JP3786458B2 - Axial turbine blade - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement of a stationary blade or a moving blade of an axial flow turbine, and in particular, for the purpose of heating, cooling, and flow control of a blade, a fluid is introduced into the blade and blown out from the blade trailing edge or the blade surface. The present invention relates to an axial-flow turbine blade having an improved shape of a blow-out port portion for flow optimization.
[0002]
[Prior art]
A turbine blade that has a hollow part inside the axial flow turbine blades and guides a fluid higher in pressure than the mainstream working fluid that flows around the blades to the inside of the blades and outflows from the trailing edge or blade surface. In order to improve the reliability, the gas turbine is generally used, and a configuration example applied to the steam turbine has already been proposed.
[0003]
In a gas turbine, in order to cool the turbine blades, air at a temperature lower than that of the turbine working fluid is extracted from the compressor and guided to the hollow portions inside the stationary blades and the moving blades of the turbine stage. It is blowing out from the surface.
[0004]
On the other hand, with regard to steam turbines, high-temperature and high-pressure steam is introduced into the turbine vanes used in wet steam to heat the vanes to re-evaporate the condensed water flowing on the surface, and the lower flow blades are eroded by moisture. Japanese Laid-Open Patent Application No. 50-112604 proposes a technique for preventing and further reducing the loss caused by the collision of water droplets.
[0005]
Further, for the purpose of reducing the secondary flow loss and the wake loss in the paragraph of a general axial flow fluid machine, a structure in which a part of the main flow is sucked from the blade surface and guided to the inside of the blade and blown out from the trailing edge is disclosed in JP-B-56. It is proposed in -14845.
[0006]
Of the above conventional techniques, a technique related to the steam turbine described in Japanese Patent Application Laid-Open No. 50-112604 will be specifically described.
[0007]
8 and 9 are examples of the steam turbine described above, and are examples of application to the low-pressure final stage. The paragraph of the turbine is composed of a plurality of stationary blades 1 arranged in the circumferential direction and a plurality of moving blades 2 arranged in the circumferential direction. The rotor blade 2 is implanted in the rotor 3 and rotates together with the rotor 3.
[0008]
The stationary blade 2 is fixed to the casing 4, and the passage-side surface of the casing 4 forms an outer peripheral wall 10 that surrounds the mainstream working fluid Fm flowing through the stationary blade 1 from the outside. The surface of the part forms an inner peripheral wall 11. A high-temperature and high-pressure working fluid suction port 5 is provided at the stationary blade inlet portion of the upstream stage of the final stage, and the steam taken from the suction port 5 passes through the bypass passage 6 and is a hollow portion 7 inside the stationary blade 1. Led to.
[0009]
9 is a cross-sectional view taken along the line AA in FIG. A trailing edge outlet 9 as an outlet is formed at the rear edge of the stationary blade 1, and the steam in the hollow portion 7 is guided to the trailing edge outlet 9 by the outlet passage 8.
[0010]
In the steam turbine configured as described above, steam which is normally dry at a higher temperature and pressure than the last stage is taken in from the suction port 5 and led to the hollow portion 7 through the bypass passage 6. The stationary blade 1 is heated by this steam, and a part of the condensed water flowing on the surface is evaporated again to become steam.
[0011]
The steam in the hollow portion 7 is blown out from the trailing edge blowout port 9 into the mainstream steam through the blowout passage 8. At this time, the water that has reached the trailing edge without being evaporated due to the heating of the stationary blade 1 is blown off and refined. As a result, both the total amount of moisture colliding with the moving blade 2 and the number of relatively large water droplets with strong erosion action are reduced, and the erosion of the moving blade 2 is reduced. The resulting degradation in paragraph performance is also reduced.
[0012]
In this prior art, the direction of injection from the trailing edge outlet 9 is made to substantially coincide with the direction of outflow of the working fluid, and the injection speed is equal to or slightly higher than the speed of the main flow of the working fluid. Has been.
