US20180274553A1 - Stationary vane and centrifugal compressor provided with stationary vane - Google Patents
Stationary vane and centrifugal compressor provided with stationary vane Download PDFInfo
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- US20180274553A1 US20180274553A1 US15/763,311 US201615763311A US2018274553A1 US 20180274553 A1 US20180274553 A1 US 20180274553A1 US 201615763311 A US201615763311 A US 201615763311A US 2018274553 A1 US2018274553 A1 US 2018274553A1
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- fluid
- vane
- flow path
- return
- centrifugal compressor
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/40—Casings; Connections of working fluid
- F04D29/42—Casings; Connections of working fluid for radial or helico-centrifugal pumps
- F04D29/44—Fluid-guiding means, e.g. diffusers
- F04D29/441—Fluid-guiding means, e.g. diffusers especially adapted for elastic fluid pumps
- F04D29/444—Bladed diffusers
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D17/00—Radial-flow pumps, e.g. centrifugal pumps; Helico-centrifugal pumps
- F04D17/08—Centrifugal pumps
- F04D17/10—Centrifugal pumps for compressing or evacuating
- F04D17/12—Multi-stage pumps
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D17/00—Radial-flow pumps, e.g. centrifugal pumps; Helico-centrifugal pumps
- F04D17/08—Centrifugal pumps
- F04D17/10—Centrifugal pumps for compressing or evacuating
- F04D17/12—Multi-stage pumps
- F04D17/122—Multi-stage pumps the individual rotor discs being, one for each stage, on a common shaft and axially spaced, e.g. conventional centrifugal multi- stage compressors
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
- F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
- F05D2240/00—Components
- F05D2240/10—Stators
- F05D2240/12—Fluid guiding means, e.g. vanes
- F05D2240/122—Fluid guiding means, e.g. vanes related to the trailing edge of a stator vane
Definitions
- the present invention relates to a stationary vane to be provided to a fluid machine and a centrifugal compressor provided with the stationary vane.
- a centrifugal compressor which is a fluid machine (driven machine), is capable of pumping (compressing) fluid, using centrifugal force by the impeller rotating together with the rotating shaft.
- stationary vanes provided in the flow path where fluid flows improve the flow of fluid and thus improve the efficiency of the energy exchange.
- stationary vanes to be provided to centrifugal compressors include diffuser vanes disposed downstream of the impeller in the flow direction (see Patent Document 1) and return vanes.
- Patent Document 1 Japanese Utility Model Registration Application Publication No. Hei 1-174599
- the stationary vanes provided in the flow path cause partial irregularities of the fluid in the vicinities of the stationary vanes while improving the overall flow of the fluid in the flow path.
- the flow of fluid at the trailing edge of a stationary vane (the downstream edge in the flow direction of the fluid) and in the vicinity thereof in a fluid machine is illustrated in FIG. 6 .
- fluid G 1 flows well along a stationary vane 150
- fluid G 2 a part of the fluid, separates from surfaces 151 and 153 of the stationary vane 150
- fluid G 3 a part of the fluid, flows being swirled into the space downstream of the stationary vane 150 in the flow direction (on the lower side in FIG. 6 ), which generates transverse vortexes 190 .
- the separation of the fluid and the generation of the transverse vortexes as described above are fluid loss and affect the efficiency of the fluid machine.
- the cross-sectional shape of a trailing edge 150 a of the stationary vane 150 is sometimes formed to be in an arc shape S or the like (see the chain double-dashed line in FIG. 6 ).
- Such a cross-sectional shape of the trailing edge 150 a of the stationary vane 150 can suppress the separation of the fluid and the generation of the transverse vortexes to some extent, but it cannot sufficiently suppress the separation of the fluid and the generation of the transverse vortexes in the case where the speed of the fluid G 1 (flow speed) flowing along the stationary vane 150 is high or the case where the direction of the flow of the fluid G 1 is changed sharply by the stationary vane 150 .
- One or more embodiments of the invention reduce fluid loss at the stationary vanes and improve the efficiency of the fluid machine.
- One or more embodiments of the invention are directed to a stationary vane provided to a fluid machine, characterized in that the stationary vane includes: a side surface to be exposed to fluid, the side surface being formed along a flow direction of the fluid; and a corner formed on the side surface, the corner being capable of generating a streamwise vortex having a vortex axis extending along the flow direction of the fluid, on a downstream side in the flow direction of the fluid.
- One or more embodiments of the invention are directed to a stationary vane, characterized in that the corner is formed by a ditch recessed from the side surface.
- One or more embodiments of the invention are directed to a stationary vane, characterized in that a plurality of the ditches are formed on the side surface so as to be arranged in a direction intersecting the flow direction of the fluid, and the ditches have different shapes depending on a speed of the fluid flowing along the side surface in a vicinity of each ditch.
- centrifugal compressor that includes: a casing, a rotating shaft rotatably supported by the casing, an impeller which is provided to the rotating shaft and is rotationally driven together with the rotating shaft, and a flow path which is formed in the casing and houses the impeller, the centrifugal compressor being configured to compress fluid by passing the fluid through the flow path, characterized in that the centrifugal compressor comprises the stationary vane according to one or more embodiments of the invention in the flow path.
- the corner formed on the side surface generates a streamwise vortex on the downstream side of the stationary vane in the flow direction, and the streamwise vortex draws the fluid flowing along the side surface of the stationary vane, which suppresses the separation of the fluid from the side surface.
- the streamwise vortex generated downstream of the stationary vane in the flow direction interferes with the transverse vortex similarly generated downstream of the stationary vane in the flow direction, and thus can break the transverse vortex.
- the generation of the streamwise vortex suppresses the separation of the fluid and breaks the transverse vortex, which reduces the fluid loss at the stationary vane and improves the efficiency of the fluid machine.
- the stationary vane makes it possible to form the corner on the side surface with a simple configuration.
- each of the ditches by forming each of the ditches to be in a shape in accordance with the flow speed of the fluid flowing along the side surface, it is possible to suppress turbulent flows and other irregularities of the fluid and uniform the strengths of the generated streamwise vortexes.
- the centrifugal compressor makes it possible to reduce fluid loss in other stationary vanes such as struts, inlet guide vanes, diffuser vanes, and the like in a centrifugal compressor which compresses fluid using centrifugal force by the impeller rotating together with the rotating shaft, and improve the efficiency of the centrifugal compressor.
- FIG. 1 is a longitudinal cross-sectional view illustrating a schematic structure of a centrifugal compressor including return vanes according to one or more embodiments of the invention.
- FIG. 2 is an explanatory diagram illustrating arrangement of the return vanes according to one or more embodiments of the invention in a return flow path (a cross-sectional view seen from arrows II-II in FIG. 1 ).
- FIG. 3A is a schematic perspective view illustrating a trailing edge of the return vane according to one or more embodiments of the invention.
- FIG. 3B is a schematic perspective view illustrating an example in which the number of ditches and other factors at the trailing edge of the return vane according to one or more embodiments of the invention is changed.
- FIG. 4A is an explanatory diagram illustrating the trailing edge of the return vane according to one or more embodiments of the invention (a view seen from arrow IV in FIG. 3A ).
