JP2014118916A - Rotating machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To further surely suppress a rotating stall, and to enlarge a working area.SOLUTION: This rotating machine comprises: a cylindrical casing 20; a rotating shaft 10 rotatably arranged in the casing 20; a plurality of vanes 12 which are arranged in a flow passage 29 between the rotating shaft 10 and the casing 20 in the circumferential direction around the rotating shaft 10; and a suppression part 40A which is arranged at the internal peripheral face 20a of the casing 20 or the external peripheral face of the rotating shaft 10 at the upstream side of the flow direction of a fluid in the flow passage 29 rather than front edges 12a of the vanes 12 so as to be relatively rotatable with respect to the vanes 12, and suppresses the growth of a swirl formed in the vicinity of the front edges 12a of the vanes 12.

Description

  The present invention relates to a rotary machine such as an axial compressor and a centrifugal compressor.

  In order to compress a fluid, an axial compressor and a centrifugal compressor (hereinafter simply referred to as a compressor) having an impeller that swirls the fluid in a casing are known. In these compressors, when the flow rate is decreased while the rotation speed of the compressor is kept constant, a phenomenon called rotation stall may occur. The turning stall is a phenomenon in which a local stall region generated in the casing propagates in the circumferential direction at a speed different from the rotational speed of the impeller.

When this rotating stall occurs, the performance of the compressor is significantly lowered, and the intermittent vibration stress is applied to the blades, which may impair the durability of the compressor. Further, if the flow rate is further reduced after the occurrence of the rotating stall, a flow pulsation (surging) with strong sound occurs, and the operating limit of the compressor is reached.
For this reason, in order to expand the operating range in which the compressor operates stably, it is necessary to suppress the occurrence of turning stall and surge.

As a means for suppressing the occurrence of swirling stall and surge, it is known to form a groove for forming a recirculation flow in a casing portion having a blade row. As a result, the fluid compressed in the blade row and in the high pressure region is recirculated through the groove to the low pressure flow region and ejected, thereby suppressing the occurrence of stall and growth in the stall region. .
In addition, a method of suppressing the occurrence of stall by increasing the axial flow speed upstream of the bleed point by bleeding (bleeding) a part of the fluid in the casing when stall occurs.

Patent Document 1 discloses a configuration in which an operating region of a compressor is expanded by providing a suction ring groove in a circular arc shape for recirculating a part of a fluid from a high pressure region to a low pressure region.
Patent Document 2 discloses a configuration in which the extraction port is provided asymmetrically in the circumferential direction of the casing, thereby disturbing the pattern in which the stall region turns to suppress the development of turning stall.

International Publication No. 2011/099416 JP 2008-111435 A

However, in the rotary machine including the compressor, it is always required to more effectively suppress the rotating stall and expand the operation range.
The present invention has been made in view of such a problem, and an object of the present invention is to provide a rotating machine that can more effectively suppress the turning stall and expand the operating range.

The present invention employs the following means in order to solve the above problems.
That is, the rotating machine of the present invention includes a cylindrical casing, a rotating shaft rotatably provided in the casing, a flow path between the rotating shaft and the casing, and around the rotating shaft. A plurality of blades arranged in the circumferential direction, and provided on the inner peripheral surface of the casing or the outer peripheral surface of the rotating shaft on the upstream side in the flow direction of the fluid in the flow path from the leading edge of the blades. And a suppressor that rotates relative to the blade and suppresses the growth of the vortex of the fluid formed on the leading edge side of the blade.

  Providing the suppression portion on the upstream side in the flow direction with respect to the front edge of the blade can suppress the fluid vortex formed near the front edge of the blade due to the rotating stall from growing upstream in the flow direction.

  A plurality of the restraining portions are provided in the circumferential direction of the rotating shaft, and at least one of the plurality of restraining portions has a height in the radial direction of the rotating shaft relative to the other restraining portions, and a circumferential direction of the rotating shaft. May be formed such that at least one of the length, the shape, and the interval between the adjacent other suppression portions is different.

  Thereby, the disturbance pattern which cancels the disturbance wave of the flow at the time of turning stall generation | occurrence | production can be produced, and generation | occurrence | production of turning stall can be suppressed effectively. Furthermore, it can be avoided that the generation period (frequency) of the turbulent wave due to the installation of the suppression unit coincides with or is close to the swirl period (frequency) of the vortex.

  A plurality of the suppressing portions may be provided in the circumferential direction of the rotating shaft, and the number of the suppressing portions in the circumferential direction and the number of the blades in the circumferential direction may be relatively prime.