[0013]
[Problems to be solved by the invention]
The steam turbine configured as described above causes a part of the steam to flow out together with moisture compared to a method in which condensed moisture on the stationary blade is sucked from the surface of the stationary blade and discharged to the outside. This seems to be desirable because it does not impair the performance of the paragraph and prevents erosion of the rotor blades. Therefore, the influence of blowout from the trailing edge on the paragraph performance was examined by the annular cascade test, and the following problems were clarified.
[0014]
FIG. 10 shows the loss distribution of the stationary blade in terms of the total pressure loss coefficient. The vertical axis represents the height position of the stationary blade outlet made dimensionless with the trailing edge height, and the horizontal axis represents the total pressure loss coefficient made dimensionless with the total pressure loss coefficient ζPCD at the center of the flow path when there is no blowing. ing. A solid line indicates a measured value when there is no trailing edge balloon, and a broken line indicates a measured value when there is a trailing edge balloon.
[0015]
The sudden increase in loss at a dimensionless height of 0.8 or more is due to the secondary flow generated by the low energy fluid on the outer peripheral wall surface 10 flowing into the main flow. In this part, the loss when there is a trailing edge blowout exceeds that without a blowout.
[0016]
On the other hand, when the dimensionless height is 0.5 to 0.7, the loss with blowing is slightly reduced. Therefore, when blowing is performed at a height between 0.8 and 1.0 on the outer peripheral wall side, the reduction in efficiency due to the blowing is large, and when blowing is performed at a height between 0.5 and 1.0. Is somewhat improved by reducing the loss near the center, but efficiency is still reduced.
[0017]
FIG. 11 is an explanatory diagram showing a simplified secondary flow downstream of the blade row. The portion of the low-energy flow that forms a boundary layer on the outer peripheral wall and the inner peripheral wall moves to the blade back side due to the pressure gradient from the ventral side to the back side of the cascade passage. The low-energy fluid that has reached the dorsal side further enters a position at a certain height on the dorsal side, where it forms a vortex away from the wing surface.
[0018]
Therefore, it can be seen that there is a velocity component toward the center of the flow path along the trailing edge in the influence region of the secondary flow. When blowing from the trailing edge here, the blown fluid is drawn into the secondary flow vortex and deflected in the same direction, and as a result, energy is supplied to the secondary flow vortex to increase the secondary flow loss. Conceivable.
[0019]
8 and 9, the circumferential angle of the blowing can be directed in the direction of the main flow of the working fluid by providing the blowing passage 8 as a relatively long running section. The flow direction along the flow path cannot be restricted at all, and as a result, the flow direction is determined by the state of the inlet and outlet of the blowing passage 8.
[0020]
As is apparent from the structure of the hollow portion 7 in FIG. 8, a flow from the outer peripheral wall toward the center of the flow path is generated in the hollow portion, which promotes the tendency to blow out in the direction of the secondary flow described above. . In order to clarify the phenomenon that the loss is reduced by the blowout near the center of the channel where the influence of the secondary flow does not reach much, a highly accurate numerical simulation of the flow is performed, and it usually occurs at the trailing edge without the blowout It was found that the backflow region was filled with the blowout flow, and the flow was stable without any disturbance due to the backflow.
[0021]
Therefore, in the center of the flow path, which is a two-dimensional flow, the blowout reduces the blade loss, but in some way near the inner and outer walls where the flow has a significant three-dimensionality, the flow direction of the blowout in the radial direction is somehow. Unless the air pressure is controlled, the blowout acts in the direction of increasing the secondary flow, and the efficiency of the turbine is reduced when viewed in the whole paragraph.
[0022]
Other conventional techniques have similar problems. Japanese Patent Publication No. 56-14845 does not control the blowout in the direction along the trailing edge. Instead, as a measure for reducing the secondary flow, the circumferential blowout outflow angle is changed to the geometric stationary blade outflow angle. 3 to 5 degrees offset from
[0023]
However, since the blade outflow angle varies with fluid conditions such as outflow velocity, and there is a difference of more than 1 degree in the main flow direction and in the wake just downstream of the trailing edge, finding an effective offset angle is not possible. It is actually quite difficult and the degree of effect is not considered sufficient.
