EP1012445B1 - Blade for a turbo-machine and steam turbine - Google Patents

Abstract

A blade for a fluid-flow machine is directed along a blade axis. Cross-sectional profiles which are disposed at a distance from one another axially and at right angles to the blade axis are offset from one another equidirectionally in each case in a root end region and in a tip end region of the blade towards a center region, so that the blade is displaced in a bulged manner along the blade axis. Furthermore, cross-sectional profiles at a distance from one another axially are twisted relative to one another in the root end region and/or in the tip end region. A steam turbine is also provided.

Description

The invention relates to a blade for a turbomachine, wherein the blade is directed along a blade axis and along this blade axis a foot end area, a head end portion and one in between Middle area and a cross-sectional area perpendicular to Has blade axis. The invention further relates to a Steam turbine, in particular a high-pressure or medium-pressure steam turbine.

The efficiency of a turbomachine, especially one Steam turbine, is reduced by occurring flow losses. With the improvement in efficiency and thus also the reduction of such flow losses is concerned e.g. the article "Advanced Steam Turbine Technology for Improved Operating Efficiency "by R.B. Scarlin, in" Power-Gen Europe 95 ", May 16-18, 1995, Amsterdam RAI the Netherlands, Book 2, Vol. 4, page 229 ff. Here is the development three-dimensional turbine blades described taking into account various types of flow losses, such as gap losses, Losses through the blade profile as well as losses in the end regions of the turbine blade (endwall losses). to Reduction of the latter losses will be an inclination of the Turbine blade specified in the circumferential direction. An inclination the turbine blade in the area of the blade tip and the The hub area of the turbine blade leads to a curved one Blade, such a bend due to the mechanical Properties can only be used with guide vanes. Farther is stated in the article that a twist The scoop also has an impact on the inclination of the Shovel has, so that in a three-dimensional design in the end areas of the blade both the blade inclination, the blade rotation as well as the blade profile Disposition.

EP-A-0 704 602 deals with the design of a Turbine guide vane in an intermediate stator along one a turbine axis directed steam turbine. The shovel extends here along a radially directed Blade axis and has a pressure side and a suction side as well as an entry edge and an exit edge. there the blade is designed along the radial direction in such a way that the pressure side of a blade root area too one along the blade axis the blade root area opposite vane head area a convex Has curvature behavior.

In a particularly preferred embodiment, the Curvature achieved in that with radially successive, spaced cross-sectional profiles a corresponding rotation of the cross-sectional profiles around the fixed common trailing edge of the setting angle (bit angular angle) parabolic with respect to the turbine axis is varied. The channel width for the steam can thus be in the Bucket head area and in the blade root area reduced and increased in an intermediate bucket center area become. This leads to a relocation of part of the Steam mass flow, away from the two lossy ones Edge areas of the turbine guide vane.

In the article "Modern Blade Design for Improving Steam Turbine Efficiency "by M. Jansen and W. Ulm in" VDI Reports " No. 1185, 1995, pages 277-290, is also on an increase the efficiency of a steam turbine, in particular a high pressure or medium pressure steam turbine. The influence of different flow losses for different ones Steam turbines are set out. Through a special design The turbine blade will reduce flow losses reached. The three-dimensionally trained Turbine blades point in a foot area as well an inclination at a head region of the turbine blade. In the article is a comparison regarding flow losses these three-dimensionally designed turbine blades purely cylindrical blades. Such cylindrical Buckets have pressure and parallel to the bucket axis Suction sides and thus have neither a twist nor a Tilt up. As another alternative to the three-dimensional designed turbine blades are so-called twisted turbine blades described which an increasing over their height Twist and have a changing blade profile.

DE 31 48 995 A1 describes an axial turbine, such as a steam turbine or a gas turbine with a variety of circumference described with spaced vanes. The guide vanes used are twisted over their height and have a changing inlet angle. The Change in the inlet angle increases measured from a certain height from the blade root (root) continuously in the area of Tip of the guide vane is too linear. The twist takes also continuously increases over the height of the guide vane. The cross-sectional profile of the guide vane changes from Blade foot to the blade tip continuously, the Guide vane is getting slimmer. When shaping the Guide vane will make further changes about the amount of Guide vane regarding the outlet angle, size and shape the guide vane.

