JP2012122443A - Centrifugal turbomachine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve design point performance and expand an operation range, in a centrifugal turbomachine such as a centrifugal fan, a centrifugal blower, a centrifugal compressor and a centrifugal pump.SOLUTION: In a centrifugal fluid machine 300, at least one or more impellers are installed on the same rotary shaft. On the downstream side of at least any of the impellers, a blade-attached diffuser is provided. The blade-attached diffuser is a curve element three-dimensional diffuser having wings 309c arranged at intervals in the circumferential direction on a concentric disk 309a and extending to the shroud side from the hub side of the impellers. The wings are formed by stacking reference wings in the wing height direction which is a direction of a gap between a hub and a shroud. The dihedral distribution in which moving in the direction opposite to the rotation direction of the impeller and vertical to the wing chord direction for connecting the leading edge and the trailing edge of the reference wing is set as positive movement, becomes the nonuniform distribution toward an intermediate part of a wing height from a hub side end part.

Description

  The present invention relates to a centrifugal turbomachine including a centrifugal impeller such as a centrifugal compressor, a centrifugal blower, a centrifugal fan, or a centrifugal pump.

  In a multistage centrifugal compressor which is a type of centrifugal turbomachine, a large number of impellers are attached to the same shaft, and a diffuser and a return guide vane are provided downstream of each impeller. The impeller, diffuser, and return guide vane constitute a paragraph. Here, as the diffuser, a vaneless diffuser, a vaned diffuser, a low string ratio diffuser which is a kind of vaned diffuser, and the like are used depending on the purpose and application.

  Among these diffusers, the low chord ratio ratio diffuser does not have a geometric throat, and thus has a characteristic that a choke margin that is an operating range on the large flow rate side can be expanded. At the same time, in the small flow rate region, the blade surface separation is suppressed by the boundary layer sweeping effect on the blade surface due to the secondary flow, so that the surge margin that is the operating range on the small flow rate side can be sufficiently secured. have. For this reason, a low-string ratio diffuser is frequently used.

  A two-dimensional blade in which the same airfoil is stacked in the height direction of the blade is generally used for a diffuser with a blade for centrifugal turbomachines represented by a small chord ratio diffuser. However, due to the demand for further performance improvement, three-dimensional blades have also been attempted. For example, in the centrifugal compressor described in Patent Document 1, the difference angle of the cross section of the diffuser blades is gradually changed in the height direction of the diffuser. The wing is designed to achieve both high efficiency and a wide operating range by realizing collisionless inflow for non-uniformly distributed inflow.

  Further, in the centrifugal compressor described in Patent Document 2, the central portion of the blade height is curved in the downstream direction at the front edge portion of the diffuser to change the diffuser inlet diameter. This realizes collisionless inflow with respect to the non-uniformly distributed inflow, thereby achieving both high efficiency and a wide operating range.

Special table 2009-504974 JP 2004-92482 A

  In the blade type diffuser for a centrifugal compressor described in Patent Document 1, when forming a three-dimensional diffuser blade, the diffuser blade is virtually divided into a plurality of axial directions (directions from the hub surface toward the shroud surface). It is described that they are stacked. At that time, a bow diffuser blade has been suggested in which the lean angle, which is the angle formed by the blade stacking direction with respect to the direction perpendicular to the hub surface or the shroud surface, is changed along the span of the diffuser blade.

  However, there are many choices for curved element blades, and it is not always a sufficient improvement according to the authors' consideration. In other words, when applying a lean distribution to a wing, the secondary flow may be increased depending on how it is given, which may lead to performance degradation. Therefore, there is a need to clarify the stacking pattern of the divided wings, which leads to improved performance. .

  Further, in the centrifugal compressor disclosed in Patent Document 2, the inflow angle is matched by applying a lean to a local portion called the diffuser leading edge, but the configuration of the curve element diffuser is not adopted, and the curve There is no consideration for controlling the secondary flow of the flow path between the diffuser blades that becomes noticeable when the element diffuser is employed.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems of the prior art, and the object thereof is a secondary flow between blades in a bladed diffuser used in a centrifugal turbomachine when a curved element diffuser is used to improve efficiency. Is to effectively suppress the performance and improve the performance. Another object of the present invention is to obtain a stacking pattern of divided blades for improving performance in such a curved element diffuser used in a centrifugal compressor.

