JPH0196401A - Turbine nozzle - Google Patents

Abstract

PURPOSE:To prevent occurrence of secondary vortex by inclining the joint end section of a nozzle blade in the direction of blade row with respect to a reference line passing through the center of rotation of a turbine, thereby suppressing growth of border layer on the circumferential wall face. CONSTITUTION:A plurality of nozzle blades 1b are arranged in a row in the circumferential direction of a circular path 4 formed between a nozzle inner ring 3 and a nozzle outer ring 2. A joint end member of the nozzle blade 1b at the side of the inner ring 3 inclines in the direction of the blade row against a reference line E passing through the center of rotation of a turbine, and the central face 9 faces a circumferential wall face D formed at the circumferential wall side of the inner ring 3. Consequently, working fluid flowing into the inclined member flows along the central face 9 of the inclined nozzle blade 1b and is pressed in the direction of a border layer. As a result, growth of the border layer on the circumferential wall face D is suppressed and production of secondary vortex is prevented.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a turbine nozzle for an axial flow turbine, and in particular to suppressing the development of a boundary layer that occurs on the peripheral wall surface of an annular flow path of the turbine nozzle. The present invention relates to a turbine nozzle that can improve turbine performance by preventing the generation of secondary flows and reducing pressure loss due to secondary vortices generated when the secondary flows are disturbed.

(Prior Art) In recent years, it has become an important issue to improve turbine performance in order to improve the operational economy of power plants and improve power generation efficiency.

In order to improve turbine performance, it is necessary to reduce pressure loss in each turbine stage. Internal losses in the turbine stage include airfoil loss, leakage loss, outflow loss, etc.
Particularly in turbines with low nozzle adjustment heights, the ratio of secondary loss due to secondary flow is high, and reducing the airfoil loss has become a major issue.

FIG. 10 shows the stage configuration of a typical axial flow turbine. A plurality of nozzle blades 1 are fixedly installed in an annular flow path 4 formed between a nozzle outer ring 2 and a nozzle inner ring 3. A plurality of rotor blades 5 are disposed on the downstream side facing the nozzle blade 1 . The actuators (2) 5 are implanted in rows at predetermined intervals in the circumferential direction of the outer periphery of the rotor disk 6. A shroud 7 is fixed to the outer peripheral end of the first a5 in order to fix the rotor blade tip and to prevent leakage of working fluid. On the other hand, a nozzle labyrinth 8 is attached to the nozzle outer ring 2 so as to face the shroud 7 in order to prevent leakage loss of the working fluid.

Next, a mechanism for generating a secondary flow in the nozzle blade 1 in the above-mentioned paragraph configuration will be explained with reference to FIG. 11. FIG. 11 is a perspective view of the turbine nozzle shown in FIG. 10, viewed from the nozzle outlet side.

Each nozzle blade 1 is shown as an example in which it is not inclined with respect to a reference line E passing through the center of rotation of the rotor disk 6, but is disposed perpendicularly to the outer circumferential surface of the nozzle inner ring 3.

Working fluids such as high-pressure steam are F! l! ! When flowing through the inter-blade flow path between the nozzle blades 1.1 provided, the flow is bent into an arc shape in the flow path. At this time, centrifugal force is generated from the back surface 10 of the nozzle blade 1 in the direction of the ventral surface 9, and since this centrifugal force and static pressure are in balance, the static pressure on the ventral surface 9 increases, while the flow rate of the working fluid on the back surface 10 increases. is large, so the static pressure is low. Therefore, a pressure gradient is generated in the flow path from the ventral surface 9 side to the back surface 10 side. This pressure gradient is the same in the slow flow layer, that is, the boundary layer, formed on the peripheral wall surfaces of the nozzle outer ring 2 and the nozzle inner ring 3.

However, near the boundary layer, the flow velocity is low and the centrifugal force acting is also small, so the pressure gradient from the ventral surface 9 side to the back surface 10 cannot be resisted, and the ventral surface 9g! A flow toward the back surface 10 side, that is, a secondary flow 11 is generated.

