Axial flow turbomachinery

Abstract

To suppress the exfoliation of a boundary layer.SOLUTION: An axial flow type turbo machine comprises: a hub 31; a plurality of blades 33a protruding outward from the hub 31 in a radial direction; and even-number pieces of grooves g formed between the blades 33a which adjoin each other at a surface of the hub 31, or at least at a part of a region shifted to a blade root 33b at a negative pressure face SS of each blade 33a, in which each groove G extends along a flow direction FD of fluid.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to axial flow turbomachines. [Background technology]

[0002] Boundary layer separation can be a problem in turbomachinery. For this reason, various configurations have been proposed to suppress boundary layer separation. For example, Patent Document 1 discloses a centrifugal diffuser used in vacuum cleaners. This diffuser includes a shroud plate, a partition plate, and multiple diffuser vanes provided in a stationary flow passage between the shroud plate and the partition plate. Both ends of the diffuser vanes are fixed to the shroud plate and the partition plate. One or more recesses are formed in the partition plate between adjacent diffuser vanes. The recesses generate longitudinal vortices and reduce boundary layer separation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-32749 Summary of the Invention [Problem to be solved by the invention]

[0004] Among turbomachines, axial flow turbomachines can suffer from boundary layer separation around the hub. Therefore, it is desirable to propose a configuration for axial flow turbomachines that can suppress such boundary layer separation.

[0005] An object of the present disclosure is to provide an axial flow turbomachine that can suppress boundary layer separation. [Means for solving the problem]

[0006] In order to solve the above problem, an axial flow turbomachine according to one aspect of the present disclosure includes a hub and a plurality of rotors protruding radially outward from the hub. motionAdjacent to the wing on the surface of the hub motion Wings In between an even number of grooves formed, each groove extending along the direction of fluid flow; a plurality of stator vanes disposed downstream of the plurality of rotor blades; Equipped with Each groove extends to the surface of the hub just before the gap between the rotor blade and the stator blade. .

[0009] Axial flow turbomachines have adjacent rotors on the surface of the hub. motion The blade may further include at least one recess formed between the wings.

[0010] groove At least one of the grooves may be continuous with the recess.

[0011] In a cross section perpendicular to the direction of fluid flow, the even number of grooves may have different cross-sectional areas.

[0012] motion Grooves closer to the suction side of the airfoil may have a larger cross-sectional area.

[0013] The even number of grooves may have different lengths in the direction of fluid flow.

[0014] The even number of grooves may include four or more grooves.

[0015] each The grooves are arranged in the direction of fluid flow as follows: Each rotor blade The circumferentially adjacent motion The blade may be formed downstream of a line segment connecting the apex of the pressure surface and the apex of the suction surface of the blade.

[0016] Axial flow turbomachinery consists of It is formed in the area near the root of the blade on the suction surface of the blade. an even number of second grooves may be provided; each Second The groove may be formed downstream of the apex of the suction side in the direction of fluid flow. [Effects of the Invention]

[0017] According to the present disclosure, boundary layer separation can be suppressed. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a schematic cross-sectional view of an axial flow turbomachine according to an embodiment. [Figure 2] FIG. 2 is a schematic partial perspective view showing a part of the compressor. [Figure 3] FIG. 3 is a schematic partial cross-sectional view showing the rotor and blades. [Figure 4] FIG. 4 is a schematic cross-sectional view showing a rotor and blades. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Specific dimensions, materials, numerical values, etc. shown in the embodiments are merely examples for ease of understanding and do not limit the present disclosure unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation, and elements not directly related to the present disclosure are not shown.

[0020] 1 is a schematic cross-sectional view of an axial turbomachine 100 according to an embodiment. The axial turbomachine (hereinafter simply referred to as "turbomachine") 100 may be, for example, a turbofan engine, turbojet engine, turboprop engine, turboshaft engine, or turboramjet engine for an aircraft, a gas turbine for power generation, or a gas turbine for a ship. The turbomachine 100 is not limited to these, and may be another axial turbomachine.

[0021] The turbomachine 100 includes a fan 2, a compressor 3, a combustion chamber 4, a high-pressure turbine 5a, a low-pressure turbine 5b, an outer cowl 6a, and an inner cowl 6b.

[0022] The compressor 3 compresses the fluid, such as air, drawn in by the fan 2. The combustion chamber 4 burns a mixture of the compressed fluid and fuel. The high-pressure turbine 5a and the low-pressure turbine 5b each convert the pressure energy of the expanding combustion gas into rotational energy. The rotational energy from the high-pressure turbine 5a is transmitted via a shaft 7a to the rotor 31 of the compressor 3, causing the rotor 31 to rotate. The rotational energy from the low-pressure turbine 5b is transmitted via a shaft 7b within the shaft 7a to the fan 2, causing the fan 2 to rotate. The combustion gas is discharged to the outside through an exhaust duct 8.