  First, some terms used in this specification are defined as follows with reference to FIGS. FIG. 1 is a plan view of one diffuser blade for explaining the movement of an airfoil, and FIG. 2 is a perspective view showing one blade of a diffuser with blades taken out. It is a figure which shows a mode that it accumulates in a direction. The coordinate system is a cylindrical coordinate system (R, θ, Z) in which the radial direction of the impeller is R, the rotational direction of the impeller is θ, and the axial direction of the rotation shaft is Z. Z is positive in the direction from the shroud 102 side toward the hub 101 side.

Chord (C): A line connecting the leading edge 208 and the trailing edge 209 in the airfoil 104 as a reference of the diffuser blade 103.
Lean: Degree of inclination of the diffuser blade 103 with respect to the hub 101 surface, which can be regarded as a combination of sweep and dihedral described below.
Stagger angle (θ _SG ): Angle formed by the chord C and the radial direction (R direction) (tan θ _SG = dC / dR).
Sweep (Δσ): In the case represented by the one-dot chain line in FIG. 1, the case where the airfoil 104 of the diffuser blade 103 is moved in the chord C direction and moved downstream is defined as positive.
Dihedral (Δδ): In the case represented by a broken line in FIG. 1, the airfoil 104 of the diffuser blade 103 is moved in a direction perpendicular to the chord C. The case where the impeller is moved in the direction opposite to the rotation direction is positive.

  Blade height (h): The height of the diffuser blade measured from the hub surface side. When the hub surface and the shroud surface are parallel walls perpendicular to the axis, the height is in the −Z direction. If at least one of the hub surface and the shroud surface is an inclined surface, the height from the line connecting the leading edge and the trailing edge on the hub side of the diffuser blade is set. The height of the middle point in the flow direction between the leading edge and trailing edge, with reference to the line connecting the hub edge of the diffuser blade and the leading edge of the shroud and the line connecting the hub edge of the diffuser blade and the trailing edge of the shroud To decide. The total height of the wing is represented by H.

  In order to solve the above problems, the present invention uses such a definition to include a hub, a shroud, and a plurality of blades arranged at intervals in the circumferential direction between the hub and the shroud on the same rotating shaft. In a centrifugal turbomachine equipped with at least one impeller and having a vaned diffuser downstream of at least one of the at least one impeller, the vaned diffuser is formed on the downstream side of the impeller. A plurality of blades are arranged in the flow path at intervals in the circumferential direction, and each blade has a shape in which the reference blades are stacked in the blade height direction, which is the axial direction of the rotating shaft. Dihedral distribution with positive movement to move in the direction perpendicular to the chord direction connecting the leading edge and trailing edge of the reference wing and opposite to the rotation direction of the impeller The hub wall It is characterized in that it has a non-uniform towards the intermediate portion of the blade height from the hub-side end portion on the side.

  In this feature, the dihedral distribution of each of the diffuser blades is a distribution that increases from the hub side end portion toward the middle portion of the blade height, and each of the diffuser blades is the leading edge portion of the hub side end portion. It is preferable that an imaginary plane and the suction surface of the diffuser blade form an obtuse angle.

  Further, the dihedral distribution is a distribution that increases from the shroud side end toward the middle part of the blade height, and each of the diffuser blades is a plane that is virtually formed at the front edge of the shroud side end. It is preferable to make an obtuse angle with the suction surface of the diffuser blade.

  In the above feature, the dihedral distribution of each diffuser blade is a distribution that decreases from the end on the hub side to the middle portion of the blade height, and is parallel to the chord direction of the reference blade and downstream. The sweep distribution in which the movement is a positive movement may be a distribution that decreases from the hub side end toward the middle of the blade height.

  In any of the above features, each of the diffuser blades preferably has at least one of the dihedral distribution and the sweep distribution applied to at least the first half of the flow direction of the blade.

  According to the present invention, in a diffuser with blades used in a centrifugal turbomachine, a curved element three-dimensional blade is applied to a diffuser blade, and a flow distribution loss to the diffuser blade is reduced by giving a sweep distribution and a dihedral distribution. In addition, since the flow in the blade intermediate part can be controlled, the secondary flow between the blades can be effectively suppressed to improve the diffuser performance and the compressor performance. Furthermore, in the present invention, in such a curved element diffuser used for a centrifugal compressor, it was possible to obtain a stacking pattern of divided blades that led to an improvement in performance.

