Axial flow compressor

Abstract

The present invention provides an axial flow compressor that can suppress the performance degradation of the axial flow compressor caused by wakes generated from the trailing edge of the final stage stator vane interfering with the outlet guide vane. [Solution] An axial flow compressor is provided with an outlet guide vane located downstream of the final stage stator vane. In a cross-section perpendicular to the blade height direction of the final stage stator vane, the straight line extending from the trailing edge of the final stage stator vane along the camber line is called the camber line extension. The shortest distance between the camber line extension and the negative pressure surface of the outlet guide vane is Dmim, and the chord length of the outlet guide vane is C. Then, the final stage stator vane and the outlet guide vane satisfy 0.07 ≤ Dmin / C ≤ 0.20 over the entire range in the blade height direction of the final stage stator vane.

Description

Technical Field

[0001] The present disclosure relates to an axial flow compressor.

Background Art

[0002] Patent Document 1 discloses an axial flow compressor for compressing a fluid, which has a two-stage stator structure with an outlet guide vane provided on the downstream side of the final-stage stator in the flow direction of the fluid.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] According to the findings of the inventor of the present application, in an axial flow compressor having an outlet guide vane on the downstream side of the final-stage stator, when the wake (vortex) generated from the trailing edge of the final-stage stator interferes with the outlet guide vane, flow separation occurs on the surface of the outlet guide vane, leading to a decrease in the performance of the axial flow compressor.

[0005] In view of the above circumstances, at least one embodiment of the present disclosure aims to provide an axial flow compressor capable of suppressing a decrease in the performance of the axial flow compressor caused by the wake generated from the trailing edge of the final-stage stator interfering with the outlet guide vane.

Means for Solving the Problems

[0006] To achieve the above object, an axial flow compressor according to at least one embodiment of the present disclosure is an axial flow compressor for compressing a fluid, including a final-stage stator, an outlet guide vane provided on the downstream side of the final-stage stator in the flow direction of the fluid, and In a cross-section perpendicular to the wing height direction of the final stage stator vane, the straight line extending the camber line of the final stage stator vane from the trailing edge of the final stage stator vane is called the camber line extension, and the shortest distance between the camber line extension and the negative pressure surface of the exit guide vane is Dmim, and the chord length of the exit guide vane is C. Then, the final stage stator vane and the exit guide vane satisfy the following equation (a) over the entire range in the wing height direction of the final stage stator vane. 0.07 ≤ Dmin / C ≤ 0.20 …(a) [Effects of the Invention]

[0007] According to at least one embodiment of the present disclosure, an axial flow compressor is provided that can suppress the performance degradation of the axial flow compressor caused by wakes generated from the trailing edge of the final stage stator vane interfering with the outlet guide vane. [Brief explanation of the drawing]

[0008] [Figure 1] This figure shows a schematic cross-section along the axial direction of an axial flow compressor 2 according to one embodiment. [Figure 2] This figure shows a cross-section perpendicular to the blade height direction at position Po, which belongs to the outer end 16fo of the final stage stator blade 16f of the final stage stator blade 16f, of the axial flow compressor 2. [Figure 3] This figure shows a cross-section perpendicular to the blade height direction at position Pm, which belongs to the central part 16fm in the blade height direction of the final stage stator blade 16f and the outlet guide blade 20 of the axial flow compressor 2. [Figure 4] This figure shows a cross-section perpendicular to the blade height direction at position Pi, which belongs to the inner end 16fi of the final stage stator blade 16f of the final stage stator blade 16f and the outlet guide blade 20 of the axial flow compressor 2. [Figure 5A] This figure shows the flow velocity distribution on the negative pressure surface 46 of the outlet guide vane 20 for one comparative configuration. [Figure 5B] This figure shows the flow velocity distribution on the negative pressure surface 46 of the outlet guide vane 20 for one comparative configuration. [Figure 5C]This figure shows the flow velocity distribution on the negative pressure surface 46 of the outlet guide vane 20 for one comparative configuration. [Figure 6] This figure shows the flow velocity distribution on the negative pressure surface 46 of the outlet guide vane 20 in one embodiment. [Modes for carrying out the invention]

[0009] Hereinafter, several embodiments of this disclosure will be described with reference to the attached drawings. However, the dimensions, materials, shapes, relative arrangements, etc., of the components described or shown in the drawings as embodiments are not intended to limit the scope of the invention, but are merely illustrative examples. For example, expressions describing relative or absolute arrangements such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" should not only strictly describe such arrangements, but also describe states of relative displacement with tolerances or angles or distances that allow for the same function to be achieved. For example, expressions such as "identical," "equal," and "homogeneous" that describe things being in an equal state not only describe a state of being strictly equal, but also describe a state in which there is a tolerance or a difference that is sufficient to achieve the same function. For example, expressions describing shapes such as squares or cylinders shall not only represent geometrically precise shapes such as squares or cylinders, but also shapes that include protrusions, chamfers, etc., to the extent that the same effect can be achieved. On the other hand, expressions such as "to possess," "to be equipped with," "to have," "to include," or "to have" a single component are not exclusive expressions that exclude the existence of other components.

