FLOWPROFILE AND MECHANICAL MACHINE EQUIPPED WITH IT

Abstract

A flow profile with: an airfoil section (40; 80) having an airfoil surface (45, 46; 85, 86) extending along a spanwise direction between a leading edge (41; 81) and a trailing edge (42; 82), and at least one connecting hole (50, 51) extending at least in the airfoil section and having a first opening end (52, 53) open to the airfoil surface, through which the first opening end is connected to a second opening end (54, 55) provided in a cover ring (94, 96) to which the airfoil is connected or in a device on which the airfoil is installed, wherein, at a cross section (S1) perpendicular to the spanwise direction through a position of the first opening end of the spanwise direction, an angle A1 satisfying a condition (a) lies in an angular range equal to or greater than minus 10 degrees and equal to or less than 10 degrees with respect to an extension line obtained by extending a camber line (CL) of the airfoil section from the leading edge while selecting the leading edge as a center, and wherein the condition (a) is a condition that a static pressure at a position of the first opening end is equal to a static pressure at a position of the second opening end when the airfoil section receives a fluid flow from a direction of the angle A1 to the leading edge.

Description

TECHNICAL FIELDThis disclosure relates to an airfoil and a mechanical machine equipped therewith.BACKGROUNDIn airfoils applied to mechanical machines such as a turbomachine or a fluid machine, loss due to stall occurs on an airfoil surface or the like, thereby reducing the performance or operating efficiency of the mechanical machine in some cases. In this regard, an airfoil has been developed to reduce loss caused due to fluid separation or the like in some cases.Patent Document 1 discloses a turbine blade (airfoil) provided with a bypass flow passage provided around a support wall surface to pass from a bulge side (positive pressure side) to a back side (suction pressure side) in the vicinity of a maximum thickness portion of the airfoil portion. In this turbine blade, a pressure difference between the bulge side and the back side around the support wall surface is reduced by bypassing a part of the working fluid from the bulge side to the back side via the bypass flow passage described above, so that the flow loss is reduced by reducing a secondary flow.Citing listPatent LiteraturePatent Document 1: JP 2005-98203ASUMMARYIn recent years, the requirements regarding the operating condition of the mechanical machine such as a rotary machine have been diversified, and its operation is under an operating condition (such as a partial load operation) deviated from a design point in some cases. Therefore, there is a demand for an airfoil that can prevent fluid separation even under an engine operating condition that deviates from the design point.In view of the above-described problems, at least one embodiment of the invention has been made, and an object thereof is to provide an airfoil and a mechanical machine equipped therewith that can reduce or prevent flow separation that might occur at an airfoil surface.(1) According to at least one embodiment of the present invention, there is provided an airfoil comprising: an airfoil portion having an airfoil surface extending along a span direction between a leading edge and a trailing edge; and at least one communication hole extending at least in the airfoil portion and having a first opening end opened to the airfoil surface through which the first opening end communicates with a second opening end provided in a portion of the airfoil other than the airfoil portion or in a device on which the airfoil is installed, wherein, at a cross section perpendicular to the span direction through a position of the first opening end of the span direction, an angle A 1 satisfying a condition (a) is in an angle range, which is equal to or greater than minus 10 degrees and equal to or less than 10 degrees with respect to an extension line obtained by extending a camber line of the airfoil portion from the leading edge while the leading edge is selected as a center, and wherein the condition (a) is a condition that a static pressure at a position of the first opening end is equal to a static pressure at a position of the second opening end when the airfoil portion receives a fluid flow from a direction of the angle A 1 to the leading edge.In some cases, the airfoil apparatus is configured such that the direction of the fluid (main flow) flowing to the airfoil follows an extension line obtained by extending the camber line (camber line) of the airfoil portion from the leading edge. In such an airfoil, the above-described angle A 1 indicates a direction following the extension line of the camber line of the airfoil portion. The angle A 1 thus indicates the angle of impingement (corresponding to the angle of attack) of the fluid on the airfoil section during operation of the device with the airfoil at the design point.In this regard, in the configuration of paragraph (1) above, in the operation at the design point (i.e., under the operating condition in which the fluid flows to the airfoil portion from the direction of the angle A 1), the first and second opening ends of the communication hole are provided at the positions where the static pressures become equal to each other. Therefore, under the operating condition in the vicinity of the design point, there is substantially no pressure difference between the positions of the first and two opening ends, and a flow passing through the communication hole is substantially not generated. When the operating condition deviates from the design point (i.e., when the incident angle of the fluid deviates from the angle A 1), a pressure difference is generated between the positions of the first and second opening ends. As a result, a flow passing through the communication hole is generated from one of the opening ends of the high pressure side to the other opening end of the low pressure side. In addition, since this flow is discharged from the low-pressure side opening end, a moment of the flow (main flow) is impressed around the surface of the low-pressure side element provided with the opening end (typically, the airfoil portion), so that it is possible to reduce or prevent flow separation that might occur at this surface.Therefore, in the configuration according to paragraph (1), it is possible to reduce or prevent performance deterioration in the operation in the vicinity of the design point, and reduce or prevent flow separation on the airfoil surface that might occur when the operation condition deviates from the design point.Note that the question of which of the first and second opening ends has the position with a higher or lower pressure when the operating condition of the device with the airfoil deviates from the design point depends on the shape of the airfoil portion, the positions of the first and second opening ends to what extent the operating condition deviates from the design point (i.e. the deviation direction of the angle of impingement of the fluid), or the like.(2) According to some embodiments, in the configuration according to paragraph (1) above, the apparatus comprises a fuselage of an aircraft, and the airfoil portion comprises a vertical tail or a horizontal tail of the aircraft.In the configuration according to paragraph (2) above, the first opening end is provided to be open to the airfoil surface of the vertical tail or the horizontal tail of the aircraft. In addition, the second opening end is provided at the position on the surface of the fuselage that has the same static pressure as that from the position of the first opening end in operation to the design point of the aircraft (for example, a cruise mode operation). Therefore, as described in paragraph (1) above, performance reduction in operation in the vicinity of the design point can be reduced or prevented, and stall on the surface (airfoil surface) of the vertical tail or the horizontal tail that may occur when the operating condition deviates from the design point is reduced or prevented.(3) According to some embodiments, in the configuration of paragraph (2), the airfoil surface includes a left side surface and a right side surface of the vertical tail at the top. In addition, the first opening end is opened to the left side surface of the vertical tail, while the second opening end is opened to a surface of a right side portion of the fuselage. Alternatively, the first opening end is opened to the right side surface of the vertical tail while the second opening end is opened to a surface of a portion of a left side of the fuselage.In the configuration of paragraph (3) above, when the first opening end is provided on the left side surface of the vertical rear and the second opening end is provided on the right side portion of the fuselage, under a flight condition (operating condition) in which the air flow from the right side is directed toward the fuselage (i.e., a flight condition deviating from the design point), a flow passing through the communication hole from the second opening end of the right side toward the left surface of the vertical rear is generated. When the first opening end is provided on the right side surface of the vertical rear and the second opening end is provided on the left side portion of the fuselage, a flow passing through the communication hole from the second opening end of the left side to the right side surface of the vertical rear is generated under a flight condition in which the air flow from the left side is directed to the fuselage (i.e., when the flight condition deviates from a design point).Therefore, in the configuration of paragraph (3) above, it is possible to reduce or prevent flow separation from the left side surface or the right side surface of the vertical tail which may occur when the flight condition deviates from the design point.