[0024]
Many proposals have been made regarding gas turbine cooling blades. For example, Japanese Patent Laid-Open No. 6-137105 discloses a technique for reducing the secondary flow loss by increasing the opening area of the blow slit near the outer peripheral wall and the inner peripheral wall of the trailing edge. However, if the outflow direction is not controlled effectively only by taking a large opening area, the secondary flow is increased instead of the example described above.
[0025]
The present invention has been made in consideration of the above-described circumstances, and an axial flow turbine blade that functions so as not to increase loss by blowing high-pressure fluid from the blade trailing edge or blade surface, but rather to improve efficiency by blowing. The purpose is to provide.
[0026]
[Means for Solving the Problems]
In order to solve the above-described problem, the invention of claim 1 is a stationary blade or a moving blade of an axial-flow turbine, wherein a hollow portion is formed inside the blade, and the hollow portion is formed at a trailing edge portion of the blade. A communication outlet is formed, and the fluid guided to the hollow portion at a higher pressure than the main flow operating fluid flowing in the working fluid passage around the blade trailing edge is allowed to flow from the outlet on the blade trailing edge to the working fluid passage. The rear edge near the inner peripheral wall located on the inner peripheral side is inclined in the direction inclined toward the inner peripheral wall side, and the outer edge located near the outer peripheral side of the working fluid channel is inclined in the direction inclined toward the outer peripheral wall side. In the axial flow turbine blade blown out to the working fluid flow path, the working fluid flow path in which the axial flow turbine blade is disposed is formed as an enlarged flow path whose flow path height increases in the flow direction. , The outlet from the turbine central axis The inclination angle of the outer peripheral wall is βt, the radius of the intersection of the outer peripheral wall and the rear edge is Rt, the inclination angle of the inner peripheral wall is βr, the radius of the intersection of the inner peripheral wall and the rear edge is Rr, and the rear edge position at an arbitrary radius R The average inclination angle βm defined in
[ Equation 1 ]
βm = {βt (R−Rt) + βr (Rt−R)} / (Rt−Rr)
The meridian inclination angle β of the trailing edge balloon is
[ Equation 2 ]
For R <(Rr + Rt) / 2, β <βm,
For R> (Rr + Rt) / 2, β> βm
And the secondary flow loss is reduced.
[0027]
According to the present invention, in an axial-flow turbine blade having an enlarged flow path, a geometric average inclination angle associated with the expansion of the flow path when blown from the trailing edge of the high-pressure fluid led to the hollow portion inside the blade. With reference to βm, the air is blown so as to incline toward the inner peripheral wall near the inner peripheral wall and toward the outer peripheral wall near the outer peripheral wall, so that a flow opposite to the secondary flow Fs shown in FIG. Secondary flow vortices can be weakened and secondary flow loss can be reduced.
[0030]
According to a second aspect of the invention, in axial flow turbine blade according to claim 1, ventral wing (positive pressure side), near the inner circumferential wall and outer circumferential wall so as to face to the inner circumferential wall and the outer peripheral wall, respectively, Katsuko Horse A trailing edge line projected onto a plane or a plane perpendicular to the turbine central axis is formed to be curved in an arcuate shape, and a blowout port is provided along the trailing edge line.
[0031]
According to the present invention, since the ventral side of the blade near the inner circumferential wall and the outer peripheral wall to bend the trailing edge line arcuately to face the direction of the wall, as mainstream flow be attached pushed to the wall outlet from Cascade In addition, since the blowout from the trailing edge also faces the wall, it is possible to prevent the secondary flow vortex from winding up away from the wall, and to reduce the loss due to the secondary flow vortex rolling up.