  Thereby, it is possible to avoid resonance between the circumferential row of the suppression portions and the circumferential row of the blades, and to reduce blade vibration increase and noise generation.

The suppressing portion may have a protrusion protruding into the flow path from the inner peripheral surface of the casing or the outer peripheral surface of the rotating shaft.
By the protrusions striking the fluid vortex, the growth of the vortex can be suppressed.

  The protrusion may have a variable projecting dimension into the flow path or a circumferential length in the flow path.

  Under operating conditions where vortices do not occur, energy loss (pressure loss) due to the installation of the protrusions can be suppressed by keeping the protrusions small.

  The protrusion may be formed such that the height in the radial direction of the rotation shaft gradually increases from the upstream side to the downstream side in the fluid flow direction in the flow path.

  Since the height of the protrusion on the upstream side in the fluid flow direction is small, generation of a stagnation region of the fluid flow can be suppressed, and energy loss (pressure loss) due to the installation of the protrusion can be reduced.

The suppressing portion is formed on the inner peripheral surface of the casing or the outer peripheral surface of the rotating shaft, and forms a circulating flow that circulates a part of the fluid flowing in the flow path upstream in the flow direction. It is good also as a thing which has a recessed part which makes a vortex collide.
Vortex growth can be suppressed by the circulating flow formed by the recesses.

  The blade may include a moving blade attached to the outer peripheral surface of the rotating shaft, and the suppressing portion may be provided on the inner peripheral surface of the casing.

  Further, the blade may include a stationary blade attached to the outer peripheral surface of the casing, and the suppressing portion may be provided on the outer peripheral surface of the rotating shaft.

  According to the present invention, it is possible to more reliably suppress the turning stall and expand the operation region.

It is sectional drawing of the axial flow compressor concerning embodiment of this invention. It is a figure which shows the front edge part of the moving blade provided with the protrusion in 1st Embodiment in the upstream, Comprising: (a) is sectional side view, (b) is AA sectional drawing of (a). (A) is a diagram schematically showing how the separation vortex grows upstream in the fluid flow direction when no protrusion is provided, and (b) suppresses the growth of the separation vortex when the protrusion is provided. It is a figure which shows a mode that it does. It is a model figure which shows the peeling vortex which generate | occur | produced in the front edge of the wing | blade. It is a figure which shows a mode that a peeling vortex breaks by a processus | protrusion, (a) is a figure which shows the state before a separation vortex collides with a processus | protrusion, (b) shows the state where the release vortex collides with a processus | protrusion. FIG. 4C is a diagram showing a state in which the separation vortex is broken and disappears by collision with the protrusion. It is the figure which showed typically the pressure fluctuation waveform measured on a casing surface, (a) is a figure which shows a mode that the turning stall which is a self-excited vibration of a flow field develops, when a protrusion is not provided. (B) is the figure which showed typically a mode that the development of the rotation stall which is a self-excited vibration was suppressed, while the forced vibration disturbance wave was added with respect to a flow field by providing a protrusion. It is. It is a figure which shows the difference in an operation area | region by the presence or absence of a processus | protrusion. It is a figure which shows the modification of 1st Embodiment, and is a figure which shows the front edge part of the stationary blade provided with the protrusion in the upstream, Comprising: (a) is a sectional side view, (b) is a figure of (a). It is AA sectional drawing. It is a figure which shows the modification of 1st Embodiment, (a) is a sectional side view of the protrusion which suppressed the protrusion height of the upstream, (b)-(f) shows the example of various shapes of protrusion. It is a perspective view. It is a figure which shows the example of the further another shape of the protrusion which suppressed the protrusion height of the upstream. It is sectional drawing which shows the front edge part of the moving blade provided with the protrusion in 2nd Embodiment in the upstream. It is sectional drawing which shows the processus | protrusion provided in the circumferential direction at the unequal space | interval in the modification of 2nd Embodiment. It is a figure which shows the further another modification of 2nd Embodiment, (a) is sectional drawing which shows the several protrusion which varied height, (b) is a cross section which shows the several protrusion which varied shape FIG. It is a figure which shows the front edge part of the moving blade provided with the protrusion in 3rd Embodiment in the upstream, Comprising: (a) is sectional drawing, (b) is a perspective view of protrusion. It is a figure which shows the front edge part of the moving blade provided with the protrusion in the modification of 3rd Embodiment in the upstream, Comprising: (a) is sectional drawing, (b) is a perspective view of protrusion. It is a figure which shows the front edge part of the moving blade provided with the protrusion in 4th Embodiment in the upstream, Comprising: (a) is sectional drawing, (b), (c) is an example of the some shape of protrusion. . It is a figure which shows the front edge part of the moving blade provided with the recessed part in the upstream in 5th Embodiment, (a) is sectional side view, (b) is AA sectional drawing of (a). It is a figure which shows the front edge part of the moving blade provided with the recessed part and convex part in the modification of 5th Embodiment in the upstream, Comprising: (a) is a sectional side view, (b) is A- of (a). It is A sectional drawing. It is a figure which shows the front edge part of the moving blade provided with the recessed part and convex part in the modification of 5th Embodiment in the upstream, Comprising: (a) is a sectional side view, (b) is A- of (a). It is A sectional drawing. In the structure of FIG. 19, it is a figure which shows typically a mode that the growth of peeling vortex is suppressed by the recirculation flow in a recessed part.