The secondary flow 11 then collides with the back surface 10 side of the nozzle blade 1 and rolls up, generating secondary vortices 12a and 12b at both the joint ends of the inner ring side and the outer ring side of the nozzle vA1, respectively. The energy possessed by the working fluid is thus partially dissipated to form the secondary vortex 12.

FIG. 12 is a graph showing the distribution of total pressure loss at the nozzle outlet shown in FIG.
The pressure loss distribution in the area surrounded by 3 is shown. The numerical values in the figure are percentages of the total pressure loss, and a large value indicates a large pressure loss.

As shown in Fig. 12, a boundary layer with a large pressure loss is formed at the tip of the nozzle outer ring circumferential wall surface C and at the root portion of the nozzle inner ring circumferential wall surface, and a secondary production area B is formed near the boundary layer.
It can be seen that appears.

The secondary vortices 12a, 12 generated in the nozzle flow path in this way
b causes non-uniform flow of the working fluid, which significantly reduces nozzle performance, and also causes energy loss of the working fluid flowing into the downstream working fluid W5, reducing the performance of each turbine stage.

The secondary 'f412a generated within the nozzle flow path mentioned above.

Various turbine nozzle structures have been studied to solve the problems caused by 12b. For example, Japanese Patent Laid-Open No. 108804/1983 discloses a turbine nozzle that employs inclined nozzle blades to suppress the development of a boundary layer on a wall surface.

FIG. 13 is a perspective view showing a turbine nozzle employing the above-described inclined nozzle blade 1a. The configuration of this turbine nozzle itself is the same as the nozzle configuration of a general axial flow turbine shown in FIGS. 10 and 11. However, nozzle 1W
1a is fixed at an angle of inclination β with respect to a reference line E passing through the center of rotation of the rotor disk.

The inclination angle β of this nozzle H1a is the total length of the nozzle blade HN1
When the average arrangement pitch of the nozzle blades is PN, the dimensionless number σ, which is an index of the degree of inclination, is set to be larger than 1.3. Here, the dimensionless number σ is given by the following equation (1), and the inclination angle β is limited by the shape and arrangement pitch of the nozzle blades 1a.

(7=H-tanβ/PM ・−・・−(1) 1st
FIG. 4 is a sectional view showing the pressure gradient in the nozzle passage in a turbine nozzle employing the above-mentioned inclined nozzle llll1a, as seen from the working fluid outlet side.

Each nozzle blade 1a is fixed at an inclination angle β such that its ventral surface 9 is oriented toward the nozzle inner ring peripheral wall surface, so that there is a pressure gradient in the flow path of the working fluid flowing from the ventral surface 9 side to the back surface 10 side. F points in the direction of the nozzle inner ring circumferential wall surface.

Therefore, the streamline G of the working fluid in the nozzle flow path is formed as shown in FIG. 15. That is, the working fluid is pushed in the nozzle inner ring 3 direction in the inclined nozzle flow path by the action of the pressure gradient F, and the working fluid flows 1!
jG is largely shifted in the direction of the nozzle inner ring circumferential wall surface. Therefore, the boundary layer develops little at the nozzle blade joint end (root part) near the nozzle inner ring peripheral wall surface (the flow velocity of the working fluid does not decrease, making it difficult for secondary flow to occur).

As a result, the generation of secondary vortex 12 is also eliminated, and secondary loss at the nozzle root portion is significantly reduced.

(Problems to be Solved by the Invention) As described above, in the turbine nozzle that employs the conventional inclined nozzle blade 1a, the nozzle inner ring 3 of the nozzle blade 1a
The side root portion has the effect of reducing secondary loss.

However, in the tip portion of the nozzle l11a on the nozzle outer ring 2 side, there is a problem in that the secondary loss increases. That is, in the vicinity of the nozzle outer ring circumferential wall surface C, the flow rate of the working fluid decreases and the pressure gradient also decreases toward the root direction of the nozzle blade 1a, so that the boundary layer near the nozzle outer ring circumferential wall surface C tends to develop, and the boundary layer A so-called separation phenomenon, in which the layer separates from the wall surface C and flows out into the main flow of the working fluid, is likely to occur.

