US20130224034A1

US20130224034A1 - Blade body and rotary machine

Info

Publication number: US20130224034A1
Application number: US13/881,582
Authority: US
Inventors: Yasuro Sakamoto; Eisaku Ito; Hitoshi Kitagawa; Susumu Wakazono
Original assignee: Mitsubishi Heavy Industries Ltd
Current assignee: Mitsubishi Power Ltd
Priority date: 2009-07-09
Filing date: 2010-12-27
Publication date: 2013-08-29

Abstract

The blade body of the present invention is provided with a main body which has a dorsal face and a ventral face and also provided with a trailing edge portion which connects the dorsal face to the ventral face with a continuous curved face. The curved face of the trailing edge portion is gradually decreased in curvature radius from one of the dorsal face and the ventral face toward the rear end portion which is positioned most downstream in a direction at which a fluid flows, decreased to the greatest extent in curvature radius at the rear end portion, thereafter, gradually increased in curvature radius from the rear end portion toward the other of the dorsal face and the ventral face and arrives at the other of the dorsal face and the ventral face.

Description

TECHNICAL FIELD

The present invention relates to a blade body which is applied to a rotary machine such as a turbine unit of a gas turbine, a compressor, a fan, a steam turbine or a wind mill and also relates to the rotary machine. The present invention relates in particular to the shape of a trailing edge of the blade body.

BACKGROUND ART

Conventionally, there is a case that a blade body which is applied to a rotary machine such as a turbine unit of a gas turbine is made relatively thick for increasing the strength and a trailing edge thereof is formed into a circular arc (substantially semicircular) shape as like as a part of a true circle or a linear shape cut substantially perpendicularly with respect to a camber line. As described above, where the trailing edge is formed into a circular arc shape based on a complete roundness or a linear shape cut perpendicularly with respect to a camber line, the trailing edge is relatively increased in thickness. Thus, separation of a flow on a blade surface takes place to cause a relatively large wake from the trailing edge of the blade, which contributes to an increase in flow loss or in resistance of flow channel.
Therefore, proposed is a blade body which is formed so that there is made substantially perpendicular an angle of a point where an end portion of a ventral edge line of the blade body which is a straight line or a curved line great in curvature radius is connected to an end portion of a dorsal edge line thereof (refer to Patent Document 1, for example).

PRIOR ART DOCUMENT

Patent Document

Patent Document 1: Japanese Published Unexamined Patent Application No. 2005-76533

SUMMARY OF THE INVENTION

Problems to be Solved by the Invention

However, in the above-described conventional rotary machine, a flow loss due to a wake from the blade body and resistance of flow channel still account for a higher percentage of total loss. Therefore, it is desired to reduce the loss due to the wake and improve efficiency.
The present invention has been made in view of the above situation, an object of which is to provide a blade body capable of reducing flow loss due to a wake from a trailing edge caused by separation of a flow on a blade surface of the blade body and resistance of flow channel and also provide a rotary machine.

