CZ347599A3 - Steam turbine and blade for such steam turbine - Google Patents

Abstract

The steam turbine (1) has a flow channel (2) with a channel wall (3). In the flowchannel (2) they are in the blade rings blades (5) are arranged. Flow channel channel (3) the channel (2) has a knurled structure (6) that is targeted the flow of action fluid (11) is steam (13) flowing 7 * L by Channel Between the two blades (5) of the blade ring (55) is a spacing surface (31) having a knurled structure (6) is provided. The solution also relates to a blade (5) for a steam turbine (1).

Description

2

BACKGROUND OF THE INVENTION The present invention relates to a steam turbine with a flow passage and blades therein, as well as blades for steam turbines.

Current_technologies

DE 125 46 008 A1 describes a turbine blade for use in the wet steam region in the penultimate and final stages of turbines. Such a turbine blade is subject to erosive wear by incident droplets of water. This erosive wear is reduced in that the blade blade of the turbine blade has a surface roughness in the region of the back side of the blade or at least in a partial region thereof, which is substantially reinforced against the surface roughness of the front side of the blade. Through this surface roughness, a water film is maintained on the surface of the turbine blade. This water film reduces the erosive effect of incident water drops.

LE 36 09 541 C2 discloses a turbulently flowing body for reducing flow resistance. The reduction in resistance is achieved by reducing the turbulent wall shear stress. For this purpose, the surface of the body is provided with grooves in a plurality of grooves. These grooves are arranged opposite each other laterally to the flow direction and have a short pro? drawing in the flow direction. Specifically, LE 36 09 541 C2 discloses such a surface structure to reduce the flow resistance of the aircraft bearing surface.

DE 43 19 628 A1 describes a structure which is

forged surfaces of flow machines. Through the adjustment of the knurled structure, flow losses are minimized. In this case, there is an adjustment for special proportions of liquid pumps.

DE G 90 13 099 relates to a rotor for extracting energy from a flowing medium or transmitting energy to a flowing medium, which consists of a wheel hub and at least one rotor blade. An increase in the efficiency of the rotor is achieved in that the rotor blade has a wavy shape. In addition to the necessarily wavy shape, such a rotor blade can also be completely creased.

US-PS 3,481,531 describes an impeller for a centrifugal compressor, in particular for a gas turbine. The impeller has radially outwardly arranged wings between which the impeller wall is arranged. This impeller wall is provided with radially outwardly grooved grooves, so that the boundary layer of gas adhering to the wall is disturbed and thus the energy losses are minimized.

US-PS 4,023,350 discloses an apparatus that reduces pressure losses in a gas turbine. This device consists of a chain of protrusions which are arranged between two adjacent blades of the gas turbine blade rim. This string of protrusions serves to create a swirl, which makes it possible to reduce the thickness of the boundary layer and thus the losses due to the transverse flow.

In VDI reports No. 1109 of 1994, Jetter and Riess describe on page 241 in the article Stromungstechnische Eigenschaften von Turbinenschaufelprofilen unterschiedlicher Ferti9999 99 9 9 99 99 ·· ® and * · 9 ® O 9 9 9

9 9 9999 9 9 9

9 9 ® 9,999 9,999,999

9999 99 9 9 9 gungsqualitáten the influence of surface roughness on the efficiency of turbine blade profiles. It is stated here that surface roughness, such as milled grooves, have an effect on the profile loss, but this effect cannot be accurately evaluated until now due to the importance of other parameters.

The steam turbine is based on the book Stromungsmaschinen by Klaus Menna, B.G. Teubner Stuttgart, 1995. In this book it is stated that the common designation of flow-through machines is to include water turbines, steam turbines and gas turbines, wind wheels, circulating pumps and circulating compressors, as well as propellers. All these machines have the common feature of serving the purpose of drawing energy to the action fluid to drive another machine, or vice versa, to supply the action fluid with energy to increase its pressure. The function of the flow machine is explained on the example of a simple turbine. The action fluid enters the machine and flows first through the guide vanes of the stationary blade ring. The velocity and thus also the kinetic energy of the action fluid is increased. Its pressure and thus its potential energy is reduced. At the same time, a velocity component is formed in the shape of the guide vanes in the circumferential direction of the ring of the rotating blades, which is arranged downstream of the ring of the guide vanes. By means of the impeller ring, the action fluid transmits its kinetic energy to the rotor with which the impeller ring is connected, whereby the direction and often also the value of the action fluid velocity during the flow of the impeller changes. The ring of the rotating blades is rotated. The action fluid emerges from the machine with reduced energy content. The ratio of the mechanical energy obtained by the turbine to the energy drawn by the action fluid indicates the efficiency of the turbine.