As a result, the secondary vortex 12b is likely to be generated behind the nozzle W1a at the joint end (tip portion) of the nozzle m'+a on the nozzle outer ring side.

Therefore, the effect of reducing the pressure loss of the entire nozzle m1a after subtracting the change in pressure loss at the root portion on the inner ring side of the nozzle and the tip portion on the outer ring side of the nozzle is small.

FIG. 16 is a graph showing the distribution of total pressure loss at the outlet of a turbine nozzle formed with an inclined nozzle m1a, which is similar to the case where the nozzle blade 1 shown in FIG. 12 is formed perpendicularly along the reference line. speed up the distribution.

However, from FIG. 16, the pressure loss at the root portion of the nozzle inner ring side of the nozzle W1a is significantly reduced, the development of the boundary layer is suppressed DI, and the area of the secondary vortex region 1aB is also reduced.

On the other hand, it can be seen that in the tip portion of the nozzle blade 1a on the side of the nozzle outer ring, the boundary layer is conversely developed, the secondary vortex region B is also greatly expanded, and the pressure loss is significantly increased.

Further, according to FIG. 3, the distribution of the average total pressure loss at each position of the nozzle W1a will be explained.

In Figure 3, the horizontal axis shows the average total pressure loss in the circumferential direction of the turbine nozzle, while the vertical axis shows the dimensionless height expressed as the ratio of the height H in the blade span direction for a nozzle blade with a total height H8. There is.

In FIG. 3, the average total pressure loss curve 1! of the conventional inclined nozzle 5li11a! If and the average total pressure loss curve J of the vertical nozzle vane 1 arranged vertically along the reference line, it is found that the inclined nozzle vane 1a has an average total pressure loss curve J at the root of the nozzle 911a compared to the vertical nozzle N1. Total pressure loss is reduced.

However, the pressure increases significantly at the tip of the nozzle Wla, and the total pressure j0 loss increases for the nozzle blade 1a as a whole, resulting in a problem of deterioration of turbine performance.

Furthermore, there is a problem in that the average flow of the working fluid at each position in the blade length direction of the nozzle 11.1a becomes non-uniform, causing a mixing loss inside the rotor blade 5, resulting in a decrease in turbine stage performance. .

For example, FIG. 4 is a graph showing the distribution of the flow rate of the working fluid at each position H in the span direction of the nozzle blade. The ratio of the average flow ff1G is taken, and the Wl axis shows the dimensionless height expressed as the ratio of each position H in the blade span direction to the nozzle blade with the total height HN.

Nozzle exit circumferential average flow curve of a turbine nozzle configured with a conventional inclined nozzle Wla and nozzle exit circumferential average flow curve 1 of a turbine nozzle configured with vertical nozzle blades 1
! Comparing with i1M, in the case of inclined nozzle Mla,
Compared to the case of the conventional vertical nozzle TA'1, the vertical nozzle EQ1a
While the flow rate of the working fluid increases significantly at the root, the flow rate decreases extremely at the tip.
It can be seen that the flow rate decrease occurs even near the center of XJ1a (=J5), and that the working fluid is unevenly distributed in the root part of the turbine nozzle at t4E, forming an uneven flow.

As a result, as shown in FIG.
In the linear flow path 4, when the streamline G that has been deflected toward the nozzle root portion is introduced into the passage between the rotor blades 5, it is again bent toward the outer circumferential direction. In other words, the density of the working fluid is low at the outer periphery of the moving blade 5, and centrifugal force is applied to the working fluid by the moving blades 5.
do. As a result, the streamlines G are greatly disturbed, causing a mixing loss within the passage of the rotor blades 5, resulting in a problem of deterioration of the performance of each turbine stage.

The present invention has been made to solve the above problems, and suppresses the development of a boundary layer that occurs on the peripheral wall surface of the annular flow path of a turbine nozzle, reduces pressure loss due to the generation of secondary vortices, and It is an object of the present invention to provide a turbine nozzle that can reduce mixing loss within a rotor blade by equalizing the flow rate distribution of a working fluid in the blade span direction of the blade.

