Patent Grant
11421535
The present disclosure relates to a turbine blade, a turbocharger, and a method of producing a turbine blade.
In an engine used for an automobile and the like, an exhaust turbocharger is widely known, in which a turbine is rotated by exhaust gas energy of an engine and a centrifugal compressor directly coupled to a turbine via a rotation shaft compresses intake air and supplies the engine with the intake air, to improve the output of the engine.
In such a turbine used for an exhaust turbocharger, exhaust gas serving as a working fluid flows from the leading edge toward the trailing edge of the turbine blade. However, for instance, if a flow of a working fluid or the like called secondary flow that flows along the blade surface from the hub toward the shroud of the turbine occurs, the pressure loss of the working fluid increases, and the turbine efficiency decreases. Thus, it is required to suppress occurrence of secondary flow of the working fluid.
Furthermore, in a turbine used for an exhaust turbocharger, vibration may occur on the turbine blade. When vibration occurs on the turbine blade, the turbine blade may break, and thus it is required to suppress vibration of the turbine blade.
Thus, for instance, a turbine configured to suppress vibration of a turbine blade is known (see Patent Document 1).
The turbines described in the above Patent Documents include a blade-thickness changing portion where the blade thickness of the cross-sectional shape at the middle portion of the vane height increases rapidly relative to the blade thickness of the leading edge side, in order to adjust the natural frequency of the rotor blade and suppress vibration of the rotor blade.
However, the above described Patent Documents do not disclose any configuration for suppressing secondary flow of the working fluid.
Furthermore, the above described Patent Documents 2 to 4 disclose techniques to produce a turbine blade of an axial-flow turbine such as a gas turbine and a steam turbine, by metal additive manufacturing. However, the inventions disclosed in the above Patent Documents are about producing a turbine blade, which is a part of an axial turbine, by metal additive manufacturing, and not about producing an entire axial-flow turbine including a rotor.
In view of the above, an object of at least one embodiment of the present invention is to provide a turbine blade, a turbocharger, and a method of producing a turbine blade, whereby it is possible to suppress secondary flow of a working fluid.
(1) According to at least one embodiment of the present invention, a turbine blade configured to be coupled to a rotational shaft and rotated around an axis includes: a hub having a hub surface which is inclined with respect to the axis in a cross section along the axis; a rotor blade disposed on the hub surface; at least one rib formed on a blade surface of the rotor blade, the at least one rib extending in a direction which intersects with a span direction of the rotor blade in a meridional plane of the rotor blade.
With the above configuration (1), the at least one rib extends in a direction that intersects with the span direction of the rotor blade, and thus it is possible to suppress secondary flow in the span direction along the blade surface of the rotor blade. Accordingly, it is possible to reduce pressure loss of the working fluid, and improve the turbine efficiency. Furthermore, with the above configuration (1), the rib reinforces the rotor blade, and thus it is possible to suppress vibration that occurs on the rotor blade.
(2) In some embodiments, in the above configuration (1), in the meridional plane of the rotor blade, the at least one rib has an upstream end formed so as to be oriented in a first direction which is a direction away from the axis and a downstream end formed so as to be oriented in a second direction, and a relationship θ1>θ2 is satisfied, where θ1 is an angular degree of an acute angle formed by the first direction and a direction parallel to the axis, and θ2 is an angular degree of an acute angle formed by the second direction and the direction parallel to the axis.
With the above configuration (2), the upstream end of the rib is oriented toward the upstream side of the flow of the working fluid and the downstream end of the rib is oriented toward the downstream side of the flow of the working fluid. Thus, the at least one rib has a shape conforming to the flow of the working fluid, and thereby it is possible to reduce pressure loss of the working fluid.
(3) In some embodiments, in the above configuration (1) or (2), the at least one rib has an arc shape protruding toward the axis in the meridional plane of the rotor blade.
With the above configuration (3), the rib has an arc shape that protrudes toward the axis, and thus the at least one rib has a shape along the flow of the working fluid, whereby it is possible to reduce pressure loss of the working fluid.
(4) In some embodiments, in any one of the above configurations (1) to (3), at least a part of the at least one rib extends along a meridional line of the rotor blade in the meridional plane of the rotor blade.
With the above configuration (4), at least a part of the rib extends along the meridional line of the rotor blade, and thus the at least one rib has a shape conforming to the flow of the working fluid, whereby it is possible to reduce pressure loss of the working fluid.
