JPH06193402A - Axial flow turbine stationary blade device - Google Patents

Abstract

PURPOSE:To normalize a flowing state in a turbine stage by specifying the relation between an inclination angle of inner and outer walls and an inclination angle of a stationary blade in the peripheral direction in a turbine flow passage. CONSTITUTION:This is an axial flow turbine stationary blade device consisting of an inner wall 3a and an outer wall 3 forming a flow passage of an elastic fluid with their respective wall surfaces and a plural number of stationary blades 1 respective end parts of which are fixed on respective wall surfaces off the inner wall 3a and the outer wall 3 and which are arranged curved in the circumferential direction on a sectional surface orthogonal with a turbine shaft X, and it is formed by changing an inclination-gammato in the peripheral direction of outlet ends 4 of the respective stationary blades 1 at an intersection of the respective wall surfaces and the curved outlet ends 4. Consequently, it is possible to uniform flow in a turbine step, and to improve the turbine efficiency by way of reducing flowing loss for various kinds of flow passage shapes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved stator vane device, and more particularly to an axial turbine stator vane device suitable for reducing the flow loss of all the stator vanes arranged from a high pressure portion to a low pressure portion. Regarding

[0002]

2. Description of the Related Art In a conventional axial flow turbine vane device, as shown in FIGS. 13, 14 and 19, inner walls 3a, 3 and outer wall (inner Outer wall), and a plurality of stationary blades each end portion of which is fixedly mounted on each wall surface and is curved in the circumferential direction in a cross section orthogonal to the turbine axis X.
In an axial turbine such as a steam turbine, the pressure decreases from the upstream side toward the downstream side, and the volume change ratio of the fluid with respect to the pressure change becomes more remarkable as the pressure decreases in this process. The increasing rate of the blade length of the blade 2 and the blade 2 increases toward the low pressure portion, and the flow channel shape becomes a sharp expanded flow channel. Further, FIGS. 15 and 16 show cross-sectional views of a general steam turbine of a general high-pressure part and a low-pressure part, but the divergence angle (tilt angle) θt of the outer wall surface becomes larger at the low-pressure part. Many studies have been conducted on the theoretical examination for determining the state of the steam flow in such a turbine stage, and it is assumed that it is approximately expressed by the following relational expressions (1) and (2). The symbols used in the relational expressions (1) and (2) are illustrated in FIGS. 13, 14 and 17 to 19.

[0003]

[Equation 1]

[0004]

[Equation 2]

The equations (1) and (2) show the equilibrium relation of the pressure P in the radial direction (r direction). Not only the parameters on the meridian plane shown in FIG. Circumferential velocity component Vθ, which is a direction parameter
Also, it is clear that it is also affected by the circumferential inclination angle γ of the stationary blade, which indicates that the flow path of the steam turbine is a three-dimensional flow.

As shown in FIG. 17, a conventional technique for controlling the flow in the turbine stage to improve the performance of the turbine stage is to erect in a radial direction in which the stationary blades 1 are radially aligned with the turbine shaft center. On the other hand, as shown in FIG. 18, the circumferential tilt angle of the stationary blade 1 is γ at the root portion B.
R, those which are arranged so as to be linearly inclined so as to be γt at the tip portion A, or, as shown in FIG. 19, the inclination angle of the stationary blade 1 is sequentially changed from the root portion toward the tip portion, This is a technique in which a stationary vane having a curved shape is arranged such that the inclination angle −γt of the tip portion A is opposite to the inclination angle γR of the root portion B. That is, the shape is such that the root portion is inclined toward the ventral side of the vane and the tip portion is inclined toward the dorsal side of the vane. For example, JP-A-62-170707 and JP-A-4-124406.
This is a technique recognized in Japanese Patent Application Publication No. 4-52670 and Japanese Patent Application No. 4-52670.