- FIG. 4B is an explanatory diagram illustrating an example in which the shape of the ditches at the trailing edge of the return vane according to one or more embodiments of the invention is changed.
- FIG. 4C is an explanatory diagram illustrating an example in which the shape of the ditches at the trailing edge of the return vane according to one or more embodiments of the invention is changed.
- FIG. 4D is an explanatory diagram illustrating an example in which ditches at the trailing edge of the return vane according to one or more embodiments of the invention are changed to protrusions.
- FIG. 5A is an explanatory diagram illustrating the trailing edge of the return vane according to one or more embodiments of the invention (a cross-sectional view seen from arrows V-V in FIG. 3A ).
- FIG. 5B is an explanatory diagram illustrating an example in which the shape of the trailing edge of the return vane according to one or more embodiments of the invention is changed.
- FIG. 5C is an explanatory diagram illustrating an example in which the shape of the trailing edge of the return vane according to one or more embodiments of the invention is changed.
- FIG. 6 is an explanatory diagram illustrating the flow of fluid at the trailing edge of a stationary vane and in the vicinity thereof in a conventional fluid machine.
- the present invention is not limited to the following embodiments.
- Embodiments of the present invention may be adopted to other stationary vanes in centrifugal compressors, such as struts, inlet guide vanes, and diffuser guide vanes, or may be adopted to various stationary vanes provided in other fluid machines, such as turbochargers and pumps.
- various modifications can be made without departing from the spirit of the embodiments of the present invention.
- a centrifugal compressor (fluid machine) 1 is provided with a casing 11 in a substantially cylindrical shape.
- the casing 11 rotatably supports a rotating shaft 12 via bearings 13 .
- the rotating shaft 12 is connected to a non-illustrated drive source, such as a motor, and configured to rotate in the casing 11 when the drive source is driven.
- FIG. 1 illustrates only a half of the centrifugal compressor 1 (the upper half in FIG. 1 ).
- the casing 11 has a suction port 21 for taking fluid G into the centrifugal compressor 1 and a discharge port 22 for discharging the fluid G to the outside of the centrifugal compressor 1 .
- a flow path 30 Formed inside the centrifugal compressor 1 is a flow path 30 connecting the suction port 21 and the discharge port 22 , for sending the fluid G in one axis direction (from the left side to the right side in FIG. 1 ).
- the flow path 30 is defined by first side walls 11 a, second side walls 11 b, and other portions and formed such that the diameter thereof repeatedly decreases and increases.
- a plurality of the first side walls 11 a are provided on the radially inside of the flow path 30 (on the lower side in FIG. 1 ) along the axial direction (the right-left direction in FIG. 1 ) at intervals
- a plurality of the second side walls 11 b are provided between the first side walls 11 a so as to extend (protrude) radially inward from the radially outer side (the upper side in FIG. 1 ).
- the flow path 30 includes compression flow paths 31 for compressing (pumping) the fluid G, diffuser flow paths 32 for decelerating the fluid G pumped from the compression flow paths 31 to convert the dynamic pressure to the static pressure, and return flow paths 33 for eliminating turning components in the flow of the fluid G sent from the diffuser flow paths 32 and sending the fluid G to the compression flow path 31 in the next stage.
- the centrifugal compressor 1 includes multiple stages of the compression flow path 31 , diffuser flow path 32 , and return flow path 33 sequentially provided along the flow direction of the fluid G, and the fluid G is compressed in stages in the course of flowing the flow path 30 from the suction port 21 toward the discharge port 22 .
- the compression flow path 31 is formed to gradually curve radially outward, toward the axially rear end side (the right end side in FIG. 1 ) from the axially front end side (the left end side in FIG. 1 ), and the compression flow path 31 houses impellers 40 .
- the impellers 40 are fixed to the rotating shaft 12 and rotate together with the rotating shaft 12 when the non-illustrated drive source is driven.
- the fluid G taken in from the suction port 21 or the fluid G sent from the compression flow path 31 in the previous stage is given a centrifugal force directed radially outward (in a direction orthogonal to the rotating shaft 12 ) by the impeller 40 rotating together with the rotating shaft 12 , and sent (pumped) to the diffuser flow path 32 located immediately downstream in the flow direction (radially outward).
- the diffuser flow path 32 is formed in an annular shape extending radially outward from the compression flow path 31 located immediately upstream thereof in the flow direction (radially inward).
- the fluid G sent from compression flow path 31 is diffused radially outward and at the same time, sent to the return flow path 33 located immediately downstream thereof in the flow direction (radially outward and axially rearward). Note that by the fluid G being diffused in the diffuser flow path 32 , the flow speed thereof is reduced (decelerated), and at the same time, the kinetic energy (dynamic pressure) given to the fluid G is converted into pressure energy (static pressure).
- the return flow path 33 is formed to connect the diffuser flow path 32 located immediately upstream thereof in the flow direction (on the axially front end side and radially inward) and the compression flow path 31 located immediately downstream thereof in the flow direction (on the axially rear end side), in an annular shape extending in the radial direction and the axial direction such that the longitudinal section thereof forms a letter U.
- a return vane 50 circumferentially partitioning a part of the space in the return flow path 33 .
- the return vanes 50 are plate-like members provided to connect the first side walls 11 a and the second side walls 11 b in the casing 11 (see FIGS. 1, 3A, and 4A ), each having a shape circumferentially curving, and are arranged radially, spaced at certain intervals in the circumferential direction (see FIG. 2 ).
- the fluid G is sent from the diffuser flow path 32 , and the flow direction is inverted radially inward.
- the return flow path 33 the fluid G is flowed toward the impeller 40 (compression flow path 31 ) in the next stage, and at the same time, turning components in the flow of the fluid G are eliminated (cancelled) by the return vane 50 (see FIGS. 1 and 2 ).
- each return vane 50 has ditches 60 formed on (are open on) a side surface 51 and a rear end surface 52 .
- the side surface 51 is one surface (a suction surface) exposed to the fluid G and extending along the flow direction of the fluid G
- the rear end surface 52 is an end surface on the downstream side in the flow direction of the fluid G.
- FIG. 3A only illustrates the return vane 50 , and the casing 11 (the first side wall 11 a and the second side wall 11 b ) is not illustrated for the figure to be easier to understand.
- Each ditch 60 has a grooved surface 61 recessed from the side surface 51 of the return vane 50 , and at a trailing edge (edge on the downstream side in the flow direction) 50 a of the return vane 50 , the side surface 51 and the grooved surface 61 form corners 70 protruding in a direction intersecting the flow direction.
- the shapes of the ditch 60 and the corner 70 will be described later.
- the flow direction of the fluid G flowing along the side surface 51 of the return vane 50 changes at the trailing edge 50 a of the return vane 50 such that the fluid G is swirled by the ditches 60 (grooved surfaces 61 ).
- streamwise vortexes 80 of the fluid G are generated downstream of the return vane 50 in the flow direction.
- the streamwise vortexes 80 each have a vortex axis C 80 in parallel with the flow direction of the fluid G and are generated downstream of the return vane 50 in the flow direction (along extended lines of the side surface 51 ) starting from the corners 70 . Accordingly, the fluid G flows so as to be drawn (swirled) into the streamwise vortexes 80 after flowing along the side surface 51 of the return vane 50 , which suppresses the separation of the fluid G from the side surface 51 .
