Blade cascade and turbomachine

Abstract

A blade cascade of a turbomachine whose at least one side wall is configured to be circumferentially undulated and which has at least two elevations and at least one depression or at least two depressions having at least one elevation, as well as a turbomachine having a blade cascade of this kind.

Claims

1. A blade cascade of a turbomachine comprising: a plurality of blade channels each circumferentially bounded by a pressure side of a blade and by an opposite suction side of an adjacent blade, each blade channel radially bounded by two opposing side walls, at least one of the two side walls of the blade channels being provided with a side-wall contour, the side-wall contour being circumferentially undulated and comprising at least two elevations relative to a non-contoured surface of the at least one of the two side walls and at least one depression relative to the non-contoured surface of the at least one of the two side walls; wherein the amplitudes of the elevations differ from one another; and wherein a plurality of depressions merge into the at least one depression.

2. The blade cascade as recited in claim 1 wherein the side-wall contour extends to a downstream side-wall edge.

3. The blade cascade as recited in claim 1 wherein the elevations and the at least one depression having widths that vary circumferentially or lengths that differ in the direction of flow.

4. The blade cascade as recited in claim 1 wherein the elevations and the at least one depression have amplitudes that vary in the direction of flow.

5. The blade cascade as recited in claim 1 wherein a pressure side-proximal elevation has a greater amplitude than a pressure side-distal elevation.

6. The blade cascade as recited in claim 1 wherein radii of curvature of the side-wall contour vary.

7. A turbomachine comprising at least one blade cascade as recited in claim 1.

8. A blade cascade of a turbomachine comprising: a plurality of blade channels each circumferentially bounded by a pressure side of a blade and by an opposite suction side of an adjacent blade, each blade channel radially bounded by two opposing side walls, at least one of the two side walls of the blade channels being provided with a side-wall contour, the side-wall contour being circumferentially undulated and comprising at least two depressions relative to a non-contoured surface of the at least one of the two side walls and at least one elevation relative to the non-contoured surface of the at least one of the two side walls; wherein the amplitudes of the depressions differ from one another; and wherein a suction side-proximal depression has a greater amplitude than a suction side-distal depression.

9. The blade cascade as recited in claim 8 wherein the side-wall contour extends to a downstream side-wall edge.

10. The blade cascade as recited in claim 8 wherein the depressions and the at least one elevation have widths that vary circumferentially or lengths that differ in the direction of flow.

11. The blade cascade as recited in claim 8 wherein the depressions and the at least one elevation are configured downstream from a constriction region of the blade channel and normally to the constriction region.

12. The blade cascade as recited in claim 8 wherein a plurality of depressions merge into one of the depressions.

13. The blade cascade as recited in claim 8 wherein the depressions and the at least one elevation have amplitudes that vary in the direction of flow.

14. The blade cascade as recited in claim 8 wherein radii of curvature of the side-wall contour vary.

15. The blade cascade as recited in claim 8, wherein each of the depressions includes a trough.

16. A turbomachine comprising at least one blade cascade as recited in claim 8.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Preferred exemplary embodiments of the present invention are described in greater detail in the following with reference to greatly simplified schematic representations, in which:

(2) FIG. 1 shows a perspective front view of a blade channel of a first exemplary embodiment of a blade cascade according to the present invention;

(3) FIG. 2 shows a blade channel of a second exemplary embodiment of the blade cascade;

(4) FIG. 3 shows a section along line A-A through the blade channel of FIG. 2;

(5) FIG. 4 shows a blade channel of a third exemplary embodiment of the blade cascade; and

(6) FIG. 5 shows a blade channel of a fourth exemplary embodiment of the blade cascade.

DETAILED DESCRIPTION

(7) FIG. 1 shows a perspective front view of a blade channel of a first exemplary embodiment of a blade cascade 1 according to the present invention of an axial turbomachine, such as a stationary gas turbine or an aircraft engine.