[0032]
Invention of Claim 3 is an axial-flow turbine blade in any one of Claim 1 or 2 , Between the hollow part provided in the inside of a blade, and the outlet provided along the blade trailing edge, A plurality of flow guide plates, guide vanes, or guide passages for controlling the flow direction of the blown-out fluid in the radial direction are provided.
[0033]
According to the present invention, a guide plate, a guide vane, or a guide passage for controlling the radial flow direction of the blown fluid is provided so that the flow of the blown fluid flows out toward the wall side. A flow in the direction opposite to the secondary flow vortex can be caused, and the secondary flow loss can be reduced.
[0034]
According to a fourth aspect of the present invention, in the axial-flow turbine blade according to any one of the first to third aspects, the blowout port is excluded from the inner peripheral wall and a part very close to the outer peripheral wall of the entire length of the trailing edge. It is provided in all areas.
[0035]
According to the present invention, since the blowout port is not provided very close to the wall, it is possible to prevent the blowout flow from interfering with the boundary layer of the wall and causing loss due to mixing and friction .
[0036]
According to a sixth aspect of the present invention, there is provided a stationary blade or a moving blade of an axial flow turbine, wherein a hollow portion is formed inside the blade, and a blowout port communicating with the hollow portion is formed at a rear edge portion of the blade. In the axial flow turbine blade, the fluid guided to the hollow portion at a pressure higher than that of the main flow working fluid flowing in the working fluid flow path around the trailing edge is blown out from the blowout port on the blade trailing edge side to the working fluid flow path. The blowing direction of the high-pressure fluid is on the inner wall near the inner wall on the back side of the blade, on the outer wall near the outer wall on the blade back side, on the outer wall side near the inner wall on the blade back side, In the vicinity of the outer peripheral wall on the blade side, the blade surface outlet is formed so as to face the inner peripheral wall side to reduce the secondary flow loss .
[0037]
According to the present invention, since the high-pressure fluid is blown out from the blade surface in the direction of preventing the secondary flow, not the trailing edge, the growth of the vortex can be effectively prevented at the generation stage of the secondary flow vortex. Secondary flow loss can be reduced.
[0038]
According to a fifth aspect of the present invention, there is provided a stationary blade or a moving blade of an axial-flow turbine, wherein a hollow portion is formed inside the blade, and a blowout port communicating with the hollow portion is formed at a rear edge portion of the blade. In the axial flow turbine blade, the fluid guided to the hollow portion at a pressure higher than that of the main flow working fluid flowing in the working fluid flow path around the trailing edge is blown out from the blowout port on the blade trailing edge side to the working fluid flow path. The blowing direction of the high-pressure fluid is on the inner wall near the inner wall on the back side of the blade, on the outer wall near the outer wall on the blade back side, on the outer wall side near the inner wall on the blade back side, In the vicinity of the outer peripheral wall on the blade side, the blade surface outlet is formed so as to face the inner peripheral wall side to reduce the secondary flow loss.
[0039]
1 and 2 show a first embodiment of an axial turbine. Incidentally, in the conventional configuration that is the same or corresponding portions will be described using the same reference numerals as FIGS.
[0040]
In this embodiment, as shown in FIG. 1 and FIG. 2, dozens of sheets in the circumferential direction between the casing 4 constituting the outer peripheral wall 10 of the working fluid flow path and the stationary blade inner ring 21 constituting the inner peripheral wall 11. The stationary blade 1 is joined and fixed. In addition, several tens of moving blades 2 are attached to the rotor 3 in the circumferential direction so that the rotor 3 can rotate at high speed.
[0041]
The casing 4 is provided with a high-pressure fluid passage 16, and high-pressure fluid is supplied to the stationary blade 1 for the purpose of heating, cooling or flow control of the blades from an upstream turbine bin stage or an external compressor (not shown). It is led to the hollow part inside. In addition, although this embodiment has been described for the stationary blade, the high-pressure fluid passage 16 is provided in the rotor 3 when the moving blade is the target.