(5) In some embodiments, in any one of the above configurations (1) to (4), the at least one rib is configured to satisfy a relationship L≥2t, where L is a length of the rib in the meridional plane and ‘t’ is a thickness of the rib.
With the above configuration (5), it is possible to suppress the secondary flow in a broad range with the rib having the length L. Furthermore, with the thickness ‘t’ of the rib satisfying the relationship L≥2t, it is possible to suppress the thickness of the rib and suppress the weight increase of the turbine blade despite formation of the rib.
(6) In some embodiments, in any one of the above configurations (1) to (5), the at least one rib has an oblique portion whose height increases gradually from an upstream end of the at least one rib toward a downstream side.
With the above configuration (6), the rib has an oblique portion whose height gradually increases from the upstream end toward the downstream side, and thus it is possible to reduce pressure loss of the working fluid compared to a rib that does not have an oblique portion.
(7) In some embodiments, in any one of the above configurations (1) to (6), the at least one rib comprises a plurality of ribs.
With the above configuration (7), compared to a case where a single long rib is provided, it is possible to suppress the weight increase of the turbine blade despite formation of the rib, by forming short ribs at a plurality of locations where secondary flow can be suppressed effectively.
(8) In some embodiments, in any one of the above configurations (1) to (7), in the meridional plane of the rotor blade, the at least one rib is formed on a position which satisfies a relationship Hl>0.5×Hb, where Hb is an entire height of the rotor blade in the span direction and Hl is a height from the hub surface to the at least one rib in the span direction.
The influence of loss due to secondary flow is more significant at the side of the tip portion of the rotor blade than at the side of the root portion of the rotor blade. Further, the length of the rotor blade in the meridional direction decreases from the root portion toward the tip portion. Thus, even though the rib has the same length, the influence of loss due to secondary flow can be suppressed more effectively when the rib is formed at the side of the end portion, compared to a case where the rib is formed at the side of the root portion.
In this regard, with the above configuration (8), the at least one rib is formed on a position that satisfies Hl>0.5×Hb, and thus the rib is formed on a position closer to the tip portion than to the root portion on the blade surface, and thus it is possible to suppress the influence of loss due to secondary flow effectively.
Furthermore, vibration that occurs on the rotor blade tends to deform more largely at the side of the tip portion, and thus it is possible to suppress vibration that occurs on the rotor blade effectively by forming the at least one rib on a position closer to the tip portion than to the root portion on the blade surface.
(9) In some embodiments, in the above configuration (8), the at least one rib is formed on a suction-surface side blade surface of the rotor blade.
At the suction-surface side surface of the rotor blade, secondary flow flowing along the blade surface from the root portion toward the end portion causes problems. In this regard, with the above configuration (9), it is possible to suppress secondary flow at the suction-surface side and suppress loss.
(10) In some embodiments, in the above configuration (8), the at least one rib is formed near a tip portion of a pressure-surface side blade surface of the rotor blade.
A tip clearance exists between the tip portion of the rotor blade and the shroud. At the pressure-surface side of the rotor blade, clearance flow causes problems, in particular, when a working fluid flows to the suction surface from the pressure surface via the tip clearance. Occurrence of clearance flow leads to deterioration of the turbine efficiency and generation of loss.
In this regard, with the above configuration (10), it is possible to suppress clearance flow and suppress loss.
(11) In some embodiments, in the above configuration (10), in the meridional plane of the rotor blade, when a reference meridional line is a meridional line which passes a region of the blade surface where the at least one rib is formed, the region includes a section where a curve degree of the blade surface on the reference meridional line is maximum.
The above described clearance flow tends to increase at a section where the curve degree of the blade surface on the meridional line is large.
In this regard, with the above configuration (11), the rib is formed on a position with a high rate of clearance flow, and thus it is possible to suppress clearance flow and suppress loss.
(12) In some embodiments, in any one of the above configurations (8) to (11), the at least one rib includes: a suction-surface side rib formed on a suction-surface side blade surface of the rotor blade; and a pressure-surface side rib formed on a pressure-surface side blade surface of the rotor blade. In the meridional plane of the rotor blade, a relationship Hln<Hlp is satisfied, where Hln is a height from the hub surface to the suction-surface side rib in the span direction and Hlp is a height from the hub surface to the pressure-surface side rib in the span direction.
With the above configuration (12), it is possible to suppress secondary flow at the side of the suction surface with the suction-surface side rib and reduce loss. Further, with the above configuration (12), the pressure-surface side rib is formed closer to the tip portion of the rotor blade with respect to the suction-surface side rib, and thereby it is possible to suppress the above described clearance flow effectively and reduce loss. Furthermore, with the suction-surface side rib and the pressure-surface side rib having different heights from the hub surface in the span direction, it is possible to suppress vibration in a broad range of the rotor blade.