(8) Blade cascade 1 is preferably configured on the turbine side and has a plurality of blades 2, 4 that are configured side-by-side in the circumferential direction of the turbomachine and each define a blade channel 6, which, in accordance with the representation in FIG. 1, is traversed from the front to the back, respectively from left to right by a main flow. In the circumferential direction of the turbomachine, respectively of blade cascade 1, blade channel 6 is bounded by a pressure side wall, respectively pressure side 8 of first blade 2 and by an opposite suction side wall, respectively suction side 10 of second blade 4. Suction side 10 is not visible in the perspective view in FIG. 1. Pressure side 8 and suction side 10 each extend between a leading edge 12a, 12b and a trailing edge 14a, 14b of blades 2, 4. In the radial direction of blade cascade 1, blade channel 6 is bounded by a hub-side side, respectively radially inner side wall 16. In addition, blade channel 6 is radially bounded by a housing-side, respectively radially outer side wall 18. Inner side wall 16 is formed by a rotor section or a blade platform, for example. Outer side wall 18 is formed by a housing section of a blade shroud, for example.

(9) In the area of blade channel 6, at least inner side walls 16 are provided in accordance with the present invention with a circumferentially asymmetrical and with a circumferentially undulated side-wall contour. However, in the area of blade channel 6, at least only the outer side wall may also be provided with a circumferentially asymmetrical and with a circumferentially undulated side-wall contour. In the exemplary embodiment shown in FIG. 1, the side-wall contour has four individual contour features 20, 22, 24, 32 in the form of a pressure-side elevation 20, two depressions 22, 24, and an elevation 32 configured between the depressions.

(10) In each instance, elevations 20, 32 and depressions 22, 24 refer to a non-contoured surface section 26 of inner side wall 16 (see, for example, FIG. 2). Elevations 20, 32 extend radially outwardly from non-contoured surface section 26 and thus constitute a channel narrowing. Depressions 22, 24 extend radially inwardly from non-contoured surface section 26 and thus constitute a channel widening.

(11) The side-wall contour extends over the entire extent of inner side wall 16 and thus beyond leading edges 12a, 12b and trailing edges 14a, 14b. Thus, side-wall contour 16, respectively the two depressions 22, 24 thereof, and elevations 20, 32, extend from a leading side-wall edge 28 to a trailing side-wall edge 30 that is consequently likewise undulated in form.

(12) Pressure-side elevation 20 extends along pressure side 8 of the one blade 2 from leading edge 12a to trailing edge 14a and merges smoothly into pressure side 8.

(13) In the exemplary embodiment shown in FIG. 1, second elevation 32 is configured in the middle between depressions 22, 24. Thus, elevation 32 is flanked by depressions 22, 24 that merge directly into elevation 20 and into pressure side 8, respectively suction side 10. Elevation 32 and depressions 22, 24 extend in the flow direction and, therefore, are arcuately configured to conform with pressure side 8 and suction side 10.

(14) As a general principle, elevations 20, 32 and depressions 22, 24 may have amplitudes that differ or are the same in the circumferential direction and in the direction of flow. Preferably, a maximum amplitude of elevations 20, 32 or of depressions 22, 24 is maximally 30% of a blade pitch of blade cascade 1.

(15) FIGS. 2 and 3 show a blade channel 6 of a blade cascade 1 similar to that in FIG. 1. Here, however, a pressure-side connection of a pressure-side elevation 20 is different and, in fact, not planar as in FIG. 1, but orthogonal.

(16) As shown in FIG. 2, at least inner side walls 16 are provided in the area of blade channel 6 with a circumferentially asymmetrical and with a circumferentially undulated side-wall contour. The side-wall contour has four contour features 20, 22, 24, 32 in the form of two elevations 20, 32 and two depressions 22, 24. Contour features 20, 22, 24, 32 are graphically represented by isohypses, respectively isobaths having a plus sign as a channel narrowing (elevation) or a minus sign as a channel widening (depression).

(17) As indicated in FIG. 3 by the broken line in the area of outer side wall 18, this is likewise provided with a circumferentially asymmetrical side-wall contour that, considered circumferentially, is undulated, and that is composed of a plurality of contour features 20, 32 and 22, 24 Inner and outer side-wall contours 16, 18 may be configured to be identical or to differ from one another. In addition, merely outer side wall 18 may be provided with a circumferentially asymmetrical side-wall contour.

(18) The inner side-wall contour is explained in detail in the following.

(19) As shown in FIG. 2, first elevation 20, respectively pressure-side elevation extends along pressure side 8 from leading edge 12a to trailing edge 14a. It merges orthogonally into pressure side 8.