(4) According to some embodiments, in the configuration of paragraph (2), the airfoil surface includes a top surface and a bottom surface of the horizontal tail at the top, wherein the first opening end is opened to the top surface or the bottom surface of the horizontal tail, and the second opening end is opened to a surface of the fuselage.In the configuration of paragraph (4) above, for example, when the first opening end is provided on the lower surface of the horizontal tail and the second opening end is provided on the upper surface of the fuselage, under the flight condition in which the air flow is directed from the upper side toward the fuselage (i.e., under the flight condition deviating from the design point), a flow passing through the communication hole from the second opening end of the upper surface of the fuselage toward the lower surface of the horizontal tail is generated. Moreover, for example, when the first opening end is provided on the upper surface of the horizontal tail and the second opening end is provided on the lower surface of the bump, a flow passing through the communication hole from the second opening end of the lower surface of the fuselage to the upper surface of the horizontal tail is generated under the flight condition in which the air flow is directed from the lower side to the fuselage (i.e., under the flight condition deviating from the design point).Therefore, in the configuration of paragraph (4) above, it is possible to reduce or prevent stall on the upper or lower surface of the horizontal tail which may occur when the flight condition deviates from the design point.(5) According to at least one embodiment of the present invention, there is provided an airfoil comprising: an airfoil portion having an airfoil surface extending along a span direction between a leading edge and a trailing edge; a connecting member to which the airfoil portion is connected; and at least one connecting hole having a first opening end opened to the airfoil surface and a second opening end opened to a surface of the connecting member and extending in the airfoil portion and the connecting member.In operation at the design point of the airfoil device, a position is present with the same static pressure as that of the position on the surface of the airfoil portion (airfoil surface) on the surface of the connector in some cases.In this regard, in the configuration of paragraph (5) above, the first opening end of the communication hole is provided on the airfoil surface, and the second opening end is provided on the surface of the communication member. Therefore, the first and second opening ends may be provided in the positions where the static pressures become equal to each other in the operation at the design point of the device having the flow profile. Therefore, by providing the first and second opening ends at such positions, substantially no pressure difference is generated in the positions of the first and second opening ends under the operating condition in the vicinity of the design point, so that a flow passing through the communication hole is practically not generated. When the operating condition deviates from the design point, a pressure difference is generated between the positions of the first and second opening ends. As a result, a flow passing through the communication hole from one of the opening ends of the high pressure side to the other opening end of the low pressure side is generated. Moreover, since this flow is discharged from the opening end of the low pressure side, a moment is imparted to the flow (main flow) around the surface of the member provided with the opening end of the low pressure side (typically, the airfoil portion), so that stall that may occur at such a surface can be reduced or prevented.Therefore, in the configuration of paragraph (5) above, it is possible to reduce or prevent performance deterioration in the operation in the vicinity of the design point and reduce or prevent flow separation on the airfoil surface that may occur when the operation condition deviates from the design point.(6) According to some embodiments, in the configuration of paragraph (5) above, the airfoil surface includes a pressure surface and a suction surface, and the surface of the connecting member is connected to the airfoil portion and includes an end wall surface that forms a flow path of a working fluid of a turbine.In the airfoil having the configuration of paragraph (6) above, the airfoil portion including the pressure surface and the suction surface is connected to the end wall surface forming the flow path of the working fluid of the turbine, and the working fluid of the turbine flows around the pressure surface and the suction surface of the airfoil. When the operating condition of the turbine deviates from the design point (rated operation), stall of the working fluid may occur at the pressure surface or the suction surface. In this regard, in the configuration of paragraph (6) above, the first opening end is provided on the pressure surface or on the suction surface of the airfoil portion, and the second opening end is provided on the surface of the connecting member. Therefore, as described in paragraph (5) above, a decrease in the performance in the operation in the vicinity of the design point can be reduced or prevented, and a flow separation at the pressure surface or the suction surface that may occur when the operation condition deviates from the design point can be reduced or prevented.(7) According to some embodiments, in the configuration of paragraph (6) above, the first opening end is opened to the pressing surface or the suction surface, and the second opening end is opened to the end wall surface of the connection member.In some cases, there is a position having the same static pressure as that of the position of the pressure surface or the suction surface at the end wall surface of the joint member to which the airfoil portion is joined in the rated operation of the turbine (operation at the design point). In this regard, in the configuration of paragraph (7) above, the first opening end is opened to the pressure surface or the suction surface of the airfoil portion, and the second opening end is opened to the end wall surface of the connector. Therefore, as described in paragraph (6) above, performance deterioration in the operation in the vicinity of the design point of the turbine can be reduced or prevented, and flow separation at the pressure surface or the suction surface that may occur when the operation condition deviates from the design point can be reduced or prevented.(8) According to some embodiments, in the configuration of paragraph (6) above, the surface of the connecting member includes an upstream end surface that is disposed upstream of the airfoil portion and extends along a plane perpendicular to an axial direction, the first opening end is opened to the pressing surface or the suction surface, and the second opening end is opened to the upstream end surface.In some cases, there is a position having the same static pressure as that of the position of the pressure surface or the suction surface in the rated operation of the turbine (operation at the design point) on the upstream end surface of the connection member to which the airfoil portion is connected. In this regard, in the configuration of paragraph (8) above, the first opening end is opened to the pressure surface or the suction surface of the airfoil portion, and the second opening end is opened to the upstream end surface of the connecting member. Therefore, as described in paragraph (6) above, performance deterioration in the operation in the vicinity of the design point of the turbine can be reduced or prevented, and flow separation at the pressure surface or the suction surface that may occur when the operation condition deviates from the design point can be reduced or prevented.(9) According to some embodiments, in the configuration of paragraph (6) above, the surface of the connecting member has a downstream end surface that is disposed downstream of the airfoil and extends along a plane perpendicular to an axial direction, the first opening end is opened to the pressing surface or the suction surface, and the second opening end is opened to the downstream end surface.In some cases, there is a position having the same static pressure as that of the position of the pressure surface or the suction surface in the rated operation of the turbine (operation at the design point) on the downstream end surface of the connection member to which the airfoil portion is connected. In this regard, in the configuration of paragraph (9) above, the first opening end is opened to the pressure surface or the suction surface of the airfoil portion, and the second opening end is opened to the downstream end surface of the connecting member. Therefore, as described in paragraph (6) above, performance deterioration in operation in the vicinity of the design point of the turbine can be reduced or prevented, and flow separation at the pressure surface or the suction surface that may occur when the operation condition deviates from the design point can be reduced or prevented.