JPH05312003A - Stationary blade of axial turbo machine - Google Patents

Abstract

PURPOSE:To provide the stationary blade of a turbo machine having low loss in order to improve performance of the turbo machine. CONSTITUTION:Peripheral direction inclining angles theta of respective stationary blades 3 of a plurality of axial turbo machines which are arranged in an annular flow passage, are changed in radial direction, and each blade 3 is formed in an arc shape in axial direction. Also, an axial direction inclining angle delta is also changed in radial direction, and each blade 3 is formed in an arc shape in a meridium plane.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stationary blade of an axial flow type turbomachine such as a steam turbine, a gas turbine and an axial flow compressor.

[0002]

2. Description of the Related Art In the prior art in which the structure of a stator vane is changed to improve the flow inside the paragraph, a stator vane, for example, used in a low-pressure stage of a steam turbine, is simply arranged in the rotating direction of the rotor blade. Attempts have been made to improve the recoil degree of the root portion of the vane by tilting it to. About this, for example, Proceedings of the Proceedings of the Advance in Steam Turbine Technology for Power Generation
(Proc. Of the Advancesin Steam Turbine Technology
for Power Generation PWR ー Vol.10 ASME PowerDivisio
n) Article name Anine Vestigation of Leaned Nozzle F Equts on Low Pressure Steam Turbine Efficients (An Investigation of Leaned Nozzle Effects
on LowPressure Steam Turbine Efficiencies). Further, in order to reduce the loss due to the secondary flow vortices generated in the internal flow of the vane, there is an arcuate shape in which the vane is symmetrical in the central portion in the span direction when viewed from the axial direction. For this, see ASME Paper
No. 90-GT-55), which is described in The Influence of Blade Lean on Turbine Losses. Further, a stator blade having an asymmetrical bow shape when viewed from the axial direction is disclosed in Japanese Patent Application No. 2-67115. These conventional techniques are effective in improving the degree of reaction and reducing the loss due to the secondary flow vortex, but in order to further improve the performance of the axial flow turbomachine, a higher performance stationary blade structure is required. ing.

[0003]

Generally, in the flow between blades of an axial flow type turbomachine, a secondary flow vortex is generated as a three-dimensional flow phenomenon due to the viscosity of the fluid. In other words, when a boundary layer flow with a low flow velocity that develops on the side walls that support the stationary blades and rotor blades and a main flow part with a low flow velocity that does not affect it and is deflected by the blades, the difference in centrifugal force acting on the fluid causes Flow is generated, and as a result, a pair of vortices is formed in the inter-blade flow.
Since this secondary flow vortex causes loss, it is desirable to prevent it as much as possible. It is well known that this secondary flow vortex can be reduced by, for example, suction of the sidewall boundary layer, but it is not realistic to apply it to an actual turbomachine because of its complicated structure.

An object of the present invention is to provide a vane structure for reducing the strength of secondary flow vortices generated in such an inter-blade flow and realizing a high performance turbomachine.

[0005]

The first aspect of the present invention is to change the circumferential inclination angle θ of a stationary blade of an axial flow type turbomachine in a radial direction so that the stationary blade has an arcuate shape when viewed from the axial direction. The axial inclination angle δ of is also changed in the radial direction so that the meridian plane becomes arcuate.

In the second aspect of the present invention, the radial distribution of the circumferential inclination angle θ and the axial inclination angle δ of the stationary blade is set so as not to be symmetric with respect to the central portion of the blade span, and the stationary blade has an arched shape. It is characterized in that it is not symmetrical with respect to the central part of the blade span either when viewed in the axial direction or when viewed in the meridian plane.

In the third aspect of the present invention, the radial distribution of the circumferential tilt angle θ is distributed so as to have an arcuate shape protruding in the blade pressure surface direction, and the radial distribution of the axial tilt angle δ is set to the blade leading edge. It is characterized in that it is distributed so as to have an arched shape protruding in the direction.