(20) Second elevation 32, respectively middle elevation is configured approximately in the middle between blades 2, 4. It extends from an axial position of leading edges 12a, 12b across a constriction region 36 between blades 2, 4 to an axial position of trailing edges 14a, 14b.

(21) First depression 22, respectively suction-side depression is configured proximally to suction side 10. It extends in the direction of flow over entire side wall 16 from front side-wall edge 28 to rear side-wall edge 30. In the area of leading edge 12b and trailing edge 14b, it is spaced apart from blade 4 by a non-contoured surface section 26, but merges directly into suction side 10 in a blade that corresponds approximately to a 40% axial extent of blade 4.

(22) Second depression 24, respectively pressure-side depression extends in the direction of flow over entire side wall 16 from front side-wall edge 28 to rear side-wall edge 30. In a front region of blade channel 6, pressure-side depression 24 is configured approximately in the middle between elevations 20, 32. In a rear region of blade channel 6, pressure-side depression 24 is positioned proximally to middle elevation 32 and distally from pressure-side elevation 20.

(23) Depressions 22, 24 are circumferentially spaced apart from elevations 20, 32 over the entire length thereof, in each case by a non-contoured surface section 26. They each have a deepest portion 38, 40 that extends approximately from an axial position of leading edges 12a, 12b to an axial position that corresponds to approximately 70% to 80% of an axial blade width.

(24) To positively influence a flow deflection angle proximally to the side wall, middle elevation 32 and depressions 22, 24 are oriented behind constriction region 36 normally to the same, i.e., at an angle of 85 to 95.

(25) In addition, as shown in FIG. 2, elevations 20, 32 and depressions 22, 24 have widths that differ in the direction of flow. Thus, in a position that corresponds to approximately 50% of an axial blade width thereof, elevations 20, 32 and depressions 22, 24 have the greatest width thereof and, at front blade wall edge 28 and rear blade wall edge 30, a small width.

(26) As shown by the cross-sectional view in FIG. 3, in the circumferential direction, pressure-side elevation 20 has an amplitude A.sup.+.sub.1; middle elevation an amplitude A.sup.+.sub.2; pressure-side elevation 24 an amplitude A.sup..sub.1; and suction-side depression 22 an amplitude A.sup..sub.2. Amplitudes A.sup.+.sub.1, A.sup.+.sub.2, A.sup..sub.1 and A.sup..sub.1 may each vary in the axial direction.

(27) In the illustrated exemplary embodiment, amplitude A.sup.+.sub.1 of pressure-side and pressure side-proximal elevation 20 is greater than amplitude A.sup.+.sub.2 or pressure side-distal middle elevation 32. As is also discernible in FIG. 3, pressure side-proximal elevation 20 merges transitionally, approximately orthogonally into pressure side 8. Amplitude A.sup..sub.2 of suction-side, respectively suction side-proximal depression 22 is greater than amplitude A.sup..sub.1 of suction side-distal depression 24.

(28) FIG. 4 shows a circumferentially undulated side-wall contour of an inner side wall 16 in a blade channel 6 between two blades 2, 4 of a blade cascade 1 of a turbomachine that has a pressure-side elevation 20, a middle elevation 32 and two depressions 22, 24 that merge transitionally into a rear, common depression 42.

(29) Pressure-side elevation 20 extends along a pressure side 8 of blade 2 from a leading edge 12a of blade 2 to trailing edge 14a thereof.

(30) Middle elevation 32 is positioned approximately in the middle between blades 2, 4. It extends approximately from one axial position of leading edges 12a, 12b of blades 2, 4 to an axial position that corresponds to approximately 60% of an axial blade width.

(31) Depressions 22, 24 are configured laterally from middle elevation 32 and, in each case, spaced apart therefrom by a non-contoured surface section 26. Circumferentially, the widths thereof are approximately the same. In addition, pressure-side depression 24 configured between pressure-side elevation 20 and middle elevation 32 is spaced apart from pressure-side elevation by a non-contoured surface section 26. In the same way, suction-side depression 22 configured between blade 4 and middle elevation 32 is spaced apart from pressure-side elevation 20 by a non-contoured surface section 26.

(32) Depressions 22, 24 extend from front side-wall edge 28 of side wall 16 and form common depression 42 downstream of middle elevation 32 that extends to rear side-wall edge 30 of side wall 16. The deepest portions 38, 40 thereof extend approximately from the axial position of leading edges 12a, 12b and, in a constriction region 36 between blades 2, 4, merge into a deepest portion 44 of common depression 42.