(10) According to some embodiments, in the configuration of paragraph (6) above, the surface of the joint member includes a circumferential end surface, the circumferential end surface of the joint member of the airfoil, and a circumferential end surface of a joint member of an airfoil adjacent to the airfoil in a circumferential direction face each other with interposition of a clearance, the first opening end is opened to the pressing surface or the suction surface, and the second opening end is opened to the circumferential end surface.In some cases, there is a position having the same static pressure as that of the position of the pressure surface or the suction surface in the rated operation of the turbine (operation at the design point) at the circumferential end surface of the joint member to which the airfoil portion is joined. In this regard, in the configuration of paragraph (10) above, the first opening end is opened to the pressure surface or the suction surface of the airfoil portion, and the second opening end is opened to the circumferential end surface of the connecting member. Therefore, as described in paragraph (6) above, performance deterioration in the operation in the vicinity of the design point of the turbine can be reduced or prevented, and flow separation at the pressure surface or the suction surface that may occur when the operation condition deviates from the design point can be reduced or prevented.(11) According to some embodiments, in the configuration of any one of paragraphs (6) to (10) above, the first opening end is opened to the pressure surface at a position on the leading edge side from a point on the pressure surface having a tangential line parallel to a chord direction of the airfoil portion.In the airfoil applied to the turbine, when an angle of impingement (angle of attack) of the working fluid against the airfoil is negative (when the fluid flow is directed so as to collide with the suction surface relative to the design point), flow separation easily occurs at the pressure surface in the vicinity of a point at the pressure surface having a tangential line parallel to the chord direction. In this regard, in the configuration of paragraph (11) above, the first opening end is provided on the pressure surface at a position on the leading edge side from such a position on the pressure surface where flow separation easily occurs. Therefore, the fluid separation that can easily occur on the printing surface in the case of a negative incident angle as described above can be effectively reduced or prevented.(12) According to some embodiments, in the configuration of any one of paragraphs (6) to (10) above, the first opening end is opened to the suction surface at a position on a leading edge side from an intersection point between the suction surface and a straight line through the leading edge and parallel to the camber line of the airfoil portion in the leading edge (the line having the same distance from the pressure surface and the suction surface of the airfoil).In the airfoil applied to the turbine, when the angle of impingement (angle of attack) of the fluid against the airfoil is positive (i.e., when the flow of the fluid is directed to collide with the pressure surface relative to the design point), stall occurs easily at the suction surface at the position on the leading edge side from the intersection between the suction surface and the straight line through the leading edge and parallel to the camber line of the airfoil portion in the leading edge in some cases. In this regard, in the configuration of paragraph (12) above, the first opening end is provided on the suction surface in the leading edge side from the position where flow separation on the suction surface easily occurs in this manner. Therefore, fluid separation that may easily occur on the suction surface in the case of a positive incident angle as described above can be effectively reduced or prevented.(13) According to some embodiments, in the configuration of any one of paragraphs (5) to (11), at the top of a cross section perpendicular to the span direction through a position of the first opening end of the span direction, an angle A 1 satisfying a condition (a) is in an angle range equal to or greater than minus 10 degrees and equal to or less than 10 degrees with respect to an extension line obtained by extending a camber line of the airfoil portion from the leading edge while the leading edge is set as a center, and the condition (a) is a condition that a static pressure at a position of the first opening end of the airfoil surface is equal to a static pressure at a position of the second opening end at the surface of the connector, when the airfoil portion receives fluid flow from a direction of the angle A 1 toward the leading edge.In the configuration of paragraph (13) above, the first and second opening ends of the communication hole are provided in the positions where the static pressures become equal to each other in the operation at the design point of the turbine (i.e., in the operating condition in which the fluid flow to the airfoil portion flows from the direction of the angle A 1). Therefore, under the operating condition in the vicinity of the design point, there is substantially no pressure difference between the first and second opening ends, and substantially no flow passing through the communication hole is generated. When the operating condition deviates from the design point (i.e., when the incident angle of the fluid deviates from the angle A 1), a pressure difference is generated between the position of the first opening end and the position of the second opening end. As a result, a flow passing through the communication hole from one of the opening ends of the high pressure side to the other opening end of the low pressure side is generated. Moreover, since this flow is discharged from the opening end of the low pressure side, a moment is imparted to the flow around the surface of the airfoil surface provided with the opening end of the low pressure side (pressure surface or suction surface), so that flow separation that may occur at this surface can be reduced or prevented.Therefore, in the configuration of paragraph (13) above, performance deterioration in the operation in the vicinity of the design point can be reduced or prevented, and flow separation on the airfoil surface that might occur when the operating condition deviates from the design point can be reduced or prevented.(14) According to some embodiments, in the configuration of any one of paragraphs (1) to (13) above, as viewed from the span direction, an angle between a part of a tangential line of the airfoil surface at the first opening end, the part being located in the leading edge side from the first opening end, and the communication hole of the first opening end is equal to or less than 45 degrees.In the configuration of paragraph (14) above, since the communication hole has a shape matched with the airfoil surface at the position of the first opening end, mixing loss with the fluid flowing around the airfoil surface when the flow is discharged from the communication hole from the first opening end can be reduced.(15) According to at least one embodiment of the present invention, a mechanical machine having the flow profile according to one of paragraphs (1) to (14) above is provided.In the configuration of paragraph (15) above, when the airfoil has the characteristic of paragraph (1) above, the first and second opening ends of the communication hole are provided in the positions where the static pressures become equal to each other in the operation at the design point (i.e., under the operating condition in which the fluid flows from the direction of the angle A 1 to the airfoil portion). Alternatively, in the configuration of paragraph (15) above, when the airfoil has the characteristic of paragraph (5) above, the first opening end of the communication hole is provided on the airfoil surface, and the second opening end is provided on the surface of the connector. Therefore, the first and second opening ends may be provided in the positions where the static pressures become equal to each other in the operation at the design point of the device having the flow profile.Therefore, under the operating condition in the vicinity of the design point, there is substantially no pressure difference between the positions of the first and second opening ends, and the flow passing through the communication hole is not generated in principle. However, when the operating condition deviates from the design point, a pressure difference is generated between the positions of the first and second opening ends. As a result, a flow passing through the communication hole from one of the opening ends of the high pressure side to the other opening end of the low pressure side is generated. In addition, since this flow is discharged from the opening end of the low pressure side, a moment is imparted to the flow (main flow) around the surface of the member provided with the opening end of the low pressure side (typically, the airfoil portion), so that flow separation that might occur at this surface is reduced or prevented.According to at least one embodiment of the present invention, it is possible to provide an airfoil and a mechanical machine provided therewith in which stall that might occur at an airfoil surface can be reduced or prevented.BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1 is a schematic configuration diagram illustrating