- the streamwise vortexes 80 generated downstream of the return vane 50 in the flow direction interfere with transverse vortexes 90 similarly generated downstream of the return vane 50 in the flow direction.
- the transverse vortexes 90 are vortexes (for example, a Karman vortex street) each having a vortex axis C 90 orthogonal to (intersecting) the flow direction.
- transverse vortexes 90 which greatly affect the flow performance of the fluid G in conventional apparatuses, are broken by the generation of the streamwise vortexes 80 , which consequently reduces the fluid loss at the return vane 50 and improves the efficiency of the centrifugal compressor 1 .
- the return vane 50 has two ditches 60 , which are formed to be spaced with a certain distance (ditch interval a) in between so as to be arranged symmetrically in the vane width direction of the return vane 50 (the direction in which the trailing edge 50 a extends and the up-down direction in FIG. 4A ).
- the trailing edge 50 a of the return vane 50 has four corners 70 formed by the side surface 51 and the two grooved surfaces 61 . Consequently, four streamwise vortexes 80 , each starting from one of the four corners 70 , are generated downstream of the return vane 50 in the flow direction (see FIG. 3A ).
- the number of ditches 60 formed on the return vane 50 is not limited to that in these embodiments, but one or more ditches 60 may be formed on the return vane 50 .
- the ditch 60 be arranged substantially at the center in the vane width direction of the return vane 50 (not illustrated).
- the corners 70 formed by the side surface 51 of the return vane 50 and the grooved surface 61 of the ditch 60 are arranged substantially uniformly (symmetrically) in the vane width direction of the return vane 50 .
- the length of the ditch 60 (ditch width W) in the vane width direction of the return vane 50 is the distance between both corners 70 formed by the side surface 51 and the grooved surface 61 .
- the multiple ditches 60 be spaced at certain intervals (ditch interval a) and arranged symmetrically in the vane width direction of the return vane 50 (see FIG. 4A ).
- the length of the ditch 60 (ditch width W) in the vane width direction of the return vane 50 and the distance between the ditches 60 (ditch interval a) in the vane width direction of the return vane 50 be substantially the same length (distance) (see the following Formula (1)).
- the corners 70 formed by the side surface 51 of the return vane 50 and the grooved surfaces 61 of the ditches 60 are arranged substantially uniformly (symmetrically) in the vane width direction of the return vane 50 .
- the length of the ditch 60 (ditch width W) in the vane width direction of the return vane 50 is the distance between both corners 70 formed by the side surface 51 and the grooved surface 61
- the distance between the ditches 60 (ditch interval a) in the vane width direction of the return vane 50 is the distance between the corners 70 of two adjacent ditches 60 .
- the lengths of the ditches 60 in the vane thickness direction of the return vane 50 (the thickness direction of the trailing edge 50 a and the right-left direction in FIG. 5A ) and the lengths of the ditches 60 (ditch length L) in the vane length direction of the return vane 50 (the flow direction and the up-down direction in FIG. 5A ) may be set individually (independently) (see FIGS. 3A and 5A ).
- multiple ditches 60 may have different ditch lengths L while having the same ditch depth H, or multiple ditches 60 may have different ditch depths H while having the same ditch length L.
- multiple ditches 60 may have different ditch depths H and different ditch lengths L such that the ratio between the ditch depth H and the ditch length L is the same or different.
- the ditch depths H and the ditch lengths L of multiple ditches 60 be set to be a relatively changed value depending on the flow speed distribution of the fluid G flowing along the side surface 51 of the return vane 50 .
- the flow speed of the fluid G flowing along the return vane 50 is different depending on the position where the fluid G flows.
- the ditch depth H and the ditch length L are set to be a relatively changed value depending on the position (arrangement location) of each ditch 60 formed on the return vane 50 .
- the two ditches 60 are arranged to be symmetrical to each other in the vane width direction of the return vane, and there are streams of fluid G having the same flow speed in the peripheries of both ditches 60 . Accordingly, the ditch depths H and the ditch lengths L of both ditches 60 are set to the same values.
- the three ditches 60 - 1 and 60 - 2 are arranged, one at the center in the vane width direction of the return vane 50 and two symmetrically on both sides thereof (on the upper side and the lower side in FIG. 3B ), and there are streams of the fluid G 1 and G 2 having different flow speeds in the peripheries of the ditches 60 - 1 and 60 - 2 .
- the ditch depths H and the ditch lengths L 1 and L 2 of the ditches 60 - 1 and 60 - 2 are set in accordance with the speeds of the streams of the fluid G 1 and G 2 flowing in the peripheries of the ditches 60 - 1 and 60 - 2 .
- the ditch depths H of the ditches 60 - 1 and 60 - 2 are set to be equal (to the same value) while the ditch length L 1 of the ditch 60 - 1 formed at the center in the vane width direction of the return vane 50 , where the fluid G 1 with a high flow speed flows, is set longer than the ditch length L 2 of the ditches 60 - 2 formed on both sides in the vane width direction of the return vane 50 , where the fluid G 2 with a lower flow speed than that at the center flows.
- the fluid G 1 with a high flow speed flows on the grooved surface 61 - 1 , which is long in the flow direction and has a gentle inclination, at the center of the return vane 50 , and thus separation, turbulent flows, or other irregularities are unlikely to occur.
- the fluid G 2 with a slow flow speed flows on the grooved surfaces 61 - 2 , which are short in the flow direction and have a steep inclination, generating streamwise vortexes 80 strong enough to prevent separation, turbulent flows, or other irregularities.
- the fluid G flowing along the side surface 51 of the return vane 50 will not flow into the opposite side surface (pressure surface) 53 side of the return vane 50 . Accordingly, the fluid G flows being swirled by the ditch 60 , generating the streamwise vortexes 80 downstream of the return vane 50 in the flow direction (on the lower side in FIG. 5A ) starting from the corners 70 .
- the vane thickness T is the width of the rear end surface 52 of the return vane 50 in the case where the cross-sectional shape of the trailing edge 50 a is rectangular (see FIG. 5A ). In the case where the cross-sectional shape of the trailing edge 50 a is circular, the vane thickness T is the maximum width of the portion where the arc Sc is tangent to the outer shape of the return vane 50 (see FIG. 5B ). In the case where the cross-sectional shape of the trailing edge 50 a is elliptical, the vane thickness T is the maximum width of the portion where the ellipse Se is tangent to the outer shape of the return vane 50 (see FIG. 5C ).
- the corners 70 are formed by the side surface 51 of the return vane 50 and the grooved surface 61 of the ditch 60 , and the grooved surface 61 is a curved surface recessed into a curved shape from the side surface 51 .
- the corner 70 and the grooved surface 61 (ditch 60 ) are not limited to these embodiments, but may be of various shapes.
- the ditch 60 forming the corners 70 may be, for example, a ditch 60 formed by a grooved surface 61 grooved in to a rectangular shape from the side surface 51 of the return vane 50 (see FIG. 4B ), or a ditch 60 formed by a grooved surface 61 recessed in to a wedge shape from the side surface 51 of the return vane 50 (see FIG. 4C ).