In the German Auslegeschrift 11 68 599 is an axial compressor with rotor blades and / or guide vanes, one in the area The cross-section of the wall surfaces changed to compensate the flow influence caused by these wall surfaces identify, specified. In the axial compressor are along the Gas flow path in front of the rotor and guide vanes inlet guide vanes arranged. These inlet or inlet guide vanes have an arched surface except in the area of the walls Cross section on. The middle part of the blade with the arched Cross section goes in every wall area in a smooth and continuously curved surface in the non-arched cross-sectional profile in the wall areas above. About the height of the inlet guide vane The cross-sectional profiles thus change continuously of the airfoil. The inlet angle remains the whole Height of the inlet guide vane constant.

In the German Auslegeschrift 28 41 616 is a guide vane ring described for an axial turbine with guide vanes, the guide vanes between an inner and an outer ring are arranged and the profile thickness of the airfoil proportional to the blade pitch changes. The change in the blade profile takes place via the Height of the guide vane in that no change in shape the leading edge (pressure side) takes place, but the protrusion on the trailing edge in size over that Height gradually increases as thickness increases the guide vane. The profile change is carried out here that the thickness of the vane increases as its Chord length remains the same. Such a vane ring is applicable to steam turbines, gas turbines and compressors.

DE 42 28 879 A1 describes an axially flow-through turbine specified with at least one row of curved guide vanes. Due to the blade curvature, both the leading edge lie as well as the leading edge of the guide vanes not in same axial plane. The curvature of the blades runs here perpendicular to the tendon, which is caused by a shift the profile cuts both in the circumferential direction and in Axial direction is reached. From a turbine housing wall (Cylinder) towards a turbine hub the guide blades taper, so that their cross-section changes accordingly, the blade profile being substantially above the blade height remains unchanged. In addition to the curvature and rejuvenation there is still a twist over the blade length of the guide vane of the airfoil made to change the Circumferential speed of those following the guide vane Blades to be taken into account above the channel height. It takes place thus an adaptation of the airfoil by a deflection the center of gravity of the profile cuts perpendicular to Chord (curvature or bend), i.e. an axial and circumferential deflection at the same time, combined with a tendon length variation.

Inclined turbine blades for a steam turbine are also in the article "Development of three-dimensional stage viscous time marching method for optimization of short height stages "by G. Singh, P.J. Walker, B.R. Haller, in: "VDI Reports No. 1185, 1995, pp. 157-179.

The object of the invention is a scoop with low To specify flow losses for a turbomachine. A Another object of the invention is a steam turbine to be indicated with low flow losses.

According to the invention on a blade for a turbomachine directed task by such a shovel solved, which is directed along a blade axis and along this blade axis a foot end area, a Head end area and in between a middle area and a has a cross-sectional profile perpendicular to the blade axis, being axially spaced apart in the direction of the blade axis Cross-sectional profiles from the foot end area to the middle area as well as from the head end area to the middle area Direction are offset from each other and being in the foot end area and / or axially spaced apart in the head end region Cross-sectional profiles against each other by a difference angle are twisted.

When installing the blade in a turbine with a turbine shaft is synonymous axially in the direction of the blade axis with radial with respect to the turbine shaft. With the Displacement of axially spaced cross-sectional profiles in the head end area as well as in the foot end area and one additional twisting in the foot end area and / or in the head end area is a reduction in flow losses in the Edge zones (head end area, foot end area), which are the hub a turbine shaft and the inner circumference of a turbine housing are assigned. The rectified shift towards the middle area causes the turbine blade inclined in a bulbous shape perpendicular to the blade axis (bent) is. With an additional twist of the axially spaced cross-sectional profiles becomes an additional Increase in efficiency, i.e. a reduction the flow losses.

The axially spaced cross-sectional areas are preferably in the foot end area and in the head end area for Center area rotated in the same direction. This is about the entire height of the bucket from the head end to At the foot end, the twisting is withdrawn.