Means for Solving the Problems

The blade body (for example, any one of turbine blades 1, 21, 31 to be described in embodiments) of the present invention is provided with a main body (for example, a main body 4 to be described in an embodiment) having a dorsal face (for example, a dorsal face 2 to be described in an embodiment) and a ventral face (for example, a ventral face 3 to be described in an embodiment) and also provided with a trailing edge portion (for example, any one of 6, 26, 36 to be described in embodiments) which connects the dorsal face to the ventral face with a continuous curved face (for example, any one of curved faces 5, 25, 35 to be described in embodiments). The curved face of the trailing edge portion is gradually decreased in curvature radius from one of the dorsal face and the ventral face toward a rear end portion (for example, any one of rear end portions 7, 27, 37 to be described in embodiments) which is positioned most downstream in a direction at which a fluid flows and decreased to the greatest extent in curvature radius at the rear end portion, thereafter, gradually increased in curvature radius from the rear end portion toward the other of the dorsal face and the ventral face and arrives at the other of the dorsal face and the ventral face.
According to the blade body of the present invention, the curved face of the trailing edge portion continuing toward the dorsal face or the ventral face of the main body is gradually decreased in curvature radius and made thinner as it approaches the rear end portion. Therefore, a part in the vicinity of the rear end portion can be made thinner, with the strength kept, than a conventional case that a trailing edge portion is formed in such a manner that a cross section thereof is simply in a substantially semicircular shape or an angle of a point where an end portion of a dorsal edge line is connected to an end portion of a ventral edge line is made substantially perpendicular. Then, separation of a flow coming from a blade surface takes place at a backward position to make a wake from the trailing edge portion narrow, thus making it possible to reduce flow loss and improve efficiency.
Further, in the blade body of the present invention, it is acceptable that the trailing edge portion is such that a part of the curved face positioned at the dorsal face side is different from the other of the curved face positioned at the ventral face side in the rate of decrease of a curvature radius toward the rear end portion.
According to the blade body of the present invention, even where a part of the curved face positioned at the dorsal face side is different from the other of the curved face positioned at the ventral face side in the rate of decrease of a curvature radius toward the rear end portion, a blade in the vicinity of the rear end portion can be made thinner than a conventional case that a trailing edge portion is formed in such a manner that a cross section thereof is simply in a substantially semicircular shape or an angle of a point where an end portion of a dorsal edge line is connected to an end portion of a ventral edge line is made substantially perpendicular. Therefore, separation of a flow coming from a blade surface takes place at a backward position to make a wake from the trailing edge portion narrow, thus making it possible to reduce flow loss and improve efficiency.
In the blade body of the present invention, it is acceptable that the rear end portion is disposed on an extended line (for example, an extended line 10 of an embodiment) of a camber line (for example, a camber line 9 of an embodiment) of the main body.
According to the blade body of the present invention, the rear end portion is disposed on an extended line of a camber line of the main body, by which a change in curvature radius is made equal between the ventral face side and the dorsal face side. It is therefore possible to easily form the shape of a blade smoothly.
In the blade body of the present invention, it is acceptable that the rear end portion is disposed further to the dorsal face side or to the ventral face side than the extended line of the camber line of the main body.
According to the blade body of the present invention, even where the rear end portion is disposed further to the dorsal face side or to the ventral face side than the extended line of the camber line of the main body, it is possible to suppress a wake resulting from separation of a flow on a blade surface, as compared with the shape of the trailing edge of the conventional blade body.
In addition, it is acceptable that the blade bodies of the present invention are a plurality of blade bodies disposed on a rotary body at an equal interval, and the curved face of the trailing edge portion is formed so as to give a curvature radius which is capable of maintaining a throat (for example, a throat S in an embodiment) between blades where no trailing edge portion is provided.
According to the blade body of the present invention, since the trailing edge portion gives no influence on maintaining of the throat between blades, it is possible to prevent a change in flow rate due to a decrease in the size of the throat or the like.
In addition, the rotary machine of the present invention is provided with the blade body of the present invention described above.

Effects of the Invention

According to the blade body and the rotary machine of the present invention, the curved face of the trailing edge portion is gradually decreased in curvature radius from one of the dorsal face and the ventral face toward the rear end portion which is positioned furthest backward in the main body and decreased to the greatest extent in curvature radius at the rear end portion, thereafter, gradually increased in curvature radius from the rear end portion toward the other of the dorsal face and the ventral face and arrives at the other of the dorsal face and the ventral face. Thereby, a blade in the vicinity of the rear end portion of the trailing edge can be formed thinner than a conventional blade. As a result, separation of a flow coming from a blade surface takes place at a backward position to make narrow a wake from the trailing edge portion. This is, therefore, effective in reducing flow loss and resistance of a flow channel.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial sectional view which shows a gas turbine of a First Embodiment of the present invention when viewed laterally.

FIG. 2 is a view which shows a profile of a turbine blade of the First Embodiment of the present invention.