(First embodiment)
Hereinafter, a first embodiment of a rotating machine according to the present invention will be described.
As shown in FIG. 1, an axial compressor (rotary machine) 1 includes a rotor (rotary shaft) 10 having a plurality of moving blades 12 and a plurality of annular compressors arranged at intervals on the outer peripheral side of the rotor 10. , A plurality of moving blades 12 and a stationary blade holding casing (casing) 20 that covers the plurality of stationary blades 16, and a housing that covers the outer peripheral side of the stationary blade holding casing 20 and rotatably supports the rotor 10. 26.

  The rotor 10 includes a rotor body 11 that is supported by a housing 26 so as to be rotatable about a central axis Ar, and a plurality of blades 12 that are provided on the outer peripheral surface of the rotor body 11. The rotor body 11 has shaft portions 11a and 11b that are rotatably supported by the housing 26 at both ends in the direction along the central axis Ar, and regions between the shaft portions 11a and 11b are shaft portions 11a and 11b. The hub portion 11c has a larger outer diameter. The hub portion 11c of the rotor body 11 is configured by laminating a plurality of disk-shaped rotor disks in the direction of the central axis Ar.

  On the outer peripheral surface of each rotor disk forming the hub portion 11c of the rotor body 11, a plurality of moving blades 12 are provided at regular intervals in the circumferential direction, so that a moving blade row 13 is formed. The rotor 10 is provided with a plurality of blade rows 13, 13,... Along the central axis Ar direction by stacking a plurality of rotor disks having such blade rows 13 in the central axis Ar direction. It has a multistage rotor blade configuration. Here, the moving blade rows 13 and 13 that are moved back and forth in the direction of the central axis Ar are arranged at a predetermined interval.

  A cylindrical stationary blade holding casing 20 is provided as a part of the housing 26 on the outer peripheral side of these blade rows 13, 13,. On the inner peripheral surface 20a of the stationary blade holding casing 20, a plurality of stationary blades 16 are annularly arranged in the region facing the hub portion 11c at regular intervals along the circumferential direction of the stationary blade holding casing 20. . A stationary blade row 18 is formed by the annularly disposed stationary blades 16. Such a stationary blade row 18 is provided on the inner peripheral surface 20a of the stationary blade holding casing 20 in multiple stages along the central axis Ar direction. Here, each stationary blade row 18 is disposed so as to be positioned between the moving blade rows 13 and 13 that are front and rear of each other on the outer peripheral surface of the rotor 10.

  On the outer peripheral side of the shaft portions 11a and 11b of the rotor body 11, there are provided flow path forming members 22 and 23 whose outer diameters gradually increase as the distance from the hub portion 11c increases along the direction of the central axis Ar. The stationary blade holding casing 20 is opposed to the outer peripheral sides of the flow path forming members 22 and 23 with a space therebetween, so that the diffuser portion 24, between the flow path forming members 22 and 23 and the stationary blade holding casing 20 is provided. 25 is formed.

  In the housing 26, volute portions 27 and 28 formed in a spiral shape around the axis of the rotor 10 are formed on the outer peripheral side of the diffuser portions 24 and 25. A suction port 27a for sucking fluid is formed in the volute portion 27 on one end side in the central axis Ar direction, and a discharge port 28a is formed in the volute portion 28 on the other end side.