[0042]
FIG. 2 is a cross-sectional view taken along the line B-B of FIG. 1. As shown in FIG. 2R> 2, a blowing passage 8 is provided between the hollow portion 7 and the trailing edge blowing port 9. As shown in FIG. 1, the blowing passage 8 is partitioned by the guide plate 14 and the guide vanes 13, and the high-pressure fluid is blown out from the trailing edge at a meridional surface inclination angle β determined in advance for each radius. ing.
[0043]
The inclination angle of the outer peripheral wall measured from the turbine central axis is βt, the radius of the intersection of the outer peripheral wall and the rear edge is Rt, the inclination angle of the inner peripheral wall is βr, the radius of the intersection of the inner peripheral wall and the rear edge is Rr, and an arbitrary radius R The average inclination angle βm defined by the trailing edge position at
[Equation 3]
βm = {βt (R−Rr) + βr (Rt−R)} / (Rt−Rr)
The meridian inclination angle β of the trailing edge balloon is
[Equation 4]
For R <(Rr + Rt) / 2, β <βm,
For R> (Rr + Rt) / 2, β> βm
Thus, the shape of the guide plate 14 and the guide blade 13 that form the trailing edge outlet 9 and the mounting angle in the radial direction are adjusted.
[0044]
The trailing edge outlet 9 is not provided at the position between the inner peripheral wall 11 and the outer peripheral wall 10 at a length of 5% to 10% of the total length of the trailing edge, and the outlet passage inner peripheral side wall 15 and the outlet passage outer peripheral side wall are not provided. 12 are provided.
[0045]
Next, the operation of this embodiment will be described. While the high-pressure fluid flow Fh is blown from the hollow portion 7 through the blowout passage 8 to the mainstream working fluid Fm from the trailing edge blowout port 9, the guide plate 14, guide vanes 13 and blowout provided in the blowout passage 8 are blown out. The passage outer peripheral side wall 12 and the blowout passage inner peripheral side wall 15 give a speed component from the center of the flow path toward the outer peripheral wall 10 near the outer peripheral wall and toward the inner peripheral wall 11 near the inner peripheral wall. On the other hand, since the outlet is not open at a position very close to the wall, the fluids blown out near the wall flow smoothly without colliding with each other.
[0046]
Thus, according to the present embodiment, the direction of blowing from the rear edge can be inclined along the rear edge in the direction of the inner peripheral wall 11 and the outer peripheral wall 10, and excessive concentration is made at a position very close to the wall. Therefore, it is possible to effectively suppress the secondary flow and reduce the turbine stage loss.
[0047]
The conventional secondary flow suppression means that inclines or curves the blade in the circumferential direction can only expect an average effect in the circumferential direction, but in this embodiment, the vicinity of the wake where the secondary flow vortices concentrate In addition, the flow in the opposite direction to the vortex of the secondary flow is caused intensively, and the vortex can be attenuated more effectively.
[0048]
FIG. 3 shows the loss distribution in the radial direction of the turbine stage to which the present invention is applied. Contrary to the conventional example, the secondary flow loss is greatly reduced by performing the trailing edge blowing.
[0049]
FIG. 4 shows an axial turbine blade according to the second embodiment of the present invention. In the present embodiment, the stationary blade 1 is bonded and fixed between the inner peripheral wall 11 and the outer peripheral wall 10. A high-pressure fluid inlet 17 is opened in the outer peripheral wall 1 and communicates with the hollow portion 7 inside the stationary blade.
[0050]
A guide plate 14 is provided in the blowout passage 8 between the hollow portion 7 and the trailing edge blowout port 9 in order to direct the flow Fh of the high-pressure fluid in the wall direction. The stationary blade 1 is a rear edge projected on a surface orthogonal to the turbine shaft center so that the ventral side (positive pressure surface) is directed toward the inner peripheral wall 11 and the outer peripheral wall 10 near the inner peripheral wall 11 and the outer peripheral wall 10. The line is curved in a bow shape.