[Structure of the invention]

(Means for solving the problem) The present invention arranges a plurality of nozzle blades in a row in the circumferential direction of an annular flow path formed between a nozzle inner ring and a nozzle outer ring, and each nozzle blade is connected to a nozzle. In a turbine nozzle configured such that the joint end on the inner ring side and the joint end on the nozzle outer ring side are fixed, the nozzle blades at at least one joint end are inclined in the blade row direction with respect to a reference line passing through the rotation center of the turbine. It is characterized by

(Function) According to the turbine nozzle having the above configuration, the working fluid flowing near the joint end of the nozzle blade flows along the ventral surface of the nozzle blade inclined in the direction of the blade row, and the pressure is applied to the peripheral wall surface of the annular flow path. receive. Therefore, the development of a boundary layer on the peripheral wall surface is effectively suppressed, and the generation of secondary vortices can be prevented.

On the other hand, since the center portion of the nozzle blade is not inclined but is formed perpendicularly along the reference line passing through the rotation center of the turbine, no pressing force is applied to the working fluid in the direction of the reference line. Therefore, the flow line of the main flow of the working fluid is not shifted in the direction of the peripheral wall surface, and is maintained in a substantially straight line. Therefore lf
The flow rate distribution of the working fluid within the i-shaped channel is maintained uniformly, and there is little disturbance of the flow. As a result, the secondary insertion loss at the fixed joint end of the tip and loop portions of the nozzle blades is significantly reduced.

Furthermore, since the deflection phenomenon of the working fluid streamline in the flow path between the dynamic ellipses does not occur, the mixing loss in the dynamic ellipse J3 is also reduced, and the turbine efficiency can be significantly improved.

(Embodiment) An embodiment of the present invention will be described below with reference to the accompanying drawings FIGS. 1 to 6. FIG. 1 is a perspective view of one embodiment (Embodiment 1) of a turbine nozzle according to the present invention, and the same elements as those of the conventional example shown in FIGS. 11 and 13 are given the same reference numerals and details thereof. Further explanations will be omitted.

The basic difference between the turbine nozzle of this embodiment and the conventional turbine nozzle configured with inclined nozzles shown in FIG. It is configured so that it is inclined in the row manufacturing direction by an angle β with respect to E, and the ventral surface 9 of the joint end is oriented toward the peripheral wall surface on the nozzle inner ring 3 side.

Further, the height Hl of the inclined joint end is in a range of 0.05 to 0.35 with respect to the height HN of the nozzle blade 1b, and is set to a height of 5FM1 or more. Also, the joint end inclination angle β is 2 with respect to the reference line E passing through the rotation center of the turbine.
．． It is set between 5 and 25 degrees.

Note that the side lines of the back surface 10 and the ventral surface 9 of the inclined joint end may be straight lines as shown in FIG. 1, but they may also be formed in a curved shape with a certain curvature.

In the turbine nozzle of this embodiment, the joint end of the nozzle blade 1b on the nozzle inner ring 3 side is inclined in the blade row direction, and its belly surface is oriented toward the peripheral wall surface formed on the peripheral wall side of the nozzle inner ring 3. Because of this structure, the working fluid that has flowed into the inclined portion flows along the ventral surface of the inclined nozzle image 1b and is pushed toward the boundary layer. Therefore, the development of a boundary layer on the peripheral wall surface is suppressed, and the generation of secondary vortices is prevented.

On the other hand, the nozzle blades 1b other than the inclined joint end are not inclined and are arranged perpendicularly along the reference line E, so that no pressing force is applied in the direction of the reference line E, and the movement within the nozzle fJI Fluid streamlines and flow distribution remain uniform.

As a result, pressure loss across the nozzle blade 1b is prevented, and turbine efficiency can be significantly improved.

Furthermore, the effect of reducing pressure loss will be explained according to the drawings. FIG. 2 is a graph showing the distribution of total pressure loss at the outlet of the turbine nozzle shown in FIG. Compared to the conventional example using the vertical nozzle blade 1 shown in FIG. 12, according to this embodiment, the pressure loss distribution in the region from the tip of the nozzle blade 1b to the center of the nozzle flow path is almost similar.