[0023] The shafts 7a, 7b and the elements rotating therewith have a common central axial direction, radial directions, and circumferential directions. In this disclosure, the central axial directions, radial directions, and circumferential directions of the shafts 7a, 7b and these elements may be referred to simply as the "central axial direction," the "radial direction," and the "circumferential direction."

[0024] The compressor 3 includes a rotor (hub) 31, a plurality of stator blade rows 32, and a plurality of rotor blade rows 33. A fluid flow path is defined between the rotor 31 and the inner cowl 6b. The stator blade rows 32 and the rotor blade rows 33 are alternately arranged along the central axis direction within the flow path.

[0025] Each of the high-pressure turbine 5a and the low-pressure turbine 5b includes a rotor (hub) 51, a plurality of stator blade rows 52, and a plurality of rotor blade rows 53. A fluid flow path is defined between the rotor 51 and the inner cowl 6b. The stator blade rows 52 and rotor blade rows 53 are alternately arranged along the central axis direction within the flow path.

[0026] FIG. 2 is a schematic partial perspective view showing a portion of the compressor 3. For better understanding, FIG. 2 shows only a portion of the surface of the rotor 31 and three rotor blades 33a of one row of rotor blade row 33. Arrow FD indicates the direction of fluid flow. Each rotor blade row 33 includes a plurality of rotor blades 33a. The rotor blades 33a protrude radially outward from the rotor 31. The plurality of rotor blades 33a are arranged spaced apart from one another in the circumferential direction.

[0027] The rotor blade 33a includes a leading edge LE, a trailing edge TE, a pressure surface PS, and a suction surface SS. The rotor blade 33a also includes a blade root 33b. The blade root 33b is one end of the rotor blade 33a in the radial direction and is a connection portion between the rotor blade 33a and the rotor 31. Referring to FIG. 1, the rotor blade 33a also includes a blade tip 33c. The blade tip 33c is the other end of the rotor blade 33a in the radial direction and faces the inner circumferential surface of the inner cowl 6b.

[0028] 2, the suction surface SS includes a vertex 33d. The vertex 33d refers to the portion of the suction surface SS that protrudes most in the circumferential direction in a cross section perpendicular to the radial direction, i.e., in the airfoil.

[0029] The compressor 3 includes an even number of grooves g on the surface of the rotor 31. The even number of grooves g are formed between adjacent rotor blades 33a on the surface of the rotor 31. Note that although the grooves g are shown only between one pair of adjacent rotor blades 33a in FIG. 2, the grooves g may also be formed between other pairs.

[0030] In this embodiment, four grooves g are formed in the rotor 31. In other embodiments, two grooves g may be formed in the rotor 31, or six or more grooves g may be formed in the rotor 31 as long as the number of grooves g is an even number. The grooves g extend along the direction FD of fluid flow. For example, the width of the grooves g is generally uniform along the direction FD. In other embodiments, the width of the grooves g may vary along the direction FD.

[0031] The four grooves g on the rotor 31 have different lengths in the direction FD. Specifically, the grooves g closer to the suction surface SS of the rotor blade 33a have longer lengths. In other embodiments, the four grooves g may have equal lengths.

[0032] FIG. 3 is a schematic partial cross-sectional view showing the rotor 31 and the blades 33a, viewed from the radial direction. For better understanding, FIG. 3 shows only a portion of the surface of the rotor 31 and two blades 33a. As described above, the grooves g extend along the fluid flow direction FD. Therefore, the grooves g on the rotor 31 extend downstream from a line segment LS connecting the apex 33e of the pressure surface PS of the blade 33a adjacent in the circumferential direction facing the suction surface SS to the apex 33d of the suction surface SS, inclining toward the suction surface SS from the central axis. In other words, the grooves g do not extend upstream of the line segment LS in the direction FD. In other embodiments, the grooves g may extend upstream of the line segment LS.

[0033] The grooves g on the rotor 31 extend to just before the gap between the rotor blades 33 a and the stator blades (not shown) on the surface of the rotor 31. In other words, the grooves g do not extend to the gap between the rotor blades 33 a and the stator blades. In other embodiments, the grooves g may extend to the gap between the rotor blades 33 a and the stator blades.