The blade is preferably for arrangement in a blade ring designed which has a circumferential direction, where the cross-sectional direction is local to the circumferential direction coincides. This takes place in the edge zones of the blade a circumferential bend with a simultaneous one Rotation (angle adjustment) in the end areas of the blade, thereby reducing flow losses and thus an increase in the efficiency of a turbomachine can be achieved is. This is particularly the case with steam turbines on the one hand an increase in the mechanical exit energy with the same thermal energy input and on the other hand a reduction in the use of thermal energy and thus the Environmental pollution due to pollutant emissions with the same Exit energy compared to pure cylindrical or pure inclined or curved blades.

The cross-sectional profiles are preferably one turn with respect to their center of area or with respect to the blade axis (if different, e.g. due to inhomogeneous mass distribution) turned. The angle of rotation that occurs is in following as a stagger angle and performing the rotation referred to as a change in stagger angle.

This is in a cross section perpendicular to the blade axis Cross-sectional profile preferably along the blade axis the same everywhere. The cross-sectional profile changes accordingly not about the height of the bucket. Here is preferred the cross-sectional area of the cross-sectional profiles is also constant. The blade preferably has a combination a circumferential deflection of the center of gravity of the cross-sectional profiles (Bend in the circumferential direction) and a staggering of the Cross-sectional profiles (without changing the profile) in Head end and foot end area (hub and housing area).

Depending on the expansion of the blade in the direction of the blade axis (Blade length, blade height) to expand the blade in a direction perpendicular to the blade axis (blade width) and the flow conditions when using the blade in one Turbomachine is the blade in the middle area preferably cylindrical. The pages (printed page, Suction side) of the blade therefore run parallel to the Blade axis.

The blade is preferably a guide blade or a moving blade a steam turbine, in particular a high pressure or Medium pressure steam turbine executed. Preferably, the Shovel a small length to width ratio on how it is particularly with blades for a high pressure steam turbine the case is.

The task aimed at a steam turbine is for a Steam turbine, which is directed along a turbine axis is and an inflow area, an outflow area and a Blading area arranged between them in terms of flow has, solved in that in the blading area one directed along a blade axis Blade is arranged, which is a via the blade axis Inclination and a twist, each of one Increase foot end area to a middle area and from that Remove the central area from a head end area.

With such a configuration of the steam turbine comprehensive the blade with increasing and decreasing inclination and twisting is a reduction in flow losses in the area of turbine shaft directed along the turbine axis and a reaches the turbine housing surrounding the turbine shaft.

The bucket with increasing and decreasing inclination and twisting is preferably assigned to the inflow area. It is therefore preferably in the first stage and / or the subsequent ones Stages arranged. This applies to both levels comprehensively a blade ring made of moving blades or guide blades. There in the first stages of a high pressure or medium pressure steam turbine the proportion of so-called secondary losses (Edge losses) particularly high in the hub and housing area is (e.g. up to 30% of the total losses) and by the specified Blade shape is reduced, this can be a noticeable Increased efficiency can be achieved.

The outflow area is preferably a twisted blade, i.e. a scoop with increasing twist along its length and changing the cross-sectional profile and / or the cross-sectional area, arranged. Enclosed axially between the stages the twisted shovel and the shovel with increasing and decreasing Inclination as well as change of stagger angle is a pure one cylindrical blade, i.e. with parallel to the blade axis Side walls, provided. With such an arrangement of Buckets of different geometry is a steam turbine given with low flow losses and high efficiency.

FIG 1

einen Längsschnitt durch eine Hochdruck-Dampfturbine,

FIG 2

einen Querschnitt eines Ausschnitts durch einen Schaufelkranz,

FIG 3

eine räumliche Darstellung des Schaufelblattbereichs einer Schaufel,

FIG 4

einen Querschnitt durch den Schaufelblattbereich der Schaufel gemäß Figur 3 und

FIG 5

einen weiteren Querschnitt durch die Schaufel gemäß Figur 3 axial in Richtung der Schaufelachse beabstandet von dem Querschnitt gemäß Figur 4.