It is a figure explaining the inclination in a diffuser with a blade | wing. It is a figure explaining three-dimensionalization of the wing | blade which a diffuser with a blade | wing has. 1 is a longitudinal sectional view of an embodiment of a centrifugal turbomachine according to the present invention. It is a figure explaining the classification | category of a diffuser with a blade | wing. It is a figure which shows the dihedral distribution of one Example of the diffuser which the compressor shown in FIG. 3 has. FIG. 6 is a perspective view and a partially enlarged view of a diffuser having a dihedral distribution shown in FIG. 5. It is a figure which shows the dihedral distribution of the other Example of the diffuser which the compressor shown in FIG. 3 has. FIG. 8 is a perspective view of a diffuser having a dihedral distribution shown in FIG. 7 and a partially enlarged view thereof. It is a figure which shows the dihedral distribution and sweep distribution of further another Example of the diffuser which the compressor shown in FIG. 3 has. FIG. 10 is a perspective view of a diffuser having a dihedral distribution and a sweep distribution shown in FIG. 9 and a partially enlarged view thereof. It is a figure which shows an example of the performance diagram in the centrifugal compressor provided with the diffuser which concerns on this invention.

  Hereinafter, some embodiments of the present invention will be described with reference to the drawings. First, a multistage centrifugal compressor 300 as an example of a centrifugal turbomachine will be described with reference to a longitudinal sectional view of FIG. The multistage centrifugal compressor 300 is a two-stage centrifugal compressor. The subject of the present invention may be a single-stage or multi-stage centrifugal turbomachine, and is not particularly limited to a two-stage compressor.

  The multistage centrifugal compressor 300 shown in FIG. 3 is a two-stage compressor including a first stage 301 and a second stage 302. The first stage impeller 308 and the second stage impeller 311 are attached to the same rotating shaft 303 to constitute a rotating body. The rotary shaft 303 is rotatably supported by a journal bearing 304 and a thrust bearing 305 attached to a compressor casing 306 that houses the rotary shaft 303 and the impellers 308 and 311.

  On the downstream side of the first stage impeller 308, a diffuser 309 that recovers the pressure of the working gas compressed by the impeller 308 to form a radially outward flow, and a working gas that is made radially outward by the diffuser 309. A return guide vane 310 is arranged to guide the second flow impeller 311 inward in the radial direction. Similarly, downstream of the two-stage impeller 311, a diffuser 312 and a collecting means 313 called a collector or a scroll for collectively sending the working gas whose pressure has been increased by the two-stage diffuser 312 to the outside of the apparatus are arranged.

  The impellers 308 and 311 at each stage have a plurality of blades 308c and 311c arranged at substantially equal intervals in the circumferential direction between the core plates 308a and 311a and the side plates 308b and 311b and the core plates 308a and 311a and the side plates 308b and 311b. And have. A suction labyrinth seal 315 is disposed on the outer peripheral portion of the impellers 308 and 311 on the side plate 308b and 311b side, and shaft seals 316 and 317 are disposed on the back side of the core plates 308a and 311a. The working gas flowing in from the suction nozzle 307 passes through the first stage impeller 308, the vaned diffuser 309, the return guide vane 310, the second stage impeller 311, and the vaned diffuser 312 in this order, and a collecting means such as a collector and a scroll. Guided to 313 without leaking.

  The diffusers 309 and 312 used in the centrifugal compressor 300 configured as described above will be described in detail below. The diffuser 309 is attached to a diaphragm constituting a part of the compressor casing 306, and a hub 309 a whose flow path surface is substantially in the same axial position as the flow path surface of the impeller 308, and a surface around the hub 309. And a plurality of wings 309c erected at intervals in the direction. And the wall surface of the inner casing which comprises a part of compressor casing 306 forms a flow path as a shroud surface. Although explanation is omitted, the diffuser 312 has the same configuration. In the present embodiment, the above configuration will be described. However, the configuration of the diffuser is not limited to this, and a configuration in which the diffuser is separated from the diaphragm is included in the present invention.

FIG. 4 shows the vaned diffuser 400 used for the following description in a classified manner. FIG. 4A is a cross-sectional view of the diffuser 400. A plurality of diffuser blades 420a are erected on the hub plate 410a at substantially equal intervals in the circumferential direction. A flow exiting an impeller (not shown) is guided to flow along the blade 420a from the inner peripheral side as indicated by an arrow FL in the figure. Rotational direction of the impeller (not shown) this time is the direction of the arrow R _N.