- the corners 70 maybe formed by, for example, protrusions 62 formed by protruded surfaces 63 protruding from the side surface 51 of the return vane 50 (see FIG. 4D ).
- the vicinity of the protrusion 62 may be flush with the side surface 51 of the return vane 50 , or it may be a grooved surface 61 recessed from the side surface 51 of the return vane 50 as indicated by chain double-dashed lines in FIG. 4D .
- the grooved surface 61 recessed from the side surface 51 of the return vane 50 in the vicinity of the protrusion 62 it is possible to increase the length of the protrusions 62 (protrusion heights H 1 and H 2 ) in the vane thickness direction (right-left direction in FIG. 4D ) of the return vane 50 (H 1 ⁇ H 2 ), and thus possible to strengthen the streamwise vortexes 80 generated downstream of the return vane 50 in the flow direction.
- the shape of the corner 70 does not have any limitation as long as the shape of the corner 70 allows the flow of the fluid G flowing along the side surface 51 of the return vane 50 to change and generates the streamwise vortexes 80 downstream of the return vane 50 in the flow direction.
- the shape of the corner 70 capable of easily generating a streamwise vortex 80 or generating a strong streamwise vortex 80 , it is preferable that the corner 70 have an acute angle rather than an obtuse angle, and be formed of straight lines rather than curved lines.
- the fluid G sent out radially outward from the compression flow path 31 flows into the diffuser flow path 32 , and part of the dynamic pressure given by the impeller 40 is converted into static pressure.
- the fluid G the pressure of which has been increased while passing from the compression flow path 31 through the diffuser flow path 32 flows into the return flow path 33 , where turning components in the flow of the fluid G are eliminated by the return vanes 50 and sent to the compression flow path 31 in the next stage (see FIGS. 1 and 2 ).
- the flow direction of the fluid G flowing along the side surface 51 of the return vane 50 changes such that the fluid G is swirled by the ditches 60 (grooved surfaces 61 ), and the streamwise vortexes 80 of the fluid G are generated downstream of the return vane 50 in the flow direction (see FIG. 3A ).
- These streamwise vortexes 80 suppress the separation of the fluid G from the side surface 51 and breaks the transverse vortexes 90 similarly generated downstream of the return vane 50 in the flow direction.
- the centrifugal compressor 1 including the return vanes 50 reduces the fluid loss at the return vanes 50 and improves the efficiency of the centrifugal compressor 1 .
- the corners 70 are formed on one side surface (pressure surface) 51 of the return vane 50 , where the separation of the fluid G is likely to occur, to suppress the separation of the fluid G on the side surface 51 .
- the present invention is not limited to this.
- the corners 70 (ditches 60 or protrusions 62 ) may be formed on the other (opposite) side surface (pressure surface) 53 of the return vane 50 to suppress the separation of the fluid G on the side surface 53 .
- One or more embodiments of the present invention relate to stationary vanes to be provided in a fluid machine and a centrifugal compressor including the stationary vanes.
- One or more embodiments of the present invention reduce the fluid loss at the stationary vanes and improve the efficiency of the fluid machine.
- one or more embodiments of the present invention can be utilized extremely usefully for various fluid machines including stationary vanes, such as centrifugal compressors, turbochargers, and pumps.
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Abstract
A stationary vane includes: a side surface exposed to a fluid and that is provided along a flow direction of the fluid; and corner portions provided in the side surface and that generates, at a downstream side in the flow direction of the fluid, streamwise vortexes each having a vortex axis that is parallel to the flow direction of the fluid.
Description
- The present invention relates to a stationary vane to be provided to a fluid machine and a centrifugal compressor provided with the stationary vane.
- The fluid machine exchanges energy between fluid and the machine. For example, a centrifugal compressor, which is a fluid machine (driven machine), is capable of pumping (compressing) fluid, using centrifugal force by the impeller rotating together with the rotating shaft.
- In a fluid machine such as the centrifugal compressor described above, various stationary vanes provided in the flow path where fluid flows improve the flow of fluid and thus improve the efficiency of the energy exchange. Examples of stationary vanes to be provided to centrifugal compressors include diffuser vanes disposed downstream of the impeller in the flow direction (see Patent Document 1) and return vanes.
- Patent Document 1: Japanese Utility Model Registration Application Publication No. Hei 1-174599
- However, the stationary vanes provided in the flow path cause partial irregularities of the fluid in the vicinities of the stationary vanes while improving the overall flow of the fluid in the flow path. Here, the flow of fluid at the trailing edge of a stationary vane (the downstream edge in the flow direction of the fluid) and in the vicinity thereof in a fluid machine is illustrated in
FIG. 6 . - As illustrated in
FIG. 6 , although fluid G1 flows well along astationary vane 150, fluid G2, a part of the fluid, separates fromsurfaces stationary vane 150, and in addition, fluid G3, a part of the fluid, flows being swirled into the space downstream of thestationary vane 150 in the flow direction (on the lower side inFIG. 6 ), which generatestransverse vortexes 190. The separation of the fluid and the generation of the transverse vortexes as described above are fluid loss and affect the efficiency of the fluid machine. - In order to suppress the separation of the fluid and the generation of the transverse vortexes, the cross-sectional shape of a
trailing edge 150 a of thestationary vane 150 is sometimes formed to be in an arc shape S or the like (see the chain double-dashed line inFIG. 6 ). Such a cross-sectional shape of thetrailing edge 150 a of thestationary vane 150 can suppress the separation of the fluid and the generation of the transverse vortexes to some extent, but it cannot sufficiently suppress the separation of the fluid and the generation of the transverse vortexes in the case where the speed of the fluid G1 (flow speed) flowing along thestationary vane 150 is high or the case where the direction of the flow of the fluid G1 is changed sharply by thestationary vane 150. - One or more embodiments of the invention reduce fluid loss at the stationary vanes and improve the efficiency of the fluid machine.
- One or more embodiments of the invention are directed to a stationary vane provided to a fluid machine, characterized in that the stationary vane includes: a side surface to be exposed to fluid, the side surface being formed along a flow direction of the fluid; and a corner formed on the side surface, the corner being capable of generating a streamwise vortex having a vortex axis extending along the flow direction of the fluid, on a downstream side in the flow direction of the fluid.
- One or more embodiments of the invention are directed to a stationary vane, characterized in that the corner is formed by a ditch recessed from the side surface.
- One or more embodiments of the invention are directed to a stationary vane, characterized in that a plurality of the ditches are formed on the side surface so as to be arranged in a direction intersecting the flow direction of the fluid, and the ditches have different shapes depending on a speed of the fluid flowing along the side surface in a vicinity of each ditch.
- One or more embodiments of the invention are directed to a centrifugal compressor that includes: a casing, a rotating shaft rotatably supported by the casing, an impeller which is provided to the rotating shaft and is rotationally driven together with the rotating shaft, and a flow path which is formed in the casing and houses the impeller, the centrifugal compressor being configured to compress fluid by passing the fluid through the flow path, characterized in that the centrifugal compressor comprises the stationary vane according to one or more embodiments of the invention in the flow path.