(13) In some embodiments, in any one of the above configurations (1) to (12), the rotor blade and the rib comprise the same metal material, and the at least one rib has a smaller density than the rotor blade.
In the turbine blade, the strength required for the rotor blade and the strength required for the rib are different. That is, the rotor blade needs to have a high strength to resist a centrifugal force.
On the other side, the rib formed on the rotor blade does not need to be as strong as the rotor blade, for the rotor blade has a high strength. Thus, it is desirable to suppress the weight of the rib to suppress weight increase of the turbine blade.
Furthermore, in a case where the rotor blade and the rib are formed integrally in the turbine blade, to suppress the weight of the rib, the density of the rib may be reduced compared to that of the rotor blade by changing the density between the rib and the rotor blade.
In this regard, with the above configuration (13), the rib has a smaller density than the rotor blade, and thereby it is possible to suppress the weight of the rib, and suppress weight increase of the turbine blade.
(14) According to at least one embodiment of the present invention, a turbocharger includes: a rotational shaft; a compressor wheel coupled to a first end side of the rotational shaft; and the turbine blade according to any one of the above (1) to (13), coupled to a second end side of the rotational shaft.
With the above configuration (14), the turbocharger is provided with the turbine blade described in the above (1), and thus it is possible to improve the turbine efficiency of the turbocharger. Furthermore, with the above configuration (14), the turbocharger has the turbine blade with the above configuration (1), and thus it is possible to suppress vibration that occurs on the rotor blade.
(15) According to at least one embodiment of the present invention, a method of producing the turbine blade according to any one of the above (1) to (13) includes: forming the hub, the rotor blade, and the rib integrally by additive manufacturing of metal powder.
For instance, when producing a turbine blade by fine casing, wax is injected into a mold, and a wax mold is produced. The wax mold needs to be removed from the mold, and thus a protruding portion or the like that extends in a direction that intersects with the direction of mold removal cannot be formed on the position of the wax mold that corresponds to the surface of the turbine blade. Thus, fine casting is not suitable to producing a turbine blade that has a rib formed on the blade surface extending in a direction that intersects with the span direction of the rotor blade in the meridional plane of the rotor blade as in the above configuration (1).
In this regard, according to the above method (15), additive manufacturing of metal powder makes it possible to produce a turbine blade including a rib by integrally forming the hub, the rotor blade, and the rib.
According to at least one embodiment of the present invention, it is possible to improve the turbine efficiency.
Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It is intended, however, that unless particularly identified, dimensions, materials, shapes, relative positions and the like of components described in the embodiments shall be interpreted as illustrative only and not intended to limit the scope of the present invention.
For instance, an expression of relative or absolute arrangement such as “in a direction”, “along a direction”, “parallel”, “orthogonal”, “centered”, “concentric” and “coaxial” shall not be construed as indicating only the arrangement in a strict literal sense, but also includes a state where the arrangement is relatively displaced by a tolerance, or by an angle or a distance whereby it is possible to achieve the same function.
For instance, an expression of an equal state such as “same” “equal” and “uniform” shall not be construed as indicating only the state in which the feature is strictly equal, but also includes a state in which there is a tolerance or a difference that can still achieve the same function.
Further, for instance, an expression of a shape such as a rectangular shape or a cylindrical shape shall not be construed as only the geometrically strict shape, but also includes a shape with unevenness or chamfered corners within the range in which the same effect can be achieved.
On the other hand, an expression such as “comprise”, “include”, “have”, “contain” and “constitute” are not intended to be exclusive of other components.
According to some embodiments, the turbocharger 1 is a device for supercharging intake air of an engine, mounted to a vehicle such as a car.
The turbocharger 1 includes a turbine wheel (turbine blade) 3 and a compressor wheel 4 coupled to one another via a rotor shaft 2 being a rotational shaft, a turbine housing 5 that houses the turbine blade 3, and a compressor housing 6 that houses the compressor wheel 4. Further, the turbine housing 5 has a scroll 7. The compressor housing 6 has a scroll 8.
Further, a shroud 9 is formed on the outer peripheral side of the turbine blade 3 of the turbine housing 5 so as to cover the turbine blade 3.