However, the pressure loss in the region from the nozzle root to the center has been significantly reduced, and the thickness of the boundary layer has also been reduced.
Furthermore, it turns out that the secondary vortex region B is also reduced.

On the other hand, when comparing the present example with the conventional example using the conventional inclined nozzle 11a shown in FIG. It can be seen that the pressure 10 loss is significantly reduced in the region.

Further, FIG. 3 is a graph showing the average total pressure loss ξ in the circumferential direction of the nozzle exit at each position H of the nozzle H1b in comparison with the conventional example, and the vertical axis is the ratio of the position H1 to the total height 118 of the nozzle blade 1b. represents the dimensionless height expressed as . Comparing the average total pressure loss curve J according to this example with the loss curve when a conventional vertical nozzle blade 1 is used, it is found that while the loss curve is similar at the nozzle blade tip, the pressure loss is significant at the nozzle blade root. The pressure loss of the nozzle blade as a whole is significantly reduced.

On the other hand, the pressure loss curve I when using the inclined nozzle blade 1a
! Compared to IIT, although the pressure loss is slightly higher at the nozzle blade root, the pressure loss is significantly reduced at the nozzle tip, and the nozzle blade as a whole exhibits superior characteristics than conventional inclined nozzle blades.

Next, the flow rate distribution of the working fluid will be explained with reference to FIG.

FIG. 4 is a graph showing the flow rate distribution of the working fluid at each position of the nozzle W in comparison with a conventional example, where the vertical axis is the dimensionless height HlHN, and the horizontal axis is the nozzle exit circumferential average 1ffi ratio G.
/I am taking GA.

Comparing the flow rate curve N according to this example with the flow rate curve M when vertical nozzle blades 1 are used, it is found that in this example, the flow rate is slightly higher at the root, and slightly decreased near the center, but at the tip. are almost the same.

In addition, the conventional example Ryuseikoku 1 using the inclined nozzle vA1a
! ! When compared with L, it can be seen that in this example, the working fluid is not deflected in the blade span direction inside the nozzle flow path, and a stable flow is formed.

That is, in this embodiment, since only a part of the nozzle lb is inclined, the nozzle vtJla is inclined as a whole.
Due to the pressure generated in this case that acts from the ventral side to the back side of the nozzle blade 1a, the main flow of the working fluid is not deflected toward the nozzle blade root portion, and the flow rate distribution is maintained substantially uniform.

As a result, the streamlines of the working fluid shown in FIG. 15 are greatly deviated and disturbed in the blade length direction, causing mixing loss inside the rotor blades 5, which is the conventional problem of causing a reduction in stage performance. points are also resolved.

Next, we will compare the change in turbine stage efficiency when the height Hl of the inclined joint end and the slope β of the nozzle W1b of this example are changed with respect to the stage efficiency of a turbine nozzle using a conventional vertical nozzle blade. Compare and explain.

Figure 5 shows the dimensionless relative stage efficiency η expressed as the slope angle β and the ratio of the stage efficiency η8 of this example to the conventional stage efficiency η□.
8/η4 and the dimensionless nozzle height H/HN. This is a diagram.

As a result of carrying out test runs with various changes in the angle of inclination β and the height Hl of the inclined joint end, the measurement point N in Fig. 5 was
The dimensionless relative stage efficiency ηB/η exceeds 1.0 in the region surrounded by P It has been demonstrated that this can be improved.

Here, a comparison will be made between the turbine nozzle disclosed in Japanese Patent Application Laid-Open No. 61-108804 in which the total height of the nozzle blades is inclined, and the turbine nozzle in which the total height of the nozzle blades is partially inclined according to the present embodiment. In the nozzle ila whose entire structure is inclined, the inclination angle β is limited so that the dimensionless quantity σ indicating the degree of inclination exceeds 1.3, as shown in the first equation described above.

Therefore, by changing the total nozzle blade height H8 and the average arrangement pitch PN, we find the minimum inclination angle β10 that satisfies the conditions of the first equation, that is, σ-1, 3, as shown in Fig. 6. It will be as shown in.