[0010] Figure 1 is a schematic cross-section along the axial direction in an axial flow compressor 2 according to one embodiment. As shown in Figure 1, the axial flow compressor 2 comprises a rotor 4 and a casing 6 that houses the rotor 4. A flow path 7 is formed between the rotor 4 and the casing 6 through which the fluid to be compressed flows.

[0011] The rotor 4 includes a rotating shaft 8 and a plurality of moving blade rows 10 provided on the outer peripheral surface of the rotating shaft 8. The plurality of moving blade rows 10 are arranged at intervals in the axial direction. In this specification, unless otherwise specified, the "axial direction" means the axial direction of the axial flow compressor 2, that is, the axial direction of the rotating shaft 8, the "radial direction" means the radial direction of the axial flow compressor 2, that is, the radial direction of the rotating shaft 8, and the "circumferential direction" means the circumferential direction of the axial flow compressor 2, that is, the circumferential direction of the rotating shaft 8. Also, in this specification, unless otherwise specified, the "upstream side" means the upstream side in the flow direction of the fluid flowing through the flow path 7, that is, the upstream side in the axial direction, and the "downstream side" means the downstream side in the flow direction of the fluid flowing through the flow path 7, that is, the downstream side in the axial direction.

[0012] Each of the plurality of moving blade rows 10 includes a plurality of moving blades 12 provided at intervals in the circumferential direction along an arc on the outer peripheral surface of the rotating shaft 8.

[0013] The axial flow compressor 2 also includes a plurality of stationary blade rows 14 provided on the inner peripheral surface of the casing 6. The plurality of stationary blade rows 14 are arranged at intervals in the axial direction. The moving blade rows 10 and the stationary blade rows 14 are arranged alternately in the axial direction. The stationary blade row 14 includes a plurality of stationary blades 16 provided at intervals in the circumferential direction along an arc on the inner peripheral surface of the casing 6.

[0014] Here, the moving blade row 10 and the stationary blade row 14 arranged adjacent to the moving blade row 10 on the downstream side of the moving blade row 10 constitute one stage 18 of the axial flow compressor 2, and the axial flow compressor 2 includes a plurality of stages 18 arranged in series in the axial direction. Here, the stage located on the most downstream side among the plurality of stages 18 is referred to as the final stage 18f, the stationary blade row 14 belonging to the final stage 18f is referred to as the final stage stationary blade row 14f, and each of the stationary blades 16 constituting the final stage stationary blade row 14f is referred to as the final stage stationary blade 16f. Also, in this specification, unless otherwise specified, the "blade height direction" means the blade height direction of the final stage stationary blade 16f, the "outer side" in the blade height direction means the outer side in the radial direction (the casing 6 side in the blade height direction), and the "inner side" in the blade height direction means the inner side in the radial direction (the rotating shaft 8 side in the blade height direction).

[0015] The axial compressor 2 includes a plurality of outlet guide vanes 20 provided at circumferential intervals along an arc on the inner circumferential surface of the casing 6. Each of the plurality of outlet guide vanes 20 is provided in a one-to-one correspondence with each of the plurality of final-stage stationary vanes 16f, and is disposed adjacent to the corresponding final-stage stationary vane 16f on the downstream side of each of the plurality of final-stage stationary vanes 16f.

[0016] Each of FIGS. 2 to 4 is a diagram showing an example of the arrangement of the final-stage stationary vane 16f and the outlet guide vane 20 on the downstream side of the final-stage stationary vane 16f in a cross section orthogonal to the blade height direction. FIG. 2 shows a cross section orthogonal to the blade height direction at a position Po belonging to the outer end 16fo (see FIG. 1) in the blade height direction of the final-stage stationary vane 16f. FIG. 3 shows a cross section orthogonal to the blade height direction at a position Pm belonging to the central portion 16fm (see FIG. 1) in the blade height direction of the final-stage stationary vane 16f. FIG. 4 shows a cross section orthogonal to the blade height direction at a position Pi belonging to the inner end 16fi (see FIG. 1) in the blade height direction of the final-stage stationary vane 16f. The end 16fo is located outside the central portion 16fm in the blade height direction, and the end 16fi is located inside the central portion 16fm in the blade height direction.