(33) To positively influence the flow deflection angle proximally to the side wall, middle elevation 32 and common depression 42 are oriented behind constriction region 36 normally to the same, i.e., at an angle of 85 to 95.

(34) FIG. 5 shows a circumferentially undulated side-wall contour of an inner side wall 16 in a blade channel 6 between two blades 2, 4 of a blade cascade 1 of a turbomachine that has a pressure-side elevation 20, a middle elevation 32 and a depression 42 that are subdivided downstream into two depressions 22, 24. By dividing a front quasi common depression 42 on the leading side into two individual rear depressions 22, 24, advantages may be attained in combination with a favorable influencing of the main flow over a rear side-wall edge 30 of side wall 16.

(35) Pressure-side elevation 20 extends along a pressure side 8 of blade 2 from a leading edge 12a of blade 2 to trailing edge 14a thereof.

(36) Middle elevation 32 is positioned approximately in the middle between blades 2, 4. It extends approximately within a range of between 50% and 100% of an axial blade width. Thus, middle elevation 32 extends approximately from an axial middle blade channel region to the axial position of trailing edges 14a, 14b of blades 2, 4.

(37) Depression 42 extends from a leading side-wall edge 28 of side wall 16 to a middle elevation 32. Middle elevation 32 divides depression 42 into two individual depressions 22, 24 that extend laterally of the same and that both extend to rear body edge 30 of side wall 16. As shown in FIG. 5, both depressions 22, 24 have an approximately same width in the circumferential direction. Depression 42 has two deepest portions 38, 40 that are spaced apart circumferentially and each continue individually into depressions 22, 24 to an axial position of rear edges 14a, 14b.

(38) To positively influence the flow deflection angle proximally to the side wall, middle elevation 32 and depressions 22, 24 are oriented behind a constriction region 36 between blades 2, 4 normally to the same, i.e., at an angle of 85 to 95.

(39) As already mentioned in connection with FIG. 1, in all of the exemplary embodiments, elevations 20, 20, 32, 32 and depressions 22, 22, 24, 24, 42 refer in each case to a non-contoured surface section 26 of the inner side wall. Elevations 20, 20, 32, 32 extend radially outwardly from non-contoured surface section 26 and thus constitute a channel narrowing. Depressions 22, 22, 24, 24, 38, 42 extend radially inwardly from non-contoured surface section 26 and thus constitute a channel widening.

(40) In addition, elevations 20, 20, 32, 32 and depressions 22, 22, 24, 24, 42 may have amplitudes that differ or are the same in the circumferential direction and in the direction of flow. The amplitudes of elevations 20, 20, 32, 32 and the amplitudes of depressions 22, 22, 24, 24, 42 are preferably maximally 30% of a blade pitch of blade cascade 1.

(41) In the same way, the width of elevations 20, 20, 32, 32 and the width of depressions 22, 22, 24, 24, 42 may each vary circumferentially and longitudinally.

(42) In addition, the radii of curvature of the undulation of the side-wall contour, respectively side-wall contours may vary circumferentially. Thus, an elevation 20, 20, 32, 32 may have a significantly smaller radius of curvature than an adjacent depression 22, 22, 24, 24, 42.

(43) A blade cascade of a turbomachine is described whose at least one side wall is configured to be circumferentially undulated and has at least two elevations having at least one depression or at least two depressions having at least one elevation, as well as a turbomachine having a blade cascade of this kind.

LIST OF REFERENCE NUMERALS

(44) 1 blade cascade

(45) 2 blade

(46) 4 blade

(47) 6 blade channel

(48) 8 pressure side

(49) 10 suction side

(50) 12a, b leading edge

(51) 14a, b trailing edge

(52) 16 inner side wall

(53) 18 outer side wall

(54) 20, 20 pressure-side elevation

(55) 22, 22 depression

(56) 24, 24 depression

(57) 26 non-contoured surface section

(58) 28 leading side-wall edge

(59) 30 trailing side-wall edge

(60) 32, 32 elevation

(61) 36 constriction region

(62) 38 deepest portion

(63) 40 deepest portion

(64) 42 common depression

(65) 44 deepest portion