- According to one or more embodiments of the invention, the corner formed on the side surface generates a streamwise vortex on the downstream side of the stationary vane in the flow direction, and the streamwise vortex draws the fluid flowing along the side surface of the stationary vane, which suppresses the separation of the fluid from the side surface. In addition, the streamwise vortex generated downstream of the stationary vane in the flow direction interferes with the transverse vortex similarly generated downstream of the stationary vane in the flow direction, and thus can break the transverse vortex. As above, the generation of the streamwise vortex suppresses the separation of the fluid and breaks the transverse vortex, which reduces the fluid loss at the stationary vane and improves the efficiency of the fluid machine.
- According to one or more embodiments of the invention, the stationary vane makes it possible to form the corner on the side surface with a simple configuration.
- According to one or more embodiments of the invention, by forming each of the ditches to be in a shape in accordance with the flow speed of the fluid flowing along the side surface, it is possible to suppress turbulent flows and other irregularities of the fluid and uniform the strengths of the generated streamwise vortexes.
- According to one or more embodiments of the invention, the centrifugal compressor makes it possible to reduce fluid loss in other stationary vanes such as struts, inlet guide vanes, diffuser vanes, and the like in a centrifugal compressor which compresses fluid using centrifugal force by the impeller rotating together with the rotating shaft, and improve the efficiency of the centrifugal compressor.
-
FIG. 1 is a longitudinal cross-sectional view illustrating a schematic structure of a centrifugal compressor including return vanes according to one or more embodiments of the invention. -
FIG. 2 is an explanatory diagram illustrating arrangement of the return vanes according to one or more embodiments of the invention in a return flow path (a cross-sectional view seen from arrows II-II inFIG. 1 ). -
FIG. 3A is a schematic perspective view illustrating a trailing edge of the return vane according to one or more embodiments of the invention. -
FIG. 3B is a schematic perspective view illustrating an example in which the number of ditches and other factors at the trailing edge of the return vane according to one or more embodiments of the invention is changed. -
FIG. 4A is an explanatory diagram illustrating the trailing edge of the return vane according to one or more embodiments of the invention (a view seen from arrow IV inFIG. 3A ). -
FIG. 4B is an explanatory diagram illustrating an example in which the shape of the ditches at the trailing edge of the return vane according to one or more embodiments of the invention is changed. -
FIG. 4C is an explanatory diagram illustrating an example in which the shape of the ditches at the trailing edge of the return vane according to one or more embodiments of the invention is changed. -
FIG. 4D is an explanatory diagram illustrating an example in which ditches at the trailing edge of the return vane according to one or more embodiments of the invention are changed to protrusions. -
FIG. 5A is an explanatory diagram illustrating the trailing edge of the return vane according to one or more embodiments of the invention (a cross-sectional view seen from arrows V-V inFIG. 3A ). -
FIG. 5B is an explanatory diagram illustrating an example in which the shape of the trailing edge of the return vane according to one or more embodiments of the invention is changed. -
FIG. 5C is an explanatory diagram illustrating an example in which the shape of the trailing edge of the return vane according to one or more embodiments of the invention is changed. -
FIG. 6 is an explanatory diagram illustrating the flow of fluid at the trailing edge of a stationary vane and in the vicinity thereof in a conventional fluid machine. - Hereinafter, embodiments of a stationary vane will be described in detail with reference to the attached drawings. Note that the following embodiments employs the stationary vane in return vanes provided in a multistage centrifugal compressor.
- As a matter of course, the present invention is not limited to the following embodiments. Embodiments of the present invention may be adopted to other stationary vanes in centrifugal compressors, such as struts, inlet guide vanes, and diffuser guide vanes, or may be adopted to various stationary vanes provided in other fluid machines, such as turbochargers and pumps. In addition, it goes without saying that various modifications can be made without departing from the spirit of the embodiments of the present invention.
- Descriptions will be provided for the structure of a centrifugal compressor including return vanes according to one or more embodiments of the present invention with reference to
FIGS. 1, 2, 3A and 4A . - As illustrated in
FIG. 1 , a centrifugal compressor (fluid machine) 1 is provided with acasing 11 in a substantially cylindrical shape. Thecasing 11 rotatably supports a rotatingshaft 12 viabearings 13. The rotatingshaft 12 is connected to a non-illustrated drive source, such as a motor, and configured to rotate in thecasing 11 when the drive source is driven. Note thatFIG. 1 illustrates only a half of the centrifugal compressor 1 (the upper half inFIG. 1 ). - The
casing 11 has asuction port 21 for taking fluid G into thecentrifugal compressor 1 and adischarge port 22 for discharging the fluid G to the outside of thecentrifugal compressor 1. Formed inside thecentrifugal compressor 1 is aflow path 30 connecting thesuction port 21 and thedischarge port 22, for sending the fluid G in one axis direction (from the left side to the right side inFIG. 1 ). - The
flow path 30 is defined byfirst side walls 11 a,second side walls 11 b, and other portions and formed such that the diameter thereof repeatedly decreases and increases. Here, a plurality of thefirst side walls 11 a are provided on the radially inside of the flow path 30 (on the lower side inFIG. 1 ) along the axial direction (the right-left direction inFIG. 1 ) at intervals, and a plurality of thesecond side walls 11 b are provided between thefirst side walls 11 a so as to extend (protrude) radially inward from the radially outer side (the upper side inFIG. 1 ). - The
flow path 30 includescompression flow paths 31 for compressing (pumping) the fluid G,diffuser flow paths 32 for decelerating the fluid G pumped from thecompression flow paths 31 to convert the dynamic pressure to the static pressure, and returnflow paths 33 for eliminating turning components in the flow of the fluid G sent from thediffuser flow paths 32 and sending the fluid G to thecompression flow path 31 in the next stage. - The
centrifugal compressor 1 includes multiple stages of thecompression flow path 31,diffuser flow path 32, and returnflow path 33 sequentially provided along the flow direction of the fluid G, and the fluid G is compressed in stages in the course of flowing theflow path 30 from thesuction port 21 toward thedischarge port 22. - The
compression flow path 31 is formed to gradually curve radially outward, toward the axially rear end side (the right end side inFIG. 1 ) from the axially front end side (the left end side inFIG. 1 ), and thecompression flow path 31 houses impellers 40. Theimpellers 40 are fixed to therotating shaft 12 and rotate together with the rotatingshaft 12 when the non-illustrated drive source is driven. - Accordingly, in the
compression flow path 31, the fluid G taken in from thesuction port 21 or the fluid G sent from thecompression flow path 31 in the previous stage is given a centrifugal force directed radially outward (in a direction orthogonal to the rotating shaft 12) by theimpeller 40 rotating together with the rotatingshaft 12, and sent (pumped) to thediffuser flow path 32 located immediately downstream in the flow direction (radially outward). - The