  The shape of the diffuser is represented by a conventionally used two-dimensional diffuser (FIG. 4 (b)), a linear element having a lean three-dimensional diffuser (FIG. 4 (c)), and a set of curved elements having the same lean. The curved element is classified into a three-dimensional diffuser (FIG. 4D). Here, each of the diffuser blades 420b to 420d is represented as a shape in which the contours of the hub plate side cross sections 421b to 421d and the contours of the shroud side cross sections 422b to 422d are connected by line elements 423b to 423d. The same flow is discharged from the impeller to each of the diffuser blades 420b to 420d to form a diffuser inlet flow 402.

  The linear element two-dimensional diffuser blade 420b shown in FIG. 4B is a two-dimensional diffuser composed of non-inclined linear elements 423b that stack the same airfoil straight in the height direction of the blade 420b. That is, the linear element 423b is perpendicular to the hub plate 410a. In a diffuser having such a blade 420b, it is possible to prevent the flow from colliding with the blade 420b at any height direction (h direction) position of the leading edge of the blade 420b when the inflow flow 402 is distributed. However, there is a limit to high performance.

In the linear element three-dimensional diffuser shown in FIG. 4C, the difference angle (θ _SG ) is changed to give a twist to the diffuser blade 420c. As a result, the flow exiting the impeller can flow in without colliding with the diffuser blade 420c. That is, even if a non-uniform flow is discharged from the impeller, the front edge portion of the diffuser blade 420c can have a blade 420c shape corresponding to the inflow flow 402.

  In this linear element three-dimensional diffuser blade 420c, the linear element 423c that connects the contour of the hub plate side section 421c and the contour of the shroud side section 422c is a straight line, and the lean distribution in the height direction (h direction) of the blade 420c is also a straight line. Is. However, the line element 423c is not necessarily perpendicular to the hub surface 410a. After the flow flows between the blades 420c and 420c, the airfoil shape of the blade 420c is basically formed by, for example, a NACA blade, and therefore cannot be changed to a value corresponding to the flow angle. Therefore, although an improvement in efficiency can be expected as compared with the two-dimensional diffuser, it is difficult to sufficiently control the flow.

  In the curved element three-dimensional diffuser shown in FIG. 4D, the airfoils are stacked along an arbitrary curved element 423d. That is, the curved element 423d that connects the outline of the hub plate side section 421d and the outline of the shroud side section 422d is a curve. In this diffuser, the lean angle is varied in the height direction (h direction) of the blade 420d. Therefore, the curved element three-dimensional diffuser can not only realize collisionless inflow at the leading edge of the blade 420d, but also can change the direction of operation of the blade force by curving the flow path surface of the blade 420d.

  Therefore, it is possible to control the flow in the flow path between the blades 420d and 420d. Therefore, in the present invention, as shown in FIG. 3, the vaned diffusers 309 and 312 that collect the dynamic pressure at the outlets of the impellers 308 and 311 as static pressures are formed into a three-dimensional curved element.

  By the way, various methods are conceivable for making the diffuser three-dimensional. If the above-described dihedral and sweep are used, three-dimensionalization can be handled systematically. Therefore, a specific example of a curved element three-dimensional diffuser represented by using a dihedral and a sweep will be described with reference to FIGS. In the following description, the first-stage diffuser 309 will be described as an example, but the second-stage and subsequent diffusers can be handled in the same manner.

  An example of a curved element three-dimensional diffuser will be described with reference to FIGS. Only the dihedral distribution is shown. FIG. 5 is a diagram showing a dihedral distribution with respect to the blade height direction (h direction) of the blade 620. The amount of the die helical (Δδ) is dimensionless by the chord length (C), and the blade height is dimensionless at the total height H. It has become. 6A and 6B are perspective views of the diffuser 600 having the dihedral distribution of FIG. 5, in which FIG. 6A is an overall perspective view, FIG. 6B is a detailed view of a portion C of FIG. 5A, and FIG. (A) is the D section detailed drawing of figure (a). The diffuser plate 610 is attached to the hub side of the impeller.

  As shown in FIG. 5, in this embodiment, the die heddle increases in the blade height direction in the vicinity of the hub side end face (h = 0) (see a circle 501). That is, the negative pressure surface 601 of the diffuser blade 620 forms an obtuse angle with the hub surface 603. The negative pressure surface of the diffuser blade 620 is a blade surface on the back side with respect to the rotation direction of the impeller.