• · • ·

It is an object of the present invention to provide a high efficiency steam turbine. It is a further object of the present invention to provide a vane for a steam turbine with which high efficiency is achieved with a steam turbine.

According to the present invention, a steam turbine object having a flow channel with a channel wall and blades arranged in a flow channel along the axis, the channel wall having a groove structure arranged at least in regions with groove ridges spaced apart from one another is provided.

In such a steam turbine, the flow of the flow channel through the action fluid along a locally different main flow direction is specifically influenced by the groove structure provided on the channel wall. The channel wall does not have to be a continuous surface. Preferably, the channel wall is comprised of an inner wall and an outer wall of the annular flow channel. Flow control is particularly related to the transverse flow directions directed transverse to the main flow direction of the action fluid, for example, swirls, which are attenuated by the increased flow resistance caused by the grooved structure. Since such transverse flows could result in a reduction in efficiency, damping such transverse flows contributes to increasing the efficiency of the steam turbine.

Preferably, each vane is arranged in a vane ring, and a spacer surface is provided between two adjacent vanes, which is part of the channel wall. A grooved structure with groove ridges is provided on this spacer surface. Action fluid flows between two blades of the adjacent blades

along the main flow direction, which is defined here by the blades. The spacing surface may be provided on the connecting line between the end points of adjacent blades in the main flow direction. The notion that a spacer surface is provided between two adjacent vanes is intended to indicate the position of the spacer surfaces rather than accurately determine the elongation along the main flow direction. The spacing surfaces of the blade rim provide a particularly effective possibility of damping any transverse flows that may arise through the grooved structures provided on these surfaces. For example, a scoop ring means a blade arrangement in which the blades are arranged between an inner and an outer, each annular limit, or such an arrangement in which the blades are mounted only on one side, for example on a turbine rotor.

Preferably, each blade has a blade blade with a blade blade contour adjacent to the spacer surface, with each groove comb provided on the spacer surface being associated with the next further blade blade contour to which the groove comb is directed approximately parallel.

As a result, the grooved structure is directed approximately along the main flow direction of the action fluid and thus also approximately perpendicular to the transverse flows that may be produced. This leads to an increase in the flow resistance perpendicular to the flow direction and thus also to damp the transverse flows.

It is further preferred that the first part of the blades is designed as circulating blades. Preferably, the second part of the blades is designed as guide vanes.

Preferably they have. some of the paddles always have a heel portion through which they are inserted into the circumferential, for all of these blades. ♦ ♦ • «♦ * · · · · · · · · · · · · · · · ·

-βίο blades of common rotor or housing groove. In the blades of the so-formed blade rim, their heel portions abut one another. Each of these heel portions has on the channel side a surface of the heel portion which forms part of the channel wall. This makes it possible to provide the channel wall with a grooved structure which is provided on the surface of the channel-side heel portions, i.e. the heel portions of the vanes. Thus, in terms of production, it is possible in a simple manner to adjust the individual blades on the heel part before they are mounted in the flow machine.

According to a further preferred embodiment, one of the blades is flush with one groove of the rotor or housing provided for only one blade. Preferably, the entire blade ring is formed by such blades. In such a case, the spacer surface is essentially formed by a surface of the rotor that is provided between the corresponding grooves of the adjacent blades of the blade rim.

Preferably, a portion of the vanes are connected to each other in a bundle, particularly by means of welding, for example, that each of these vanes is releasable from the bundle only by breaking it. Preferably, the bundle forms a paddle ring or a portion of the paddle ring. The paddle ring or a portion of the paddle ring can be made, for example, by welding or eroding the blades from a compact workpiece or from a plurality of compact workpieces, which are subsequently joined together.