Although various ideas have been made for the shape and arrangement of the vanes as described above, the case where each vane structure shown in FIGS. 17 to 19 has an inclination angle on the outer wall surface on the tip side is taken as an example. ,
The flow condition in the flow path will be described with reference to the streamline F.
As shown in. In FIG. 20, since the stationary blade 1 is not inclined in the circumferential direction, the flow rate decreases in the low flow rate region A1 near the root portion due to the relationship between the radial pressure gradient of the elastic fluid and the centrifugal force, and the flow rate at the tip end portion becomes small. It tends to increase. Figure 21
Is an example in which the stationary blade is linearly inclined in the circumferential direction.
A tendency opposite to the state of 0 is shown, and a low flow rate region A2 is generated near the tip. The curved vane shape shown in FIG. 19 was devised in order to eliminate the above-mentioned drawbacks in the vane arrangement, and the flow condition in this case is as shown in FIG. 22 and shown in FIGS. 20 and 21. Disadvantages are eliminated and almost good flow conditions are obtained. However, as is clear from the equation (1), such a flow condition forms an enlarged flow path, so that the outer wall 3 and the inner wall 3a inclined with respect to the turbine shaft are formed.
The condition is that the circumferential tilt angles γR and −γt with respect to the tilt angle are appropriate, but this relationship has not been clarified in the prior art.

As shown in FIGS. 15 and 16, the inner and outer walls forming the turbine passage have an inclination angle of zero on the inner wall (root side) and move away from the turbine shaft toward the downstream on the outer wall (tip side). 23 and 24 are cross-sectional views of the actual turbine, not limited to those formed as described above.
As shown in the example, the outer wall is formed so that the inclination angle expands toward the downstream side, but the inner wall has an inclination angle away from the turbine axis and an inclination angle toward the turbine axis. There are cases. As described above, the inclination angles of the inner and outer walls in the turbine flow path are selected in a very large number due to the relationship of the overall structure, and the inner and outer wall shapes are shown in FIG.
~ It becomes like FIG. 25 to 27 are examples in which the outer wall is parallel to the turbine axis and has no tilt angle, and the inner wall has different tilt angles. 28 to 30 are examples in which the outer wall is formed so as to be separated from the turbine shaft toward the downstream side, and the inclination angle of the inner wall is different. 31 to 33 are examples in which the outer wall is formed in a direction toward the turbine shaft toward the downstream side, and the inclination angle of the inner wall is different.

[0009]

In the conventional axial flow turbine vane device, since the turbine flow passages have a wide variety of shapes, they are effective over the entire paragraph of the turbine when the vanes are simply curved in the circumferential direction. However, it is necessary to define the circumferential inclination angle of the vane according to the inclination angle of the inner and outer walls. This is a necessary condition for achieving the radial pressure distribution state in the flow path.

The object of the present invention is to specify the relationship between the inclination angle of the inner and outer walls of the turbine flow path and the circumferential inclination angle of the stationary blade based on analytical and experimental studies, and to determine the flow condition in the turbine stage. An object is to provide a normalizing axial flow turbine vane device.

[0011]

In order to achieve the above-mentioned object, an axial flow turbine stationary blade device according to the present invention has an inner wall and an outer wall which form a flow path of elastic fluid in respective wall surfaces, and an inner wall and an outer wall. In an axial-flow turbine stationary blade device including a plurality of stationary blades each end portion of which is fixed and curved in a circumferential direction in a cross section orthogonal to the turbine shaft, each wall surface and the turbine shaft are formed. Corresponding to the inclination angle, it is formed by changing the circumferential inclination angle of the outlet end of each stationary blade at the intersection of each wall surface and the curved outlet end.

An inner wall and an outer wall that form a flow path for the elastic fluid, and end portions of the inner wall and the outer wall are fixed to the respective wall surfaces, and are curved in a circumferential direction in a cross section orthogonal to the turbine axis. In the axial turbine vane device composed of a plurality of stationary blades, each of the wall surfaces corresponds to an inclination angle that is separated from the turbine axis toward the downstream side of the wall surface or an inclination angle that approaches the turbine axis toward the downstream side. The circumferential inclination angle of the outlet end of each vane at the intersection of the wall surface and the curved outlet end is formed to be large on the ventral side, and the outlet end of each vane at the intersection of the outer wall surface and the curved outlet end is formed. A configuration in which the inclination angle in the circumferential direction is formed larger toward the back side may be used.