  According to the studies by the present inventors, in the dihedral distribution shown in FIG. 5, the influence of the dihedral distribution and the sweep distribution on the performance is generally small in a portion other than the rounded portion 501, that is, the vicinity of the hub side end surface 501. . Therefore, the part other than the hub side end face vicinity 501 can set the die-hedra distribution and the sweep distribution in consideration of the workability and handleability of the blade 309c.

  As shown in FIG. 6B, in the diffuser 600 of the present embodiment, a blade force component 602 is generated in the blade height direction. The blade force component 602 has an effect of pushing back the secondary flow because the boundary layer on the hub surface 603 is in the opposite direction to the secondary flow that tries to go around the hub-side negative pressure surface 601. Therefore, according to the present embodiment, the secondary flow is suppressed, the flow distribution between the blades is made uniform, and the diffuser performance is improved.

  Another embodiment of the present invention will be described with reference to FIGS. These drawings are the same as those in the above embodiment, FIG. 7 is a dihedral distribution diagram, and FIG. 8 is a perspective view of the diffuser 800 having the dihedral distribution shown in FIG. 8A is a perspective view of the entire diffuser 800, FIG. 8B is a detailed view of an E portion of FIG. 8A, and FIG. 8C is a detailed view of an F portion of FIG. 8A. . Also in this diffuser 800, the diffuser plate 810 is attached to the hub side of the impeller. It differs from the above embodiment in that the die heddle is reduced in the blade height direction in the vicinity of the shroud side end face (circled 702).

  In the above embodiment, the influence of the dihedral distribution is large on the hub surface side, but it has been found that the dihedral distribution on the shroud surface side also affects the diffuser depending on the flow flowing out of the impeller. Even in this case, the shroud-side dihedral distribution needs to be the same as in the above embodiment. A specific example will be described below.

  On the hub side end face, the die helical amount (Δδ) is increased in the blade height direction (h direction) as in the above-described embodiment (see a circle 701). Also in this embodiment, the sensitivity given to the performance by the dihedral distribution and the sweep distribution in the center region in the blade height direction excluding the two regions near the hub side end surface and the shroud side end surface was small. That is, in the vicinity of both end surfaces on the hub side and the shroud side, the angle formed between the suction surfaces 801 and 802 of the diffuser blade 820 and the hub end surface and the shroud end surface is an obtuse angle. The flow can be suppressed.

  When the impeller outlet flow is relatively uniform, the distribution shown in FIG. 7 should be used. On the other hand, when the non-uniformity is strong, the distribution shown in FIG. 5 should be used. This is because the diffuser blade 820 is affected by the uniformity of the impeller exit flow. In other words, if the non-uniformity of the impeller exit flow is strong, if the flow on the hub surface side where the main flow exists is controlled intensively, the high-energy part in the flow is controlled, so the entire flow is effectively Can be controlled.

  Still another embodiment of the present invention will be described with reference to FIGS. FIG. 9A is a dihedral distribution diagram, and FIG. 9B is a sweep distribution diagram that is dimensionless by the chord length. 10 is a perspective view of the diffuser 309 having the distribution shown in FIG. 9, where FIG. 10A is an overall view of the diffuser, FIG. 10B is a detailed view of the G portion of FIG. 9A, and FIG. c) is a detailed view of a portion H in FIG. As in the above embodiments, the hub plate 1010 is attached to the hub side of the impeller.

  In the above two embodiments, the hub-side dihedral distribution is important, and increasing in the blade height direction is effective from the viewpoint of flow control, but the dihedral distribution in the blade height direction is reduced. Even in this case, it has been found that the effect may be obtained by combining with the sweep. A specific example will be described below.

  As shown in FIG. 9, in this embodiment, the die heddle is reduced in the blade height direction in the vicinity of the hub side end surface (see the circled box 901), and the sweep is performed in the vicinity of the same hub side end surface (see the circled box 902). It is decreased by. That is, the diffuser 1000 is a lean combined with a dihedral and a sweep, and uses a three-dimensional curve element. Since the sensitivity to performance was small in a region other than the vicinity of the hub side end face, any of the dihedral and the sweep can be arbitrarily determined within a range where no extreme change occurs.