[0051]
According to the configuration of the second embodiment, the flow of the high-pressure fluid passing through the blowing passage 8 naturally faces the wall direction by curving the trailing edge in an arc shape so that the ventral side of the wing faces the wall direction. Thus, the flow loss of the high-pressure fluid can be kept low. Therefore, even when the pressure difference between the mainstream working fluid and the high-pressure fluid supplied into the blade is small, the effect of suppressing the secondary flow can be exhibited.
[0052]
FIG. 5 shows an axial turbine blade according to the third embodiment of the present invention. In the present embodiment, the hollow portion 7 is formed inside the stationary blade 1 joined and fixed between the outer peripheral wall 10 and the inner peripheral wall 11, and the high-pressure fluid inlet 17 is on the outer peripheral wall 10 side of the hollow portion 7. Is open. The trailing edge 20 of the stationary blade 1 is curved in an arc shape so that the central portion of the trailing edge protrudes downstream as viewed from the meridian plane.
[0053]
However, the curved portion of the rear edge 20 ends at a position very close to the inner and outer walls, and the angle formed by the rear edge line and the inner and outer walls does not become an acute angle. Inside the trailing edge 20 portion is provided blowout passage 8, blowout passage 8 is partition is by the passage peripheral side wall 15 and blowing passage peripheral side wall 12 balloon near the inner and outer walls.
[0054]
According to the third embodiment as described above, the high-pressure fluid supplied to the hollow portion 7 is ejected through the blowing passage 8 in a direction substantially perpendicular to the trailing edge 20. In this case, since the shape of the trailing edge 20 is curved, the flow of the high-pressure fluid near the wall is directed toward the inner and outer walls. Accordingly, the same effects as those of the first embodiment can be obtained. That is, in the third embodiment, since the blowing flow blows out substantially straight to the trailing edge 20, the guide plate and the guide vanes inside the blowing passage can be omitted, and the secondary flow suppression effect can be achieved with a simpler shape. realizable.
[0055]
6 and 7 show an axial turbine blade according to the fourth embodiment of the present invention. This embodiment is different from the other embodiments in that a ventral surface outlet 18 and a back surface outlet 19 are provided from the hollow portion 7 inside the stationary blade 1. Further, the ventral surface outlet 18 is opened so as to blow out toward the center of the flow path, and the back side outlet 19 is blown out toward the wall, both of which are opposite to the direction of the secondary flow vortex. It has the effect of creating a flow and reducing losses.
[0056]
【The invention's effect】
As described in detail above, according to the axial turbine blade according to the present invention, it is possible to generate a blow-out flow in a direction opposite to the secondary flow of the blade row, thereby attenuating the secondary flow vortex. it can. Therefore, the loss does not increase due to the blowout from the trailing edge or the blade surface, but rather the effect of improving the efficiency due to the blowout is achieved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a first embodiment of an axial turbine blade according to the present invention.
FIG. 2 is a cross-sectional view taken along the line BB in FIG.
FIG. 3 is a distribution diagram in the height direction of total pressure loss for explaining the effect of the first embodiment;
FIG. 4 is a perspective view showing a second embodiment of an axial turbine blade according to the present invention.
FIG. 5 is a cross-sectional view showing a third embodiment of an axial turbine blade according to the present invention.
FIG. 6 is a sectional view showing a fourth embodiment of an axial turbine blade according to the present invention.
FIG. 7 is a cross-sectional view showing a fourth embodiment of an axial turbine blade according to the present invention in a different plane.
FIG. 8 is a sectional view showing a conventional axial turbine blade.
9 is a cross-sectional view taken along the line Α-Α in FIG. 8;
FIG. 10 is a distribution diagram in the height direction of the total pressure loss coefficient for explaining problems of a conventional axial turbine blade.
