Blade with simplified root geometry

Abstract

The invention relates to a blade (01) of a compressor, comprising a blade wing (02) and a blade root (03). The blade root comprises a retaining section (04) extending along the blade axis (11), a connecting section (05) arranged between the blade wing (02) and the retaining section (03), and a base section (06) on the side facing away from the blade wing (02). In the lateral direction, the holding section (04) is delimited by flat holding surfaces (14) which lie opposite one another and are inclined, and the base section (06) is delimited by flat base surfaces (16) which lie opposite one another and are inclined. Furthermore, a flat mating surface (08), which is spaced apart from the end of the blade root, is provided on the underside.

Description

Technical Field

[0001] The present invention relates to a turbine blade having a blade airfoil and a blade root, wherein the blade root has a geometry that facilitates manufacturing. Background Technology

[0002] Currently, this type of turbine has alternating guide vanes and rotor blades. The guide vanes are housed within the casing, while the rotor blades are mounted on the rotor. Typically, the guide vanes and rotor blades are fixed separately, which simplifies manufacturing and allows for the use of optimal materials and manufacturing processes for the blades and their support components.

[0003] Here, the blade is typically secured in a specific retaining groove by means of the blade root. In the simplest case, the groove used for this purpose is similar to a dovetail groove. The blade has a radially extending blade airfoil and a blade root, and in the simplest case, the blade root has retaining surfaces that extend along the retaining groove and are arranged opposite each other, depending on the shape of the retaining groove, wherein the retaining surfaces are oriented at an angle relative to the radial direction.

[0004] Typically, a large arc portion is provided at the blade root on the side opposite to the blade airfoil. To ensure a near-gap fit within the retaining groove, a central shoulder is further provided on the lower side of the blade root opposite to the blade airfoil. This allows for a near-gap fit of the blade root within the retaining groove. The combination of the arc portion and the shoulder ensures a small gap at the arc portion.

[0005] Although known blade designs with easily maintained root geometries have proven effective, their manufacture still requires specialized tools and a great deal of work.

[0006] Document EP 2569514 B1 discloses a simpler geometry for the leaf root. In this case, the arc portion is omitted, and instead, inclined planes are provided on both sides of the leaf root.

[0007] Furthermore, it is preferable to install the blade root in the retaining groove without any gaps. To this end, in a design with a simplified blade root, a lower side recess is provided in the lower side of the blade root, and a corresponding groove bottom recess is provided in the retaining groove, wherein, when installing the blade root, a C-shaped clamping element is inserted into the gap between the lower side recess and the groove bottom recess.

[0008] While this ensures that the blade roots are firmly positioned in the retaining groove and that axial fixation is achieved even in an inclined orientation, the limited installation space between the two rows of blades makes the assembly and disassembly of the necessary clamping elements more difficult.

[0009] Another drawback is the amount of work required to manufacture the lower side notch and the groove bottom side notch, especially considering the tolerances that need to be maintained, particularly the tolerances along the blade root direction. Summary of the Invention

[0010] Therefore, the object of the present invention is to enable the manufacture and assembly / disassembly of blades at a lower cost.

[0011] This objective is achieved through the implementation described in claim 1. Advantageous implementations are the subject of the dependent claims.

[0012] The blade according to the invention basically comprises a radially extending blade airfoil and a blade root. The blade root extends along the blade axis and has a retaining section extending in profile length, a base section on a side opposite to the blade airfoil, and a connecting section connecting the retaining section to the blade airfoil. The retaining section defines the root width of the blade root in a direction transverse to the blade axis.

[0013] The retaining sections are defined on opposite sides (in a direction transverse to the blade axis) by planar, mutually inclined retaining surfaces. Similarly, the base sections are defined on opposite sides by planar, mutually inclined base surfaces.

[0014] By providing a flat mating surface on the side of the base section away from the blade airfoil, spaced apart from the opposite end of the blade root, lower manufacturing costs are achieved through simpler assembly.

[0015] This type of blade is used in turbines. Here, the turbine has a rotor and a stator, which define the rotor axis and a radial direction perpendicular to the rotor axis. The blade includes a blade airfoil and a blade root disposed at one end of the blade airfoil, wherein the blade airfoil extends in the radial direction.