FIG. 3 is a partially enlarged view which shows the vicinity of a trailing edge portion given in FIG. 2.

FIG. 4 is a partially enlarged view which shows a part corresponding to that given in FIG. 3 or another mode of the First Embodiment of the present invention.

FIG. 5 is a view which shows a throat of the turbine blade of the First Embodiment of the present invention.

FIG. 6 is a partially enlarged view which shows a part corresponding to that given in FIG. 3 of a Second Embodiment of the present invention.

FIG. 7 is a partially enlarged view which shows a part corresponding to that given in FIG. 3 or another mode of the Second Embodiment of the present invention.

FIG. 8 is a partially enlarged view which shows a part corresponding to that given in FIG. 3 of a Third Embodiment of the present invention.

FIG. 9 is a partially enlarged view which shows a part corresponding to that given in FIG. 3 or another mode of the Third Embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Next, a description will be given of the blade body and the rotary machine of the First Embodiment of the present invention with reference to drawings. In the First Embodiment, as the blade body, a description will be given with reference to turbine blades which are disposed on a rotor mounted on a turbine unit of a gas turbine, with an equal interval kept (hereinafter, the same shall apply to the Second Embodiment and Third Embodiment).
As shown in FIG. 1, a gas turbine 100 is provided with a compressor 102 for generating compressed air, a burner 103 for supplying a fuel to the compressed air supplied from the compressor 102 to generate a combustion gas and a turbine 107 on which turbine vanes 104 and turbine blades 1 are alternately placed and which rotates a rotor 106 having turbine blades 1 by the combustion gas supplied from the burner 103. In the turbine 107, an interior of a tubular casing 108 placed coaxially with an axis line O of the rotor 106 acts as a combustion gas flow channel F. The combustion gas flow channel F is separated on an outer circumference side thereof from the casing 108 by a tubular outer-circumferential side end wall 110 installed on an inner circumference side of the casing 108 and also separated on an inner circumference from the rotor 106 by a tubular inner-circumferential side end wall 111 installed on an outer circumference side of the rotor 106. Thus, the combustion gas flow channel F is provided as a flow channel having a donut-shaped cross section along a direction of the axis line O. Then, the plurality of turbine vanes 104 and turbine blades 1 made up of several stages are placed in a radial manner, respectively, inside the combustion gas flow channel F.
FIG. 2 shows a profile of the turbine blade 1 which is the blade body of the present embodiment. The turbine blade 1 is provided with a main body 4 having a dorsal face 2 and a ventral face 3. The dorsal face 2 is formed as a curved face relatively small in curvature radius, and the ventral face 3 is formed as a curved face greater in curvature radius than the dorsal face.
The turbine blade 1 is also provided with a trailing edge portion 6 which connects the dorsal face 2 of the main body 4 to the ventral face 3 thereof with a continuous curved face 5 on a downstream side (a side indicated with an arrow in FIG. 3) in a direction at which a fluid flows. As shown in FIG. 3, the trailing edge portion 6 is gradually decreased in curvature radius from one of the dorsal face 2 and the ventral face 3 toward the rear end portion 7 which is positioned most downstream in the direction at which the fluid flows and decreased to the greatest extent in curvature radius at the rear end portion 7, thereafter gradually increased in curvature radius from the rear end portion 7 toward the other of the dorsal face 2 and the ventral face 3 and arrives at the other of the dorsal face 2 and the ventral face 3. The trailing edge portion 6 is connected to the dorsal face 2 and the ventral face 3 smoothly so as not to have a step or an angular part, and the rear end portion 7 is disposed on an extended line 10 of the camber line 9 which is a center of the blade of the main body 4.
A circular arc 8 indicated with a broken line in FIG. 3 is the shape of a trailing edge of a conventional blade body, that is, a completely round circular arc (half round). The trailing edge portion 6 of the present embodiment is such that the curved face 5 is gradually decreased in curvature radius as it approaches the rear end portion 7. Therefore, the trailing edge portion 6 is formed so as to extend narrowly further downstream than the circular arc 8, and a base end side of the trailing edge portion 6 is formed so as to give thickness equal to that of the trailing edge of the conventional blade body. As a result, a wake can be made narrow, while the trailing edge portion 6 is kept sufficiently strong. The shape in which the trailing edge portion 6 is gradually decreased in curvature radius as it approaches the rear end portion 7 may include, for example, an oval arc 12 in which a long axis is superimposed on the extended line 10 of the camber line 9 as shown in FIG. 4.
As shown in FIG. 5, in an interspace between turbine blades 1 adjacent to each other of the plurality of the turbine blades 1 disposed at an equal interval, the trailing edge portion 6 is gradually decreased in curvature radius according to the shape of the dorsal face 2 of the blade 1 in such a manner that the cross-sectional area of the throat S that is a part at which the width of a flow channel between turbine blades 1 adjacent to each other is narrowest than the other part can be maintain equal the size of the cross-sectional area of the throat S before an improvement in the trailing edge portion 6.