a gas turbine according to an embodiment. FIG. 2 is a schematic perspective view showing a blade (airfoil) according to an embodiment. FIG. 3 is a schematic perspective view showing a blade (airfoil) according to an embodiment. FIG. 4 is a schematic perspective view showing a blade (airfoil) according to an embodiment. FIG. 5 is a schematic perspective view showing a blade (airfoil) according to an embodiment. FIG. 6 is a partial schematic view showing a turbine with blades (rotor blades; airfoil) according to an embodiment. FIG. 7 is a schematic configuration diagram illustrating an aircraft according to an embodiment. FIG. 8 is a schematic perspective view illustrating a fin (airfoil) according to an embodiment. FIG. 9 is a cross-sectional view showing a blade (airfoil) according to an embodiment. FIG. 10 is a cross-sectional view illustrating a fin (airfoil) according to an embodiment. FIG. 11 is a diagram showing an example static pressure distribution on an airfoil surface under an operating condition at a design point of a gas turbine with the blade of FIG. 2. FIG. 12 is a graph showing an example static pressure distribution on an airfoil surface under an operating condition that deviates from the design point of the gas turbine with the blade of FIG. 2. FIG. 13 is a diagram showing an exemplary relationship between a loss coefficient and an incident angle of the blade. FIG. 14 is a diagram showing an example static pressure distribution on an airfoil surface under an operating condition at a design point of the gas turbine with the blade of FIG. 4. FIG. 15 is a graph showing an example static pressure distribution on an airfoil surface under an operating condition that deviates from a design point of the gas turbine with the blade of FIG. 4. FIG. 16 is a diagram showing an exemplary relationship between a loss coefficient and an incident angle of a blade (airfoil). FIG. 17 is a partial sectional view showing a blade (airfoil) according to an embodiment. FIG. 18 is a partial sectional view showing a blade (airfoil) according to an embodiment.DETAILED DESCRIPTIONEmbodiments of the present invention will now be described in detail with reference to the accompanying drawings. However, unless specifically stated, dimensions, materials, shapes, relative positions, and the like of components described in the embodiments should be understood only as illustrative and not in the sense of limiting the scope of the present invention.The airfoil according to some embodiments is applied to a mechanical machine such as an aircraft or a fluid machine (such as a gas turbine). Although described in further detail below, the airfoil according to some embodiments includes an airfoil portion having an airfoil surface and a communication hole extending at least in the airfoil portion. A first opening end of the communication hole is opened to the airfoil surface of the airfoil portion, and a second opening end of the communication hole is formed in a part of the airfoil other than the airfoil portion (e.g., a platform or shroud of a turbine blade) or in an apparatus in which the airfoil is installed (e.g., a fuselage of an aircraft).Hereinafter, an airfoil applied to a gas turbine and an aircraft will be described as the airfoil according to some embodiments.FIG. 1 is a schematic configuration diagram of a gas turbine according to an embodiment. As shown in FIG. 1, a gas turbine 1 includes a compressor 2 for generating compressed air, a combustor 4 for generating combustion gas using the compressed air and fuel, and a turbine 6 rotated by the combustion gas. In the case of a gas turbine 1 for power generation, a power generator not illustrated is connected to the turbine 6.The compressor 2 includes a plurality of stator vanes 16 fixed to one side of a compressor housing 10 and a plurality of rotor blades 18 inserted into a rotor 8 and arranged alternately with the stator vanes 16.The air introduced from an air inlet 12 is supplied to the compressor 2, where the air is compressed via a plurality of stator vanes 16 and a plurality of rotor blades 18 to generate compressed air of high temperature and high pressure.Fuel and compressed air generated by the compressor 2 are supplied to the combustor 4 so that the fuel is burned in the combustor 4 to generate the combustion gas as operating fluid of the turbine 6. As shown in FIG. 1, the gas turbine 1 includes a plurality of combustors 4 arranged in a casing 20 along a circumferential direction with respect to the rotor 8.The turbine 6 includes a combustion gas passage 28 formed by the turbine casing 22, and a plurality of stator vanes 24 and a plurality of rotor blades 26 arranged in the combustion gas passage 28. The stator vanes 24 and the rotor blades 26 of the turbine 6 are arranged downstream of the combustor 4 in the flow of the combustion gas.The stator vanes 24 are fixed to the turbine casing 22 side, and a plurality of stator vanes 24 arranged along the circumferential direction of the rotor 8 form a stator vane row. The rotor blades 26 are inserted into the rotor 8, and a plurality of rotor blades 26 arranged along the circumferential direction of the rotor 8 form a rotor blade row. The stator blade rows and the rotor blade rows are arranged alternately along the axial direction of the rotor 8.In the turbine 6, the combustion gas flowing from the combustor 4 to the combustion gas passage 28 passes through a plurality of stator vanes 24 and a plurality of rotor blades 26, thereby rotating the rotor 8. Subsequently, the current generator connected to the rotor 8 is driven to generate current. The combustion gas used for driving the turbine 6 is discharged to the outside through a discharge chamber 30.At least one / one of the stator vanes 24 or rotor blades 26 described above may have the airfoil according to an embodiment of the invention. FIGS. 2 to 5 are perspective views showing respective blades (airfoils) 32 according to an embodiment. The blades 32 shown in FIGS. 2 to 5 are usable as the above-described rotor blades 26.As shown in FIGS. 2 to 5, according to one embodiment, the blade 32 (blades 32A to 32D; rotor blades 26) includes an airfoil portion 40 extending between a base end 43 and an outer end 44, a platform 38 (connecting member) to which the airfoil portion 40 is connected, and a connecting hole 50 extending in the airfoil portion 40 and the platform 38.Airfoil portion 40 includes a pressure surface 45 (airfoil surface) and a suction surface 46 (airfoil surface) that extend along a span direction between a leading edge 41 and a trailing edge 42. As viewed in the span direction, the pressing surface 45 has a recess shape recessed toward an inner side of the airfoil portion 40, and the suction surface 46 has a protrusion shape protruding outward from the inner side of the airfoil portion 40. Note that here, the span direction refers to a direction obtained by connecting the base end 43 and the outer end 44 of the airfoil portion 40 and substantially coincides with a radial direction of the rotor 8 when the blade 32 is installed in the turbine 6 (when the rotor blade 26 is installed in the rotor 8).The platform 38 is provided between a blade root portion (not shown) embedded in the rotor 8 and the airfoil portion 40 in the span direction. Platform 38 has an end wall surface 62 to which airfoil portion 63 is connected, an upstream end surface 64 positioned upstream of airfoil portion 40, a downstream end surface 66 positioned downstream of airfoil portion 40, and a pair of circumferential end surfaces 68 and 69.Herein, "upstream" refers to an upstream side in the fluid flow around the blade, and "downstream" refers to a downstream side in the fluid flow around the blade. Note that in the case of the turbine 6 of the gas turbine ( 1) of FIG. 1, a fluid flow direction around the blade typically follows the axial direction of the rotor 8.The end wall surface 62 forms a flow path of the working fluid (combustion gas passage 28: see FIG. 1 ) in the turbine 6 together with the turbine housing 22.The upstream end surface 64 and the downstream end surface 66 extend along a plane perpendicular to the axial direction of the rotor 8, here, the axial direction of the rotor 8 typically coincides with the chord direction of the airfoil portion 40 (the direction obtained by connecting the leading edge 41 and the trailing edge 42 of the airfoil portion 40).Here, FIG. 6 is a partial schematic view that includes the turbine 6 having the blade 32 (rotor blade 26) according to an embodiment to show the blade 32 (rotor blade 26) and the stator blade 24 provided in the vicinity of the upstream side thereof applied to the turbine 6. The stator vane of FIG. 6 includes an airfoil portion 92, an inner shroud 94 provided radially inward of the airfoil portion 92, and an outer shroud 96 provided radially outward of the airfoil portion 92. The outer shroud 96 is supported by the turbine housing 22.As shown in FIG. 6, the upstream end surface 64 of the blade 32 (rotor blade 26) is provided to face a cavity (space) 98 between the rotor blade row formed by the blades 32 (rotor blades 26) and having the upstream end surfaces 64 and the stator blade row formed by the stator blades 24 provided adjacent to the blades 32 (rotor blades 26) upstream of the blades 32 (rotor blades 26). The downstream end surface 66 of the blade 32 (rotor blade 26) is provided to face a cavity (space) 99 between the rotor blade row formed by the blades 32 (rotor blades 26) with the downstream end surface 66 and the stator blade row formed by the stator blades 24 (not shown in FIG. 6 ) provided adjacent to the blades 32 (rotor blade 26) downstream of the blades 32 (rotor blades 26).As shown in FIGS. 2 to 5, the circumferential end surfaces 68 and 69 of the platform 38 are provided to face the circumferential end surfaces 69' and 68' of the platform 38' of the blade 32' (see the blade 32D' of FIG. 5 ) adjacent to the blade 32 with the platform 38 in the circumferential direction. Note that here, the "circumferential direction" refers to a circumferential direction of the rotor 8 perpendicular to the axial direction.The end wall surface 62, the upstream end surface 64, the downstream end surface 66, and the circumferential end surfaces 68 and 69 constitute a surface of the platform 38 (connecting member).Note that, in some embodiments, the blade 32 (such as the bucket 24 or the rotor blade 26 of the turbine 6) may have an outer shroud or "shotgun" (such as the outer shroud 69 of FIG. 6 ) provided radially outward of the airfoil portion or an inner shroud or "shotgun" (such as the inner shroud 94 of FIG. 6 ) provided radially inward of the airfoil. In this case, the "connecting member" may include the outer cover ring or the inner cover ring.The communication hole 50 extending in the airfoil portion 40 and the platform 38 (connector) has a first opening end 52 opened to the pressure surface 45 (airfoil surface) or the suction surface 46 (airfoil surface) of the airfoil portion 40 and a second opening end 54 opened to the surface of the platform 38.More specifically, in the blade 32A according to an exemplary embodiment of FIG. 2, the first opening end 52 is opened to the pressure surface 45 of the airfoil portion 40, and the second opening end 54 is opened to the end wall surface 62 of the platform 38. The second opening end 54 may be positioned upstream of the first opening end 52 in the chord direction of the airfoil portion 40. Alternatively, the second opening end 54 may be positioned upstream of the leading edge 41 of the airfoil portion 45 in the chord direction of the airfoil portion 40 at the cross section S 1 perpendicular to the span direction above the position of the first opening end 52 in the span direction.In the blade 32B according to an exemplary embodiment of FIG. 3, the first opening end 52 is opened to the pressure surface 45 of the airfoil portion 40, and the second opening end 54 is opened to the upstream end surface 64 of the platform 38.In the blade 32C according to an exemplary embodiment of FIG. 4, the first opening end 52 is opened to the suction surface 46 of the airfoil portion 40, and the second opening end 54 is opened to the downstream end surface 66 of the platform 38.According to an exemplary embodiment of FIG. 5, the circumferential end surface 68 of the platform 38 of the blade 32D and the circumferential end surface 69' of the platform 38' of the blade 32D' are provided adjacent to the blade 32D so as to face each other at least partially while interposing a clearance in the circumferential direction.In addition, the first opening end 52 is opened to the suction surface 46 of the airfoil portion 40 and the second opening end 54 is opened to the circumferential end surface 68 of the platform 38.Note that the blade 32D' adjacent to the blade 32D has a similar configuration in the circumferential direction to that of the blade 32D, and an apostrophe (') is added to the reference sign indicating the element of the blade 32D' in FIG. 5.Note that a combination of the opening position of the first opening end 52 and the opening position of the second opening end 54 is not limited to those shown in the drawings. For example, according to one embodiment, the first opening end 52 may be open to the suction surface 46 of the airfoil portion 40 and the second opening end 54 may be open to the end wall surface 62 of the platform 38. According to one embodiment, the first opening end 52 may be opened to the suction surface 46 of the airfoil portion 40 and the second opening end 54 may be opened to the upstream end surface 64 of the platform 38. According to one embodiment, the first opening end 52 may be opened to the pressure surface 45 of the airfoil portion 40 and the second opening end 54 may be opened to the downstream end surface 66 of the platform 38. According to one embodiment, the first opening end 52 may be open to the pressure surface 45 of the airfoil portion 40 and the second opening end 54 may be open to the circumferential end surface 68 of the platform 38.FIG. 7 is a schematic configuration diagram illustrating an aircraft according to an embodiment. As shown in FIG. 7, the aircraft 70 includes a fuselage 72, a pair of airfoils 74 (left airfoil 74L and right airfoil 74R), a pair of horizontal tail fins or tail tail tail tail tail tail units 76 (left horizontal tail unit 76L and right horizontal tail unit 76R), and a / a vertical tail fin(s) or tail unit 78. Moreover, the aircraft 70 has a coupling hole 51A extending in the vertical tail tail tail empennage 78 and the fuselage 72 and a coupling hole 51B extending in the horizontal tail empenries 76 and the fuselage 72. At least one of the left horizontal tail empennage 76L, the right horizontal tail empenage 76R, or the vertical tail empenage 78 includes the airfoil according to the embodiment of the present invention.FIG. 8 is a schematic perspective view showing a fin (airfoil) 33 according to an embodiment (horizontal tail fin 76 or vertical tail fin 78). As shown in FIG. 8, the fin 33 according to an embodiment has an airfoil portion 80 that extends between the base end 83 connected to the fuselage 72 and the outer end 84, and a communication hole 51 ( 51A and 51B) that passes through at least the airfoil portion 80.Airfoil portion 80 has a pair of airfoil surfaces 85 and 86 that extend along the span direction between leading edge 81 and trailing edge 82. When the fin 33 is the horizontal tail fin 76, a pair of airfoil surfaces 85 and 86 include an upper surface positioned in the upper half and a lower surface positioned in the lower half. When the fin 33 is the vertical tail fin 78, a pair of airfoil surfaces 85 and 86 include a left side surface positioned in the left half and a right side surface positioned in the right half.When the airfoil portion 80 is viewed from the span direction, each of the pair of airfoil surfaces 85 and 86 has a protruding shape that protrudes outward from the airfoil portion 80 from the inside. In the exemplary embodiment of FIG. 8, airfoil portion 80 is a symmetric fin or rib in which airfoil surfaces 85 and 86 are substantially symmetric with respect to the chord line.As shown in FIGS. 7 and 8, the communication hole 51 ( 51A or 51B) has a first opening end 53 ( 53A or 53B) opened to the airfoil surface 85 or 86 and extending in the airfoil portion 80 and the fuselage 72 to communicate communication between the first opening end 53 ( 53A or 53B) and the second opening end 55 ( 55A or 55B) formed in the fuselage 72.According to some embodiments, for example, as shown in FIG. 7, the vertical tail fin 78 has, as a fin 33, a communication hole 51A in which the first opening end 53A is opened to the right side surface (airfoil surface) of the vertical tail fin 78, and the second opening end 55A of the communication hole 51A is opened to the surface of the left side portion of the trunk 72.Note that, although not shown in the drawing, the vertical tail fin 78 as a fin 33 may have a communication hole 51 having a first opening end 53 opened to the left side surface (airfoil surface) of the vertical tail fin 78. In this case, the second opening end 55 of the communication hole 51 is opened to the surface of the right side portion of the trunk 72.According to some embodiments, for example, as shown in FIG. 7, the left horizontal tail fin 76L as a fin 33 has a communication hole 51B having a first opening end 53B opened to the lower surface (airfoil surface) of the left horizontal tail fin 76L and the second opening end 55B of the communication hole 51B opened to a surface of the trunk 72. The second opening end 55B may be opened to the upper surface of the trunk 72. In addition, the second opening end 55B may be provided in a front part of the fuselage 72, for example, in front of the wing 74.Note that similarly, the first opening end 53 may be provided in the right horizontal tail fin 76R, and a communication hole 51 that connects a connection between the first opening end 53 and the second opening end 55 formed in the fuselage 72 to each other may also be provided.Although not shown in the drawing, according to some embodiments, the left horizontal tail fin 76L may have, as a rib 33, a communication hole 51 having a first opening end 53 opened to the upper surface (airfoil surface) of the left horizontal tail fin 76L. In this case, the second opening end 55 of the communication hole 51 may be opened to the lower surface of the trunk 72. In addition, the second opening end 55 may be provided in a front part of the fuselage 72, for example, in front of the wing 74.Similarly, the right horizontal tail fin 76R may have a first opening end 53, and a communication hole 51 that enables communication between the first opening end 53 and the second opening end 55 formed in the fuselage 72 may also be provided.The following describes the blade (airfoil) 32 (such as a blade of the turbine 6) and the fin (airfoil) 33 (such as a tail fin of the aircraft 70) in detail, in accordance with some embodiments.FIG. 9 is a cross-sectional view illustrating the blade 32 according to an embodiment, and illustrates a cross section