, and the efficiency of the turbine can be improved.

FIG. 3 is a perspective view of a sidewall-integrated turbine nozzle showing a second embodiment of the present invention.
The same parts as those in FIG. In the second embodiment, as shown in FIGS. 3A and 3B, strips are provided on the respective surfaces of the nozzle pieces 4 which are in contact with the inner ring diaphragm 5 and the outer ring diaphragm 6 of the inner ring side substrate 1 and the outer ring side substrate 2 respectively. And annular grooves corresponding to the projections 1a and 2a provided on the inner ring side substrate 1 and the outer ring side substrate 2 of each nozzle piece 4 on the inner ring diaphragm 5 and the outer ring diaphragm 6, respectively. 5a and 6a are provided respectively, and the protrusions 1a and 2a of the inner ring side substrate 1 and the outer ring side substrate 2 of each nozzle piece 4 are fitted into the grooves 5a and 6a of the inner ring diaphragm 5 and the outer ring diaphragm 6 to form a ring. After the combination, the whole is integrally tightened and fixed by bolts.

Here, the shapes and configurations of the nozzle blades 3 of the nozzle pieces 4 and the inner ring side substrate 1 and the outer ring side substrate 2 are the same as those in FIG.
With the turbine nozzle having the sidewall integral structure having such a configuration, the same operation and effect as those of the first embodiment can be obtained.
And the outer ring diaphragm 6 can be easily positioned, and only the bolts need to be fastened and fixed, so that the assembling work can be greatly reduced.

FIG. 4 is a perspective view of a turbine nozzle of a side wall integrated type showing a third embodiment of the present invention.
The same parts as those in FIG. In the third embodiment, as shown in FIGS. 4 (a) and 4 (b), ring-shaped inner ring side band plates 7 and outer ring side band plates 8 provided on the sides in contact with the inner ring diaphragm 5 and the outer ring diaphragm 6, respectively. Inner ring side substrate 1 and outer ring side substrate 2 of nozzle piece 4
Through holes 7a and 8a are provided at predetermined intervals to allow the nozzle pieces 4 to be inserted into the through holes 7a and 8a.
Is inserted into the inner ring diaphragm 5 and the outer ring diaphragm 6 and integrated with the inner ring diaphragm 5 and the outer ring diaphragm 6 by welding. In this case, the inner ring side band plate 7 and the outer ring side band plate 8 have the same thickness as the thickness of the inner ring side substrate 1 and the outer ring side substrate 2, and the shapes of the through holes 7a, 8a are the inner ring side substrate 1 and the outer ring side substrate. It has the same shape as 2.

Here, since the shapes and configurations of the nozzle blades 3 of the nozzle pieces 4 and the inner ring side substrate 1 and the outer ring side substrate 2 are the same as those in FIG. 1, the description is omitted here.
With the sidewall-integrated turbine nozzle having such a configuration, the same operation and effect as those of the first embodiment can be obtained, and in addition, the inner ring-side substrate 1 and the outer ring-side substrate 2 of each nozzle piece 4 can be used. The nozzle pieces 4 can be positioned simply by inserting them into the through holes 7a and 8a provided in the inner ring side band plate 7 and the outer ring side band plate 8, so that the workability can be improved.

FIG. 5 is a perspective view of a turbine nozzle of a side wall integrated type showing a fourth embodiment of the present invention.
The same parts as those in FIG. In the fourth embodiment, as shown in FIG. 5, a nozzle piece 4, an inner ring piece 5b constituting an inner ring diaphragm 5 provided on the inner diameter side of the nozzle piece 4, and an outer ring diaphragm 6 provided on the outer diameter side are formed. The outer ring piece 6b to be formed is integrally formed, and a plurality of these are arranged side by side in a ring shape and joined by welding or bolts.

Here, the nozzle blade 3, the inner ring piece 5b and the outer ring piece 6b of each nozzle piece 4 have the same shape and configuration as those of the nozzle blade 3 and the inner ring side substrate 1 and the outer ring side substrate 2 in FIG. It is.

