CENTRIFUGAL COMPRESSOR

Abstract

A centrifugal compressor having a stator which is designed as an inlet stator, in particular for a compressor, with at least one vane having a vane airfoil around which a fluid can flow, with a plurality of vanes arranged in the form of a ring, with an adjustment device for adjusting the vane, wherein a curvature of a profile center line of the vane airfoil has at least one inflection point.

Claims

1.-11. (canceled)

12. A centrifugal compressor, comprising: a stator which is designed as an inlet stator, at least one vane having a vane airfoil around which a fluid can flow, a plurality of vanes arranged in the form of a ring, an adjustment device for adjusting the vane, wherein a curvature of a profile center line of the vane airfoil has at least one inflection point.

13. The centrifugal compressor as claimed in claim 12, wherein the curvature of the profile center line of the vane airfoil has one inflection point or two points of inflection.

14. The centrifugal compressor as claimed in claim 12, wherein a number of points of inflection and/or a position of the at least one inflection point and/or a magnitude and/or a course of the curvature is/are dependent on an aerodynamic specification.

15. The centrifugal compressor as claimed in claim 12, wherein the vane airfoil is designed such that a profile depth of the vane airfoil changes over the span of the latter.

16. The centrifugal compressor as claimed in claim 12, wherein the vane airfoil is designed such that a profile thickness changes along with the profile depth that changes over the span of the vane airfoil.

17. The centrifugal compressor as claimed in claim 16, wherein the profile thickness changes according to the change in profile depth.

18. The centrifugal compressor as claimed in claim 13, wherein the curvature of the profile center line of the vane airfoil has one inflection point forming a reflexed camber profile.

19. The centrifugal compressor as claimed in claim 14, wherein the an aerodynamic specification comprises incident flow conditions of the vane airfoil that are to be determined.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In the drawings:

[0046] FIG. 1 is a diagram of an inlet stator for a turbomachine;

[0047] FIG. 2 is a diagram of an adjustable vane for an inlet stator;

[0048] FIG. 3 is a diagram of a profile of an adjustable vane for an inlet stator (profile section III-III).

DETAILED DESCRIPTION OF INVENTION

[0049] Exemplary embodiment: profiling of guide vanes of stators in turbomachinery, in particular of inlet stators for compressors

[0050] FIG. 1 is a cutaway view of a multi-shaft geared compressor 10, for example for air fractionation, having a (first) compressor stage 15 arranged in a volute casing 14.

[0051] Arranged axially upstream of this (first) compressor stage 15, or of its impeller 27, at an axial inlet 16 of this volute casing 14 as shown in FIG. 1, there is an inlet stator 1 (or Inlet Guide Vane).

[0052] As also shown in FIG. 1, the inlet stator 1 has a multiplicity of guide vanes 4 (cf. FIG. 2, FIG. 3) that are arranged in a ring shape and have adjustable, profiled vane airfoils 3 (stator ring 13, inlet stator wheel 13).

[0053] The geared compressor 10 is controlled, inter alia, by means of the adjustable inlet stator 1, that is to say by adjusting the vanes 4 or their vane airfoils 3 (using an adjustment mechanism 12), which changes—depending on the angle of attack of the vanes 4 or of the vane airfoils 3 of the inlet stator wheel 13—the flow of process gas 2 onto, around and from the vane airfoils 3 of the inlet stator 1 and consequently the flow of process gas 2 into or onto the (first) compressor stage 15, or the impeller 27 thereof.

[0054] In order to avoid, even in the case of high angles of attack, for example greater than 15°, or over a large adjustment range, flow losses at the vanes 4 or vane airfoils 3 (as a consequence of a fluid flow/process gas flow that no longer follows the profile contour 17 of the vane airfoils 3, or as a consequence of the fluid flow/process gas flow separating from the vane airfoils 3), the vane airfoils 3 have, as illustrated in particular in FIG. 3, a special profile 23, i.e. in this case a reflexed camber profile 23 (with a simple “S shape”).

[0055] FIG. 2 shows a/the adjustable vane 4 of the inlet stator wheel 13 of the inlet stator 1 of the geared compressor 10, this vane representing all of the (accordingly formed) vanes 4 of the inlet stator wheel 13 of the inlet stator 1.

[0056] As shown in FIG. 2, the adjustable vane 4 has the profiled vane airfoil 3, which can be (angularly) adjusted by means of the adjustment mechanism 12 which is represented here only by way of indication by a connecting shaft 18, or a peg 24 and plate 25.