[0008]

When the radial distribution of the circumferential inclination angle θ of the stationary blade is made to have an arched shape protruding in the blade pressure surface direction, as is well known, the flow near the side wall is pressed against the side wall. It has the effect of suppressing the development of the boundary layer and at the same time reducing secondary flow vortices generated in the inter-blade flow. This has been confirmed experimentally. However, at the same time, it has been confirmed that the flow angle of the flow near the side wall is deflected in the axial direction from the design point, and it is not preferable to increase the circumferential inclination angle θ from the viewpoint of the outflow angle.
In order to overcome this drawback, the radial distribution of the circumferential inclination angle θ is made to have an arched shape protruding in the blade pressure surface direction, and at the same time, the radial distribution of the axial inclination angle δ is projected in the blade leading edge direction. If it is distributed so as to have a bow shape, the flow will be pushed toward the side wall side, and since it is not the inclination in the circumferential direction, the development of the side wall boundary layer is suppressed and the development of the side wall boundary layer is suppressed without greatly changing the outflow angle. Secondary flow vortices generated in the flow can be reduced. That is, paying attention to the blade shape near the side wall, when the radial distribution of the axial inclination angle δ is distributed so as to have an arched shape protruding toward the blade leading edge direction, the blade surface downstream from the curved portion of the blade is Is inclined toward the upstream side from the side wall to the central portion, and forms a flow path that presses the flow toward the side wall. This flow path shape pushes the flow in the direction of the side wall without deflection of the outflow angle, so that the flow in the vane outflow part is kept good,
It suppresses the development of the sidewall boundary layer and at the same time reduces the secondary flow vortices generated in the inter-blade flow.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a diagram showing the inclination of the vane 3 when the vane of the present invention is viewed from the axial direction on the downstream side, and FIG. 2 is a diagram of the vane of the present invention seen from the meridian plane. As is clear from FIG. 1, the radial distribution of the inclination angle θ in the circumferential direction is distributed so as to have an arched shape protruding in the direction of the blade pressure surface. At the same time, as is clear from FIG. 2, the radial distribution of the inclination angle δ in the axial direction is distributed so as to have an arched shape protruding toward the blade leading edge 5. Therefore, the flow path of the vane of the present invention is shaped so as to press the flow in the side wall direction, as shown in FIG. Further, in order to show the change of the flow path shape according to FIG. 2, FIG. 3 shows the blade surface inclination when the stationary blade is moved to the upstream side as it is separated from the side wall. As shown in FIG. 2, by making the radial distribution of the axial tilt angle δ into an arc shape that projects toward the blade leading edge direction, the blade surface from the bent portion to the downstream side of the stationary blade is The shape is such that it is pressed against the side wall. As a result, it is possible to realize the inter-blade flow that suppresses the secondary flow vortices generated in the boundary layer that develops on the side wall and the inter-blade flow path. Moreover,
The arched shape that protrudes toward the leading edge of the blade has the effect of suppressing the secondary flow vortices generated in the boundary layer that develops on the stronger side wall and in the inter-blade passage without significantly affecting the outflow angle.
As a result, the flow loss distribution generated in the vanes is reduced as shown in FIG. In FIG. 4, a is a conventional stationary blade that is not arcuate in shape, b is a conventional stationary blade that is arcuate only in the circumferential direction, and c is the stationary blade of the present invention that is also in the circumferential direction. This is the loss distribution in the blade length direction when the shape is also arcuate in the axial direction. As is clear from FIG. 4, the vane loss of the present invention is the smallest. FIG. 5 is a diagram showing the distribution of the flow angle of the vane outflow portion in the blade length direction, where a is a conventional vane which is not arcuate, and b is an arcuate only in the circumferential direction. The stationary vane, c is the stationary vane of the present invention, and is the outflow angle distribution in the blade length direction when the blade is arcuate in both the circumferential direction and the axial direction. In the conventional vane having the arcuate shape only in the circumferential direction of b, the outflow angle distribution of the conventional vane having no arcuate shape is different from that of the conventional vane of a, but the outflow of the vane of the present invention of c is different. It can be seen that the angular distribution and the outflow angle distribution of a conventional vane that is arcuate only in the circumferential direction of b are almost the same,
According to the present invention in which the outflow angle is arcuate only in the circumferential direction and the axial direction, the loss of flow is reduced while the outflow angle of the conventional vane in which the outflow angle is arcuate only in the circumferential direction is almost the same. be able to.

In the actual flow between blades of a turbomachine, the flow in the upper half and the flow in the lower half are rarely symmetrical at the central portion in the blade span direction. An embodiment of the present invention for coping with such a flow will be shown below.