  In the present embodiment, the direction of the die heddle on the end surface on the hub side is opposite to that of the above-described embodiments. As a result, the angle formed by the surface of the hub plate 1010 and the diffuser negative pressure surface 1001 becomes an acute angle, and a blade force opposite to the blade force 601 shown in FIG. 6 is generated. The reverse wing force seems to increase the secondary flow at first glance, but actually acts to suppress the secondary flow. The reason is as follows.

  In this embodiment, a diffuser blade 1020 is configured by combining a die heddle and a sweep. Since the diffuser blade 1020 has the sweep 1002, a notch-shaped gap 1003 is formed between the front edge 1005 of the diffuser blade 1020 and the surface of the hub plate 1010. In this notch-shaped gap 1003, a flow that wraps around from the pressure surface of the diffuser blade 1020 to the suction surface is generated, and a vertical vortex 1004 is generated. At the corner portion formed by the suction surface of the diffuser blade 1020 and the surface of the hub plate 1010, a vorticity 1006 that suppresses the secondary flow is generated. At the same time, the blade surface separation at the diffuser blade 1020 is suppressed by the promotion of stirring with the surrounding fluid and the negative pressure effect at the center of the vortex. Thus, the secondary flow is suppressed by the action of the vertical vortex, the flow field is made uniform, and the performance of the curved element three-dimensional diffuser is improved.

FIG. 11 shows how the performance of the compressor is improved when the curved element three-dimensional diffuser shown in the present embodiment is used for the compressor using the linear element two-dimensional diffuser. The horizontal axis of the graph is the flow rate Q made dimensionless by the design point flow rate Qdes, and the vertical axis is the adiabatic efficiency η of the compressor stage made dimensionless by _2DIM and the pressure coefficient ψ of the two-dimensional diffuser. _This is the pressure coefficient ψ made dimensionless by _2DIM .

  In addition to the design flow rate, the heat insulation efficiency η and the pressure coefficient ψ are improved over a wide flow rate range. Further, since the performance improvement amount increases with increasing distance from the design point flow rate (Q = 1.0), the vaned diffuser according to the present invention is superior in performance at the non-design point (Q ≠ 1.0). That is, the operating range of the compressor is improved.

  In each of the above embodiments, the curved element three-dimensional diffuser is realized by having at least one of the sweep distribution and the dihedral distribution in the diffuser blade. The secondary flow near the hub wall surface and shroud wall surface of the diffuser and the collision flow near the front edge of the diffuser blade are controlled by the method of tilting these diffuser blades. As a result, the performance of the diffuser can be improved. In addition, the sweep distribution and the dihedral distribution shown in each of the above-described examples are merely exemplary, and both distributions regarding a part that is not limited in shape because the sensitivity to performance is small are also illustrated. Not too much.

  Furthermore, it is desirable that the characteristics of the shape shown in each embodiment be in the entire blade. However, since the shape of the first half (upstream side) of the diffuser blade has a relatively large influence on the performance, the flow of the diffuser is particularly important. Even if it has the shape described above only in the first half of the direction, the effect of the present invention can be obtained. Therefore, it is possible to use a linear element two-dimensional diffuser or the like frequently used in the latter half of the flow direction.

  In each of the above embodiments, the diffuser blades are provided on the hub plate. However, it goes without saying that the diffuser blades may be provided on the plate facing the hub plate, that is, on the shroud surface. In any case, it is attached to either the hub side or the shroud side for ease of assembly. Further, it is not necessary to provide a vaned diffuser in all of the multistage machines, and if the vaned diffuser is provided in at least one compressor stage and the present invention is applied to the diffuser, the effects of the present invention can be obtained.