The blade for a turbomachine and the steam turbine are explained in more detail using the exemplary embodiments shown in the drawing. They show a partially schematic and not to scale representation

FIG. 1

a longitudinal section through a high pressure steam turbine,

FIG 2

3 shows a cross section of a detail through a blade ring,

FIG 3

a spatial representation of the blade area of a blade,

FIG 4

a cross section through the blade area of the blade according to Figure 3 and

FIG 5

3 shows a further cross section through the blade according to FIG. 3 axially spaced from the cross section according to FIG. 4 in the direction of the blade axis.

The same reference numerals have in each of the figures same meaning.

In Figure 1 is a turbomachine, a high pressure steam turbine 11, shown in a longitudinal section along a turbine axis 17 is directed. The steam turbine 11 has a turbine shaft directed along the turbine axis 17 20, which are surrounded by a turbine housing 18 is. The steam turbine 11 points along the turbine axis 17 an inflow area 12 for action fluid, superheated steam, and an outflow area 13 for the superheated steam. Axially between Inflow area 12 and outflow area 13 is a blading area 14 provided. In the blading area 14 follow each other alternately in the axial direction summarized in a corresponding blade ring 21 Guide vanes 9 and blades 8. Each blade 8 and each guide vane 9 points along a vane axis 2 (see FIG. 3) a foot end area 3, a head end area 4 and arranged axially in between in the direction of the blade axis 2 a central area 10. With the foot end area 3 a blade 8 borders on the turbine shaft 20 and one Guide blade 9 to the turbine housing. For the head end area 4 the reverse applies. The inflow area 12 closest blades 8 and / or guide blades 9 are each designed as a blade 1, which in the Foot end area 3 and in the head end area 4 inclined and twisted is. Blade 8 closest to outflow area 13 and guide blades 9 are each twisted blades 19 with increasing rotation over the blade axis 2 and itself changing cross-sectional profile. In the blading area 14 axially between the inclined and twisted Blades 1 and the twisted blades 19 are purely cylindrical Paddles 16 arranged, the suction and pressure side are each parallel to the blade axis 2.

FIG. 2 shows a section of a blade ring 21, in the blades 1 arranged side by side in the circumferential direction 6a are. For the sake of clarity, the blade ring is 21 unwound along the circumferential direction 6a and with only two blades 1 shown. The circumferential direction 6a corresponds to the circumference of the turbine shaft 20 in one section perpendicular to the turbine axis 17. The main flow direction 22 of the steam flowing in the steam turbine 11 is vertical to the circumferential direction 6a of the blade ring 21.

3 shows the aerofoil area in a spatial representation 23 one directed along a blade axis 2 Shovel 1 shown. The airfoil area 23 has a foot end area 3, a head end area 4 and in between a central area 10. For the sake of clarity not shown is an adjoining the foot end area 3 Fastening area with which the door window shovel 1 in the turbine shaft 20 or the turbine housing 18 attached is. Furthermore, there is also an if applicable the cover band adjoining the head end region 4 is not shown. In the head end area 4 and the foot end area 3 the turbine blade 1 in a cross-sectional direction 6, the preferably the circumferential direction 6a of the blade ring 21 corresponds, inclined, and in the axial direction by a difference angle Δβ (see Figures 4 and 5) rotated. The one in the foot end area 3 enlarging towards the central region 10 Corresponds to twisting and increasing circumferential bending the same twist and circumferential bend as in the head end area 4. Starting from the foot end area 3, this means that along the blade axis 2 rotated and shifted a cross-sectional profile 5 becomes towards the central area 10 and from that Middle region 10 to the head end region 4 the twist and Shift is withdrawn. About the height of the middle area 10 remains the degree of displacement and twisting constant. The size of the back turn and back shift over the head end area 4 is preferably as large as the displacement and rotation in the foot end area 3.