According to some embodiments, the turbine blade 3 is coupled to the rotor shaft (rotational shaft) 2 and configured to be rotated around the axis AX. According to some embodiments, the turbine blade 3 includes a hub 31 that has, in a cross section along the axis AX, a hub surface 32 inclined from the axis AX and a plurality of rotor blades 33 disposed on the hub surface 32. While the turbine blade 3 shown in
In the turbocharger 1 having the above configuration, exhaust gas serving as a working fluid flows from the leading edge 36 toward the trailing edge 37 of the turbine blade 3. However, for instance, if flow of a working fluid or the like called secondary flow that flows along the blade surface from the hub surface 32 toward the shroud 9 occurs, the pressure loss of the working fluid increases, and the turbine efficiency decreases. Thus, it is required to suppress occurrence of secondary flow of the working fluid.
Furthermore, in the turbocharger 1, vibration may occur on the rotor blades 33 of the turbine blade 3. Vibration that occurs on the rotor blades 33 may cause damage to the turbine blade 3, and thus it is required to suppress vibration of the rotor blades 33.
Thus, according to some embodiments, the turbine blade 3 is configured to suppress the above described secondary flow and vibration of the rotor blades 33 with ribs formed on the blade surfaces of the rotor blades 33. Hereinafter, the ribs of the turbine blade 3 according to some embodiments will be described.
As depicted in
In the following description, when the rib 10A and the rib 10B do not need to be differentiated, the suffixed alphabet of the reference numeral is omitted and the rib is merely referred to as the rib 10.
Each of the ribs 10 extends, in the meridional plane of the rotor blade 33, in a direction that intersects with the span direction of the rotor blade 33.
Herein, “span direction” is defined as a direction that passes through the first position and the second position, where Lt is the entire length of the tip portion 34 of the rotor blade 33, Lb is the entire length of the root portion 35 of the rotor blade 33 (connection position to the hub surface), the first position is a position on the tip portion 34 of the rotor blade 33 that is away from the leading edge 36 by a predetermined distance Lt1, and the second position is a position on the root portion 35 of the rotor blade 33 that is away from the leading edge 36 by a predetermined distance Lb1 (where Lb1=Lb×Lt1/Lt), as depicted in
As depicted in
Furthermore, as depicted in
Further, according to some embodiments, the turbocharger 1 includes a turbine blade according to some embodiments depicted in
The vibration suppression effect achieved by the ribs 10 will be described below in detail.
In some embodiments depicted in
In some embodiments depicted in
As described above, in some embodiments, with the upstream end 11 of each rib 10 oriented toward the upstream side of the flow of exhaust gas and the downstream end 12 of each rib 10 oriented toward the downstream side of the flow of exhaust gas, each rib 10 has a shape conforming to the flow of exhaust gas, and thereby it is possible to reduce pressure loss of exhaust gas.
In some embodiments depicted in
In some embodiments depicted in
Herein, “meridional line” is defined as a line whose height position in the span direction is constant from the leading edge 36 to the trailing edge 37 of the rotor blade 33 in the meridional plane. In
Accordingly, with at least a part of each rib 10 extending along the meridional line M of the rotor blade 33, each rib 10 has a shape conforming to the flow of exhaust gas, and thereby it is possible to reduce pressure loss of exhaust gas.
In some embodiments depicted in
Accordingly, it is possible to suppress the secondary flow in a broad range with the rib 10 having the length L. Furthermore, with the thickness ‘t’ of the rib 10 satisfying the relationship L≥2t, it is possible to suppress the thickness of the rib 10 and suppress the weight increase of the turbine blade 3 despite formation of the rib 10.
Accordingly, it is possible to reduce pressure loss of exhaust gas more efficiently compared to a case where the rib 10 does not include the oblique portion 111.
Furthermore, an oblique portion (not depicted) whose height gradually decreases from the upstream side toward the downstream end 12 may be disposed at the downstream side of the rib 10 that is formed along the flow of exhaust gas.
Furthermore, the height of the rib 10 may not necessarily be constant at a portion other than the oblique portion 111 at the upstream side and the oblique portion at the downstream side.
Furthermore, a single rib 10 may be disposed at one location of a rotor blade 33, or a plurality of ribs 10 may be disposed at different locations of a rotor blade 33. For instance, a plurality of ribs 10 may be disposed on one of the pressure surface 38 or the suction surface 39 of the rotor blade 33, or at least one rib 10 may be disposed on each of the pressure surface 38 and the suction surface 39.