[0017] As shown in FIGS. 2 to 4, the final-stage stationary vane 16f includes a leading edge 30, a trailing edge 32, a pressure surface 34 connecting the leading edge 30 and the trailing edge 32, and a suction surface 36 connecting the leading edge 30 and the trailing edge 32. The outlet guide vane 20 includes a leading edge 40, a trailing edge 42, a pressure surface 44 connecting the leading edge 40 and the trailing edge 42, and a suction surface 46 connecting the leading edge 40 and the trailing edge 42.

[0018] As shown in FIGS. 2 to 4, in each cross section orthogonal to the blade height direction, the camber line Lc of the final-stage stationary vane 16f is referred to as a camber line extension line Le which is a straight line extended from the trailing edge 32 of the final-stage stationary vane 16f. When the shortest distance between the camber line extension line Le and the suction surface 46 of the outlet guide vane 20 is Dmin and the chord length of the outlet guide vane is C, the final-stage stationary vane 16f and the outlet guide vane 20 are configured to satisfy the following formula (a) in the entire range in the blade height direction of the final-stage stationary vane 16f. 0.07 ≤ Dmin / C ≤ 0.20 …(a)

[0019] Furthermore, "the camber line Lc of the final stage stator vane 16f" refers to the line that passes through the leading edge 30 and the trailing edge 32 and connects the central position of the thickness of the final stage stator vane 16 (a line that connects a position equidistant from the pressure surface 34 and the negative pressure surface 36). Also, "the straight line extending the camber line Lc of the final stage stator vane 16f from the trailing edge 32 of the final stage stator vane 16f" refers to the straight line extending the camber line Lc from the trailing edge 32 of the final stage stator vane 16f along the direction of the tangent to the camber line Lc at the position of the trailing edge 32. In addition, "the shortest distance between the camber line extension line Le and the negative pressure surface 46 of the exit guide vane 20" refers to the distance between the tangent line Lt, which is parallel to the camber line extension line Le and tangent to the negative pressure surface 46, and the extension line Le. Furthermore, "the entire range of the final stage stator vane 16f in the wing height direction" means the range from the outer edge to the inner edge of the final stage stator vane 16f in the wing height direction, and "the entire range of the final stage stator vane 16f in the wing height direction satisfies the following equation (a)" means that the above cross-section (cross-section perpendicular to the wing height direction) at all positions from the outer edge to the inner edge of the final stage stator vane 16f in the wing height direction satisfies the above equation (a).

[0020] Here, the effects obtained by satisfying the above equation (a) will be explained using Figures 5A to 5C and Figure 6. Figures 5A to 5C show the velocity distribution on the negative pressure surface 46 of the outlet guide vane 20 for several comparative configurations. Figure 5A shows the case where the ratio Dmin / C in the cross section perpendicular to the vane height direction at position Pm belonging to the central part 16fm is 0.056. Figure 5B shows the case where the ratio Dmin / C in the cross section at position Pm belonging to the central part 16fm is 0.066. Figure 5C shows the case where the ratio Dmin / C in the cross section at position Pm belonging to the central part 16fm is 0.069. Figure 6 shows the velocity distribution on the negative pressure surface 46 of the outlet guide vane 20 in one embodiment. Figure 6 shows the case where the ratio Dmin / C in the cross section at position Pm belonging to the central part 16fm is 0.11.

[0021] In the comparative configuration shown in Figure 5A, flow separation occurs in the area S near the outer edge 20o in the blade height direction on the negative pressure surface 46 of the outlet guide vane 20. According to the inventors' findings, such separation on the negative pressure surface 46 of the outlet guide vane 20 is caused by wakes (vortices) generated from the trailing edge 32 of the final stage stator vane 16f interfering with the outlet guide vane 20, leading to a decrease in the performance of the axial flow compressor 2. Furthermore, as shown in Figures 5A to 5C, as the ratio Dmin / C decreases, the area S of separation on the negative pressure surface 46 of the outlet guide vane 20 shrinks, and in the embodiment shown in Figure 6, it can be seen that no flow separation occurs on the negative pressure surface 46 of the outlet guide vane 20.