With the turbine nozzle having the sidewall integral type having the above-described structure, the same operation and effect as those of the first embodiment can be obtained, and the nozzle piece 4 and the inner ring piece 5 can be obtained.
Since the b and the outer ring piece 6b are integrally formed, it is not necessary to individually weld the nozzle pieces 4 to the inner ring diaphragm 5 and the outer ring diaphragm 6 by welding.

FIG. 6 is a perspective view of a turbine nozzle integrated with a side wall, showing a fifth embodiment of the present invention.
The same parts as those in FIG. In the fifth embodiment, as shown in FIG. 6, a nozzle piece 4 and an outer ring piece 6b serving as an outer ring diaphragm 6 provided on the outer diameter side of the nozzle piece 4 are integrally formed, and this is formed into an inner ring diaphragm. A predetermined number of rings are arranged side by side along the peripheral surface of No. 5 and joined by welding or bolts.

In this case, the nozzle wings 3 and the outer ring pieces 6b of each nozzle piece 4 have the same shape and configuration as the nozzle wings 3 and the outer ring side substrate 2 of FIG. 2, and the nozzle wings 3 and the inner ring side substrate 1 are also illustrated. It has the same shape as 2.

With the turbine nozzle having the above-described structure, the same effect as that of the first embodiment can be obtained. In addition, the nozzle piece 4 and the outer ring piece 6 can be obtained.
Since b is integrally formed, it is not necessary to individually weld each nozzle piece 4 and the outer ring diaphragm 6 by welding, and the workability is improved accordingly.

FIG. 7 is a perspective view of a turbine nozzle of a side wall integrated type showing a sixth embodiment of the present invention.
The same parts as those in FIG. In the sixth embodiment, as shown in FIG. 7, a nozzle piece 4 and an inner ring piece 5b serving as an inner ring diaphragm 5 provided on the inner diameter side of the nozzle piece 4 are integrally formed. A predetermined number of rings are arranged side by side along the peripheral surface of the member and joined by welding or bolts.

In this case, the nozzle blade 3 and the inner ring piece 5b of each nozzle piece 4 have the same shape and configuration as the nozzle blade 3 and the inner ring side substrate 1 of FIG. 2, and the nozzle blade 3 and the outer ring side substrate 2 are also shown in FIG. It has the same shape as 2.

With the turbine nozzle having the above-described structure, the same effect as that of the first embodiment can be obtained, and the nozzle piece 4 and the inner ring piece 5 can be obtained.
Since b is integrally formed, it is not necessary to join each nozzle piece 4 and the inner ring diaphragm 5 by welding, and the workability is improved accordingly.

[0040]

As described above, according to the present invention, it is possible to provide a turbine nozzle capable of improving the efficiency of the turbine by minimizing the loss of kinetic energy given to the moving blade.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a nozzle piece of a turbine nozzle according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing the turbine nozzle of the embodiment.

FIG. 3 is a perspective view showing a second embodiment of the turbine nozzle according to the present invention.

FIG. 4 is a perspective view showing a third embodiment of the turbine nozzle according to the present invention.

FIG. 5 is a perspective view showing a fourth embodiment of the turbine nozzle according to the present invention.

FIG. 6 is a perspective view showing a fifth embodiment of a turbine nozzle according to the present invention.

FIG. 7 is a perspective view showing a sixth embodiment of a turbine nozzle according to the present invention.

FIG. 8 is a perspective view showing a general nozzle diaphragm.

FIG. 9 is a flow distribution diagram of a turbine nozzle.