Preferably, the spacing of adjacent grooves is between 0.01 mm and 10 mm. Furthermore, preferably two adjacent grooves comb one groove bottom and form a groove, the groove depth of each groove measured from the line between the groove grooves. * * * * »« »« «« «« «« «« * * * * * * * * * * * * «« «

- 7 ridges to the deepest point of the groove bottom, having a value between 1 µm to 1 mm.

Preferably, each blade has a blade, wherein at least one blade has a grooved structure at least in the region. As a result, the flow of the jet machine through the action fluid can also be influenced by the grooved structure on the blade blades.

According to the invention, the vane task is solved by a vane for a flow machine, which is directed along a vane axis having a vane surface area with a foot portion having a fastening portion for mounting in a steam turbine and a heel portion adjacent a vane blade having a vane leaf surface. an area with a heel area, a central area, and a head area that are self-arranged along the blade axis, the blade surface having a grooved structure with grooved ridges spaced from each other to specifically target the blade surface by-action fluid; the structure is provided in the heel region and / or in the head region and the central region is smooth.

By means of this arrangement, by-pass of the blade through the knurled structure is always influenced in the peripheral regions of the blade blade. By the term smooth regions it is meant herein that the surface area of the central region has grooves, roughness or elevations that are lower or smaller than the grooves in the heel region and / or in the head region.

Preferably, each groove comb is provided at an angle of expansion of 9 °. 9 °. 9 °. 9 °. The first groove comb is provided with a first spreading angle and the second groove comb is provided with a second spreading angle which is different from the first spreading angle.

Due to the grooved surface structure of the blades, the bypass of the blades mounted in the flow machine is so influential that an improvement in the efficiency of the flow machine is produced. In particular, any transverse flows that may occur may be reduced by means of a grooved structure. Transverse flows are secondary flows that occur transversely to the main flow direction of the action fluid. Since such transverse flows can cause efficiency losses, reducing them can increase efficiency.

The foot portion of the blade constitutes an adjoining fastening device adjacent the blade blade through which the blade can be coupled to a flow machine, for example a rotor or an internal turbine casing. In this case, the heel portions of a plurality of vanes of the impeller can also be combined into a single part, for example forming a wheel. The vane may also have a head portion which is suitable, for example, for sealing leakage current through a slot between the vane and the housing or rotor of the flow machine.

The term grooved structure also encompasses the fact that in different regions of the paddle surface, the formation of the structure may be different or that the separated regions of the paddle surface may, in certain circumstances, have differently formed grooves. Thus, the grooves may differ from one location to the other of the paddle surface, for example in terms of their depth, width, shape or direction of spreading.

Preferably, the first groove comb is provided in the region of the heel portion or in the heel region, the first spreading angle being between 0 ° and 20 °.

Preferably, the heel portion has a surface of the heel portion over which the grooved structure is at least partially provided. Furthermore, it is advantageous that the head portion which is opposite the shoulder portion along the blade axis is provided with a surface portion of the head portion on which the grooved structure is at least partially provided, in particular a second groove comb is provided in the surface portion of the head portion. The knurled structure may have a different direction of spreading on the surface of the head portion than in other areas of the paddle surface. It is in the peripheral regions of the blade that transverse flows can be generated, the reduction of which can be of great importance for improving efficiency. Advantageously, if the head region and / or the heel region has a grooved structure, any transverse flows that may occur in these regions can be reduced in a targeted manner.

Preferably, the spacing of adjacent grooves is between 0.01 mm and 10 mm. In addition, preferably two adjacent grooves comb in the groove bottom and form a groove, the groove depth of each groove measured from the junction between the groove ridges to the deepest point of the groove bottom is between 1 µm and 1 mm.

The embodiments of the invention are explained in more detail below with reference to the drawing.

Fig. 1 schematically shows a longitudinal section through a steam turbine.

FIG. 2 is a perspective view of a section of a scoop with a knurled structure.

FIG. 3 is a schematic side view of a turbine blade. Figure 4 is a cross-sectional view of the turbine blade of Figure 3.

Fig. 5 schematically shows a knurled structure.

FIG. 6 shows a side view of a steam turbine blade with a foot part.