perpendicular to the span direction through the first opening end 52 (see FIGS. 2 to 5 ). FIG. 10 is a cross-sectional view illustrating the fin 33 according to an embodiment, and illustrates a cross-section perpendicular to the span direction through the first opening end 53 (see FIG. 8 ).At a cross section S 1 perpendicular to the span direction through the position of the first opening end 52 or 53 in the span direction, the blade 32 (see FIG. 9 ) or the fin 33 (see FIG. 10 ) according to some embodiments has an angle A 1 satisfying a condition (a) within an angle range equal to or greater than minus 10 degrees equal to or less than 10 degrees with respect to an extension line obtained by extending the camber line CL of the airfoil portion 40 or 80 from the leading edge 41 and 81 while the leading edge 41 or 81 is selected as the center. Here, the condition (a) is a condition that when the airfoil portion 40 or 80 receives a flow of the fluid of a direction of the angle A 1 toward the leading edge 41 or 81 (i.e., the arrow direction F in FIGS. 9 and 10 ), a static pressure at the position of the first opening end 52 or 53 becomes equal to a static pressure at the position of the second opening end 54 or 55.Note that the "extension line" described above refers to a front part of the leading edge 41 or 81 (the part opposite to the trailing edge 42 or 82 with respect to the leading edge 41 or 81) on a straight line L CAM parallel to the camber line CL of the leading edge 41 or 81 by the leading edge 41 or 81 (the straight line with inclination of the camber line CL at the leading edge 41). Note that when the fin 33 is symmetric as shown in FIG. 10, the chord line coincides with the camber line CL, and the straight line L CAM with the inclination of the camber line CL at the leading edge 81 coincides with the camber line CL.That is, when the blade 32 or the fin 33 rotates together with the rotor of the rotary machine, the above-described fluid flow direction depends on a circumferential speed of the blade 32 or the fin 33 or a flow rate of the fluid. When the blade 32 or fin 33 is applied to the aircraft, the direction of fluid flow depends on a direction (wind direction) of the fluid (typically air) around the aircraft, a direction of travel or a flight speed of the aircraft, or the like.In the following description, an angle of the fluid flow directed to the blade 32 or the fin 33 with respect to the direction of the operating condition of the design point (typically, the extension line of the camber line CL) is referred to as an angle of impingement (angle of attack). Accordingly, in the case of the operating condition of the design point, the angle of incidence becomes zero. The angle of impingement is "positive" when the fluid flow faces the pressure surface 45 or airfoil surface 85 with respect to the leading edge 41 or 81 relative to the case of the design point. Thus, in Figs. 9 and 10, the angle of incidence with respect to the leading edge 41 or 81 is "positive" in a counterclockwise direction or "negative" in a clockwise direction.Note that when the gas turbine 1 (see FIG. 1 ) is operated with a load smaller than that of the operating condition of the design point, the angle of impingement of the fluid against the rotor blade 26 as the blade 32 tends to be negative. When operated with a load larger than that of the operating condition of the design point, the angle of incidence tends to be positive.The effects obtained by using the blade 32 and the fin 33 having the configurations used above will be described below on the basis of the exemplary embodiments of FIGS. 2 and 4. However, they are similarly applicable to the effects in other embodiments.FIGS. 11 and 12 are diagrams showing exemplary static pressure distributions at airfoil surfaces under different operating conditions (i.e., at the pressure surface 45 and the suction surface 46) when the blade 32 of FIG. 2 is employed as the rotor blade 26 of the gas turbine 1 (see FIG. 1 ). FIG. 11 is a graph of the static pressure distribution under the operating condition of the design point (i.e., at an angle of incidence of 0 degrees). FIG. 12 is also a graph of the static pressure distribution when the operating condition deviates from the design point and the angle of impingement of the fluid is negative.Note that the abscissas of FIGS. 11 and 12 refer to the position in the chord direction, with the position of the leading edge 41 of the airfoil portion 40 being denoted by "0", and the position of the trailing edge 42 being denoted by "c". In addition, the position of the first opening end 52 provided on the airfoil surface is denoted by "U 1" and the position of the chord direction is denoted by "x 1".In the diagrams of FIGS. 11 and 12, the position of the second opening end 54 (denoted by "T1") provided on the end wall surface 62 of the platform 38 (connecting member) is also indicated. In the diagrams of FIGS. 11 and 12, the chord direction position x 2 of the second opening end 54 is less than zero. That is, the second opening end 54 is placed on the end wall surface 62 upstream of the leading edge 41 of the airfoil portion 40.The static pressure distribution on the airfoil surface under the design point operating condition (i.e., at an angle of impingement of 0 degrees) typically has a profile shown in the graph of FIG. 11, including a position on the airfoil surface (pressure surface 45 or suction surface 46) with the same static pressure and a position on the end wall surface 62 of the platform 38.Therefore, in the case of the communication hole 50 having the first opening end 52 provided at the position U 1 on the pressure surface 45 and the second opening end 54 provided at the position T 1 on the end wall surface 62, a flow of the fluid passing through the communication hole 50 is fundamentally not generated in the operation at the design point.In a mechanical machine such as a rotary machine using the blade 32 having such characteristics, when the operating condition deviates from the design point and the incident angle of the fluid directed to the blade 32 to the negative direction deviates from the design point, the flow of the fluid easily collides with the suction surface 46, and flow separation easily occurs in the flow at the pressure surface 45.In this case, as shown in FIG. 12, the static pressure distribution on the airfoil surface has a pressure difference between the position U 1 on the pressure surface 45 and the position T 1 on the end wall surface 62, the pressures of which are equal under the operating condition of the design point, so that the pressure at the position T 1 on the end wall surface 62 becomes a relatively high pressure. Therefore, by providing the communication hole 50 having the first opening end 52 at the position U 1 on the pressure surface 45 and the second opening end 54 at the position T 1 on the end wall surface 62, a flow passing through the communication hole 50 from the second opening end 54 at a relatively high pressure to the first opening end 52 at a relatively low pressure is generated when the incident angle of the fluid directed to the blade 32 deviates from the design point to the negative direction. In addition, since this flow is discharged to the pressure surface 45 through the first opening end 52, a moment is imparted to the flow (main flow) around the pressure surface 45, so that it is possible to reduce or prevent flow separation that might occur at the pressure surface 45.Therefore, when the communication hole 50 is provided as described above as illustrated in FIG. 13, a loss coefficient of the blade 32 in the negative impact angle range can be reduced as compared with a case where the communication hole 50 is not provided. Note that FIG. 13 is a diagram showing an exemplary relationship between the loss coefficient of the blade 32 and the incident angle by comparing the loss coefficient 102 of the blade 32 with the communication hole 50 and the loss coefficient 101 of the blade 32 without the communication hole 50.FIGS. 14 and 15 are diagrams showing exemplary static pressure distributions on the airfoil surfaces (i.e., the pressure surface 45 and the suction surface 46) under different operating conditions when the blade 32 of FIG. 4 is employed as the rotor blade 26 of the gas turbine 1 (see FIG. 1 ). FIG. 14 is a diagram under the operating condition of the design point (i.e., at an angle of incidence of 0 degrees). In addition, FIG. 15 is a diagram when the operating condition deviates from the design point and the incident angle of the fluid becomes positive.Note that the abscissas of the plots of FIGS. 14 and 15 refer to the position of the chord direction, where the position of the leading edge 41 of the airfoil portion 40 is labeled "0", and the position of the trailing edge 42 is labeled "c". In addition, the position of the first opening end 52 provided on the airfoil surface is denoted by "U 2", and the position of the chord direction is denoted by "x 3".In the diagrams of FIGS. 14 and 15, the position (denoted by "T 2") of the second opening end 54 provided on the downstream end surface 66 of the platform 38 (connecting member) is also indicated. In the diagrams of FIGS. 14 and 15, the chord direction position "x 4" of the second opening end 54 is greater than the chord direction position "c", that is, the second opening end 54 is located at the downstream end surface 66 downstream from the trailing edge 42 of the airfoil portion 40.The static pressure distribution on the airfoil surface under the design point operating