[0034] 4 is a schematic cross-sectional view showing the rotor 31 and the moving blades 33a, and shows a cross section perpendicular to the fluid flow direction FD. Note that in FIG. 4, for better understanding, only a portion of the surface of the rotor 31 and two moving blades 33a are shown, and the surface of the rotor 31 is shown in a flat plane. Also, in FIG. 4, for better understanding, the size of the groove g may be exaggerated.

[0035] In a cross section perpendicular to the direction of fluid flow, the four grooves g on the rotor 31 have different cross-sectional areas. Specifically, the groove g closer to the suction surface SS of the rotor blade 33a has a larger cross-sectional area. In other embodiments, the four grooves g may have the same cross-sectional area.

[0036] Referring to Figure 2, the compressor 3 also includes an even number of grooves g on the suction surface SS of each rotor blade 33a. The grooves g are formed in a region on the suction surface SS closer to the blade root 33b. For example, the "region closer to the blade root 33b" can refer to the region between the blade root 33b and the midpoint of the length of the rotor blade 33a in the radial direction, i.e., the midpoint of the height of the rotor blade 33a. Note that although Figure 2 shows the grooves g on only one rotor blade 33a, the grooves g can also be formed on the other rotor blades 33a.

[0037] In this embodiment, four grooves g are formed on the suction surface SS. In other embodiments, two grooves g may be formed on the rotor blade 33a, or six or more grooves g may be formed on the rotor blade 33a as long as the number of grooves g is an even number. Each groove g extends along the fluid flow direction FD.

[0038] The four grooves g on the suction surface SS have approximately equal lengths in the direction FD. In other embodiments, the four grooves g may have different lengths. For example, the grooves g closer to the blade root 33b may have a longer length.

[0039] Groove g on suction surface SS is located downstream of apex 33d in direction FD. In other words, groove g does not extend upstream of apex 33d in direction FD. In other embodiments, groove g may extend upstream of apex 33d.

[0040] The grooves g on the suction surface SS extend to just before the trailing edge TE on the surface of the rotor 31. In other words, the grooves g do not reach the trailing edge TE. In other embodiments, the grooves g may reach the trailing edge TE.

[0041] 4, in a cross section perpendicular to the direction of fluid flow, the four grooves g on the suction surface SS have the same cross-sectional area. In other embodiments, the four grooves g may have different cross-sectional areas. For example, the grooves g closer to the blade root 33b may have a larger cross-sectional area.

[0042] The grooves g on the rotor 31 and the suction surface SS of the blades 33a can have various cross-sectional shapes. For example, the grooves g have a triangular cross-sectional shape. In other embodiments, the grooves g may have other cross-sectional shapes, such as a semicircular, square, rectangular, or trapezoidal shape.

[0043] The shape and dimensions of the grooves g may be determined based on an analysis such as computational fluid dynamics (CFD) so as to suppress boundary layer separation around the rotor 31 due to the longitudinal vortices V described below. For example, the grooves g may be formed by machining. Also, for example, the grooves g may be defined by scallops formed between adjacent tool paths when machining the rotor 31 and the rotor blades 33a. Specifically, such grooves g can be formed by roughly machining the area where the grooves g are intended to be formed. For example, an even number of grooves g may be defined by an odd number of protrusions, such as scallops.

[0044] Referring to FIG. 2 , the compressor 3 also includes a recess C on the surface of the rotor 31. At least one recess C is formed on the surface of the rotor 31 between adjacent rotor blades 33a. In this embodiment, the width of the recess C in the direction along the fluid flow direction FD is shorter than that of the groove g, and the width in the direction intersecting the fluid flow direction FD is also equal to the width along the fluid flow direction FD. The recess C can have various shapes. For example, the recess C has a hemispherical shape. In other embodiments, the recess C may have other shapes, such as a cylindrical shape. The diameter of the recess C is greater than the width of the groove g, i.e., the length of the groove g in the circumferential direction. For example, the recess C may have a depth greater than the depth of the groove g.

[0045] The recess C is connected to one groove g and is continuous with this groove g. For example, the recess C is connected to the groove g from the upstream side. In other embodiments, the recess C may be connected to multiple grooves g. Furthermore, in still other embodiments, the recess C may not be connected to the groove g or may be discontinuous with the groove g.

[0046] The shape and dimensions of the recess C may be determined based on an analysis such as computational fluid dynamics (CFD) to control the direction of the boundary layer so that the boundary layer is aligned with the rotor 31. Also, for example, the recess C may be formed based on US2017 / 0074101A1 filed by the same applicant as the present application, the contents of which are incorporated herein by reference.

[0047] Next, the function of the groove g will be explained.