As is clear from FIG. 6, the degree of inclination is excessive in the application range of the nozzle interior 1a where the whole of the conventional example is inclined, and the stage efficiency is lower than in the case of vertical nozzle blades 1 which are not inclined. That is, in FIG. 5, the conventional inclined nozzle X corresponds to a dimensionless height H1/HN of 1.0. At this time, in order for the dimensionless relative stage efficiency η8/η^ to be 1.0 or more, it is necessary to set the inclination angle to be quite small, but in the conventional example of the inclined nozzle blade 1a, the inclination angle β is included in this range. Not possible.

On the other hand, in order to set σ>1.3, it is necessary to set the inclination angle β to be quite large, but in that case, the dimensionless stage efficiency becomes less than 1.0, resulting in an inclination, as shown by the broken line in Figure 5. The stage efficiency is lower than in the case of the conventional vertical nozzle IA1 that does not have the above structure.

As is clear from the above description, the turbine nozzle in which the joint end shown in this embodiment is constructed with a partially inclined nozzle blade 1b is better than the conventional turbine nozzle constructed with a wholly inclined nozzle blade 1a. The paragraph performance is significantly better.

In particular, the inclination angle β is in the range of 2°5 to 25°, and the height H of the inclined joint end is set in the range of 0°05 to 0.35 with respect to the total height HN of the nozzle blade 1b. The degree of improvement in turbine stage efficiency becomes significant when

Next, another embodiment (Embodiment 2) of the present invention will be described with reference to FIG. FIG. 7 is a perspective view of the turbine nozzle viewed from the outlet side, and the same elements as those in the embodiment shown in FIG. 1 are given the same reference numerals and explanations will be omitted.

The nozzle blades 1C constituting the turbine nozzle of this embodiment are fixedly installed at a joint end (tip portion) on the side of the nozzle outer ring 2 at a predetermined inclination angle β in the blade row direction with respect to the directrix E. I) (Constructed so that the ventral surface 9 of 1c is oriented toward the nozzle outer ring circumferential wall surface C. Also, the portion from the center of the nozzle TA1C to the nozzle inner ring circumferential wall surface is oriented toward the nozzle inner ring circumferential wall surface along the reference line E. It is formed perpendicularly to the

Note that the side line of the inclined portion of the nozzle mlc may be formed in a straight line in the blade span direction as shown in FIG. 7, but it may also be formed in a curved line with a certain curvature.

The working fluid passing near the nozzle outer ring peripheral wall surface C of the nozzle blade 1C having the above configuration is pressed toward the nozzle outer ring peripheral wall surface C by the inclined ventral surface 9 of the nozzle blade 1C. Also ventral surface 9
The working fluid flowing from the side to the back surface 10 side is similarly pressed toward the nozzle outer ring circumferential wall surface C side. Therefore, the development of a boundary layer formed on the peripheral wall surface C of the nozzle outer ring is suppressed, and the generation of a secondary vortex formed by the secondary flow is also prevented. As a result, the pressure loss of the working fluid in the region from the nozzle outer ring circumferential wall surface C to the vicinity of the center of the nozzle flow path is significantly reduced.

On the other hand, in the region from near the center of the nozzle flow path to the nozzle inner ring circumferential wall surface, the nozzle blades 1C are not inclined but are formed perpendicular to the nozzle inner ring circumferential wall surface along the reference line E, so that the working fluid The streamlines are not deflected. Therefore, the flow rate distribution of the working fluid in the span direction of the nozzle is maintained uniform, and pressure loss due to turbulent mixing of the working fluid is reduced.

The above pressure loss reduction effect is shown in Fig. 8. Fig. 8 is a graph showing the relationship between the average total pressure loss ξ in the circumferential direction of the nozzle exit and the dimensionless height H/HN together with a conventional example. Average total pressure loss curve I of a turbine nozzle configured with nozzle blades 1a whose entire blade length is inclined as shown in Fig. 13, and nozzle 1 whose only root portion is partially inclined shown in Fig. 1.
1b, and a pressure loss curve T of the turbine nozzle shown in FIG. 7, in which only the tip portion is constructed with a partially inclined nozzle H1c.

