JP3005839B2 - Axial turbine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a stationary blade, and more particularly, to a shaft suitable for reducing a flow loss of a stationary blade in all stages disposed from a high pressure section to a low pressure section. The present invention relates to a structure of a stationary blade of a flow turbine.

[0002]

2. Description of the Related Art A conventional axial turbine is shown in FIGS.
4, as shown in FIG. 19, the inner wall 3a and the outer wall 3 forming the flow path R of the elastic fluid, and the respective ends thereof are fixed to the inner wall 3a and the outer wall 3, and the cross section orthogonal to the turbine axis X has a circumferential direction. And a plurality of stationary blades arranged in a curved manner. In an axial flow turbine such as a steam turbine, the pressure decreases from the upstream side to the downstream side, and in this process, the ratio of the volume change of the fluid to the pressure change becomes more remarkable as the pressure becomes lower. The increasing rate of the blade length between the blade and the moving blade 2 increases toward the low pressure portion, and the flow path shape becomes a sharply expanded flow path. FIGS. 15 and 16 are cross-sectional views of general high-pressure and low-pressure steam turbines. The spreading angle (inclination angle) θt of the outer wall surface becomes larger as the pressure becomes lower. In the present specification and drawings,
About the wall inclination angle θt and the inner wall inclination angle θR, from the upstream
Downstream, the wall moves away from the turbine axis, ie
If the diameter of the wall is large, express it with a plus.
-When approaching the bin axis, that is, when the wall diameter is small
I'll use a minus sign.

Many studies have been made on theoretical studies for determining the state of the steam flow in such a turbine stage, and are roughly expressed by the following relational expressions (1) and (2).
ing. The symbols used in (1) and (2) are as shown in FIG.
3 , FIG. 14 , and FIGS. 17-19 .

[0004]

(Equation 1)

[0005]

(Equation 2)

Equations (1) and (2) are used in the radial direction (r direction).
13 shows not only the parameters on the meridional plane shown in FIG. 13 but also the circumferential velocity component Vθ, which is a parameter in the circumferential direction of the steam turbine, and the circumferential inclination angle γ of the stationary blade. It is clear that it is affected, indicating that the flow path of the steam turbine is a three-dimensional flow.

[0007] In the prior art for controlling the flow in a turbine stage and improving the performance of the turbine stage, as shown in FIG. 17, a radial upright is provided in which the stationary blades 1 are radially aligned with the turbine axis as the center. and what hand, as shown in FIG. 18, as the circumferential angle of inclination of the stationary blade 1 is γR at the root portion B, so that γt at the tip a, arranged to be inclined linearly, FIG As shown in FIG. 19, the inclination angle of the stationary blade 1 is sequentially changed from the root portion to the tip portion so that the inclination angle −γt of the tip portion A is in the opposite direction to the inclination angle γR of the root portion B. , Nadogaa that arranged vanes curved shape
You. The example of FIG. 19 has a shape that is inclined toward the ventral side of the stationary blade at the root portion and inclined toward the rear side of the stationary blade at the tip portion. They are,
JP-A-62-170707 , JP-A-4-1244
No. 06 , Japanese Patent Application No. 4-52670, etc.
I have.

[0008] As described above, the shape of the stationary blade and located Nitsu
Although various ideas have been devised , FIGS.
In the case of the configuration of each of the stationary blades shown in FIG.
20 are as shown in FIGS . 20, because the stationary blade 1 is not inclined in the circumferential direction, the relationship between the radial pressure gradient and centrifugal force of the elastic fluid, the flow rate is reduced at low flow region A1 near the root portion, the distal portion The flow rate tends to increase. Figure 21 is a stationary blade although an example in which linearly inclined in the circumferential direction, the state of FIG. 20 shows an opposite trend, low flow region A2 is generated near the tip. It was created to eliminate these <br/> flaws in the arrangement of vanes .
Is the shape of the curved vane of FIG. The flow state in this case is as shown in FIG. 22, and the defects shown in FIGS. 20 and 21 are eliminated, and a substantially favorable flow state is obtained.