[0048] Referring to Fig. 4, when a fluid passes through the space between the rotor blades, the boundary layer around the rotor may separate. However, in the present disclosure, the grooves g generate longitudinal vortices V with the fluid flow direction FD as the central axis. Larger grooves g generate larger longitudinal vortices V. Furthermore, longer grooves g generate longer longitudinal vortices V.

[0049] In the present disclosure, an even number of grooves g are formed between adjacent rotor blades 33a on the surface of the rotor 31. Therefore, a pair of adjacent grooves g generates a pair of longitudinal vortices V having opposite rotation directions.

[0050] For example, of the four grooves g on the rotor 31, the leftmost groove g generates a clockwise longitudinal vortex V, and the second groove g from the left generates a counterclockwise longitudinal vortex V. Therefore, these grooves g generate a pair of longitudinal vortices V having a rotational direction that draws the boundary layer between them. This pair of longitudinal vortices V suppresses separation of the boundary layer.

[0051] Similarly, of the four grooves g on the rotor 31, the rightmost groove g generates a counterclockwise longitudinal vortex V, and the second groove g from the right generates a clockwise longitudinal vortex V. Therefore, these grooves g also generate a pair of longitudinal vortices V having a rotation direction that draws the boundary layer between them. Therefore, the pair of longitudinal vortices V suppresses separation of the boundary layer.

[0052] The same applies to the four grooves g on the suction surface SS of the rotor blade 33a.

[0053] In some cases, the grooves g may generate longitudinal vortices V having a rotation direction opposite to that shown in Fig. 4. However, since four grooves g are formed on each of the rotor 31 and the suction surface SS, even in this case, the two middle grooves g generate a pair of longitudinal vortices V having a rotation direction that draws in the boundary layer between them.

[0054] Furthermore, the recessed portion C controls the direction of the boundary layer so that the boundary layer is aligned with the rotor 31. Therefore, separation and development of the boundary layer are further suppressed.

[0055] The turbomachine 100 described above includes a rotor 31, a plurality of blades 33a protruding radially outward from the rotor 31, and an even number of grooves g formed between adjacent blades 33a on the surface of the rotor 31 and in a region of the suction surface SS of each blade 33a near the blade root 33b. Each groove g extends along the fluid flow direction FD (therefore, each groove g does not include a portion that turns back from downstream to upstream along the extension direction). With this configuration, a pair of adjacent grooves g can generate a pair of longitudinal vortices V having a rotational direction that draws in the boundary layer between them. This makes it possible to suppress separation of the boundary layer around the rotor 31.

[0056] Furthermore, in the turbomachine 100, the grooves g are formed in an area around the rotating body, i.e., an area around the rotor 31 that rotates the rotor blades 33a. In axial flow turbomachines, boundary layer separation around the rotating body can be a problem. Therefore, with the above-described configuration, boundary layer separation around the rotating rotor 31 can be suppressed.

[0057] The turbomachine 100 further includes a plurality of stator vanes arranged downstream of the plurality of rotor blades 33a, and an even number of grooves g are formed between adjacent rotor blades 33a on the surface of the rotor 31, and each groove g extends to just before the gap between the rotor blade 33a and the stator vane on the surface of the rotor 31. The longitudinal vortices V formed by the grooves g may reduce the efficiency of the compressor 3 in the stator vane row 32. With the above configuration, the grooves g do not extend to the gap between the rotor blade row 33 and the stator vane row 32, so a reduction in the efficiency of the compressor 3 can be prevented.

[0058] The turbomachine 100 further includes at least one recess C formed between adjacent rotor blades 33a on the surface of the rotor 31. The recess C controls the direction of the boundary layer so that the boundary layer follows the rotor 31. Therefore, separation of the boundary layer can be further suppressed.

[0059] Furthermore, in the turbomachine 100, an even number of grooves g are formed between adjacent rotor blades 33a on the surface of the rotor 31, and at least one of the grooves g is continuous with the recessed portion C. With this configuration, the boundary layer can be continuously controlled by the recessed portion C and the grooves g. Therefore, separation of the boundary layer can be efficiently suppressed.

[0060] Furthermore, in the turbomachine 100, the even number of grooves g on the rotor 31 have different cross-sectional areas in a cross section perpendicular to the fluid flow direction FD. The boundary layer may be separated significantly depending on the position. According to the above configuration, the even number of grooves g having different cross-sectional areas can generate longitudinal vortices V of different sizes. Therefore, the size of the longitudinal vortices V can be adjusted depending on the position.