  In such an axial flow compressor 1, when the rotor 10 is rotated around the central axis by a drive source such as a motor, fluid is sucked into the housing 26 from the suction port 27 a and passes through the volute part 27 and the diffuser part 24. Then, it flows into a flow passage 29 having an annular cross section formed between the inner peripheral surface 20 a of the stationary blade holding casing 20 and the outer peripheral surface of the hub portion 11 c of the rotor 10. In the flow path 29, the fluid is compressed by the multistage moving blade row 13 and the stationary blade row 18. The compressed fluid is discharged to the outside from the discharge port 28a through the diffuser portion 25 and the volute portion 28.

  Here, in the axial flow compressor 1 of the present embodiment, as shown in FIG. 2, a protrusion (inhibiting portion) 40 </ b> A on the upstream side in the fluid flow direction in the stationary blade holding casing 20 with respect to the moving blade row 13. Is provided. The protrusion 40 </ b> A is formed on the inner peripheral surface 20 a of the stationary blade holding casing 20 so as to be positioned close to the upstream side of the front edge 13 a of the moving blade row 13.

  One or more such protrusions 40A are formed on the inner circumferential surface 20a of the stationary blade holding casing 20 in the circumferential direction, and preferably a plurality of projections 40A are spaced apart in the circumferential direction. These protrusions 40A preferably have a protrusion height from the inner peripheral surface 20a of 30% or less of the height of the rotor blade 12. The number of protrusions 40A in the circumferential direction should be a prime relationship (a relationship not having a common divisor other than 1) with respect to the number of blades 12 constituting the blade row 13. preferable.

According to the configuration as described above, when the rotor 10 is rotated, the leading edge of each blade 12 constituting the blade row 13 as shown in FIG. The separation vortex S generated by the rotating stall at 12a grows from the vicinity of the leading edge 12a of the moving blade 12 toward the upstream side in the fluid flow direction (left side in FIG. 3A).
At this time, as shown in FIG. 4, the separation vortex S rotates at a peripheral speed different from the peripheral speed of the moving blade 12 together with the moving blade 12 rotating together with the rotor 10. As shown in FIGS. 3B and 5, when the separation vortex S collides with the protrusion 40A during this turning, the separation vortex S is broken and its growth is forcibly suppressed.

Further, due to the influence of the installed protrusions 40A, peeling according to the installation interval in the size / circumferential direction of the protrusions 40A occurs in a forced vibration manner. FIG. 6 (a) shows that, when the projection 40A is not provided, in the flow path 29 between the inner peripheral surface 20a of the stationary blade holding casing 20 and the outer peripheral surface 11d of the hub portion 11c, a turning stall that is a self-excited vibration occurs. It shows how it develops. On the other hand, as shown in FIG. 6B, the outer peripheral surface of the inner peripheral surface 20a of the stationary blade holding casing 20 and the outer periphery of the hub portion 11c is caused by a synchronization phenomenon (lock-in phenomenon) of disturbance waves caused by the separation at the protrusion 40A. The development of the rotation stall, which is the self-excited vibration of the flow field between the surface 11d, is suppressed.
In this way, as shown in FIG. 7, it becomes difficult for rotation stall and surge to occur even in a low flow rate region, and the operating range of the axial compressor 1 can be expanded.

  Here, by setting the number of protrusions 40A in the circumferential direction to be relatively prime with respect to the number of moving blades 12 constituting the moving blade row 13, resonance with the moving blade row 13 is avoided and blade vibration increases. In addition, noise generation can be reduced.

(Modification of the first embodiment)
In this embodiment, the protrusion 40A may be provided on the front edge side of only one row of moving blade rows 13, but the protrusion 40A may be provided on the front edge side of the plurality of rows of moving blade rows 13 in the same manner.

Further, instead of the moving blade row 13, as shown in FIG. 8, a protrusion (suppressing portion) 40 </ b> B can be formed in the vicinity of the front edge 18 a of the stationary blade row 18. In this case, a protrusion 40B may be provided on the outer peripheral surface 11d of the hub portion 11c of the rotor 10 on the upstream side of the front edge 18a of the stationary blade row 18. As a result, the growth of the separation vortex S generated at the leading edge 16a of the stationary blade 16 constituting the stationary blade row 18 can be suppressed in the same manner as described above, and the same effect can be obtained.
Of course, the protrusions 40 </ b> A can be provided in the vicinity of the front edge 13 a of the moving blade row 13 and the front edge 18 a of the stationary blade row 18.

Furthermore, the number of the projections 40A and 40B with respect to one moving blade row 13 or the stationary blade row 18 and the interval between them, and the height and shape of the projections 40A and 40B may be anything.
For example, as illustrated in FIG. 9A, the protrusions (restricting portions) 40 </ b> C to 40 </ b> G are end portions 40 b that are close to the front edge 13 a of the moving blade row 13 on the downstream side from the upstream end portion 40 a in the fluid flow direction. The protrusion height (protrusion height in the radial direction of the rotor 10) from the inner peripheral surface 20a of the stationary blade holding casing 20 toward the flow field may be gradually increased.