Therefore, according to the turbine blade 1 and the rotary machine of the above-described embodiment, the curved face 5 is gradually decreased in curvature radius and made thinner as the curved face 5 of the trailing edge portion 6 continued to the dorsal face 2 or the ventral face 3 of the main body 4 approaches the rear end portion 7. Thus, as compared with a conventional case that a trailing edge portion of a blade body is formed so that a cross section thereof simply gives a substantially semicircular shape, with the strength secured, or an angle of a point at which the dorsal face is connected to the ventral face is made substantially perpendicular, separation of a flow coming from a blade surface takes place at a backward position, by which a wake from the trailing edge portion 6 can be made narrow. As a result, it is possible to reduce flow loss and improve efficiency.
Since the rear end portion 7 is disposed on the extended line 10 of the camber line 9 of the main body 4, a change in curvature radius is made equal between the ventral face side and the dorsal face side, thus making it possible to easily form the shape of a blade smoothly.
In addition, since the trailing edge portion 6 does not affect to maintain the throat S between blades, it is possible to prevent a change in flow rate due to a reduction in the size of throat or the like.
It is noted that in the above embodiment, a description has been given with reference to the turbine blade of a gas turbine, as an example. However, the present invention shall not be limited thereto and may be applicable to a turbine vane. Further, the present invention shall not be limited to the blade body of the gas turbine but may be applicable to a blade body used in a compressor, a fan, a steam turbine, a wind mill or an airplane. The description has been given of a case where the present invention is applied to the shape of a blade in which the dorsal face is different from the ventral face in curvature radius but may be applicable to a symmetrical shape of a blade in which a dorsal face and a ventral face of the blade are symmetrical in shape with each other.
Next, a description will be given of a turbine blade 21 which is a blade body of the Second Embodiment of the present invention with reference to FIG. 6 and FIG. 7. Parts which are the same as those of the turbine blade 1 of the First Embodiment will be given the same reference numerals in describing them.
As shown in FIG. 6, the turbine blade 21 of the Second Embodiment is provided with a main body 4 having a dorsal face 2 and a ventral face 3 and also provided with a trailing edge portion 26 which connects the dorsal face 2 to the ventral face 3 with a continuous curved face 25 on a downstream side in a direction at which a fluid flows. The curved face 25 of the trailing edge portion 26 is such that a rear end portion 27 which is positioned most downstream in the direction at which the fluid flows is disposed on an extended line 10 of a camber line 9.
The curved face 25 of the trailing edge portion 26 is gradually decreased in curvature radius from one of the dorsal face 2 and the ventral face 3 toward the rear end portion 27, decreased to the greatest extent in curvature radius at the rear end portion 27, thereafter, increased gradually in curvature radius from the rear end portion 27 toward the other of the dorsal face 2 and the ventral face 3 and arrives at the other of the dorsal face 2 and the ventral face 3.
Here, the curved face 25 of the trailing edge portion 26 shown in FIG. 6 is configured with a curved face 25 a on a dorsal face side which arrives at the rear end portion 27 from the dorsal face 2 and a curved face 25 b on a ventral face side which arrives at the rear end portion 27 from the ventral face 3. The curved face 25 a and the curved face 25 b are formed so as to be decreased in curvature radius as they approach each other to the rear end portion 27 but are mutually different in the ratio of decrease of the curvature radius.
More specifically, the curved face 25 a is formed so as to be relatively constant in the rate of decrease of the curvature radius from the dorsal face 2 toward the rear end portion 27. However, the curved face 25 b is formed so as to be lower in the rate of decrease of the curvature radius at a position away from the rear end portion 27 from the ventral face 3 toward the rear end portion 27 and so as to be higher in the vicinity of the rear end portion 27. Then, the curved face 25 a is lower than the curved face 25 b in the rate of decrease of the curvature radius in the vicinity of the rear end portion 27 toward the rear end portion 27.
Even where, as found in the above-described turbine blade 21 of the Second Embodiment, the curved face 25 a of the trailing edge portion 26 on the dorsal face side is different from the curved face 25 b on the ventral face side in the rate of decrease of the curvature radius toward the rear end portion 27, the vicinity of the rear end portion 27 can be formed thinner with the continuous curved face 25 than a conventional case that a blade body of a trailing edge portion is formed so that a cross section thereof simply gives a substantially semicircular shape or an angle of a point where an end of a dorsal edge line is connected to an end of a ventral edge line is made substantially perpendicular. Therefore, separation of a flow from a blade surface takes places at a backward position, by which a wake from the trailing edge portion 26 can be made narrow. As a result, it is possible to reduce flow loss and improve efficiency.