condition (i.e., at an angle of impingement of 0 degrees) typically has a profile shown in the graph of FIG. 14, including a position on the airfoil surface (pressure surface 45 or suction surface 46) and a position on the downstream end surface 66 of the platform 38 having the same static pressure. For example, in the diagram of FIG. 14, the position U 2 on the suction surface 46 and the position T 2 on the downstream end surface 66 have the same static pressure under the operating condition of the design point.Therefore, in the case of the communication hole 50 having the first opening end 52 at the position U 2 on the suction surface 46 and the second opening end 54 at the position T 2 on the downstream end surface 66, basically, a flow of the fluid passing through the communication hole 50 is not generated in the operation at the design point.In a mechanical machine such as a rotary machine using the blade 32 having such characteristics, however, when the operating condition deviates from the design point and the incident angle of the fluid directed to the blade 32 deviates from the design point in a positive direction, the flow of the fluid easily collides with the pressure surface 45 and flow separation easily occurs in the flow at the suction surface 46.In this case, as shown in FIG. 15, the static pressure distribution on the airfoil surface has a pressure difference between the position U 2 on the suction surface 46 and the position T 2 on the downstream end surface 66, the pressures of which are equal under the operating condition of the design point, so that the pressure at the position T 2 on the downstream end surface 66 becomes relatively higher. Therefore, by providing the communication hole 50 having the first opening end 52 at the position U 2 on the suction surface 46 and the second opening end 54 at the position T 2 on the downstream end surface 66, a flow passing through the communication hole 50 from the second opening end 54 at a relatively high pressure to the first opening end 52 at a relatively low pressure is generated when the incident angle of the flow directed to the blade 32 deviates from the design point toward the positive direction. In addition, since this flow is discharged through the first opening end 52 toward the suction surface 46, a moment is imparted to the flow (main flow) around the suction surface 46, so that it is possible to reduce or prevent flow separation that might occur at the suction surface 46.Therefore, when the communication hole 50 is provided as described above and as illustrated in FIG. 16, a loss coefficient of the blade 32 in the positive impact angle range can be reduced as compared with a case where the communication hole 50 is not provided. Note that FIG. 16 is a diagram showing an exemplary relationship between the loss coefficient of the blade 32 and the incident angle by comparing the loss coefficient 104 of the blade 32 with the communication hole 50 and the loss coefficient 103 of the blade 32 without the communication hole 50.From the above description, it is understood that the blade 32 or fin 33 according to the above-described embodiment has an angle A 1 satisfying the condition (a). Therefore, the static pressure becomes equal between the position of the first opening end 52 or 53 at the airfoil surface and the position of the second opening end 54 or 55 when operating at the design point of the mechanical machine (such as the gas turbine 1 or the aircraft 70). When the operating condition of the mechanical machine deviates from the design point, a pressure difference is generated between the position of the first opening end 52 or 53 and the position of the second opening end 54 or 55.For this reason, there is substantially no pressure difference between the first opening end 52 or 53 and the second opening end 54 or 55, and a flow passing through the communication hole 50 or 51 is not generated basically under the operating condition in the vicinity of the design point of the mechanical machine. However, when the operating condition deviates from the design point (i.e., when the incident angle of the fluid deviates from the angle A 1), a pressure difference is generated between the position of the first opening end 52 or 53 and the position of the second opening end 54 or 55. As a result, a flow is generated which passes through the communication hole 50 or 51 from one of the opening ends of the high pressure side to the other opening end of the low pressure side. In addition, since this flow is discharged from the opening end of the low pressure side, a moment is imparted to the flow (main flow) around the surface of the member provided with the opening end of the low pressure side (typically, the airfoil portion 40 or 80), so that flow separation that might occur at this surface can be reduced or prevented.Therefore, a reduction in the performance of the mechanical machine in operation in the vicinity of the design point can be reduced or prevented, and stall on the airfoil surface that might occur when the operating condition deviates from the design point can be reduced or prevented.Note that in the embodiment of FIG. 7, the second opening end 55A of the communication hole 51A may be placed with the first opening end 53A at the surface (for example, the right side surface) of the vertical tail fin 78 (fin 33) above the base end in the vicinity of the base end (connection portion with the fuselage 72) of the airfoil 74 (for example, the left airfoil 74L) in the fuselage 72.In the embodiment of FIG. 7, the second opening end 55B of the communication hole 51B may be provided with the first opening end 53B on the surface (e.g., the bottom surface) of the horizontal tail fin 76 (fin 33) on the top surface of the fuselage 72 in front of the airfoil 74 in the fuselage 72.In any case, the first opening end 53 and the second opening end 55 of the communication hole 51 are provided at positions where the pressures become equal when operating in the vicinity of the design point of the aircraft 70 (for example, in a cruising speed flight).The blade 32 and / or fin 33, in accordance with some embodiments, may further have the following characteristics.According to some embodiments, the first opening end 52 of the blade 32 is opened to the pressure surface 45 in the leading edge 41 side from a point P A( see FIG. 9 ) on the pressure surface 45 having a tangential line LT P( see FIG. 9 ) parallel to the chord direction of the airfoil portion 40.In the mechanical machine (such as the gas turbine 1) having the blade 32, when the angle of impingement of the fluid against the blade 32 is negative (i.e., the fluid flow is directed to easily collide with the suction surface 46 as compared with the operating condition at the design point), flow separation easily occurs at the pressure surface 45 at the position of the trailing edge 42 side from the point P A at the pressure surface 45 having a tangential line LT P parallel to the chord direction in some cases. In this regard, according to the above-described embodiment, the first opening end 52 is provided in the leading edge 41 side from the position where flow separation occurs easily at the pressure surface 45 in this manner. Therefore, fluid separation that may easily occur on the print surface 45 when the angle of impingement is negative can be effectively reduced or prevented.According to some embodiments, the first opening end 52 of the blade 32 is opened to the suction surface 46 at a position of the leading edge 41 side from the intersection P B between the suction surface 46 and the straight line L CAM through the leading edge 41 and parallel to the camber line CL of the airfoil portion 40 in the leading edge 41.In the mechanical machine (such as the gas turbine 1) having the blade 32, when the angle of impingement of the fluid against the blade 32 is positive (i.e., the flow of the fluid is directed to collide with the pressure surface 45 as compared with the operating condition at the design point), stall easily occurs at the suction surface 46 at a position of the leading edge 42 side from the intersection P B between the suction surface 46 and the line L CAM through the leading edge 41 and parallel to the camber line CL of the airfoil portion 40 in the leading edge 41 in some cases. In this regard, according to the embodiment described above, the second opening end 54 is provided in the side of the leading edge 41 from the position where the flow separation on the suction surface 46 easily occurs in this manner. Therefore, fluid separation that may easily occur at the suction surface 46 when the incident angle is positive as described above can be effectively reduced or prevented.Each of FIGS. 17 and 18 is a partial sectional view showing the blade according to an embodiment to show a cross section perpendicular to the span direction through the first opening end 52.When the blade 32 or fin 33 is viewed from the span direction, an angle between a portion of the tangential line of the airfoil surface in the first opening end 52 or 53 close to the leading edge 41 or 81 side of the first opening end 52 or 53 and the communication hole 50 or 51 in the first opening end 52 or 53 is equal to or less than 45 degrees, according to some embodiments.For example, in the exemplary embodiment of FIG. 17, the first opening end 52 of the communication hole 50 is opened to the pressure surface 45, and an angle θ 1 between a portion of the tangential line TL 1 of the first opening end 52 and the pressure surface 45 (airfoil surface) close to the leading edge 