[0022] As a result of diligent research by the inventors of this application, it has been found that when the ratio Dmin / C satisfies equation (a) over the entire range in the blade height direction of the final stage stator vane 16f, the distance between the wake (vortex) generated from the trailing edge 32 of the final stage stator vane 16f and the outlet guide vane is appropriately secured, preventing the wake from interfering with the outlet guide vane 20. Compared to the comparative configuration shown in Figures 5A to 5C, separation at the negative pressure surface 46 of the outlet guide vane 20 can be suppressed. Therefore, when the ratio Dmin / C satisfies equation (a) over the entire range in the blade height direction of the final stage stator vane 16f, the performance degradation of the axial flow compressor 2 caused by the wake generated from the trailing edge 32 of the final stage stator vane 16f interfering with the outlet guide vane 20 can be suppressed.

[0023] In some embodiments, if the shortest distance Dmin in the cross-section shown in Figure 2 (cross-section at position Po, which belongs to the outer end 16fo in the blade height direction of the final stage stator vane 16f) is Dmino, the shortest distance Dmin in the cross-section shown in Figure 3 (cross-section at position Pm, which belongs to the central part 16fm in the blade height direction of the final stage stator vane 16f) is Dminm, and the shortest distance Dmin in the cross-section shown in Figure 4 (cross-section at position Pi, which belongs to the inner end 16fi in the blade height direction of the final stage stator vane 16f) is Dmini, then the final stage stator vane 16f and the exit guide vane 20 are configured to satisfy the following equation (b). Dmino <Dminm<Dmini …(b)

[0024] If the outlet guide vane 20 has a twisted shape such that the shortest distance Dmin decreases as it moves outward in the blade height direction, then equation (b) above will be satisfied. However, in such a case, the shortest distance Dmino tends to decrease, and as shown in Figure 5A, the above separation is more likely to occur near the outer end 20o of the outlet guide vane 20 in the blade height direction. Even in such a case, by satisfying equation (a) above over the entire range in the blade height direction of the final stage stator vane 16f, it is possible to suppress the performance degradation of the axial flow compressor 2 caused by wakes generated from the trailing edge 32 of the final stage stator vane 16f interfering with the outlet guide vane 20.

[0025] In some embodiments, if the chord length C of the exit guide vane 20 in the cross-section shown in Figure 2 (cross-section at position Po, which belongs to the outer end 16fo in the blade height direction of the final stage stator vane 16f) is Co, the chord length C of the exit guide vane 20 in the cross-section shown in Figure 3 (cross-section at position Pm, which belongs to the central part 16fm in the blade height direction of the final stage stator vane 16f) is Cm, and the chord length C of the exit guide vane 20 in the cross-section shown in Figure 4 (cross-section at position Pi, which belongs to the inner end 16fi in the blade height direction of the final stage stator vane 16f) is Ci, then the final stage stator vane 16f and the exit guide vane 20 are configured to satisfy the following equation (c). Cm <Ci<Co …(c)

[0026] Even in such cases, by satisfying equation (a) over the entire range in the blade height direction of the final stage stator vane 16f, it is possible to suppress the performance degradation of the axial flow compressor 2 caused by wakes generated from the trailing edge 32 of the final stage stator vane 16f interfering with the outlet guide vane 20.

[0027] In some embodiments, if the ratio Dmin / C in the cross-section shown in Figure 2 (cross-section at position Po, which belongs to the outer end 16fo in the blade height direction of the final stage stator vane 16f) is Eo, the ratio Dmin / C in the cross-section shown in Figure 3 (cross-section at position Pm, which belongs to the central part 16fm in the blade height direction of the final stage stator vane 16f) is Em, and the ratio Dmin / C in the cross-section shown in Figure 4 (cross-section at position Pi, which belongs to the inner end 16fi in the blade height direction of the final stage stator vane 16f) is Ei, then the final stage stator vane 16f and the exit guide vane 20 are configured to satisfy the following equation (d). Eo <Em<Ei …(d)

[0028] When equation (d) above is satisfied, the above-mentioned separation may easily occur near the outer edge 20o in the blade height direction of the outlet guide vane 20. Even in such cases, by satisfying equation (a) above over the entire range in the blade height direction of the final stage stator vane 16f, it is possible to suppress the performance degradation of the axial flow compressor 2 caused by wakes generated from the trailing edge 32 of the final stage stator vane 16f interfering with the outlet guide vane 20.

[0029] This disclosure is not limited to the embodiments described above, but also includes modified forms of the embodiments described above, as well as forms that combine these forms as appropriate.