[0016] Furthermore, a second device for mounting the blade can be installed at the other end of the blade airfoil, opposite the blade root. The blade airfoil typically does not have a flat surface but is composed of curved surfaces. Therefore, the blade airfoil also extends in both the axial and tangential directions.

[0017] A blade root is provided at one end of the blade airfoil for fixing it in the turbine. Here, the blade root defines the blade axis. This blade axis extends transversely to the radial direction, along the tangential direction, and / or the rotor axis. Measured along the blade axis, the blade root has a profile length. Measured transversely to the blade axis and transversely to the radial direction, the blade root has a blade width.

[0018] The blade root itself includes a retaining section extending along the blade axis. This retaining section is particularly used to secure the blade in a turbine. For this purpose, retaining surfaces extending along the blade axis and facing each other are arranged on the retaining section. Thus, the retaining section is defined by the retaining surfaces in directions transverse to the blade axis and perpendicular to the radial direction. In a typical embodiment, the retaining surfaces are planar, i.e., flat, and inclined relative to the radial direction. The retaining angle between the retaining surfaces is open away from the blade airfoil.

[0019] Preferably, the holding angle between the two opposing holding surfaces is between 25° and 60°. Particularly preferably, the holding angle is at least 35°. Conversely, the holding angle should preferably be at most 50°.

[0020] If the radial height of the retaining section is at least 0.3 times the root width, it facilitates a favorable fixation in the turbine while ensuring the necessary stability. This results in a sufficient cross-sectional area to transfer forces to the rotor blades, as well as a sufficiently large retaining surface. Particularly preferably, the radial height of the retaining section is at least 0.35 times the root width.

[0021] Conversely, excessively large leaf roots should be avoided. Therefore, it is advantageous to keep the radial height of the segment no more than 0.6 times the root width. It is particularly advantageous to keep the radial height of the segment at most 0.5 times the root width.

[0022] In addition, the blade root includes a base section which is arranged on the side of the retaining section opposite to the blade wing and extends along the blade axis of equal length.

[0023] In the following description, the ends of the retaining section and the base section are considered as the ends of the blade root at two opposite sides along the blade axis. Any other sections on the blade root that may extend beyond the blade root, i.e., the ends of the retaining section and the base section, are temporarily disregarded.

[0024] Furthermore, the base section is defined by two opposing base surfaces extending along the blade axis, which are also planar, i.e., flat. Therefore, the base surfaces are arranged opposite each other on the base section and extend along the blade axis. Here, the base surfaces are oriented at an angle to each other.

[0025] By omitting the conventionally provided arc at the blade root, blade manufacturing becomes simpler. The clearance that may exist at the blade root during installation in the turbine is then acceptable. Therefore, a cost advantage can be achieved.

[0026] According to the present invention, by having a mating surface at the base section on the side opposite to the blade airfoil, low-cost and gapless installation can be achieved. Here, the mating surface is a plane, i.e., a flat surface. It is specified that the mating surface does not extend along the blade axis to the opposite end of the blade root. Therefore, the opposite lateral edges of the mating surface are spaced apart from the corresponding associated ends of the blade root.

[0027] Preferably, the base angle between the two opposing base planes is between 60° and 120°. Particularly preferably, the base angle is at least 70°. Conversely, the base angle is particularly preferably at most 100°.

[0028] It is advantageous to manufacture the blade root and its corresponding housing in the turbine if the radial height of the base section is at least 0.15 times the root width. Particularly preferred is that the radial height of the base section is at least 0.2 times the root width.

[0029] Excessively large leaf roots should be avoided. Therefore, it is advantageous if the radial height of the base section is no more than 0.35 times the root width. It is particularly advantageous if the radial height of the base section is at most 0.3 times the root width.

[0030] It is also advantageous that the width of the base section on the side opposite the blade airfoil is approximately equal to or slightly less than the minimum width of the retaining section. Therefore, the minimum width of the base section should be at least 0.6 times the minimum width of the retaining section. Conversely, the minimum width of the base section should not exceed 1.2 times the minimum width of the retaining section.

[0031] It is particularly advantageous that the minimum width of the base section is at least 0.8 times and / or at most 1.0 times the minimum width of the retaining section.