A second embodiment of the present invention is shown in FIGS. This embodiment is designed to deal with the case where the side wall boundary layer at the blade root portion and the secondary flow are large, and FIG. 6 shows the stationary blade of the present invention as seen from the axial direction on the downstream side, like FIG. It is a figure which shows the inclination of the stationary blade at the time, and FIG. 7 is a figure when the stationary blade of this invention is seen in a meridian surface like FIG. As shown in FIGS. 6 and 7, when the sidewall boundary layer at the blade root portion and the secondary flow are large, the inclination in the circumferential direction in the blade root direction and the inclination in the axial direction are increased, so that The overall performance of the flow can be good.

A third embodiment of the present invention is shown in FIGS. This embodiment is designed to deal with the case where the side wall boundary layer at the blade tip portion and the secondary flow are large, and FIG. 8 shows the stator blade of the present invention as seen from the axial direction on the downstream side, like FIG. FIG. 9 is a view showing the inclination of the stationary blade at the time, and FIG. 9 is a view of the stationary blade of the present invention seen from the meridional plane, as in FIG. 2. As shown in FIGS. 8 and 9, when the sidewall boundary layer at the blade tip portion and the secondary flow are large, the inclination of the blade tip in the circumferential direction and the inclination of the axial direction are increased to increase the stationary blade blade. The overall performance of the interflow can be improved.

[0013]

According to the present invention, the radial distribution of the inclination angle θ in the circumferential direction is made into an arc shape so as to project in the direction of the blade pressure surface, and at the same time, the radial distribution of the inclination angle δ of the axial direction is changed in the blade leading edge direction. By distributing so that the radial distribution of the circumferential tilt angle θ projects toward the blade pressure surface, the flow is more lateral It is possible to suppress the development of the side wall boundary layer and reduce the secondary flow vortices that occur in the blade-to-blade flow, while suppressing the development of the side wall boundary layer, and to reduce the flow angle of the static blade in a low-loss turbomachine. Can be realized.

[Brief description of drawings]

FIG. 1 is an explanatory view showing the inclination of a stationary blade when the stationary blade of the first embodiment of the present invention is viewed from the axial direction on the downstream side.

FIG. 2 is an explanatory view of the vane of the present invention seen from the meridian plane.

FIG. 3 is an explanatory view of a blade surface when the stationary blade moves to the upstream side as it separates from the side wall.

FIG. 4 is an explanatory diagram of a flow loss distribution generated in a stationary blade.

FIG. 5 is an explanatory diagram of a vane outflow angle distribution.

FIG. 6 is an explanatory view showing the inclination of the vane when the vane of the second embodiment of the present invention is viewed from the axial direction on the downstream side.

FIG. 7 is an explanatory view of the vane of the present invention seen from the meridian plane.

FIG. 8 is an explanatory view showing the inclination of the vane when the vane of the third embodiment of the present invention is viewed from the axial direction on the downstream side.

FIG. 9 is an explanatory view of the vane of the present invention seen from the meridian plane.

[Explanation of reference numerals] 1 ... upper diaphragm, 2 ... lower diaphragm, 3 ... stator blade, 4 ... moving blade rotation direction, 5 ... stator blade leading edge, 6 ... stator blade trailing edge,
7 ... flow direction, 8 ... stationary vane on side wall, 9 ... stationary vane away from side wall.

Claims (3)

[Claims] 1. A stator vane of an axial flow type turbomachine, wherein a plurality of vanes are arranged in an annular flow path, and the vanes are arcuate when viewed from the axial direction by changing a circumferential inclination angle θ in the radial direction. The axial vane of the axial flow turbomachine is characterized in that the axial tilt angle δ is also changed in the radial direction so that the meridian surface has an arcuate shape. 2. A stator blade of an axial flow type turbomachine, wherein a plurality of stator blades are arranged in an annular passage, and a radial distribution of a circumferential inclination angle θ and an axial inclination angle δ of the stator blades is distributed in a blade span central portion. It is set so as not to be symmetric with respect to each other, and the arcuate shape of the vane is not symmetrical with respect to the central portion of the blade span even when viewed from the axial direction and the meridian plane. Stator blade of axial flow turbomachine. 3. The radial distribution of the circumferential tilt angle θ according to claim 2, wherein the radial distribution of the circumferential tilt angle θ is distributed so as to have an arched shape protruding in the blade pressure surface direction, and the radial distribution of the axial tilt angle δ is set in front of the blade. Stator blades of axial flow turbomachines distributed in an arc shape that protrudes in the edge direction.