[0009] However, (1) As apparent from the equation, this flow situation, by forming an enlarged flow path,
It circumferential inclination with respect to the angle of inclination of the outer wall 3 and the inner wall 3a inclined to turbine axis γR and -γt is appropriate is a condition, in the prior art, this relationship is not clear.

As shown in FIGS . 15 and 16, the inclination angle of the inner and outer walls forming the turbine flow path is zero on the inner wall (root side), and is separated from the turbine shaft downstream on the outer wall (tip side). However, the present invention is not limited to this. Actual turbine
The cross-sectional structure is shown as in the examples shown in FIGS.
On the outer wall, the inclination angle is formed so that the flow path expands toward the downstream side. On the inner wall, there are a case where the inclination angle is away from the turbine axis and a case where the inclination angle is toward the turbine axis. Thus, the inclination angle of the inner and outer walls in the turbine flow path, from the relationship of the overall structure, there is a great variety.

The inner and outer wall shapes are shown in FIGS.
become that way. 25 to 27 show an example in which the outer wall is parallel to the turbine axis and has no inclination angle, and the inclination angle of the inner wall is different.
28 to 30 are examples in which the outer wall is formed so as to be more distant from the turbine shaft toward the downstream side, and the inclination angle of the inner wall is different . FIGS . 31 to 33 show examples in which the outer wall is formed in a direction approaching the turbine shaft toward the downstream side, and the inclination angle of the inner wall is different.

[0012]

In the THE INVENTION Problems to be Solved by conventional axial flow turbine, since the turbine flow path shape variety, the only state which is formed by bending the stationary blade in the circumferential direction, the turbine effective over the entire paragraph Instead, it is necessary to define the circumferential inclination angle of the stationary blade in accordance with the inclination angle of the inner and outer walls.
This is a necessary condition for achieving a radial pressure distribution state in the flow path.

An object of the present invention is to specify the relationship between the inclination angles of the inner and outer walls of the turbine flow passage and the circumferential inclination angles of the stationary blades based on analytical and experimental investigations, and to determine the flow situation in the turbine stage. It is to provide an optimized axial turbine.

[0014]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention has an inner wall and an outer wall, each of which defines a flow path for an elastic fluid, and an end which is fixed to the inner wall and the outer wall. And in the axial flow turbine having a plurality of stationary blades arranged in a cross section orthogonal to the turbine axis and curved in the circumferential direction, each of the stationary blades has an inclination angle between each wall surface and the turbine shaft. And the outer wall inclination angle θt goes from the plus side to the minus side,
The circumferential inclination angle γto of the outlet end at the intersection between the outer wall surface and the curved outlet end is increased to the minus side, and / or the inner wall surface angle increases as the inner wall slope angle θR goes from the plus side to the minus side. An axial turbine is proposed in which the circumferential inclination angle γRo of the outlet end at the intersection with the curved outlet end is increased to the plus side.

[0015]

According to the present invention, the influence parameter for determining the flow conditions in the turbine stage is indicated by (2), other parameters except the circumferential angle of inclination of the vanes, thermal fluid, the strength of turbine design In addition, due to structural constraints, the shape should be further defined according to the inclination angle of the inner and outer walls, based on the effect of the circumferential inclination angle of the stator vanes, which has already been clarified.
The low flow rate region generated on the inner and outer walls in the turbine stage is eliminated, and the flow loss is reduced.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG .
An embodiment will be described. FIG. 1 is a perspective view of a part of a stator vane arranged on a circumference around a turbine axis .
You. The axial turbine has an inner wall 3 that forms a flow path of the elastic fluid.
a and the outer wall 3 and (inner and outer walls), a solid end portion on each of the walls
And a plurality of vanes 1 and disposed curved in the circumferential direction in the cross section perpendicular to the constant to and turbine shaft X. Each vane 1 corresponds to the inclination angle between each wall surface and the turbine axis X, and each wall surface and the curved outlet end 4
Are formed by changing the circumferential inclination angle -γto of the outlet end 4 of each of the stationary blades 1 at the intersection with . That is, as in the example shown in FIG. 29, the outer wall 3 has an inclination angle of + θt with respect to the A axis parallel to the turbine axis, and the inner wall 3
a has an inclination angle of -θR with respect to the B axis parallel to the turbine axis. Further, the stationary blade 1 has a radial line r perpendicular to the turbine axis X at an intersection G where the outlet end 4 is joined to the outer wall 3.
at the intersection F with the outlet end 4 on the inner wall 3a side with respect to the radial line rRo perpendicular to the turbine axis on the inner wall 3a side.
It is inclined at o. Thus, the stationary blade 1 is at the base (inner wall)
From the tip to the outer wall.To smoothly form this curved shape, it is possible to use a method of drawing an arc when tangent angles at both ends are given geometrically <br / > It cuts. For example, it is possible to adopt a method as shown in "Thermal Calculation of Turbine" by Ge A. Filipov, translated by Nagashima (Bunichi Sogo Shuppan , 1974).