DESCRIPTION OF SYMBOLS 101 ... Hub, 102 ... Shroud, 103 ... Diffuser blade | wing, 104 ... Airfoil type, 105 ... Diffuser board, 208 ... Leading edge, 209 ... Trailing edge, 300 ... Centrifugal turbomachine (multistage centrifugal compressor), 301 ... First stage, 302 ... Second stage, 303 ... Rotating shaft, 304 ... Journal bearing, 305 ... Thrust bearing, 306 ... Compressor casing, 307 ... Suction nozzle, 308 ... First stage impeller, 308a ... Hub, 308b ... Shroud, 308c ... Vane, 309 ... Diffuser with blade, 309a ... Hub, 309c ... Wing, 310 ... Return guide vane, 311 ... Second stage impeller, 311a ... Hub, 311b ... Shroud, 311c ... Blade, 312 ... Diffuser with blade, 313 ... Recovery means (Scroll or collector), 315 ... labyrinth seal, 316 317: Shaft seal, 400 ... Diffuser with blades, 401 ... Linear element, 402 ... Inflow, 403 ... Hub side blade section, 404 ... Shroud side blade section, 405 ... Linear element, 407 ... Hub side blade section, 408 ... Shroud side blade section, 409 ... curve element, 410 ... hub plate, 411 ... hub side blade cross section, 412 ... shroud side blade cross section, 420a-420d ... diffuser blade, 421b-421d ... hub surface, 422b-422d ... shroud surface, 423b-423d ... wire element, 501: Dihedral distribution, 600: Diffuser with blades, 601 ... Hub-side negative pressure surface, 602 ... Blade force component, 603 ... Hub surface, 610 ... Hub plate, 620 ... Blade, 701 ... Dihedral distribution, 702 ... Dihedral distribution, 800 ... Diffuser with blades, 801 ... Hub side negative pressure surface, 80 ... Shroud side suction surface, 810 ... Hub surface, 820 ... Wings, 901 ... Dihedral distribution, 902 ... Sweep distribution, 1000 ... Diffener with blades, 1001 ... Hub side suction surface, 1002 ... Sweep, 1003 ... Notch, 1004 ... Vertical eddy, 1005 ... diffuser leading edge, 1006 ... vorticity, 1010 ... hub plate, 1020 ... wing, C ... chord, FL ... incoming flows, h ... diffuser blade height, H ... diffuser vanes full height, R N _... blade Rotating direction of the vehicle, Δδ: Dihedral amount, Δσ ... Sweep amount, Q ... Flow rate, Qdes ... Design point flow rate, η ... Adiabatic efficiency, _η2DIM ... Efficiency of two-dimensional blade diffuser, ψ ... Pressure coefficient, _ψ2DIM ... Two-dimensional The pressure coefficient of the wing diffuser.

Claims (7)

At least one impeller comprising a hub, a shroud, and a plurality of blades spaced circumferentially between the hub and the shroud is attached to the same rotating shaft, and at least one of the at least one impeller In a centrifugal turbomachine with a vaned diffuser on either downstream,
The vaned diffuser is configured such that a plurality of blades are arranged at intervals in a circumferential direction in a flow path formed on the downstream side of the impeller, and each of the blades rotates a reference blade. It is formed in a shape stacked in the blade height direction which is the axial direction of the shaft, and is the direction perpendicular to the chord direction connecting the leading edge and the trailing edge of the reference blade, and the rotation direction of the impeller A centrifugal turbomachine characterized in that a dihedral distribution in which the movement in the opposite direction is a positive movement is non-uniform from the hub side end toward the middle of the blade height on the hub wall surface side.   2. The centrifugal turbomachine according to claim 1, wherein the dihedral distribution of each of the diffuser blades is a distribution that increases from a hub side end portion toward an intermediate portion of the blade height.   3. The centrifugal mold according to claim 2, wherein each of the diffuser blades has an obtuse angle between a plane virtually formed at a front end portion of the diffuser blade and at a hub side end portion and a suction surface of the diffuser blade. Turbo machine.   4. The distribution according to claim 3, wherein the dihedral distribution is a distribution that increases from a shroud side end toward an intermediate portion of the blade height and from a hub side end toward an intermediate portion of the blade height. Centrifugal turbomachine.   In each of the diffuser blades, the angle formed by the plane formed virtually at the leading edge of the shroud side end and the suction surface of the diffuser blade and the angle formed by the hub plate and the suction surface of the diffuser blade are The centrifugal turbomachine according to claim 4, wherein the centrifugal turbomachine has an obtuse angle.   The dihedral distribution of each of the diffuser blades is a distribution that decreases from the hub side end portion toward the middle portion of the blade height, and is moved in a direction parallel to the chord direction of the reference blade and moved downstream. 2. The centrifugal turbomachine according to claim 1, wherein a sweep distribution with a positive movement is reduced from the hub side end toward an intermediate portion of the blade height.   7. The diffuser blade according to claim 1, wherein at least one of the dihedral distribution and the sweep distribution is applied to at least a first half portion in the flow direction of the blade. 8. Centrifugal turbomachine.

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