Here, the cross-sectional shapes orthogonal to the central axis Ar direction of the protrusions 40C to 40G are a rectangular protrusion 40C (FIG. 9B) that is long in the circumferential direction, a trapezoid protrusion 40D (FIG. 9C), a triangle Shaped protrusion 40E (FIG. 9D), semicircular protrusion 40F (FIG. 9E), and rectangular protrusion 40G having a long side in the radial direction of the stationary blade holding casing 20 (FIG. 9F) ) Etc.
In addition to this, the protruding height from the end portion 40a toward the end portion 40b may be increased in a curved line including an arc shape in addition to increasing linearly.

According to these configurations, in the protrusions 40C to 40G, the protrusion height from the inner peripheral surface 20a of the stationary blade holding casing 20 toward the flow field at the upstream end 40a in the fluid flow direction is small. Generation | occurrence | production of the stagnation area | region of a flow can be suppressed and the energy loss (pressure loss) by installation of protrusion 40C-40G can be reduced.
Therefore, the axial flow compressor 1 provided with such protrusions 40C to 40G is less likely to cause rotational stall and surge even in the low flow rate region, as in the first embodiment. It is possible to suppress energy loss while exhibiting the operational effect that the operating range can be expanded.

  In the protrusions 40C to 40G, the protruding height from the inner peripheral surface 20a of the stationary blade holding casing 20 at the end 40a upstream in the fluid flow direction may be any height as long as it is smaller than the end 40b side. However, from the viewpoint of suppressing the occurrence of the stagnation region, it is preferable that the protruding height at the end portion 40a is 0 (zero).

  Furthermore, if the protrusion height from the inner peripheral surface 20a of the stationary blade holding casing 20 at the end 40a on the upstream side in the fluid flow direction is 0 (zero), as shown in FIG. (Suppressing part) 40H may be hemispherical. In addition, as shown in FIG. 10B, the protrusion (restraining part) 40I has a semicircular cross-sectional shape along the central axis Ar direction, and has a constant length in the circumferential direction of the stationary blade holding casing 20. It can also be a shape.

(Second Embodiment)
Next, a second embodiment of the rotating machine according to the present invention will be described. In the configuration of the present embodiment, the overall configuration of the axial compressor 1 is the same as that in the first embodiment. Therefore, in the following description, the description will focus on the configuration that is different from the first embodiment, and the description of the configuration that is common to the first embodiment will be omitted.

  In this embodiment, as shown in FIG. 11, a plurality of projections similar to those shown in the first embodiment, for example, a plurality of projections 40A are not provided at equal intervals in the circumferential direction, but at least one projection is provided. The two protrusions 40A are installed at unequal intervals so that the distance between the adjacent protrusions 40A is different from the distance between the other protrusions 40A and the adjacent protrusions 40A.

In this way, a plurality of protrusions 40A are provided with unequal intervals between the protrusions 40A, and the protrusions 40A are irregularly arranged in the circumferential direction, thereby canceling the disturbance wave of the flow when the turning stall occurs. And the occurrence of turning stall can be effectively suppressed.
Furthermore, it is possible to avoid that the generation period (frequency) of the disturbance wave due to the installation of the protrusion 40A coincides with or close to the turning period (frequency) of the separation vortex S. This prevents encouraging the growth of the turning stall.
Therefore, the operating range of the axial flow compressor 1 can be expanded more effectively.

(Modification of the second embodiment)
As shown in FIG. 12, in the plurality of protrusions 40A, the width w in which each protrusion 40A continues in the circumferential direction may be formed so that at least one protrusion 40A is different from the other protrusions 40A.
Furthermore, as shown in FIG. 13A, at least one of the plurality of protrusions 40A may be formed such that the height h of each protrusion 40A is different from the other protrusion 40A. Good.
In addition, as shown in FIG. 13B, the shape of at least one protrusion 40A among the plurality of protrusions 40A may be different from each other.

Also with these configurations, by arranging the protrusions 40A irregularly in the circumferential direction, it is possible to generate a turbulence pattern that cancels the disturbance wave of the flow at the time of turning stall occurrence, and to effectively suppress the turning stall occurrence.
Furthermore, it is possible to avoid that the generation period (frequency) of the disturbance wave due to the installation of the protrusion 40A coincides with or close to the turning period (frequency) of the separation vortex S. This prevents encouraging the growth of the turning stall.
Thereby, the operating range of the axial compressor 1 can be expanded more effectively.