In addition, the axial flow turbine is configured to include any one of the above axial flow turbine vane devices.

[0014]

According to the present invention, the influential parameters that determine the flow condition in the turbine stage are expressed by equation (2), and the other parameters except the circumferential inclination angle of the stationary blade are the thermal fluid and strength in the turbine design. Also, due to structural constraints, the effect of the circumferential inclination angle of the stationary blade has already been stipulated, and it is specified according to the inclination angle of the inner and outer walls, and a stationary blade based on this specification is provided. This eliminates the low flow rate region that occurs on the inner and outer walls in the turbine stage and reduces the flow loss.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. FIG. 1 is a perspective view showing a part of a vane arranged circumferentially around a turbine shaft. As shown in FIG. 1, an inner wall 3a and an outer wall 3 (inner and outer walls) that form a flow path of an elastic fluid with respective wall surfaces, and a cross section in which respective end portions are fixedly mounted on the respective wall surfaces and are orthogonal to the turbine axis X. An axial flow turbine stationary blade device comprising a plurality of stationary blades 1 arranged in a curved shape in the circumferential direction, corresponding to the inclination angle formed by each wall surface and the turbine axis X. The configuration is formed by changing the circumferential inclination angle −γto of the outlet end 4 of each stationary blade 1 at the intersection with the curved outlet end 4. 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 3a has an inclination of −θR with respect to the B axis parallel to the turbine axis. Has horns. Further, the stator blade 1 has the turbine shaft X at the intersection G where the outlet end 4 joins the outer wall 3.
Circumferential inclination angle −γt with respect to a radial line rto perpendicular to
At the intersection F with the outlet end 4, the inner wall 3a is inclined at a circumferential inclination angle γRo with respect to a radial line rRo that is perpendicular to the turbine axis. In this way the stationary wing 1
Has a shape that curves from the root (inner wall) to the tip (outer wall). In order to form this curved shape smoothly,
A method of drawing a circular arc when the tangent angles at both ends are geometrically given can be used. For example, it is possible to adopt the method as shown in "Thermal Calculation of Turbines" by Ge a Filipov, translated by Nagashima (Bunichi Sogo Shuppan, 1974).

In the vane shown in FIG. 1, the inclination angle of the outer wall +
In order to reduce the flow loss that occurs in the turbine stage by defining the relationship between θt, the inclination angle of the inner wall −θR, the circumferential inclination angle of the tip side of the stationary blade −γto, and the root side γRo, the test turbine Summarizing the results and the examination results based on the flow analysis in the paragraph, the most effective relationship of these four kinds of angles is as shown in FIG. As shown in FIG. 2, the relationship between the inclination angle θt of the outer wall and the circumferential inclination angle −γto on the tip side of the vane is that the inclination angle θt on the tip side of the vane increases as θt goes from the plus side to the minus side. It is necessary to increase −γto on the negative side. Further, the relationship between the inclination angle θR of the inner wall and the circumferential inclination angle γRo on the root side of the vane is that the inclination angle γRo on the root side of the vane becomes positive as the inclination angle θR of the inner wall goes from positive to negative. Shows that it needs to be larger on the side.