In the stationary blade shown in FIG. 1, the inclination angle of the outer wall +
In order to reduce the flow loss occurring in the turbine stage, the relationship between θt , the inclination angle of the inner wall −θR , the inclination angle in the circumferential direction on the tip side of the stationary blade −γto, and γRo on the root side is defined. to summarize the results and consider results based on flow analysis in a paragraph, the most effective relationship between these four angles, as shown in FIG. As shown in FIG. 2, the inclination angle θt of the outer wall and the circumferential inclination angle −γto on the tip side of the stationary blade
Is that the circumferential inclination angle -γto on the tip side of the stationary blade needs to be increased to the minus side as θt goes from the plus side to the minus side. Also, the inclination angle θ of the inner wall
The relationship between R and the circumferential inclination angle γRo on the base side of the stator vanes is such that as the inclination angle θR of the inner wall goes from plus to minus, the circumferential inclination angle γRo on the base side of the stator vanes needs to increase toward the plus side. It indicates that there is.

Next, regarding the above-mentioned stationary blade structure, the effect on the turbine stage is shown by the efficiency distribution in the blade length direction as shown in FIG. As shown in FIG. 3, curve 10 is the efficiency distribution in the stator blade structure of FIG. 17, the distribution of the combination of the curve 40 and the curve 50, have are the shape of the stationary blade is curved
Figure 1 does not take into account the relationship with the inclination angles of the inner and outer walls
This corresponds to 9. Also, the distribution in combination with the curve 20 and the curve 30 is due to the present embodiment, the relationship between the circumferential direction inclination angle of the inclined angle and stator blade of inner and outer walls most
As a result of optimization, including efficiency improvement near the inner and outer walls ,
High efficiency can be achieved. When indicating the situations in which the efficiency distribution in Figure 3 in flow lines, is shown in Figure 4 through 12, FIGS. 25 3
This corresponds to the flow path shape of the actual turbine shown in FIG. FIG. 4-
12, the solid line of flow lines is due to the present embodiment, the streamline indicated by the chain line is due to the prior art.
Furthermore, the region a is a basin for generation of vortex flow is separated from the inner and outer walls in the prior art, in the present embodiment, the inner and outer walls side by a circumferential angle of inclination of the vane corresponding to the inclination angle of the inner and outer walls You can adjust the acting force from the moving blade
Because the flow within the turbine stage normalized, it is possible to eliminate the vortex due to separation flow found in the prior art, a large effect is exhibited in a high efficiency of the turbine stage. Comparing such an effect with the paragraph effect in which the efficiency distribution in the blade length direction is averaged, the efficiency improvement amount according to the present embodiment is as follows.
It has been found that it reaches 2-4%.

[0019]

According to the present invention, the circumferential direction of the vane at the intersection between the respective wall surface and the curved exit end corresponds to the inclination angle of the inner and outer walls of the curved vane disposed in the turbine flow path. Because the relationship of the inclination angle is specified, the flow in the turbine stage is made uniform and the flow loss is reduced for various flow path shapes.
As a result, turbine efficiency can be improved .

[Brief description of the drawings]

FIG. 1 is a perspective view showing a main part of an embodiment of an axial flow turbine according to the present invention.