[0057] As also shown in FIG. 2, the vane airfoil 3 is essentially trapezoidal in terms of its outer dimensions, that is to say that the profile depth 8 decreases continuously over the span 9 of the vane airfoil 3 (the extent of the vane airfoil 3 from its vane airfoil root 19 to its free vane airfoil end 20).

[0058] Thus, in clear and simple terms, the vane airfoil 3 changes, and in this case reduces, its profile depth 8 between its vane airfoil root 19 and its free vane airfoil end 20, that is to say over its span 9.

[0059] In accordance with this decreasing profile depth 8 (from the vane airfoil root 19 to the vane airfoil end 20, or over the span 9), the entire vane airfoil 3 scales with or in its (reflexed camber) profile 23.

[0060] That is to say that the profile thickness 11 (accordingly also the maximum profile thickness) (also) decreases over the span 9 of the vane airfoil 3, in accordance with the decreasing profile depth 8. The relative maximum profile thickness (here, the maximum profile thickness is relative to the profile depth 8) and the maximum profile curvature and relative maximum profile curvature (here, the maximum profile curvature is relative to the profile depth 8) remain unchanged over the span 9 of the vane airfoil 3.

[0061] FIG. 3 shows the (flow line) profile section, denoted by the section III-III (in FIG. 2), through the vane airfoil 3 of the vane 4 of the stator wheel 13 of the inlet stator 1, for short the profile 23 of the vane airfoil 3.

[0062] As shown in FIG. 3, the vane airfoil 3, or its profile 23, forms a reflexed camber profile 23 (with simply “reflexed camber”), with a (simply) “S-shaped” curved profile center line 6 or camber line 6.

[0063] That is to say that the (“S-shaped”) curvature 5 of the profile center line/camber line 6 of the vane airfoil 3 has, in this case, exactly one inflection point 7, wherein in the forward region of the profile 23, that is to say in the region of the leading edge 21 of the vane airfoil 3, the profile center line/camber line 6 faces downward in an “S shape”, and faces upward in an “S shape” in the rear region of the profile 23, that is to say in the region of the trailing edge 22 of the vane airfoil 3.

[0064] In that context, the flow around the profile 23 is also dependent on (or is in particular also influenced by) a shape of the “S-shaped course”, or of the “reflexed camber” of the profile 23, that is to say, among other things, on the course and the magnitude of the curvature 5 and on the position of the inflection point 7 (in this case one but otherwise also a number of inflection points) (inflection point position 28 (the distance between the leading edge 21 of the vane airfoil 3 and the inflection point 7 as projected onto the chord 26 of the vane airfoil 3 (the chord 26 is the straight line connecting the leading edge 21 and the trailing edge 22 of the profile 23)).

[0065] The shape of the “reflexed camber” profile 23 of the vane airfoil 3 (by means of which it is possible to influence the flow conditions at the vane airfoil 3) is then dependent on the aerodynamic specification of the inlet stator 1 (optimization to the aerodynamic specification (or the operating point)), in particular of incident flow conditions of the vane airfoil 3 and/or of the impeller 27 of the (first) compressor stage 15 (at the operating point) that are to be determined.

[0066] If—as is the case here by way of example—a (design) angle of attack of the vanes 4 of the inlet stator 1 of approximately 15° is provided for the operating or design point of the compressor 10, then the “reflexed camber” profile 23, or its shape, is optimized for flow conditions there (incident flow on the vane airfoil 3 at this (design) angle of attack) such that the flow leaves the vane airfoil 3—at this assumed (design) angle of attack—with a certain, predefined swirl (with respect to the impeller 27), but wherein the flow around the vane airfoil 3 (at this assumed (design) angle of attack) does not separate or takes place with small flow losses.

[0067] As shown in FIG. 3, in this case—under known aspects—the “reflexed camber” profile 23 has only a weak “reflexed camber” (that is to say only one inflection point 7 with weak curvature 5 (“upward and downward”)) with a slender profile thickness 11. The inflection point position 28 of the inflection point 7 of the “reflexed camber” or of the “reflexed camber” profile 23 of the vane airfoil 3 is slightly to the rear, i.e. in the direction of the profile trailing edge 22, of the center of the chord 26.

[0068] Although the invention has been described and illustrated in detail by way of the preferred exemplary embodiment(s), the invention is not restricted by the disclosed examples and other variations can be derived herefrom by a person skilled in the art without departing from the scope of protection of the invention.