diffuser flow path 32 is formed in an annular shape extending radially outward from thecompression flow path 31 located immediately upstream thereof in the flow direction (radially inward). In thediffuser flow path 32, the fluid G sent fromcompression flow path 31 is diffused radially outward and at the same time, sent to thereturn flow path 33 located immediately downstream thereof in the flow direction (radially outward and axially rearward). Note that by the fluid G being diffused in thediffuser flow path 32, the flow speed thereof is reduced (decelerated), and at the same time, the kinetic energy (dynamic pressure) given to the fluid G is converted into pressure energy (static pressure). - The
return flow path 33 is formed to connect thediffuser flow path 32 located immediately upstream thereof in the flow direction (on the axially front end side and radially inward) and thecompression flow path 31 located immediately downstream thereof in the flow direction (on the axially rear end side), in an annular shape extending in the radial direction and the axial direction such that the longitudinal section thereof forms a letter U. Provided in thereturn flow path 33 is areturn vane 50 circumferentially partitioning a part of the space in thereturn flow path 33. - The return vanes 50 are plate-like members provided to connect the
first side walls 11 a and thesecond side walls 11 b in the casing 11 (seeFIGS. 1, 3A, and 4A ), each having a shape circumferentially curving, and are arranged radially, spaced at certain intervals in the circumferential direction (seeFIG. 2 ). Thus, the fluid G is sent from thediffuser flow path 32, and the flow direction is inverted radially inward. Then, in thereturn flow path 33, the fluid G is flowed toward the impeller 40 (compression flow path 31) in the next stage, and at the same time, turning components in the flow of the fluid G are eliminated (cancelled) by the return vane 50 (seeFIGS. 1 and 2 ). - As illustrated in
FIG. 3A , eachreturn vane 50 hasditches 60 formed on (are open on) aside surface 51 and arear end surface 52. Here, theside surface 51 is one surface (a suction surface) exposed to the fluid G and extending along the flow direction of the fluid G, and therear end surface 52 is an end surface on the downstream side in the flow direction of the fluid G. Note thatFIG. 3A only illustrates thereturn vane 50, and the casing 11 (thefirst side wall 11 a and thesecond side wall 11 b) is not illustrated for the figure to be easier to understand. - Each
ditch 60 has a groovedsurface 61 recessed from theside surface 51 of thereturn vane 50, and at a trailing edge (edge on the downstream side in the flow direction) 50 a of thereturn vane 50, theside surface 51 and thegrooved surface 61form corners 70 protruding in a direction intersecting the flow direction. The shapes of theditch 60 and thecorner 70 will be described later. - Thus, the flow direction of the fluid G flowing along the
side surface 51 of thereturn vane 50 changes at the trailingedge 50 a of thereturn vane 50 such that the fluid G is swirled by the ditches 60 (grooved surfaces 61). As a result,streamwise vortexes 80 of the fluid G are generated downstream of thereturn vane 50 in the flow direction. - The
streamwise vortexes 80 each have a vortex axis C80 in parallel with the flow direction of the fluid G and are generated downstream of thereturn vane 50 in the flow direction (along extended lines of the side surface 51) starting from thecorners 70. Accordingly, the fluid G flows so as to be drawn (swirled) into thestreamwise vortexes 80 after flowing along theside surface 51 of thereturn vane 50, which suppresses the separation of the fluid G from theside surface 51. - In addition, the
streamwise vortexes 80 generated downstream of thereturn vane 50 in the flow direction interfere withtransverse vortexes 90 similarly generated downstream of thereturn vane 50 in the flow direction. Here, thetransverse vortexes 90 are vortexes (for example, a Karman vortex street) each having a vortex axis C90 orthogonal to (intersecting) the flow direction. Thesestreamwise vortexes 80 andtransverse vortexes 90 interfere with and cancel (break) each other. More specifically, thetransverse vortexes 90, which greatly affect the flow performance of the fluid G in conventional apparatuses, are broken by the generation of thestreamwise vortexes 80, which consequently reduces the fluid loss at thereturn vane 50 and improves the efficiency of thecentrifugal compressor 1. - The shapes of the
ditch 60 and thecorner 70 will be described in detail with reference toFIGS. 3A to 5C . - As illustrated in
FIGS. 3A and 4A , thereturn vane 50 has twoditches 60, which are formed to be spaced with a certain distance (ditch interval a) in between so as to be arranged symmetrically in the vane width direction of the return vane 50 (the direction in which the trailingedge 50 a extends and the up-down direction inFIG. 4A ). - Accordingly, the trailing
edge 50 a of thereturn vane 50 has fourcorners 70 formed by theside surface 51 and the twogrooved surfaces 61. Consequently, fourstreamwise vortexes 80, each starting from one of the fourcorners 70, are generated downstream of thereturn vane 50 in the flow direction (seeFIG. 3A ). As a matter of course, the number ofditches 60 formed on thereturn vane 50 is not limited to that in these embodiments, but one ormore ditches 60 may be formed on thereturn vane 50. - Here, in the case where one
ditch 60 is formed on thereturn vane 50, it is preferable that theditch 60 be arranged substantially at the center in the vane width direction of the return vane 50 (not illustrated). By arranging the oneditch 60 substantially at the center in the vane width direction of thereturn vane 50 as above, thecorners 70 formed by theside surface 51 of thereturn vane 50 and thegrooved surface 61 of theditch 60 are arranged substantially uniformly (symmetrically) in the vane width direction of thereturn vane 50. Note that in this case, the length of the ditch 60 (ditch width W) in the vane width direction of thereturn vane 50 is the distance between bothcorners 70 formed by theside surface 51 and thegrooved surface 61. - In the case where
multiple ditches 60 are formed on thereturn vane 50, it is preferable that themultiple ditches 60 be spaced at certain intervals (ditch interval a) and arranged symmetrically in the vane width direction of the return vane 50 (seeFIG. 4A ). In this case, it is preferred that the length of the ditch 60 (ditch width W) in the vane width direction of thereturn vane 50 and the distance between the ditches 60 (ditch interval a) in the vane width direction of thereturn vane 50 be substantially the same length (distance) (see the following Formula (1)). -
[Math.1] -
0.9<a/W<1.1 (1) - By spacing the
multiple ditches 60 as described in Formula (1) as above and by arranging them symmetrically in the vane width direction of thereturn vane 50, thecorners 70 formed by theside surface 51 of thereturn vane 50 and thegrooved surfaces 61 of theditches 60 are arranged substantially uniformly (symmetrically) in the vane width direction of thereturn vane 50. Note that in this case, the length of the ditch 60 (ditch width W) in the vane width direction of thereturn vane 50 is the distance between bothcorners 70 formed by theside surface 51 and thegrooved surface 61, and the distance between the ditches 60 (ditch interval a) in the vane width direction of thereturn vane 50 is the distance between thecorners 70 of twoadjacent ditches 60. - As described above, in the case where one or