The same reference characters have the same meaning in all different figures.

invention

FIG. 1 shows a longitudinal section through the steam turbine 1 which is directed along the axis 4 from the inlet side 1A to the outlet side 1B. Here, only half of the mirror axis 4 of the symmetrical representation is shown. The rotor 14 with the surface area 143 is provided along the axis 4 and is surrounded by the housing 15 with the inner side 15A in the areas. The housing 15 has a circular steam inlet channel 16 directed perpendicularly to the axis 4. The steam turbine 1 driving the actuating fluid is steam 13. The inlet channel 16 terminates in an annular flow channel 2 which is arranged along the axis 4 from the inlet side 1A to the outlet side 1B and which is bounded by the channel wall 3. The channel wall 3 consists on one on the other hand, the channel wall 3 consists of an outer wall 3B formed by a portion of the inner side 15A of the housing 15. While the inner wall 3A represents a cylinder coaxial with respect to the axis 4, the outer wall 3B forms a coaxial truncated cone to the axis 4. This truncated cone extends from the inlet side 1A to the outlet side 1B, so that the flow channel 2 has an increasing cross-sectional area along the axis 4. The flow passage 2 terminates in an outlet passage 18 which is directed perpendicular to the axis 4 and perpendicular to the inlet passage 16. A plurality of vanes 5 are arranged along the flow passage 2 in respective vane rings 55. Each vane 5 is directed along the vane axis 57, As shown in FIG. 3, each vane axis 57 of each vane 5 is directed perpendicular to the axis 4, each vane 5 being just as long as it is adjusted over the entire height of the flow passage 2. Provided there are vanes 55A, 55B having on one side guide vanes 5A and on the other side circulating vanes 5B, wherein one blade ring 55A with guide vanes 5A and one blade ring 55B with circulating blades 53 are alternately arranged along axis 4. The guide blades 5A are anchored to the housing 15. The blades 5B are connected to the rotor 14. On one bead ring 55B with the blades 5B, it is shown, for example, that one blades 5B align with the hammer head mounting portion 56A into a correspondingly shaped groove 14A. rotor 14.

In operation of such a steam turbine 1, an action fluid, here steam 13, flows through the inlet channel 16 along the locally varying main flow direction 60, as shown in Fig. 4, through the flow channel 2 and exits through the outlet channel 18 again from the steam turbine 1. In the flow passage 2, the steam 13 is deflected by the guide vanes 5A onto the impeller blades 53. The forces generated by the steam 13 and acting on the impeller blades 53 cause the rotor 14 to rotate. The kinetic energy of the steam 13 is thus converted into the kinetic energy of the rotor 14. The rotational movement of the rotor 14 can be used, for example, to generate electrical energy in a generator (not shown). Transverse flows 61 directed towards the main flow direction 60 may be formed in the flow passage 2 in addition to the main flow direction 60, as shown in FIG. 4. Such transverse flows 61 generally result in energy losses of steam 13 which are not converted to the mechanical energy of the rotor 14, which in turn means a reduction in efficiency. Such transverse flows 61 are influenced by the grooved structure 6 provided on the channel. 1 which is not shown in FIG. 1 but will be explained in more detail in connection with FIG. 2.

FIG. 2 shows schematically a cut-out of the blade ring 55B with the impeller blades 5B. The impellers 53 are arranged along the periphery of the rotor 14. Each impeller 53 is connected to the rotor 14. Each impeller blade 5B has a blade blade