(Third embodiment)
Next, a third embodiment of the rotating machine according to the present invention will be described. In the configuration of the present embodiment, the overall configuration of the axial compressor 1 is the same as that in the first embodiment. Therefore, in the following description, the description will focus on the configuration that is different from the first embodiment, and the description of the configuration that is common to the first embodiment will be omitted.

As shown in FIG. 14, in the present embodiment, the protrusion (suppressing portion) 40J is advanced and retracted in the radial direction of the rotor 10 by an actuator (not shown), so that the flow field enters the flow field from the inner peripheral surface 20a of the stationary blade holding casing 20. The projecting height toward is variable.
In such a configuration, at an operating point in a state where no turning stall occurs by a controller (not shown), the protrusion 40J does not protrude from the inner peripheral surface 20a of the stationary blade holding casing 20 into the flow field, and turning stall occurs. Project at the operating point.

  Thereby, in the state where the rotation stall does not occur, the occurrence of the stagnation region of the fluid flow in the flow field is suppressed and the generation of unnecessary pressure loss is suppressed. Further, in a state where the rotating stall occurs in the low flow rate region, the protrusion 40J is protruded to suppress the development of the rotating stall, and the operating range of the axial compressor 1 can be expanded.

  Also in this case, instead of the protrusion 40J, the protrusions 40A to 40I shown in the first to second embodiments and the modifications thereof can be employed.

(Modification of the third embodiment)
As shown in FIG. 15, the protrusion (suppressing portion) 40 </ b> K can be configured to include a fixed protrusion 41 and a slide protrusion 42. Here, the fixed protrusion 41 has a substantially fan shape having a certain length in the circumferential direction of the rotor 10. The slide protrusion 42 can be moved in the circumferential direction of the rotor 10 by an actuator or the like (not shown). Thereby, the protrusion 40K is between the state in which the slide protrusion 42 overlaps with the fixed protrusion 41 and the state in which the slide protrusion 42 protrudes in the circumferential direction of the fixed protrusion 41 by sliding from this state in the circumferential direction. The length in the circumferential direction is variable.

According to such a configuration, the circumferential length of the protrusion 40K is shortened in a state where the turning stall does not occur, and the circumferential length of the protrusion 40K is increased at the operating point where the turning stall occurs.
In this way, the occurrence of the stagnation region of the fluid flow in the flow field is reduced, and the occurrence of unnecessary pressure loss is suppressed. Further, in the state where the rotating stall occurs in the low flow rate region, the operating range of the axial flow compressor 1 can be expanded.

(Fourth embodiment)
Next, a fourth embodiment of the rotating machine according to the present invention will be described. In the following description, the description will be focused on the configuration different from the configuration shown in the first to third embodiments, and the description of the configuration common to the first to third embodiments will be omitted.
As shown in FIG. 16, in the axial compressor 1 according to the present embodiment, a recirculation flow path (recess) 50 is formed on the inner peripheral surface 20 a of the stationary blade holding casing 20 and in the vicinity of the front edge 13 a of the moving blade row 13. Is formed. In the recirculation flow path 50, the flow path inlet 51 opens to the downstream side in the fluid flow direction with respect to the front edge 13 a of the moving blade row 13, and the flow path outlet 52 extends to the front edge 13 a of the moving blade row 13. On the other hand, the opening is formed on the upstream side in the fluid flow direction.

  In such a recirculation flow path 50, a part of the fluid in the flow field is taken out from the flow path inlet 51 on the downstream side in the flow direction with respect to the leading edge 13 a of the moving blade row 13, and this is removed from the front of the moving blade row 13. It sends out into the flow field from the channel outlet 52 upstream of the edge 13a in the flow direction. As a result, a part of the fluid is circulated, whereby the apparent flow rate of the fluid in the vicinity of the leading edge 13a of the rotor blade row 13 can be increased, and the occurrence of the rotation stall and the growth of the separation vortex S can be suppressed. It can be done.