In the Second Embodiment described above, a description has been given of a case where the curved face 25 a on the dorsal face side is set lower than the curved face 25 b on the ventral face side in the rate of decrease of the curvature radius in the vicinity of the rear end portion 27 toward the rear end portion 27. Moreover, depending on conditions or the like for maintaining the throat S, it is acceptable that, for example, as shown in FIG. 7, the decrease ratio of the curvature radius is replaced between the curved face 25 a and the curved face 25 b, by which the curved face 25 b on the side of the ventral face 3 is set lower than the curved face 25 a on the dorsal face side in the rate of decrease of the curvature radius in the vicinity of the rear end portion 27 toward the rear end portion 27.
Next, a description will be given of a turbine blade 31 which is a blade body of the Third Embodiment of the present invention with reference to FIG. 8 and FIG. 9. The Third Embodiment is such that the rear end portion 27 of the Second Embodiment is deviated further to the dorsal face side or to the ventral face side than the extended line 10 of the camber line 9. Parts which are the same as those of the First Embodiment and Second Embodiment described above are given the same reference numerals in describing them.
As shown in FIG. 8, the turbine blade 31 of the Third Embodiment is, as with the turbine blade 21 of the Second Embodiment, provided with a main body 4 having a dorsal face 2 and a ventral face 3 and also provided with a trailing edge portion 36 which connects the dorsal face 2 to the ventral face 3 with a continuous curved face 35 on a downstream side in a direction at which a fluid flows.
A rear end portion 37 of the curved face 35 of the trailing edge portion 36 which is positioned most downstream in a direction at which the fluid flows is disposed further to the side of the ventral face 3 side than an extended line 10 of a camber line 9.
The curved face 35 of the trailing edge portion 36 is gradually decreased in curvature radius from one of the dorsal face 2 and the ventral face 3 toward the rear end portion 37, decreased to the greatest extent in curvature radius at the rear end portion 37, thereafter, gradually increased in curvature radius from the rear end portion 37 toward the other of the dorsal face 2 and the ventral face 3 and arrives at the other of the dorsal face 2 and the ventral face 3.
As with the Second Embodiment described above, the curved face 35 of the trailing edge portion 36 is such that the curved face 35 a on a dorsal face side is different from the curved face 35 b on a ventral face side in the rate of decrease of the curvature radius from each face to the rear end portion 37. More specifically, the curved face 35 a is formed so as to be relatively constant in the rate of decrease of the curvature radius from the dorsal face 2 to the rear end portion 37. However, the curved face 35 b is formed so as to be lowered in the rate of decrease of the curvature radius from the ventral face 3 to the rear end portion 37 at a position away from the rear end portion 37 and formed so as to be higher in the vicinity of the rear end portion 37. Then, the curved face 35 a has a lower curvature radius than the curved face 35 b in the rate of decrease of the curvature radius is lower than the curved face 35 b in a decrease ratio of the curvature radius toward the rear end portion 37.
In the turbine blade 31 of the Third Embodiment as well, as with the Second Embodiment, the vicinity of the rear end portion 27 can be formed thinner with the continuous curved face 35, than a conventional case that a trailing edge portion of a blade body is formed so that a cross section thereof simply gives a half round shape, or an angle of a point where an end portion of a dorsal edge line is connected to an end portion of a ventral edge line is made substantially perpendicular. Therefore, separation of a flow coming from a blade surface takes place at a backward position, by which a wake from the trailing edge portion 36 can be made narrow. As a result, it is possible to reduce flow loss and improve efficiency.
In the Third Embodiment described above, a description has been given of a case where the rear end portion 37 is deviated further to the ventral face 3 side than the extended line 10 and also the curved face 35 a on the dorsal face side is set lower than the curved face 35 b on the ventral face side in the rate of decrease of the curvature radius in the vicinity of the rear end portion 37 toward the rear end portion 37. Meanwhile, it is acceptable that depending on conditions or the like of retaining the throat S, for example, as shown in FIG. 9, the rear end portion 37 is deviated further to the dorsal face 2 side than the extended line 10, the decrease ratio of the curvature radius toward the rear end portion 37 described above is exchanged between the curved face 35 a and the curved face 35 b, by which the curved face 35 b on the ventral face side is set lower than the curved face 35 a on the dorsal face side in the rate of decrease of the curvature radius in the vicinity of the rear end portion 37 toward the rear end portion 37.