[0061] Furthermore, in the turbomachine 100, an even number of grooves g are formed between adjacent rotor blades 33a on the surface of the rotor 31, and the grooves g closer to the suction surface SS of the rotor blade 33a have larger cross-sectional areas. The boundary layer may separate significantly at positions closer to the suction surface SS. With the above-described configuration, a larger longitudinal vortex V can be generated at positions closer to the suction surface SS. Therefore, boundary layer separation can be efficiently suppressed.

[0062] Furthermore, in the turbomachine 100, the even number of grooves g on the rotor 31 have different lengths in the fluid flow direction FD. As described above, the boundary layer may be significantly separated depending on the position. According to the above configuration, the even number of grooves g having different lengths can generate longitudinal vortices V having different lengths. Therefore, the length of the longitudinal vortices V can be adjusted depending on the position.

[0063] Furthermore, in the turbomachine 100, the even number of grooves g on the rotor 31 includes four or more grooves g. With this configuration, at least one pair of grooves g always generates a pair of longitudinal vortices V having a rotational direction that draws the boundary layer between them. Therefore, boundary layer separation can be suppressed. Similarly, the even number of grooves g on the suction surface SS of the rotor blade 33a also includes four or more grooves g. Therefore, boundary layer separation can be suppressed.

[0064] Furthermore, in the turbomachine 100, the groove g on the rotor 31 is formed downstream of a line segment LS connecting the apex 33e of the pressure surface PS of the rotor blade 33a, which is circumferentially adjacent to the suction surface SS and faces the suction surface SS, in the fluid flow direction FD, to the apex 33d of the suction surface SS. Furthermore, the groove g on the rotor blade 33a is formed downstream of the apex 33d of the suction surface SS in the fluid flow direction FD. The boundary layer may significantly separate downstream of the apex 33d of the suction surface SS. With the above configuration, a longitudinal vortex V can be generated downstream of the apex 33d. Therefore, boundary layer separation can be efficiently suppressed.

[0065] Although the embodiments have been described above with reference to the accompanying drawings, the present disclosure is not limited to the above-described embodiments. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that such modifications also fall within the technical scope of the present disclosure.

[0066] For example, in the above embodiment, the grooves g are formed on both the rotor 31 and the suction surface SS of the blade 33a. In other embodiments, the grooves g may be formed on only one of the rotor 31 and the suction surface SS.

[0067] Also, in the above embodiment, the grooves g are formed in the rotor 31 and the moving blades 33a of the compressor 3. In other embodiments, additionally or alternatively, the grooves g may be formed in at least one of the rotor 51 or the moving blades in at least one of the high-pressure turbine 5a or the low-pressure turbine 5b.

[0068] The configuration according to the present disclosure may also be applied to a stator vane of an axial flow turbomachine. [Explanation of symbols]

[0069] 31 Rotor (hub) 33a Moving blade (wing) 33b Wing root 33d. Suction surface apex 100 Axial flow turbomachinery C recess FD Fluid flow direction g groove SS rotor blade suction surface

Claims

1. Hub and a plurality of rotor blades projecting radially outward from the hub; an even number of grooves formed on the surface of the hub between adjacent rotor blades, each groove extending along the direction of fluid flow; a plurality of stator vanes disposed downstream of the plurality of rotor blades; Equipped with Each groove extends on the surface of the hub to just before the gap between the rotor blade and the stator vane. Axial flow turbomachinery.

2. The axial turbomachine of claim 1 , further comprising at least one recess formed in a surface of the hub between adjacent rotor blades.

3. An axial flow turbomachine as described in claim 2, wherein at least one of the grooves is continuous with the recess.

4. The axial flow turbomachine according to claim 1 , wherein the even number of grooves have mutually different cross-sectional areas in a cross section perpendicular to the direction of the fluid flow.

5. An axial flow turbomachine as described in claim 4, wherein the groove closer to the negative pressure surface of the blade has a larger cross-sectional area.

6. The axial turbomachine according to claim 1 , wherein the even number of grooves have different lengths in the direction of fluid flow.

7. The axial turbomachine of claim 1 , wherein the even number of grooves includes four or more grooves.

8. An axial flow turbomachine described in any one of claims 1 to 7, wherein each groove is formed downstream of a line segment connecting the apex of the negative pressure surface of a circumferentially adjacent blade facing the negative pressure surface of each blade in the direction of flow of the fluid and the apex of the negative pressure surface of the blade.

9. Further comprising an even number of second grooves formed in a region near the blade root on the negative pressure surface of each moving blade; The axial turbomachine according to claim 1 , wherein each second groove is formed downstream of a peak on the suction surface in the direction of fluid flow.

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