FIG. 10 is a perspective view showing a conventional sidewall-integrated turbine nozzle.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Inner ring side board 2 ... Outer ring side board 1a, 2a ... Protrusion 3 ... Nozzle blade 4 ... Nozzle piece 5 ... Inner ring diaphragm 6 ... Outer ring diaphragm 5a, 6a ... Groove 5b ... Inner ring piece 6b Outer ring piece 7 Inner ring side strip 8 Outer ring side strip 7a, 8a Through hole

Claims (6)

[Claims] 1. A plurality of nozzle pieces integrally formed with a streamlined nozzle blade on the upstream side of the steam flow and thin on the downstream side between the inner ring side substrate and the outer ring side substrate. In a turbine nozzle in which an inner ring side substrate and an outer ring side substrate are joined to an inner ring diaphragm and an outer ring diaphragm by welding to form a steam flow path, each of the nozzle pieces is one end surface of the inner ring side substrate and the outer ring side substrate. Is formed on a continuous vertical surface having the same shape as the curved surface shape of the back surface of the nozzle blade, and the other end surfaces of the inner ring side substrate and the outer ring side substrate on the side of the nozzle blade abdomen are adjacent to each other. A turbine nozzle formed on a vertical surface having the same curved shape. 2. The turbine nozzle according to claim 1, wherein a strip projection is provided on each surface of each nozzle piece that contacts the inner ring diaphragm and the outer ring diaphragm of the inner ring side substrate and the outer ring side substrate, respectively. A turbine nozzle, wherein annular grooves are provided in the diaphragm and the outer ring diaphragm, into which protrusions provided on the inner ring side substrate and the outer ring side substrate are fitted. 3. The turbine nozzle according to claim 1, wherein each of the nozzle pieces has a predetermined interval between a ring-shaped inner ring-side band plate and an outer ring-side band plate provided on a side contacting the inner ring diaphragm and the outer ring diaphragm, respectively. Turbine characterized by providing through holes into which an inner ring-side substrate and an outer ring-side substrate can be inserted, respectively, and inserting the inner ring-side substrate and the outer ring-side substrate into these through-holes and incorporating them into the inner ring diaphragm and the outer ring diaphragm. nozzle. 4. A plurality of streamlined nozzle vanes arranged in a ring shape in which the upstream side of the steam flow is thick and the downstream side is thin are joined by welding to an inner ring diaphragm provided on the inner diameter side and an outer ring diaphragm provided on the outer diameter side. In the turbine nozzle configured to form a steam flow path, an inner race piece forming the inner race diaphragm, an outer race piece forming the outer race diaphragm, and a nozzle blade provided therebetween are integrally formed. One end face of the inner race piece and the outer race piece is formed as a continuous vertical surface having the same shape as the curved surface shape of the back surface of the nozzle blade, and is arranged in a ring shape and integrally joined by welding or bolts,
A turbine nozzle, characterized in that the other end face on the ventral side of the nozzle blade is formed on a vertical surface having the same curved shape as the back surface of the adjacent nozzle blade. 5. A turbine in which a plurality of streamlined nozzle blades are arranged in a ring shape in which a steam flow is thick on an upstream side and thin on a downstream side, and these are joined to an inner ring diaphragm and an outer ring diaphragm to constitute a steam flow path. In the nozzle, an outer ring piece constituting the outer ring diaphragm and a nozzle blade having an inner ring side substrate are integrally formed, and a plurality of these are juxtaposed in a ring shape and integrally joined by welding or bolts, One end surface of the outer ring piece and the inner ring side substrate is formed as a continuous vertical surface having the same shape as the curved surface shape of the back surface of the nozzle blade, and the other end surface of the nozzle blade ventral side is the same as the back surface of the adjacent nozzle blade. A turbine nozzle formed on a curved vertical surface. 6. A turbine in which a plurality of streamlined nozzle vanes are arranged in a ring shape in which the upstream side of a steam flow is thick and the downstream side is thin, and these are joined to an inner ring diaphragm and an outer ring diaphragm to form a steam flow path. In the nozzle, an inner ring piece constituting the inner ring diaphragm and a nozzle blade having an outer ring side substrate are integrally formed, and a plurality of these are juxtaposed in a ring shape and integrally joined by welding or bolts, One end surface of the inner ring piece and the outer ring side substrate is formed as a continuous vertical surface having the same shape as the curved surface shape of the back surface of the nozzle blade, and the other end surface on the ventral side of the nozzle blade is the same as the back surface of the adjacent nozzle blade. A turbine nozzle formed on a curved vertical surface.