more ditches 60 are formed on thereturn vane 50, by arranging thecorners 70 substantially uniformly (symmetrically) in the vane width direction of thereturn vane 50, the amount of flow of the fluid G contributing to the generation of thestreamwise vortexes 80 starting thecorners 70 is substantially uniform, and the strengths of thestreamwise vortexes 80 generated downstream of thereturn vane 50 in the flow direction are uniform (seeFIG. 3A ). In addition, for the fluid G flowing along theside surface 51 of thereturn vane 50, multiple (four inFIG. 3A )streamwise vortexes 80 are generated substantially uniformly (symmetrically) in the vane width direction of thereturn vane 50, which suppresses the separation of the fluid G substantially uniformly in the vane width direction of thereturn vane 50. - In addition, in the case where
multiple ditches 60 are formed on thereturn vane 50, the lengths of the ditches 60 (ditch depth H) in the vane thickness direction of the return vane 50 (the thickness direction of the trailingedge 50 a and the right-left direction inFIG. 5A ) and the lengths of the ditches 60 (ditch length L) in the vane length direction of the return vane 50 (the flow direction and the up-down direction inFIG. 5A ) may be set individually (independently) (seeFIGS. 3A and 5A ). For example,multiple ditches 60 may have different ditch lengths L while having the same ditch depth H, ormultiple ditches 60 may have different ditch depths H while having the same ditch length L. Alternatively,multiple ditches 60 may have different ditch depths H and different ditch lengths L such that the ratio between the ditch depth H and the ditch length L is the same or different. - In this case, it is preferable that the ditch depths H and the ditch lengths L of
multiple ditches 60 be set to be a relatively changed value depending on the flow speed distribution of the fluid G flowing along theside surface 51 of thereturn vane 50. This is because the flow speed of the fluid G flowing along thereturn vane 50 is different depending on the position where the fluid G flows. Hence, depending on the position (arrangement location) of eachditch 60 formed on thereturn vane 50, the ditch depth H and the ditch length L are set to be a relatively changed value. - As illustrated in
FIG. 3A , in the case where twoditches 60 are formed on thereturn vane 50, the twoditches 60 are arranged to be symmetrical to each other in the vane width direction of the return vane, and there are streams of fluid G having the same flow speed in the peripheries of both ditches 60. Accordingly, the ditch depths H and the ditch lengths L of bothditches 60 are set to the same values. - On the other hand, as illustrated in
FIG. 3B , in the case where three ditches 60-1 and 60-2 are formed on thereturn vane 50, the three ditches 60-1 and 60-2 are arranged, one at the center in the vane width direction of thereturn vane 50 and two symmetrically on both sides thereof (on the upper side and the lower side inFIG. 3B ), and there are streams of the fluid G1 and G2 having different flow speeds in the peripheries of the ditches 60-1 and 60-2. Accordingly, the ditch depths H and the ditch lengths L1 and L2 of the ditches 60-1 and 60-2 are set in accordance with the speeds of the streams of the fluid G1 and G2 flowing in the peripheries of the ditches 60-1 and 60-2. - For example, as illustrated in
FIG. 3B , the ditch depths H of the ditches 60-1 and 60-2 are set to be equal (to the same value) while the ditch length L1 of the ditch 60-1 formed at the center in the vane width direction of thereturn vane 50, where the fluid G1 with a high flow speed flows, is set longer than the ditch length L2 of the ditches 60-2 formed on both sides in the vane width direction of thereturn vane 50, where the fluid G2 with a lower flow speed than that at the center flows. - By setting the ditch depth H and the ditch lengths L1 and L2 of the multiple ditches 60-1 and 60-2 as above, the fluid G1 with a high flow speed flows on the grooved surface 61-1, which is long in the flow direction and has a gentle inclination, at the center of the
return vane 50, and thus separation, turbulent flows, or other irregularities are unlikely to occur. On both sides thereof, the fluid G2 with a slow flow speed flows on the grooved surfaces 61-2, which are short in the flow direction and have a steep inclination, generatingstreamwise vortexes 80 strong enough to prevent separation, turbulent flows, or other irregularities. - Note that as illustrated in
FIG. 5A , when the ditch depth H of theditch 60 is set, it is set to be smaller than the vane thickness T so that theditch 60 does not pass through the trailingedge 50 a of the return vane 50 (see the following Formula (2)). -
[Math.2] -
H<T (2) - By forming the
ditches 60 on thereturn vane 50 as expressed by Formula (2) as above, the fluid G flowing along theside surface 51 of thereturn vane 50 will not flow into the opposite side surface (pressure surface) 53 side of thereturn vane 50. Accordingly, the fluid G flows being swirled by theditch 60, generating thestreamwise vortexes 80 downstream of thereturn vane 50 in the flow direction (on the lower side inFIG. 5A ) starting from thecorners 70. - Note that the vane thickness T is the width of the
rear end surface 52 of thereturn vane 50 in the case where the cross-sectional shape of the trailingedge 50 a is rectangular (seeFIG. 5A ). In the case where the cross-sectional shape of the trailingedge 50 a is circular, the vane thickness T is the maximum width of the portion where the arc Sc is tangent to the outer shape of the return vane 50 (seeFIG. 5B ). In the case where the cross-sectional shape of the trailingedge 50 a is elliptical, the vane thickness T is the maximum width of the portion where the ellipse Se is tangent to the outer shape of the return vane 50 (seeFIG. 5C ). - As illustrated in
FIGS. 3A and 4A , thecorners 70 are formed by theside surface 51 of thereturn vane 50 and thegrooved surface 61 of theditch 60, and thegrooved surface 61 is a curved surface recessed into a curved shape from theside surface 51. As a matter of course, thecorner 70 and the grooved surface 61 (ditch 60) are not limited to these embodiments, but may be of various shapes. - The
ditch 60 forming thecorners 70 may be, for example, aditch 60 formed by agrooved surface 61 grooved in to a rectangular shape from theside surface 51 of the return vane 50 (seeFIG. 4B ), or aditch 60 formed by agrooved surface 61 recessed in to a wedge shape from theside surface 51 of the return vane 50 (seeFIG. 4C ). - In addition, the
corners 70 maybe formed by, for example,protrusions 62 formed by protrudedsurfaces 63 protruding from theside surface 51 of the return vane 50 (seeFIG. 4D ). In this case, the vicinity of theprotrusion 62 may be flush with theside surface 51 of thereturn vane 50, or it may be agrooved surface 61 recessed from theside surface 51 of thereturn vane 50 as indicated by chain double-dashed lines inFIG. 4D . - By forming the
grooved surface 61 recessed from theside surface 51 of thereturn vane 50 in the vicinity of theprotrusion 62 as above, it is possible to increase the length of the protrusions 62 (protrusion heights H1 and H2) in the vane thickness direction (right-left direction inFIG. 4D ) of the return vane 50 (H1<H2), and thus possible to strengthen thestreamwise vortexes 80 generated downstream of thereturn vane 50 in the flow direction. - With any foregoing shape illustrated in
FIGS. 4A to 4D , when the fluid G flowing along theside surface 51 reaches the trailingedge 50 a of thereturn vane 50, thestreamwise vortexes 80 of the fluid are formed starting from thecorners 70 formed by providing theditches 60 or theprotrusions 62, which suppresses the separation of the fluid G from the return vane 50 (side surface 51) and also cancels thetransverse vortexes 90 generated downstream of thereturn vane 50 in the flow direction. - As described above, the shape of the
corner 70 does not have any limitation as long as the shape of thecorner 70 allows the flow of the fluid G flowing along theside surface 51 of thereturn vane 50 to change and generates thestreamwise vortexes 80 downstream of thereturn vane 50 in the flow direction. Here, as for the shape of thecorner 70 capable of easily generating astreamwise vortex 80 or generating astrong streamwise vortex 80, it is preferable that thecorner 70 have an acute angle rather than an obtuse angle, and be formed of straight lines rather than curved lines. - Descriptions will be provided for operation of a centrifugal rotary machine including return vanes according to one or more embodiments of the present invention, with reference to