FIG. 11 is a conceptual diagram illustrating a secondary flow of an axial turbine.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Stator blade 2 Rotor blade 3 Rotor 4 Casing 5 Suction port 6 Bypass passage 7 Hollow part 8 Outlet passage 9 Rear edge outlet 10 Outer peripheral wall 11 Inner peripheral wall 12 Passage outer peripheral side wall 13 Guide vane 14 Guide plate 15 Outlet passage inner peripheral side wall 16 High pressure fluid passage 17 Fluid inlet 18 Ventral surface outlet 19 Back side outlet 20 Rear edge 21 Stator blade inner ring

Claims (5)

A stationary blade or a moving blade of an axial-flow turbine, in which a hollow portion is formed inside the blade, and a blowout port communicating with the hollow portion is formed in a rear edge portion of the blade so that a working fluid flow around the blade trailing edge The fluid guided to the hollow portion at a pressure higher than that of the mainstream working fluid flowing in the passage is the inner peripheral wall of the rear edge near the inner peripheral wall located on the inner peripheral side of the working fluid flow path from the outlet on the blade trailing edge side. In an axial turbine blade that is inclined in the direction inclined to the side and near the outer peripheral wall located on the outer peripheral side of the working fluid flow path, and is inclined to the direction inclined to the outer peripheral wall side, and blown out to the working fluid flow path. The working fluid flow path in which the axial turbine blade is disposed is formed as an enlarged flow path whose flow path height increases in the flow direction, and the blowout port is inclined on the outer peripheral wall from the turbine central axis. The angle of βt, the intersection of the outer wall and the trailing edge The diameter Rt, .beta.r the inclination angle of the inner peripheral wall, the radius of the intersection of the inner wall and a trailing edge and Rr, the average inclination angle βm defined trailing edge position in any radius R,
[ Equation 1 ]
βm = {βt (R−Rt) + βr (Rt−R)} / (Rt−Rr)
The meridian inclination angle β of the trailing edge balloon is
[ Equation 2 ]
For R <(Rr + Rt) / 2, β <βm,
For R> (Rr + Rt) / 2, β> βm
An axial-flow turbine blade characterized in that the secondary flow loss is reduced by forming the same . The axial-flow turbine blade according to claim 1, wherein the blade's ventral side (positive pressure side) faces the inner peripheral wall and the outer peripheral wall near the inner peripheral wall and the outer peripheral wall, respectively, and is perpendicular to the meridian plane or the turbine central axis. An axial-flow turbine blade, characterized in that a trailing edge line projected onto a flat surface is curved in an arcuate shape and a blowout port is provided along the trailing edge line. 3. The axial flow turbine blade according to claim 1, wherein a radial flow of the blown fluid is provided between a hollow portion provided in the blade and a blowout port provided along the blade trailing edge. An axial turbine blade comprising a plurality of flow guide plates, guide blades, or guide passages for controlling the direction of the flow. The axial flow turbine blade according to any one of claims 1 to 3 , wherein the blowout port is provided in the entire region excluding the inner peripheral wall and a part very close to the outer peripheral wall in the entire length of the rear edge. A characteristic axial-flow turbine blade.   A stationary blade or a moving blade of an axial-flow turbine, in which a hollow portion is formed inside the blade, and a blowout port communicating with the hollow portion is formed in a rear edge portion of the blade so that a working fluid flow around the blade trailing edge The axial flow turbine blade in which the fluid guided to the hollow portion at a pressure higher than that of the mainstream working fluid flowing in the passage is blown out from the outlet on the blade trailing edge side to the working fluid flow path has a high-pressure fluid blowing direction. Near the inner wall on the blade back side, on the inner wall side, near the outer wall on the blade back side, on the outer wall side, near the inner wall on the blade belly side, on the outer wall side, near the outer wall on the blade belly side Then, an axial flow turbine blade is characterized in that a blade surface outlet is formed so as to face the inner peripheral wall side to reduce secondary flow loss.

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