DESCRIPTION OF REFERENCE NUMERALS

1, 21, 31 . . . turbine blade,
2 . . . dorsal face,
3 . . . ventral face,
4 . . . main body,
5, 25, 35 . . . curved face,
6, 26, 36 . . . trailing edge portion,
7, 27, 37 . . . rear end portion,
9 . . . camber line,
10 . . . extended line,
100 . . . gas turbine,
S . . . throat

Claims

1. A blade body comprising:

a main body which has a dorsal face and a ventral face; and

a trailing edge portion which connects the dorsal face to the ventral face with a continuous curved face; wherein

a curved face of the trailing edge portion is gradually decreased in curvature radius from one of the dorsal face and the ventral face toward a rear end portion which is positioned most downstream in a direction at Which a fluid flows, decreased to the greatest extent in curvature radius at the rear end portion, and wherein

the curved face of the trailing edge portion is gradually increased in curvature radius from the rear end portion toward the other of the dorsal face and the ventral face and arrives at the other of the dorsal face and the ventral face.

2. The body according to claim 1, wherein

the trailing edge portion is such that the changing of the curvature radius of a part of the curved face positioned at the dorsal face side which decreases as close to the rear end portion is different from the changing of the curvature radius the other part of the curved face positioned at the ventral face side which decreases as close to the rear end portion.

3. The body according to claim 1, wherein

the rear end portion is disposed on an extended line of a camber line of the main body.

4. The body according to claim 1, wherein

the rear end portion is disposed further to the side of the dorsal face or to the side of the ventral face than the extended line of the camber line of the main body.

5. A plurality of blade bodies which are disposed on a rotary body at an equal interval,

and the blade body according to claim 1, wherein

the curved face of the trailing edge portion is formed so as to have a curvature radius capable of maintaining a throat between blades where no trailing edge portion is provided.

6. A rotary machine which is provided with the blade body according to claim 1.