Furthermore, at least one rib 10 may be disposed on at least one of the plurality of rotor blades 33. Furthermore, ribs 10 having the same shape may be disposed on the respective rotor blades 33, or the ribs 10 may have different shapes depending on the rotor blades 33.
For instance, as depicted in
In the embodiment depicted in
Furthermore, as depicted in
Furthermore, as depicted in
In the embodiment depicted in
In the embodiment depicted in
For instance, by providing a plurality of ribs 10 as depicted in
(Formation Position of the Rib 10 in the Span Direction)
As depicted in
The influence of loss due to the secondary flow is more significant at the side of the tip portion 34 of the rotor blade 33 than at the side of the root portion 35 of the rotor blade 33. Further, the length of the rotor blade 33 in the meridional line decreases from the root portion 35 toward the tip portion 34. Thus, even though the rib 10 has the same length, the influence of loss due to secondary flow can be suppressed more efficiently when the rib 10 is formed at the side of the tip portion 34, compared to a case where the rib 10 is formed at the side of the root portion 35.
In this regard, in the embodiment depicted in
Furthermore, vibration that occurs on the rotor blade 33 tends to deform more largely at the side of the tip portion 34 as described below, and thus it is possible to suppress vibration that occurs on the rotor blade 33 effectively by forming the rib 10 on a position closer to the tip portion 34 than to the root portion 35 on the blade surface.
(Rib 10 Disposed at the Side of the Suction Surface 39)
In some embodiments, as depicted in
At the side of the suction surface 39 of the rotor blade 33, secondary flow flowing along the blade surface from the root portion 35 toward the tip portion 34 causes problems. In this regard, as depicted in
(Rib 10 Disposed at the Side of the Pressure Surface 38)
Further, in some embodiments, as depicted in
Herein, the position near the tip portion 34 is a position that satisfies a relationship Hl>0.7×Hb, and more preferably, a position that satisfies a relationship Hl>0.9×Hb. Furthermore, forming the rib 10 near the tip portion 34 on the blade surface at the side of the pressure surface 38 of the rotor blade 33 includes forming the rib 10 on the tip portion 34 (Hl=1.0×Hb).
A tip clearance exists between the tip portion 34 of the rotor blade 33 and the shroud 9. At the side of the pressure surface 38 of the rotor blade 33, clearance flow causes problems, when a working fluid flows to the suction surface 39 from the pressure surface 38 via the tip clearance. Occurrence of clearance flow leads to deterioration of the turbine efficiency and generation of loss.
In this regard, as depicted in
Furthermore, the rib 10 in an embodiment depicted in
That is, in the meridional plane of the rotor blade 33, the meridional line that passes the region on the blade surface on which the rib 10 is formed is defined as the reference meridional line Ms. Further, the region may be configured so as to include a portion where the blade surface has the maximum curve degree on the reference meridional line Ms.
Herein, the portion where the blade surface has the maximum curve degree on the reference meridional line Ms will be described.
For instance, in
In
In
The angle β gradually changes along the reference meridional line Ms. When dβ is the change amount of angle β in the small section dm along the reference meridional line Ms, the curve degree of the blade surface on the reference meridional line Ms can be represented by a relationship dβ/dm. For instance, in
The above described clearance flow tends to become greater at a section where the curve degree on the blade surface on the meridional line is large. That is, as the curve degree of the blade surface on the meridional line increases, the difference between the main flow of exhaust gas from the upstream side toward the downstream side and the extension direction of the blade surface increases. Thus, for instance on the pressure surface 38, as the curve degree of the blade surface on the meridional line increases, the pressure of exhaust gas tends to increase. Thus, as the curve degree of the blade surface on the meridional line increases, the exhaust gas flows more easily in a direction other than the above main flow direction, and the clearance flow increases.
In this regard, with the region on the blade surface where the rib 10 is formed including a section where the curve degree dβ/dm of the blade surface on the reference meridional line Ms reaches its maximum as in the embodiment depicted in
(Ribs 10 Disposed at the Side of the Pressure Surface 38 and at the Side of the Suction Surface 39)
In the embodiment depicted in
In
Further, in the embodiment depicted in
Accordingly, it is possible to suppress secondary flow at the side of the suction surface 39 with the suction-surface side rib 109 and reduce loss. Further, with the pressure-surface side rib 108 formed closer to the tip portion 34 of the rotor blade 33 than the suction-surface side rib 109, it is possible to suppress the above described clearance flow effectively and reduce loss. Furthermore, with the suction-surface side rib 109 and the pressure-surface side rib 108 having different heights from the hub surface 32 in the span direction, it is possible to suppress vibration in a broad range of the rotor blade 33.