[0030] For example, in some embodiments, the final stage stator vane 16f and the exit guide vane 20 may be configured to satisfy the above equation (e). 0.09 ≤ Dmin / C ≤ 0.18 …(e) Even in this case, it is possible to suppress the performance degradation of the axial compressor 2 caused by wakes generated from the trailing edge 32 of the final stage stationary vane 16f interfering with the outlet guide vane 20.

[0031] The contents described in each of the above embodiments can be understood, for example, as follows:

[0032] [1] An axial flow compressor according to at least one embodiment of the present disclosure is An axial flow compressor for compressing a fluid (for example, the axial flow compressor 2 described above), The final stage stator vane (for example, the final stage stator vane 16f mentioned above), An outlet guide vane (for example, the outlet guide vane 20 described above) is provided downstream of the final stage stator vane in the direction of the fluid flow, Equipped with, In a cross-section perpendicular to the wing height direction of the final stage stator vane, the straight line extending from the trailing edge of the final stage stator vane along the camber line (e.g., the camber line Lc described above) is called the camber line extension (e.g., the camber line extension Le described above), and the shortest distance between the camber line extension and the negative pressure surface of the exit guide vane is Dmim, and the chord length of the exit guide vane is C. Then, the final stage stator vane and the exit guide vane satisfy the following equation (a) over the entire range in the wing height direction of the final stage stator vane. 0.07 ≤ Dmin / C ≤ 0.20 …(a)

[0033] According to the axial flow compressor described in [1] above, it is possible to appropriately ensure the distance between the wake (vortex) generated from the trailing edge of the final stage stator vane and the outlet guide vane, thereby suppressing interference between the wake and the outlet guide vane. As a result, separation on the negative pressure surface of the outlet guide vane can be suppressed, and thus the performance degradation of the axial flow compressor caused by the wake generated from the trailing edge of the final stage stator vane interfering with the outlet guide vane can be suppressed.

[0034] [2] In some embodiments, in the axial flow compressor described in [1] above, If Dmino is the shortest distance in the cross-section at a first position (e.g., position Po) belonging to the outer end (e.g., end 16fo) of the final stage stator vane in the wing height direction, Dminm is the shortest distance in the cross-section at a second position (e.g., position Pm) belonging to the central part (e.g., central part 16fm) of the final stage stator vane in the wing height direction, and Dmini is the shortest distance in the cross-section at a third position (e.g., position Pi) belonging to the inner end (e.g., end 16fi) of the final stage stator vane in the wing height direction, then the final stage stator vane and the exit guide vane satisfy the following equation (b). Dmino <Dminm<Dmini …(b)

[0035] If the outlet guide vane has a twisted shape such that the shortest distance Dmin decreases as it moves outward in the blade height direction, then equation (b) will be satisfied as described in [2] above. However, in such a case, the shortest distance Dmino tends to decrease, making it easier for the separation described above to occur near the outer edge of the outlet guide vane in the blade height direction. Even in such a case, by satisfying equation (a) over the entire range in the blade height direction of the final stage stator vane, it is possible to suppress the performance degradation of the axial flow compressor caused by wakes generated from the trailing edge of the final stage stator vane interfering with the outlet guide vane.

[0036] [3] In some embodiments, in the axial flow compressor described in [1] or [2] above, If Co is the length of the chord in the cross-section at a first position (e.g., position Po) belonging to the outer end (e.g., end 16fo) of the final stage stator vane in the wing height direction, Cm is the length of the chord in the cross-section at a second position (e.g., position Pm) belonging to the central part (e.g., central part 16fm) of the final stage stator vane in the wing height direction, and Ci is the length of the chord in the cross-section at a third position (e.g., position Pi) belonging to the inner end (e.g., end 16fi) of the final stage stator vane in the wing height direction, then the final stage stator vane and the exit guide vane satisfy the following equation (c). Cm <Ci<Co …(c)

[0037] Even in such cases, by satisfying equation (a) over the entire range in the blade height direction of the final stage stator vane, it is possible to suppress the performance degradation of the axial flow compressor caused by wakes generated from the trailing edge of the final stage stator vane interfering with the outlet guide vane.