As shown in FIG. 8, according to this embodiment, the pressure loss increases slightly in the loop I section compared to the conventional example, but the effect of reducing pressure loss in the tip section is large, and the turbine nozzle as a whole is compared with the conventional example. Pressure loss is further reduced, and the stage efficiency of the turbine is significantly improved.

Here, the inclination angle β of the joint end of the nozzle blade 1c is 2°5 to 2
Height of the joint end set at 5 degrees and inclined 11. It has been demonstrated that the improvement effect becomes significant when HN is in the range of 0.05 to 0.35 with respect to the total height HN of the nozzle WIC.

Next, another example (Example 3) of the present invention will be described in the ninth section.
This will be explained with reference to the figures. The nozzle blades 1d of this embodiment are rigidly stratified so that the joining ends on both sides of the nozzle inner ring 311III and the nozzle outer ring 2 are inclined in the blade cascade direction by angles of inclination β and β, respectively, with respect to the reference 1i1E, and the tips are The ventral surface 9 of the root section is oriented toward the nozzle outer ring circumferential wall surface C, and the ventral surface 9 of the root section is oriented toward the nozzle inner ring circumferential wall surface. It is formed. Note that the side lines of the tip portion and the sloped portion of the root portion of the nozzle 11d are as follows:
It may be formed in a straight line as shown in FIG. 9, or it may be formed in a curved line.

In the turbine nozzle of this embodiment, the working fluid flowing through both ends of the nozzle blade 1d is pressed against the nozzle outer ring circumferential wall surface C and the nozzle inner ring circumferential wall surface side by the inclined ventral surfaces 9 of the joint ends, so that the tip portion The development of a boundary layer formed at the root portion is suppressed, and the development of secondary vortices is also prevented. Therefore, the pressure loss in the turbine nozzle is further reduced, and the turbine stage efficiency is further improved.

Distribution surface r of average total pressure loss of the turbine nozzle of this example
JU is shown in FIG. According to this embodiment, the average total pressure loss of the nozzle is reduced in both the tip portion and the root portion, and the turbine performance can be further improved.

In addition, the inclination angle β of the tip part and the inclination angle β8 of the root part
and the height Hll of each joint end.

The HLR is not necessarily the same value, and an optimal value is set in consideration of the flow rate distribution characteristics of the working fluid.

In addition, if the cross-sectional shape of the nozzle Ilb, IC, 1 (j is constant over the nozzle blade height HN), it is possible to easily form the sloped part simply by bending, and it is possible to form the sloped part easily by simply bending. In comparison, a significant increase in the number of machining steps can be avoided.

(Effects of the Invention) As explained above, according to the turbine nozzle of the present invention, the working fluid flowing through the joint end of the nozzle rows flows along the ventral surface of the nozzle blades inclined in the direction of the four rows, and the working fluid flows through the annular flow path. It is pressed against the peripheral wall surface.Therefore, the development of the boundary 59 layer on the peripheral wall surface is effectively suppressed, and the occurrence of secondary holes can be prevented.

On the other hand, the nozzle blades other than the inclined joint end are not inclined and are formed perpendicularly along the reference line passing through the rotation center of the turbine, so there is no pressing force acting on the working fluid in the direction of the reference line. . Therefore, the mainstream flow line of the working fluid is not deflected, the flow rate distribution of the working fluid within the annular flow path is maintained uniformly, and pressure loss due to turbulent mixing of the flows is reduced.