Next, regarding the above-mentioned vane structure, the influence on the turbine stage is shown by the efficiency distribution in the blade length direction as shown in FIG. As shown in FIG. 3, the curve 10 is the efficiency distribution in the stationary blade structure of FIG. 17, and the distribution obtained by combining the curves 40 and 50 is similar to that of the present embodiment although the stationary blade shape is curved. It corresponds to FIG. 19 in which the relationship with the inclination angles of the inner and outer walls is not considered. The distribution of the combination of the curves 20 and 30 is due to the configuration of the present embodiment, and as a result of optimizing the relationship between the inclination angle of the inner and outer walls and the circumferential inclination angle of the stationary blade, High efficiency can be achieved including efficiency improvement in the very vicinity. 4 to 12 show the situation of the efficiency distribution of FIG. 3 by streamlines, which correspond to the flow passage shapes of the actual turbine shown in FIGS. 25 to 33, respectively. As shown in FIGS. 4 to 12, the streamline shown by the solid line is based on the configuration of this embodiment, and the streamline shown by the chain line is based on the conventional technique. Further, the region a is a flow region in which the flow separates from the inner and outer walls to generate a vortex in the conventional technique, and in the present embodiment, it is pressed against the inner and outer wall sides by the circumferential inclination angle of the vane corresponding to the inclination angle of the inner and outer walls. Since the acting force from the rotor blades can be adjusted, it is possible to normalize the flow in the turbine stage and eliminate the eddy current due to the separated flow that is recognized in the prior art, which is a great effect for improving the efficiency of the turbine stage. To be demonstrated. Comparing such effects with the paragraph effect obtained by averaging the efficiency distribution in the blade length direction, it has been confirmed that the efficiency improvement amount according to the present embodiment reaches 2 to 4%.

[0018]

According to the present invention, the circumferential direction of the vane corresponding to the inclination angle of the inner and outer walls of the curved vane arranged in the turbine flow path and at the intersection of each wall surface and the curved outlet end. Since the relationship of the inclination angle is defined, the flow in the turbine stage is made uniform, and there is an effect that the flow loss can be reduced and the turbine efficiency can be improved for various flow passage shapes.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

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

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

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

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

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

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

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

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

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

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

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

FIG. 13 is a vertical section view of a turbine stage.

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

FIG. 15 is a cross-sectional view showing an example of a blade row of an actual turbine.

FIG. 16 is a cross-sectional view showing an example of a blade row of an actual turbine.

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

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

FIG. 19 is a front view showing a conventional vane shape.

FIG. 20 is a vertical cross-sectional view showing a flow situation in a conventional vane.

FIG. 21 is a vertical cross-sectional view showing a flow situation in a conventional vane.

FIG. 22 is a vertical cross-sectional view showing a flow situation in a conventional vane.

FIG. 23 is a cross-sectional view showing an example of a blade row of an actual turbine.

FIG. 24 is a cross-sectional view showing an example of a blade row of an actual turbine.

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

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 section.

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

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

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

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

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 section.

[Explanation of symbols]

 1 stationary blade 2 moving blade 3 outer wall 3a inner wall 4 outlet end

Claims (3)

[Claims] 1. An inner wall and an outer wall that form a flow path of an elastic fluid with respective wall surfaces, and respective end portions are fixedly provided on the respective wall surfaces and are arranged in a curved shape in a circumferential direction in a cross section orthogonal to the turbine axis. In the axial flow turbine stationary blade device composed of a plurality of stationary blades, each stationary blade corresponding to an inclination angle formed by each wall surface and the turbine shaft, at each intersection of each wall surface and the curved outlet end. An axial flow turbine characterized by being formed by changing the circumferential inclination angle of the outlet end. 2. An inner wall and an outer wall that form a flow path of an elastic fluid by respective wall surfaces, and respective end portions are fixedly mounted on the respective wall surfaces and are arranged in a circumferentially curved shape in a cross section orthogonal to the turbine axis. In the axial flow turbine stationary blade device including a plurality of stationary blades, a tilt angle that is separated from the turbine shaft toward the downstream side of each wall surface or a tilt angle that approaches the turbine shaft toward the downstream side. Then, while forming the circumferential inclination angle of the outlet end of each stationary blade at the intersection of the inner wall surface and the curved outlet end to the ventral side,
An axial-flow turbine stationary blade apparatus, wherein a circumferential inclination angle of each stationary blade at an intersection of an outer wall surface and the curved outlet end is formed to be large toward the back side. 3. An axial flow turbine comprising the axial flow turbine vane device according to claim 1 or 2.