51. Each blade blade 51 is contiguous with the blade blade outline 51 on the rotor 14. A spacing surface 31 is provided between two adjacent blades 53. This is limited by the blade blade outlines 52 of both blades 53 along the direction 60 of the main steam flow 13. that flows around the paddle ring 55B. The spacing surface 31 is provided in the main flow direction 60 solely in the area provided between the two impeller blades 53. Each impeller blade 5B is adjacent its rotor 14 opposite end to the inside 15A of the housing 15 but does not touch the impeller blades 5B. there remains a slit. A suitable seal (not shown), for example the interlocking teeth of the rotating blades 5B and the housing 15, largely seals the slot. A grooved structure 6 with grooves 9 is provided on each spacer 31. Two adjacent grooves 2 each enclose the groove bottom 10 and form a groove 8. Each groove 8 is spaced w from the groove 2 to the adjacent groove 2 and groove depth. However, the grooves 8 of the grooved structure 6 may also have different widths and heights or shapes depending on the flow ratios. Each groove comb is directed parallel to the contour 52 of the blade blade 51 of the nearest groove comb 2. Each such grooved structure 6 conducts the actuating fluid flowing through the blade rim 55B along the direction 60 of the main flow as shown in FIG. Transverse flow 61 directed toward this main flow direction 60, see FIG. 4, for example, swirling, by means of an increased flow resistance for this transverse flow 61. As aforementioned, such a reduction means, as a rule, an increase in efficiency.

FIG. 3 shows a side view of the impeller 5B. The impeller 5B is directed along the vane axis 57. Along the vane axis 57 is a heel portion 56 with a hammer head-shaped mounting portion 56A and transverse to the vane axis 57 a directed plate 56B of the heel portion 56 as well as a blade 51 and head portion 54. A scored structure 6 is provided on the surface of the blade blade 21. The scored structure 6 is adapted on the blade surface 51a adjacent the heel portion 56 in the heel region 41 and adjacent the head portion 54 in the head region 43. The central region 42 of the blade leaf surface. The surface 51a is smooth. When the vane 2 is flowing through the action fluid 11, it is through the grooved structure 2

Only the flow in the peripheral regions of the blade leaf 51 is specifically influenced by the cross-currents 61. Because of these transverse flows 61, it is possible to damp these transverse flows 61 specifically. in these peripheral areas.

The impeller blade 5B is inserted into the groove 14A with its fastening portion 56A, as can be seen in FIG. 1. Thus, by means of a plurality of impellers of the same design, the bladder ring 55B is formed from corresponding foot portions 56 of adjacent impeller blades 5B. The plates 56B of the foot part 56 of the blades 5B form part of the channel wall 3. A grooved structure 6 is provided on the plates 56B of the foot part 56. This is emphasized in the cross-section shown in Fig. 4 by the impeller blades 5B.

On the trapezoidal plate 56B of the heel portion 56 a grooved structure 6 with groove ridges 6 is provided. The contour of the cross-sectional profile represents the contour 52 of the blade leaf 51, the grooves 54 following the course of the contour 52 of the blade leaf 51 ».

Fig. 5 schematically shows a knurled structure

6. The grooves 58 formed directly adjacent to each other and roughly U-shaped in cross-section are arranged on one surface. The grooves 8 are limited by the groove ridges 8 which enclose the groove bottom 10. In this embodiment, the distance w from one groove 9 to the adjacent groove 9 is always the same. The groove depth h from the lowest point of the groove bottom 10 to the connecting line between the limiting grooves 9 is also the same for each groove 8. The grooved structure 6 is directed parallel to the by-pass by the action fluid 11. In addition to the direction 11a of the main

A transverse flow 11b can be generated by the flow of the actuating fluid 11. This, however, has a greater flow resistance through the cross-directed grooved structure 6 and can thus be damped, which can lead to improved efficiency.

FIG. 6 shows a sectional side view of a steam turbine blade 5. In this embodiment, the knurled structure 6 is also provided on the transition region 44 of the heel portion 56. This also affects the flow of the vane 5 over the surface of the heel portion 56. The knurled structure 6 can be modified directly in the manufacture of the vanes 5, but can also be formed subsequently.

Claims (19)