Furthermore, since pressure loss due to mixing between the rotor blades is also reduced, turbine efficiency can be significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing one embodiment of a turbine nozzle according to the present invention, FIG. 2 is a graph showing the distribution of total pressure loss at the outlet of the turbine nozzle in FIG. 1, and FIG. 3 is a graph showing each of the nozzle blades. A graph showing the average total pressure loss at each position in comparison with the conventional example. Fig. 4 is a graph showing the flow rate distribution of the working fluid at each position of the nozzle blade in comparison with the conventional example. Fig. 5 shows the sloped joint end. Figure 6 is a graph showing the change in stage efficiency when changing the height and angle of inclination compared to the conventional example. , FIG. 7 is a perspective view showing an embodiment in which the joint end of the nozzle outer ring side of the nozzle row is inclined;
The figure is a graph showing the relationship between the circumferential average total pressure loss at the nozzle exit and the dimensionless height in this embodiment compared to the conventional example.
Fig. 9 is a perspective view showing another embodiment in which both joint ends of the nozzle row are inclined, Fig. 10 is a partial sectional view showing the stage configuration of a general axial flow turbine, and Fig. 11 is a perspective view of the nozzle blade. FIG. 12 is a graph showing the distribution of total pressure loss at the outlet of a conventional turbine nozzle. FIG. 13 is a perspective view showing a turbine nozzle employing inclined nozzle blades. The figure is a cross-sectional view showing the pressure gradient in the passage of a turbine nozzle that employs inclined nozzle blades, Figure 15 is a cross-sectional view showing the streamlines of the working fluid flowing through the passage formed by the inclined nozzle blades, and Figure 16 is the 14 is a graph showing the distribution of total pressure loss at the outlet of the turbine nozzle shown in FIG. 13. 1, 1 a, 1 b, 1 c, 1 d・i)
LtTtJ, 2... Nozzle outer ring, 3... Nozzle inner ring, 406. Annular flow path, 5... Moving blade, 6... Rotor disk, 7... Shroud, 8... Nozzle labyrinth, 9... Ventral surface, 10... Back surface, 11... Secondary flow , 12, 12a, 12b., : Next station, 13... Center trailing edge line, A... Rotating blade rotation direction, B... Secondary station area, C
... Nozzle outer ring circumferential wall surface, D... Nozzle inner ring circumferential wall surface,
E...ltl passing through the center of rotation! - line, F...pressure gradient in the flow path, G...streamline, β...angle of inclination, β1n...
・Minimum inclination angle, H,...Total height of nozzle blade, H...Nozzle blade position, PN...Average arrangement pitch of nozzle blade, Hl
...height of the inclined joint end, 1. J, Ni, T, Ll
... Average total pressure loss curve, L, M, N ... Nozzle exit circumferential direction average flow rate curve, ξ ... Average total pressure loss, η1
．． η, ...paragraph efficiency. Applicant's agent Hisashi Hatano H/HN ÷ Hitoshi Kikko 1 person - ξ (9) 3rd Kataken Hitsuji 4 times - + g Mori N's performance - Figure 7 /'///-7N Average total Pressure term missing □ - 5 (%) Figure 6 Figure 9 Ro Figure 10 Tea I2 Ro σ No.! 4 Figure f5

Claims (1)

[Claims] 1. A plurality of nozzle blades are arranged in a row in the circumferential direction of the annular flow path formed between the nozzle inner ring and the nozzle outer ring, and each nozzle blade is connected to the joint end on the nozzle inner ring side and A turbine nozzle configured to be fixed at a joint end on the outer ring side of the nozzle, wherein a nozzle blade at at least one joint end is inclined in the direction of the blade row with respect to a reference line passing through the rotation center of the turbine. nozzle. 2. The turbine nozzle according to claim 1, wherein the nozzle blade is inclined such that the ventral surface of the joint end on the inner ring side of the nozzle is oriented toward the peripheral wall surface on the inner ring side of the nozzle. 3. The turbine nozzle according to claim 1, wherein the nozzle blade is inclined such that the ventral surface of the joint end on the nozzle outer ring side faces the peripheral wall surface on the nozzle outer ring side. 4. The nozzle blade is inclined so that the membrane surface at the joint end on the nozzle outer ring side is oriented toward the peripheral wall surface on the nozzle outer ring side, while the membrane surface at the joint end on the nozzle inner ring side is oriented toward the peripheral wall surface on the nozzle inner ring side. 2. A turbine nozzle according to claim 1, which is tilted to direct. 5. The height of the inclined joint end is 0 relative to the total height of the nozzle blade.
．． 05 to 0.35, and set the inclination angle of the joint end to 2.5 with respect to the reference line passing through the rotation center of the turbine.
The turbine nozzle according to any one of claims 2 to 4, wherein the angle is set to 25 degrees. 6. The turbine nozzle according to any one of claims 1 to 5, wherein the nozzle blade has a constant cross-sectional shape over the entire height of the nozzle blade.