In the present embodiment, the protrusion 40J is provided on the inner peripheral surface 20a of the stationary blade holding casing 20 so as to cover the flow path outlet 52 of the recirculation flow path 50.
The protrusion 40J extends from the upstream end 40a in the fluid flow direction toward the end 40b adjacent to the front edge 13a of the rotor blade row 13 on the downstream side from the inner peripheral surface 20a of the stationary blade holding casing 20 into the flow field. The projecting height toward is gradually increased. As shown in FIGS. 16B and 16C, the protrusion 40J has a triangular or arcuate cross-sectional shape perpendicular to the central axis Ar.
A part of the protrusion 40J is provided so as to cover the flow path outlet 52, and an outflow concave portion 43 continuous with the flow path outlet 52 is formed on the flow path outlet 52 side so as to face the flow path outlet 52. Has been. The outflow recess 43 is formed such that its cross-sectional area gradually increases from the upstream side to the downstream side in the flow direction.

  According to such a configuration, a part of the fluid is circulated by the recirculation flow path 50, thereby increasing the apparent flow rate of the fluid in the vicinity of the leading edge 13 a of the moving blade row 13, thereby causing the rotation stall. While suppressing the growth of the separation vortex S, the protrusion 40J suppresses the development of the rotating stall in the low flow rate region, and the effect of expanding the operating range of the axial flow compressor 1 becomes even more remarkable.

  In this case, instead of the protrusion 40J, the protrusions 40A to 40K shown in the first to third embodiments and the modifications thereof can be employed.

(Fifth embodiment)
Next, a fifth embodiment of the rotating machine according to the present invention will be described. In the following description, the description will focus on the configuration different from the configuration shown in the first to fourth embodiments, and the description of the configuration common to the first to fourth embodiments will be omitted.
As shown in FIG. 17, in the axial flow compressor 1 of the present embodiment, a recess 60 is provided on the upstream side in the fluid flow direction with respect to the moving blade row 13. The concave portion 60 is formed on the inner peripheral surface 20 a of the stationary blade holding casing 20 so as to be positioned close to the upstream side of the front edge 13 a of the moving blade row 13.

  One or more such recesses 60 are formed on the inner peripheral surface 20a of the stationary blade holding casing 20 in the circumferential direction, and preferably a plurality are provided at intervals in the circumferential direction. Further, it is preferable that the number of the recesses 60 in the circumferential direction is relatively prime (no common divisor other than 1) with respect to the number of the rotor blades 12 constituting the rotor blade row 13.

  According to the above-described configuration, when the rotor 10 is rotated, the separation vortex S generated by the rotation stall at the front edge 12a of each blade 12 constituting the blade row 13 as the blade row 13 turns. Grows from the vicinity of the leading edge 12a of the rotor blade 12 toward the upstream side in the fluid flow direction. At this time, the separation vortex S is swung in the circumferential direction inside the stationary blade holding casing 20 together with the moving blade 12 swirling with the rotor 10.

  On the other hand, a part of the fluid flowing from the upstream side of the fluid flow field enters the recess 60 and collides with the inner peripheral surface 60b at the downstream end 60a of the recess 60, thereby downstream in the recess 60. The flow flows backward from the upstream side to the upstream side, and flows out from the upstream end 60c of the recess 60 into the flow field. Thereby, a part of the fluid is recirculated, and a spiral recirculation flow S2 is formed here. The recirculation flow S2 suppresses the separation vortex S from growing upstream.

Further, due to the influence of the installed recess 60, a recirculation flow S2 corresponding to the size of the recess 60 and the installation interval in the circumferential direction is generated in a forced vibration manner. Self-excitation of the flow field between the inner peripheral surface 20a of the stationary blade holding casing 20 and the outer peripheral surface 11d of the hub portion 11c due to the synchronization phenomenon (lock-in phenomenon) of turbulent waves caused by the recirculation flow S2 in the recess 60. Development of turning stall, which is vibration, is suppressed.
In this way, even in a low flow rate region, it becomes difficult to cause a rotating stall and a surge, and the operating range of the axial compressor 1 can be expanded.
In addition, the pressure loss can be suppressed by forming the recess 60 as compared with the case where the protrusion 40A or the like is provided.

  Here, by setting the number of recessed portions 60 in the circumferential direction to be relatively prime with respect to the number of moving blades 12 constituting the moving blade row 13, resonance with the moving blade row 13 is avoided, and blade vibration increases. In addition, noise generation can be reduced.

(Modification of the fifth embodiment)
In addition, as shown in FIG. 18, such a recessed part 60 can also be formed in combination with protrusion 40A-40J shown in the said 1st-4th embodiment.

  In addition, as shown in FIG. 19, with respect to the rotor blade row 13, a recess 61 or an inner portion projecting to the outer peripheral side at a part in the circumferential direction of the inner peripheral surface 20 a of the stationary blade holding casing 20 on the upstream side in the fluid flow direction. You may make it form the convex part 62 projected on the circumferential side. The concave portion 61 and the convex portion 62 are preferably curved surfaces.