FIG. 2 is a graph showing the relationship between the inclination angle of the inner and outer walls and the circumferential inclination angle of the stationary blade according to the present invention.

FIG. 3 is a graph showing an efficiency distribution in a blade length direction for explaining an effect of the present invention.

FIG. 4 is a diagram showing a flow in a flow path for explaining an effect of the present invention.

FIG. 5 is a diagram showing a flow in a flow path for explaining an effect of the present invention.

FIG. 6 is a diagram showing a flow in a flow path for explaining an effect of the present invention.

FIG. 7 is a diagram showing a flow in a flow path for explaining an effect of the present invention.

FIG. 8 is a diagram showing a flow in a flow path for explaining an effect of the present invention.

FIG. 9 is a diagram showing a flow in a flow path for explaining an effect of the present invention.

FIG. 10 is a diagram showing a flow in a flow path for explaining an effect of the present invention.

FIG. 11 is a diagram showing a flow in a flow path for explaining an effect of the present invention.

FIG. 12 is a diagram showing a flow in a flow path for explaining an effect of the present invention.

FIG. 13 is a longitudinal sectional view of a turbine stage.

FIG. 14 is a perspective view showing streamlines of a fluid in an enlarged flow channel.

FIG. 15 is a cross-sectional view showing an example of a cascade of actual turbines.

FIG. 16 is a sectional view showing an example of a cascade of actual turbines.

FIG. 17 is a front view showing the shape of a conventional stationary blade.

FIG. 18 is a front view showing the shape of a conventional stationary blade.

FIG. 19 is a front view showing the shape of a conventional stationary blade.

FIG. 20 is a longitudinal sectional view showing a state of a flow in a conventional stationary blade.

FIG. 21 is a longitudinal sectional view showing a state of a flow in a conventional stationary blade.

FIG. 22 is a longitudinal sectional view showing a state of a flow in a conventional stationary blade.

FIG. 23 is a sectional view showing an example of a cascade of actual turbines.

FIG. 24 is a cross-sectional view illustrating an example of a cascade of actual turbines.

FIG. 25 is a cross-sectional view showing an example of the inclination angles of the inner and outer walls of the actual turbine stage.

FIG. 26 is a cross-sectional view showing an example of the inclination angles of the inner and outer walls of the actual turbine stage.

FIG. 27 is a cross-sectional view showing an example of the inclination angles of the inner and outer walls of the actual turbine stage.

FIG. 28 is a cross-sectional view showing an example of the inclination angles of the inner and outer walls of the actual turbine stage.

FIG. 29 is a cross-sectional view showing an example of the inclination angles of the inner and outer walls of the actual turbine stage.

FIG. 30 is a cross-sectional view showing an example of the inclination angles of the inner and outer walls of the actual turbine stage.

FIG. 31 is a cross-sectional view showing an example of the inclination angles of the inner and outer walls of the actual turbine stage.

FIG. 32 is a cross-sectional view showing an example of the inclination angles of the inner and outer walls of the actual turbine stage.

FIG. 33 is a cross-sectional view showing an example of the inclination angles of the inner and outer walls of the actual turbine stage.

[Explanation of symbols]

 Reference Signs List 1 stationary blade 2 rotor blade 3 outer wall 3a inner wall 4 outlet end

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F01D 9/02 101

Claims (1)

(57) [Claims] An inner wall and an outer wall forming a flow path of an elastic fluid by respective wall surfaces, and respective ends are fixed to the inner wall and the outer wall, and are disposed so as to be curved in a circumferential direction in a cross section orthogonal to a turbine axis. In the axial flow turbine provided with a plurality of stationary blades, each of the stationary blades corresponds to an inclination angle between each wall surface and the turbine shaft, and the outer wall inclination angle θt goes from the plus side to the minus side. The circumferential inclination angle γ of the outlet end at the intersection of the outer wall surface and the curved outlet end
increase to on the minus side and / or tilt the inner wall
As the oblique angle θR goes from the plus side to the minus side,
An axial flow turbine, wherein a circumferential inclination angle γRo of the outlet end at an intersection of an inner wall surface and the curved outlet end is increased to the plus side.