PATENT CLAIMS Steam turbine having a flow channel (2) directed along an axis (4) with a channel wall (3) and blades (5) arranged in the flow channel (2), characterized in that the channel wall (3) has a grooved structure (6) arranged at least in the regions with groove ridges (9) spaced from one another. Steam turbine (1) according to claim 1, characterized in that each blade (5) is arranged in a blade ring (55), wherein a spacer surface (31) is provided between two blades (5) which are adjacent to each other. channel wall (3), a grooved structure (6) with groove ridges (9) being provided on this spacer surface (31). Steam turbine (1) according to claim 2, characterized in that each blade (5) has a blade blade (51) with an outline (52) of a blade blade (51) adjacent to the spacer (31), each the closest further contour (52) of the blade blade (51), to which the groove comb (9) is directed approximately parallel, is associated with the groove comb (9) provided on the spacer surface (31). Steam turbine (1) according to one of the preceding claims, characterized in that the first part of the blades (5) is designed as circulating blades (5B). Steam turbine (1) according to one of the preceding claims, characterized in that the second part of the blades (5) is designed as guide blades (5A). - 17 999 9 «9» 9 9 9 9 999 9 9 9 9 9 999 9 9 9 9 9 Steam turbine (1) according to one of the preceding claims, characterized in that some of the blades (5) each have a foot part (56) through which they are inserted into the peripheral, for all of these blades (5), common grooves (14A) of the rotor (14) or of the housing (15), the blades (5) being abutting with their heel portions (56). Steam turbine (1) according to one of the preceding claims, characterized in that one of the blades (5) is flush with one groove (14A) of the rotor (14) or the housing (15) provided for a single blade (5) . Steam turbine (1) according to one of the preceding claims, characterized in that a part of the blades (5) is connected to each other in a bundle, in particular by welding or eroding said blades (5) from a compact workpiece, 5 / can be released from the bundle only by breaking it. Steam turbine (1) according to one of the preceding claims, characterized in that the spacing (w) of adjacent grooves (9) is between 0.01 mm and 10 mm. Steam turbine (1) according to one of the preceding claims, characterized in that two adjacent grooves (9) each enclose one groove bottom (10) and form a groove (8), the groove depth (h) of each groove (8). 1, measured from the line between the groove ridges (9) to the deepest point of the groove bottom (10), has a value between 1 µm and 1 mm. Steam turbine (1) according to one of the preceding claims, 9 9 · β β β · · · · «« «« «« 9 9 9 · · · · · · 99 99 99 - 99 99 characterized in that each blade (5) has a blade (51), wherein at least one blade (51) is provided with a grooved structure (6) at least in the region. A vane (5) for a steam turbine (1) which is directed along a vane axis (57) having a vane surface area (49) with a foot portion (56) having a mounting portion (56A) for mounting in a steam turbine (1) and with a heel portion (56) an adjacent blade leaf (51) having a blade leaf surface (5a) with a heel area (41), a central area (42) and a head area (43) »which are arranged in series along the vane axis (57), characterized in that the vane surface (49) has a grooved structure (6) with groove ridges (9) spaced from each other by which the vane surface area (49) can be efficiently targeted by action fluid. 11), wherein the knurled structure (6) is provided in the heel region (41) and / or in the head region (43) and the central region (42) is smooth. The blade (5) of claim 12, wherein each groove comb (9) is disposed at an angle (β and β 1) extending to a plane perpendicular to the vane axis (57), wherein the first groove comb (9a) is provided with a first spreading angle (β1b) and a second groove comb (9b) is provided with a second spreading angle (β2). The blade (5) according to claim 13, wherein the first groove comb (9a) is provided in the region of the heel portion (56) or in the heel region (41) and the first spreading angle (1, 1) has a value between 0 ° to 20 °. - 19 A blade (5) according to claim 13 or 14, wherein:. A second groove comb (9b) is provided in the head region (43), wherein the second spreading angle (? 2) is between 20 ° and 60 °. The blade (5) of one of claims 12 to 15, wherein the heel portion (56) has a surface of the heel portion (56) over which the knurled structure (6) is provided at least partially. The blade (5) according to one of claims 12 to 16, characterized in that the head portion (54) which is opposite the foot portion (56) along the blade axis (57) is provided with a surface portion of the head portion (54) , on which the grooved structure (6) is at least partially provided, in particular a second groove comb (9b) is provided in the surface area of the head portion (54). The blade (5) according to one of claims 12 to 17, characterized in that the spacing (in) of adjacent grooves (9) has a value between 0.01 mm and 10 mm. The blade (5) according to one of claims 12 to 18, characterized in that two adjacent grooves (9) each grip the groove bottom (10) and form a groove (8), the groove depth (h) of each groove (8). measured from the link between the grooves 9 to the deepest point of the groove 10 has a value between 1 µm and 1 mm. 1/4