In such a configuration, when a part of the fluid that has flowed from the upstream side of the fluid flow field enters the recess 61, it collides with the inner peripheral surface 61b at the downstream end 61a of the recess 61, In the recess 61, the flow flows backward from the downstream side to the upstream side, and flows out from the upstream end 61c of the recess 61 into the flow field. Accordingly, as shown in FIG. 20, a part of the fluid is recirculated, and a spiral recirculation flow S2 is formed here. The recirculation flow S2 suppresses the separation vortex S from growing upstream.
Even in such a configuration, the same effect as that of the fifth embodiment can be obtained.

(Other embodiments)
The rotating machine of the present invention is not limited to the above-described embodiments described with reference to the drawings, and various modifications can be considered within the technical scope.
For example, the configurations shown in the first to fifth embodiments and the modifications thereof can be used in appropriate combination.
Further, the rotary machine of the present invention is not limited to the axial flow compressor 1 of each of the above embodiments, and can be applied to other configurations as appropriate, such as an axial flow compression unit for a gas turbine, a centrifugal compressor, and the like.
In addition to this, as long as it does not depart from the gist of the present invention, the configuration described in the above embodiment can be selected or changed to another configuration as appropriate.

1 Axial flow compressor (rotary machine)
10 Rotor (Rotating shaft)
DESCRIPTION OF SYMBOLS 11 Rotor main body 11c Hub part 12 Moving blade 12a Front edge 13 Moving blade row 13a Front edge 16 Stator blade 16a Front edge 18 Stator blade row 18a Front edge 20 Stator blade holding casing (casing)
20a Inner peripheral surfaces 22, 23 Flow path forming members 24, 25 Diffuser section 26 Housing 27, 28 Volute section 27a Suction port 28a Discharge port 29 Channels 40A to 40K Protrusions (inhibiting portions)
41 Fixed projection 42 Slide projection 43 Outflow recess 50 Recirculation flow path (recess)
51 Channel inlet 52 Channel outlet 60 Concave part 61 Concave part 62 Convex part

Claims (9)

A cylindrical casing;
A rotating shaft rotatably provided in the casing;
A plurality of blades arranged in a circumferential direction around the rotation shaft in a flow path between the rotation shaft and the casing;
Provided on the inner peripheral surface of the casing or the outer peripheral surface of the rotary shaft on the upstream side in the flow direction of the fluid in the flow path from the leading edge of the blade, and rotate relative to the blade. A suppressor that suppresses the growth of the vortex of the fluid formed on the leading edge side of
A rotating machine comprising: A plurality of the suppressing portions are provided in the circumferential direction of the rotating shaft,
At least one of the plurality of restraining portions has a radial height of the rotating shaft, a length in the circumferential direction of the rotating shaft, a shape, and an interval between the other restraining portions with respect to the other restraining portions. The rotating machine according to claim 1, wherein at least one of them is different. A plurality of the suppressing portions are provided in the circumferential direction of the rotating shaft,
3. The rotating machine according to claim 1, wherein the number of the restraining portions in the circumferential direction and the number of the blades in the circumferential direction are relatively prime.   4. The rotating machine according to claim 1, wherein the suppressing portion has a protrusion protruding into the flow path from an inner peripheral surface of the casing or an outer peripheral surface of the rotating shaft. 5.   The rotating machine according to claim 4, wherein the protrusion has a variable projecting dimension into the flow path or a length in the circumferential direction in the flow path.   5. The protrusion is formed so that a height in a radial direction of the rotation shaft gradually increases from an upstream side to a downstream side in the fluid flow direction in the flow path. 5. The rotating machine according to 5.   The suppressing portion is formed on the inner peripheral surface of the casing or the outer peripheral surface of the rotating shaft, and forms a circulating flow that circulates a part of the fluid flowing in the flow path upstream in the flow direction. A rotating machine according to any one of claims 1 to 6, further comprising a concave portion that causes the vortex to collide with the vortex. As the blade, provided with a moving blade attached to the outer peripheral surface of the rotating shaft,
The rotary machine according to any one of claims 1 to 7, wherein the suppressing portion is provided on the inner peripheral surface of the casing. As the wing, comprising a stationary blade attached to the outer peripheral surface of the casing,
The rotary machine according to any one of claims 1 to 8, wherein the suppressing portion is provided on the outer peripheral surface of the rotary shaft.