(Vibration of the Rotor Blade 33)
Vibration of the rotor blade 33 according to some embodiments will be described. According to some embodiments, vibration occurs on the rotor blade 33 in different vibration modes. For instance,
Further, in the rotor blade 33 in
As depicted in
(Density of the Rib 10)
In some embodiments, the rotor blade 33 and the rib 10 are formed of the same metal material, and the rib 10 has a smaller density than the rotor blade 33.
In the turbine blade 3, the strength required for the rotor blade 33 and the strength required for the rib 10 are different. That is, the rotor blade 33 needs to have a high strength to resist a centrifugal force.
On the other hand, the rib 10 formed on the rotor blade 33 does not need to be as strong as the rotor blade 33, as the rotor blade 33 has a high strength. Thus, it is desirable to suppress the weight of the rib 10 to suppress a weight increase of the turbine blade 3.
Furthermore, in a case where the rotor blade 33 and the rib 10 are formed integrally in the turbine blade 3, to suppress the weight of the rib 10, the density of the rib 10 may be reduced compared to the density of the rotor blade 33 by changing the density between the rib 10 and the rotor blade 33.
For instance, in a case where metal powder is irradiated with laser to produce the turbine blade 3 through additive manufacturing of the metal powder, small voids may be formed inside the rib 10 so that the rib 10 has a smaller density than the rotor blade 33.
In some embodiments, with the rib 10 having a smaller density than the rotor blade 33, it is possible to suppress the weight of the rib 10, and suppress weight increase of the turbine blade 3.
(Method of Producing the Turbine Blade 3)
As described above, the turbine blade 3 according to some embodiments is produced through additive manufacturing of metal powder, by using a device called a metal 3D printer and irradiating metal powder with laser. In this production method, additive manufacturing of metal powder is carried out by locally melting metal powder with laser and then solidifying the metal powder in laminated layers.
That is, the method of producing a turbine blade according to some embodiments is a method of producing the hub 31, the rotor blade 33, and the rib 10 integrally through additive manufacturing of metal powder.
Additive manufacturing of metal powder can be carried out by laser sintering, laser melting, and the like.
As described above, the turbocharger 1 according to some embodiments is a small turbocharger for a vehicle such as a car. The turbine blade 3 according to some embodiments have a diameter of not less than 20 mm and not more than 70 mm. Typically, turbine blades of this size have been produced by casting.
Meanwhile, for instance, the above described Patent Documents 2 to 4 disclose techniques to produce a turbine blade of an axial-flow turbine such as a gas turbine and a steam turbine, by metal additive manufacturing. However, the Patent Documents are about producing a turbine blade, which is a part of an axial turbine, by metal additive manufacturing, and not producing an axial-flow turbine as a whole including a rotor. Typically, for radial turbines and mixed-flow turbines used for a small turbocharger for a vehicle such as a car, the turbine blade, the hub, and the blade have not been produced integrally by additive manufacturing.
For instance, when producing a turbine blade by casing, wax is injected into a mold, and a wax mold is produced. The wax mold needs to be removed from the mold, and thus a protruding portion or the like that extends in a direction that intersects with the direction of mold removal cannot be disposed on the position of the wax mold that corresponds to the surface of the turbine blade. Thus, fine casting is not suitable to producing a turbine blade 3 that has a rib 10 formed on the blade surface extending in a direction that intersects with the span direction of the rotor blade 33 in the meridional plane of the rotor blade 33 like the turbine blade 3 of the above described embodiments.
In this regard, additive manufacturing of metal powder makes it possible to produce a turbine blade 3 including a rib 10 extending on the blade surface by integrally forming the hub 31, the rotor blade 33, and the rib 10 extending in a direction that intersects with the span direction of the rotor blade 33.
Embodiments of the present invention were described in detail above, but the present invention is not limited thereto, and various amendments and modifications may be implemented.
For instance, in the above description, ribs 10 having the same shape may be disposed on the respective rotor blades 33, or the ribs 10 may have different shapes depending on the rotor blades 33. However, the present invention is not limited to this. For instance, when providing a plurality of ribs 10 for a single rotor blade 33, the ribs may have different shapes.
For instance, the ribs 10 depicted in
| Filing Document | Filing Date | Country | Kind |
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| PCT/JP2017/039274 | 10/31/2017 | WO |
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| WO2019/087281 | 5/9/2019 | WO | A |
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| 20200040737 A1 | Feb 2020 | US |