The circumferential bend here means a displacement of the Cross-sectional profile 5, 5a in the direction of a cross-sectional direction 6, which preferably in the circumferential direction 6a Blade ring 21 corresponds. A rotation of the blade 1 takes place by changing the stagger angle, i.e. a change of the angle β according to FIG. 4 and FIG. 5 by rotation of the cross-sectional profile 5 about the blade axis 2, which is preferably coincides with the gravity axis of the bucket 1. In the case of a blade 1 with a more homogeneous cross section Mass distribution also corresponds to a rotation around the center of gravity 7 (center of mass 7) of the cross-section profile 5, 5a. The cross-sectional profile 5, 5a, 5b is over the entire height of the airfoil area 23 for everyone Cross-section the same, i.e. especially that cross-sectional shape and area are constant. The shown in Figure 5 Cross-sectional profile 5b is compared to that shown in Figure 4 Cross-sectional profile 5a rotated by the difference angle Δβ and shifted by the shift value ΔU. This matches with a change in the stagger angle β to the value of the Stagger angle β '(Figure 5).

Since in a steam turbine, in particular a high-pressure steam turbine, the edge losses, i.e. the fluid mechanics Losses in the vicinity of the turbine shaft and the turbine housing, can be up to about 30% of the total losses, leads to a reduction of these edge losses due to the twisting and peripheral bending of the blade in a steam turbine to increase efficiency. The degree of twist and circumferential bend is in each case related to the fluidic Ratios in a steam turbine adaptable, the Twist and circumferential bend also over the entire May extend mid-range. It is also possible that the central area is purely cylindrical, i.e. the suction side and the pressure side of the blade parallel to the blade axis are directed.

Claims (11)

1. Blade/vane (1), for a turbomachine (11), which is aligned along a blade/vane axis (2), having a root end region (3), a tip end region (4) arranged opposite to it along the blade/vane axis (2) and a central region (10) arranged between them and having a cross-sectional profile (5; 5a, 5b; 15a, 15b) at right angles to the blade/vane axis (2), cross-sectional profiles (5a, 5b) in the tip end region (4) at an axial distance from one another in the direction of the blade/vane axis (2) towards the central region (10) being offset relative to one another by a translation in a cross-sectional direction (6), and cross-sectional profiles (15a, 15b) in the root end region (3) at an axial. distance from one another towards the central region (10) being offset relative to one another by a translation in the same cross-sectional direction (6) and cross-sectional profiles (15a, 15b; 5a, 5b) at an axial distance from one another in the root end region (3) and/or in the tip end region (4) being twisted relative to one another by a respective difference angle (Δβ).
2. Blade/vane (1), according to Claim 1, the cross-sectional profiles (5a, 5b; 15a, 15b) at a distance axially from one another in the root end region (3) and in the tip end region (4) being respectively twisted in the same direction towards the central region (10).
3. Blade/vane (1), according to one of the preceding claims, for arrangement in a blade/vane row with a peripheral direction (6a), the cross-sectional direction (6) coinciding locally with the peripheral direction (6a).
4. Blade/vane (1), according to one of the preceding claims, in which cross-sectional profiles (5a, 5b; 15a, 15b) are respectively rotated relative to their centre of area (7).
5. Blade/vane (1), according to one of the preceding claims, in which the cross-sectional profile (5a, 5b; 15a, 15b) is the same overall along the blade/vane axis (2).
6. Blade/vane (1), according to one of the preceding claims, which has a cylindrical configuration in the central region (10).
7. Blade/vane (1), according to one of the preceding claims, which is configured as a guide vane (9) or rotor blade (8) of a steam turbine (11).
8. Steam turbine (11), in particular a highpressure or medium-pressure steam turbine which is aligned along a turbine axis (17), having an inlet flow region (12), an outlet flow region (13) and a blading region (14) arranged, in terms of flow, between them, a blade/vane (1) aligned along a blade/vane axis (2) being arranged in the blading region (14), which blade/vane (1) has an inclination and a twist along the blade/vane axis (2), which inclination and twist respectively increase from a root end region (3) to a central region (10) and decrease from the central region (10) to a tip end region (4).
9. Steam turbine (11), according to Claim 8, in which the blade/vane (1) with decreasing and increasing inclination and twist is associated with the inlet flow region (12).
10. Steam turbine (11), according to Claim 9, in which a warped blade/vane (19) is associated with the outlet flow region (13).
11. Steam turbine (11), according to Claim 10, in which a purely cylindrical blade/vane (16) is arranged, in the direction of the turbine axis (17), between the blade/vane (1) and the warped blade/vane (19).

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