FIGS. 1, 2, and 3A . - When a drive source of a non-illustrated motor or the like is driven, the rotating
shaft 12 is rotationally driven, and theimpellers 40 are rotationally driven (seeFIG. 1 ). The fluid G taken in from thesuction port 21 flows into thecompression flow path 31, is given a centrifugal force by theimpeller 40 rotating together with the rotatingshaft 12, and is sent (pumped) radially outward. - The fluid G sent out radially outward from the
compression flow path 31 flows into thediffuser flow path 32, and part of the dynamic pressure given by theimpeller 40 is converted into static pressure. The fluid G the pressure of which has been increased while passing from thecompression flow path 31 through thediffuser flow path 32 flows into thereturn flow path 33, where turning components in the flow of the fluid G are eliminated by thereturn vanes 50 and sent to thecompression flow path 31 in the next stage (seeFIGS. 1 and 2 ). - In this
return flow path 33, the flow direction of the fluid G flowing along theside surface 51 of thereturn vane 50 changes such that the fluid G is swirled by the ditches 60 (grooved surfaces 61), and thestreamwise vortexes 80 of the fluid G are generated downstream of thereturn vane 50 in the flow direction (seeFIG. 3A ). Thesestreamwise vortexes 80 suppress the separation of the fluid G from theside surface 51 and breaks thetransverse vortexes 90 similarly generated downstream of thereturn vane 50 in the flow direction. - As described above, the
centrifugal compressor 1 including thereturn vanes 50 reduces the fluid loss at thereturn vanes 50 and improves the efficiency of thecentrifugal compressor 1. - According to one or more embodiments of the invention, the corners 70 (ditches 60) are formed on one side surface (pressure surface) 51 of the
return vane 50, where the separation of the fluid G is likely to occur, to suppress the separation of the fluid G on theside surface 51. As a matter of course, the present invention is not limited to this. For example, the corners 70 (ditches 60 or protrusions 62) may be formed on the other (opposite) side surface (pressure surface) 53 of thereturn vane 50 to suppress the separation of the fluid G on theside surface 53. - One or more embodiments of the present invention relate to stationary vanes to be provided in a fluid machine and a centrifugal compressor including the stationary vanes. One or more embodiments of the present invention reduce the fluid loss at the stationary vanes and improve the efficiency of the fluid machine. Thus, one or more embodiments of the present invention can be utilized extremely usefully for various fluid machines including stationary vanes, such as centrifugal compressors, turbochargers, and pumps.
- 1 centrifugal compressor (fluid machine)
- 11 casing
- 11 a first side wall of casing
- 11 b second side wall of casing
- 12 rotating shaft
- 13 bearing
- 21 suction port
- 22 discharge port
- 30 flow path
- 31 compression flow path
- 32 diffuser flow path
- 33 return flow path
- 40 impeller
- 50 return vane (stationary vane)
- 50 a trailing edge of return vane (downstream edge in the flow direction)
- 51 side surface of return vane (suction surface)
- 52 rear end surface of return vane (downstream end in the flow direction)
- 53 side surface of return vane (pressure surface)
- 60 groove
- 61 grooved surface
- 70 corner
- 80 streamwise vortex
- 90 transverse vortex
- W groove width (width of groove)
- H groove depth (depth of groove)
- T vane thickness
- L groove length (length of groove)
- a groove interval (distance between grooves)
- C80 vortex axis of streamwise vortex
- C90 vortex axis of transverse vortex
- G fluid
- Although the disclosure has been described with respect to only a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that various other embodiments may be devised without departing from the scope of the present invention. Accordingly, the scope of the invention should be limited only by the attached claims.
Claims (6)
1. A stationary vane provided to a fluid machine, the stationary vane comprising:
a side surface exposed to a fluid and formed along a flow direction of the fluid; and
a corner formed on the side surface, wherein
the corner generates a streamwise vortex with a vortex axis extending along the flow direction of the fluid, on a downstream side in the flow direction of the fluid.
2. The stationary vane according to claim 1 , wherein the corner is formed by a ditch recessed from the side surface.
3. The stationary vane according to claim 2 , wherein
a plurality of the ditches are formed on the side surface, arranged in a direction intersecting the flow direction of the fluid, and
the ditches have different shapes depending on a speed of the fluid flowing along the side surface in a vicinity of each of the ditches.
4. A centrifugal compressor including:
a casing;
a rotating shaft rotatably supported by the casing;
an impeller provided to the rotating shaft and that is rotationally driven together with the rotating shaft; and
a flow path formed in the casing and that houses the impeller, wherein
the centrifugal compressor compresses a fluid by passing the fluid through the flow path, and
the centrifugal compressor comprises the stationary vane according to claim 1 in the flow path.
5. A centrifugal compressor including:
a casing;
a rotating shaft rotatably supported by the casing;
an impeller provided to the rotating shaft and that is rotationally driven together with the rotating shaft; and
a flow path formed in the casing and houses the impeller,
the centrifugal compressor compresses a fluid by passing the fluid through the flow path, and
the centrifugal compressor comprises the stationary vane according to claim 2 in the flow path.
6. A centrifugal compressor including:
a casing;
a rotating shaft rotatably supported by the casing;
an impeller provided to the rotating shaft and that is rotationally driven together with the rotating shaft; and
a flow path formed in the casing and houses the impeller,
the centrifugal compressor compresses a fluid by passing the fluid through the flow path, and
the centrifugal compressor comprises the stationary vane according to claim 3 in the flow path.
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JP2015-230264 | 2015-11-26 | ||
JP2015230264A JP2017096196A (en) | 2015-11-26 | 2015-11-26 | Stationary vane and centrifugal compressor including the stationary vane |
PCT/JP2016/084930 WO2017090713A1 (en) | 2015-11-26 | 2016-11-25 | Stationary vane and centrifugal compressor provided with stationary vane |
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US20180274553A1 true US20180274553A1 (en) | 2018-09-27 |
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US15/763,311 Abandoned US20180274553A1 (en) | 2015-11-26 | 2016-11-25 | Stationary vane and centrifugal compressor provided with stationary vane |
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JPS5195051A (en) * | 1975-02-14 | 1976-08-20 | 5*5*7*77 tetorakisu * suruhoniruokishimechiru * nafuto * 1**8* * shikurookutennoseizohoho | |
US4813635A (en) * | 1986-12-29 | 1989-03-21 | United Technologies Corporation | Projectile with reduced base drag |
JP4174693B2 (en) * | 1998-03-13 | 2008-11-05 | 株式会社Ihi | Centrifugal compressor diffuser |
US20050163610A1 (en) * | 2002-12-04 | 2005-07-28 | Hirotaka Higashimori | Diffuser for centrifugal compressor and method of producing the same |
JP5550319B2 (en) * | 2009-12-10 | 2014-07-16 | 三菱重工業株式会社 | Multiblade centrifugal fan and air conditioner using the same |
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WO2017090713A1 (en) | 2017-06-01 |
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