41 side of the first opening end 52 and the communication hole 50 in the first opening end 52 (the direction of the straight line L 1 in the drawing) is equal to or less than 45 degrees.For example, according to the exemplary embodiment of FIG. 18, the first opening end 52 of the communication hole 50 is opened to the suction surface 46, and an angle θ 2 between a portion of the tangential line TL 2 of the first opening end 52 at the suction surface 46 (airfoil surface) close to the leading edge 41 side of the first opening end 52 and the communication hole 50 in the first opening end 52 (the direction of the straight line L 2 in the drawing) is equal to or less than 45 degrees.In the case of the above-described embodiment, the communication hole 50 or 51 has a shape matched with the airfoil surface (pressure surface 45 or suction surface 46) at the position of the first opening end 52 or 53. Therefore, mixing loss with the fluid flowing along the vicinity of the airfoil surface can be reduced when the flow is discharged from the communication hole 50 or 51 from the first opening end 52 or 53.While the embodiment of the present invention has been described, the present invention is not limited to the above-described embodiments and includes modifications of the described embodiments and suitable combinations thereof.In the present specification, an expression of a relative or absolute arrangement such as "in a direction", "along a direction", "parallel", "orthogonal", "centered", "concentric" and "coaxial" is not to be interpreted as indicating only the arrangement in a strict literal sense, but also includes a state where the arrangement relatively deviates by a tolerance or by an angle or a distance, whereby the same function can be achieved.For example, an expression of a same state as "same", "same", and "uniform" is not intended to be taken as indicating only the state in which the feature is the same in the strict sense, but also includes a state in which there is a tolerance or a difference that can still achieve the same function.Further, in the present specification, an expression of a shape such as a rectangular shape or a cylindrical shape is not to be understood in terms of only the geometrically strict shape, but also includes a shape having non-uniformities or chamfered corners within the range in which the same effect can be obtained.In addition, in the present specification, an expression such as "comprising", "including", and "having" is not intended to exclude other components

Claims

An airfoil comprising: an airfoil portion (40; 80) having an airfoil surface (45, 46; 85, 86) extending along a span direction between a leading edge (41; 81) and a trailing edge (42; 82); and at least one communication hole (50, 51) extending at least in the airfoil portion and having a first opening end (52, 53) opened to the airfoil surface through which the first opening end communicates with a second opening end (54, 55) provided in a shroud (94, 96) to which the airfoil is connected or in a device to which the airfoil is installed, wherein, at a cross-section (S1) perpendicular to the span direction, an angle A1 is defined by a position of the first opening end of the span direction, which satisfies a condition (a) in an angle range equal to or greater than minus 10 degrees and equal to or less than 10 degrees with respect to an extension line obtained by extending a camber line (CL) of the airfoil portion from the leading edge while the leading edge is selected as a center, and wherein the condition (a) is a condition that a static pressure at a position of the first opening end is equal to a static pressure at a position of the second opening end when the airfoil portion receives a fluid flow from a direction of the angle A 1 to the leading edge.The airfoil of claim 1, wherein the apparatus comprises a fuselage (72) of an aircraft (70), the airfoil portion (40; 80) comprises a vertical tail (78) or a horizontal tail (76) of the aircraft, and the second opening end (54, 55) is provided in the fuselage.The airfoil of claim 2, wherein the airfoil surface (45, 46; 85, 86) comprises a left side surface and a right side surface of the vertical tail (78), and the first opening end (52, 53) is opened to the left side surface of the vertical tail while the second opening end (54, 55) is opened to a surface of a portion of a right side of the fuselage (72), or the first opening end is opened to the right side surface of the vertical tail while the second opening end is opened to a surface of a portion of a left side of the fuselage.The airfoil according to claim 2, wherein the airfoil surface (45, 46; 85, 86) comprises an upper surface and a lower surface of the horizontal tail (76), the first opening end (52, 53) is opened to the upper surface or the lower surface of the horizontal tail, and the second opening end (54, 55) is opened to a surface of the fuselage (72).An airfoil comprising: an airfoil portion (40; 80) having an airfoil surface (45, 46; 85, 86) extending along a span direction between a leading edge (41; 81) and a trailing edge (42; 82), a connecting member (38) to which the airfoil portion is connected, and at least one connecting hole (50, 51) having a first opening end (52, 53) opened to the airfoil surface and a second opening end (54, 55) opened to a surface of the connecting member and extending in the airfoil portion and the connecting member, wherein the airfoil surface (45, 46; 85, 86) a pressure surface (45) and a suction surface (46), the surface of the connector (38) having at least one of: an end wall surface (62) with which the airfoil portion (40; 80), the end wall surface forming a flow path of a working fluid of a turbine (6), an upstream end surface (64) disposed in an upstream region of the fluid path from the airfoil portion and extending along a plane perpendicular to an axial direction, a downstream end surface (66) disposed downstream of the airfoil portion and extending along a plane perpendicular to an axial direction, or a circumferential end surface (68, 69), the circumferential end surface of the connector facing a circumferential end surface of a connector from an airfoil adjacent to the airfoil in a circumferential direction with interposition of a clearance, and the second opening end (54, 55) being opened to the end wall surface, the upstream end surface, the downstream end surface, or the circumferential end surface.The airfoil of claim 5, wherein the first opening end (52, 53) is open to the pressure surface (45) or the suction surface (46), and the second opening end (54, 55) is open to the end wall surface (62) of the connector (38).The airfoil according to claim 5, wherein the first opening end (52, 53) is opened to the pressure surface (45) or the suction surface (46), and the second opening end (54, 55) is opened to the upstream end surface (64).The airfoil according to claim 5, wherein the first opening end (52, 53) is opened to the pressure surface (45) or the suction surface (46), and the second opening end (54, 55) is opened to the downstream end surface (66).The airfoil of claim 5, wherein the first opening end (52, 53) is open to the pressure surface (45) or the suction surface (46), and the second opening end (54, 55) is open to the circumferential end surface (68, 69).The airfoil according to any one of claims 5 to 9, wherein the first opening end (52, 53) is opened to the pressure surface (45) at a position on the leading edge side from a point on the pressure surface having a tangential line (LT P) parallel to a chord direction of the airfoil portion (40; 80).The airfoil according to any one of claims 5 to 9, wherein the first opening end (52, 53) is opened to the suction surface (46) at a position on the leading edge side from an intersection point (P B) between the suction surface and a straight line (L CAM) through the leading edge (41; 81) and parallel to the camber line (CL) of the airfoil portion (40; 80) in the leading edge.The airfoil according to any one of claims 5 to 11, wherein the second opening end (54, 55) is positioned upstream of the first opening end (52, 53) in a chord direction of the airfoil portion (40; 80).The airfoil according to any one of claims 5 to 12, wherein, at a cross section (S1) perpendicular to the span direction through a position of the first opening end of the span direction, an angle A1 satisfying a condition (a) is in an angle range equal to or greater than minus 10 degrees and equal to or less than 10 degrees with respect to an extension line obtained by extending a camber line (CL) of the airfoil portion (40; 80) from the leading edge (41; 81) while the leading edge is set as a center, and wherein the condition (a) is a condition that a static pressure is applied to a position of the first opening end of the airfoil surface (45, 46; 85, 86) is equal to a static pressure at a position of the second opening end (54, 55) at the surface of the connecting member (38) when the airfoil portion receives a fluid flow from a direction of the angle A 1 to the leading edge.The airfoil according to any one of claims 1 to 13, wherein, as viewed from the span direction, an angle between a part of a tangential line (LT P) of the airfoil surface (45, 46; 85, 86) at the first opening end (52, 53), the part being located in the leading edge side from the first opening end, and the first opening end communication hole (50, 51) is equal to or less than 45 degrees.A mechanical machine having the airfoil of any of claims 1 to 14.

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