[0038] [4] In some embodiments, in the axial flow compressor described in any of [1] to [3] above, If we let Eo be the ratio Dmin / C in the cross-section at a first position (e.g., position Po) belonging to the outer end (e.g., end 16fo) of the final stage stator vane in the wing height direction, Em be the ratio Dmin / C in the cross-section at a second position (e.g., position Pm) belonging to the central part (e.g., central part 16fm) of the final stage stator vane in the wing height direction, and Ei be the ratio Dmin / C at a third position (e.g., position Pi) belonging to the inner end (e.g., end 16fi) of the final stage stator vane in the wing height direction, then the final stage stator vane and the exit guide vane satisfy the following equation (d). Eo <Em<Ei …(d)

[0039] When equation (d) above is satisfied, the above-mentioned separation may be more likely to occur near the outer edge in the blade height direction of the outlet guide vane. However, even in such cases, by satisfying equation (a) above over the entire range in the blade height direction of the final stage stator vane, it is possible to suppress the performance degradation of the axial flow compressor caused by wakes generated from the trailing edge of the final stage stator vane interfering with the outlet guide vane.

[0040] [5] In some embodiments, in the axial flow compressor described in any of [1] to [4] above, The final stage stator vane and the exit guide vane satisfy the following equation (e) over the entire range in the blade height direction of the final stage stator vane. 0.09 ≤ Dmin / C ≤ 0.18 …(e)

[0041] According to the axial flow compressor described in [5] above, it is possible to suppress the performance degradation of the axial flow compressor caused by wakes generated from the trailing edge of the final stage stator vane interfering with the outlet guide vane. [Explanation of symbols]

[0042] 2-axis flow compressor 4 rotors 6. Casing 7 channels 8 rotation axes 10 Moving blade row 12 Moving blade 14 Stationary Wings 14f final stage stator blade row 16 Static Wings 16f final stage stationary blade 16fi,16fo,20o end 18 paragraphs 18f Final paragraph 20 Exit Guide Wing 36,46 suction surface 30,40 leading edge 32,42 Trailing edge 34,44 Pressure surface 46 Suction surface C, Co, Cm, Ci Code Length Dmin,Dmino,Dminm,Dmini Shortest distance Lc Camber Line Le camber line extension Lt tangent Pi,Pm,Po position S range

Claims

1. An axial flow compressor for compressing fluids, The final stage stator wing, An outlet guide vane provided downstream of the final stage stator vane in the fluid flow direction, Equipped with, In a cross-section perpendicular to the blade height direction of the final stage stator vane, the straight line extending from the trailing edge of the final stage stator vane along the camber line is called the camber line extension, and the shortest distance between the camber line extension and the negative pressure surface of the outlet guide vane is Dmin, and the chord length of the outlet guide vane is C. Thus, the final stage stator vane and the outlet guide vane satisfy the following equation (a) over the entire range in the blade height direction of the final stage stator vane, in an axial flow compressor. 0.07≦Dmin / C≦0.20…(a)

2. The axial flow compressor according to claim 1, wherein the final stage stator vane and the outlet guide vane satisfy the following equation (b), where Dmino is the shortest distance in the cross-section at a first position belonging to the outer end of the final stage stator vane in the direction of the vane height, Dminm is the shortest distance in the cross-section at a second position belonging to the central part of the final stage stator vane in the direction of the vane height, and Dmini is the shortest distance in the cross-section at a third position belonging to the inner end of the final stage stator vane in the direction of the vane height. Dmino<Dminm<Dmini…(b)

3. The axial flow compressor according to claim 1, wherein the final stage stator vane and the outlet guide vane satisfy the following formula (c), where Co is the length of the chord in the cross-section at a first position belonging to the outer end of the final stage stator vane in the direction of the vane height, Cm is the length of the chord in the cross-section at a second position belonging to the central part of the final stage stator vane in the direction of the vane height, and Ci is the length of the chord in the cross-section at a third position belonging to the inner end of the final stage stator vane in the direction of the vane height. Cm<Ci<Co...(c)

4. The axial flow compressor according to claim 1, wherein the final stage stator vane and the outlet guide vane satisfy the following equation (d), where Eo is the ratio Dmin / C in the cross-section at a first position belonging to the outer end of the final stage stator vane in the direction of the vane height, Em is the ratio Dmin / C in the cross-section at a second position belonging to the central part of the final stage stator vane in the direction of the vane height, and Ei is the ratio Dmin / C at a third position belonging to the inner end of the final stage stator vane in the direction of the vane height. Eo<Em<Ei...(d)

5. The axial flow compressor according to claim 1, wherein the final stage stator vane and the outlet guide vane satisfy the following formula (e) over the entire range in the blade height direction of the final stage stator vane. 0.09≦Dmin / C≦0.18...(e)

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