[0032] The minimum width of the retaining section is determined by the distance between the two opposing retaining surfaces at the edges facing the blade airfoil. Similarly, the minimum width of the base section can be determined by the distance between the two opposing base surfaces at the edges facing away from the blade airfoil.

[0033] The mating surfaces can be located at different positions between the ends of the blade root. However, it is advantageous if the mating surfaces are arranged at the center of the blade root. In this case, the mating surfaces do not need to maintain exactly the same distance from the ends, although this is preferred. At least necessary for this is that the mating surfaces intersect a transverse plane, wherein the transverse plane is equidistant from the two ends of the blade root.

[0034] Viewed in the transverse direction (transverse to the blade axis and transverse to the radial direction), the distance between the opposing longitudinal edges of the mating surfaces and the longitudinal side surface at the blade root, i.e., the basal surface, can be equal. Preferably, the mating surfaces extend to the basal surface. That is, the corresponding longitudinal edge of the mating surface is also part of the edge of the associated basal surface.

[0035] If the lateral edge of the mating surface is spaced apart from the end of the blade root, the lateral edge can initially have any orientation (e.g., arcuate, serrated). However, specifically, the shape depends on the geometry of the end of the blade root. A straight lateral edge is obviously preferred.

[0036] However, the lateral edges should preferably be oriented obliquely relative to the lateral direction. In a particularly preferred embodiment, the angle between the blade axis and the corresponding lateral edge is selected to be 30° to 60°.

[0037] Furthermore, it is advantageous that the lateral edges extend parallel to each other.

[0038] To allow the blade root to be fitted into the corresponding housing in the turbine, the advantageous mating surfaces only need to extend over a portion of the blade root. Preferably, the distance between the lateral edges of the mating surfaces is selected to be 0.05 to 0.3 times the profile length of the blade root. Particularly preferably, the distance between the lateral edges is at least 0.1 times the profile length. Conversely, a particularly preferred distance between the lateral edges is at most 0.2 times the profile length.

[0039] To form a mating surface spaced apart from the end of the blade root, for example, shoulders can be provided on both sides of the mating surface.

[0040] Particularly preferably, the mounting surfaces adjacent to the mating surfaces on both sides are inclined. Here, the mounting surfaces should also be planar, i.e., flat. In this case, the angle between the mounting surface and the mating surface is preferably 0.03° to 2°. Particularly preferably, the angle between the mounting surface and the mating surface is 0.5° to 1.5°.

[0041] With a particularly advantageous design at the blade root, the retaining section and the base section are defined by multiple preferably planar, i.e. flat surfaces on the opposite sides and on the lower side away from the blade wing, thereby enabling particularly low-cost manufacturing while achieving the function of precise installation of the blade root and secure retention in the corresponding receiving portion.

[0042] Whether there are small, non-functional arcuate sections or stages to prevent the formation of sharp edges is not important. Another embodiment includes a section without other functions, such as having a blade width, arranged between a retaining section with a retaining surface and a base section with a base surface.

[0043] The blades can be rotor blades at the rotor of the turbine, or preferably guide blades fixed to the stator of the turbine.

[0044] Particularly preferred is that the described scheme is applicable to the guide vanes of a gas turbine compressor. Attached Figure Description

[0045] Figure 1 An exemplary embodiment of a leaf having a simplified leaf root according to the present invention is shown.

[0046] Figure 2 A schematic diagram of the installation of the blade root according to the prior art is shown.

[0047] Figure 3 It shows Figure 1 A schematic diagram of the blade root installation in the embodiment shown.

[0048] Figure 4 A longitudinal view of the blade root according to the prior art is shown.

[0049] Figure 5 It shows Figure 1 A longitudinal view of the blade root in the illustrated embodiment.

[0050] Figure 6 It shows the relationship with Figure 5 The same leaf base and its angle.

[0051] Figure 7 Shown from below Figure 1 A perspective view of the leaf root in the illustrated embodiment.

[0052] Figure 8 It shows Figure 1 A side view of the blade root in the illustrated embodiment. Detailed Implementation

[0053] Figure 1 An embodiment of a blade according to the present invention is shown in perspective. Here, the blade can be a rotor blade or a guide blade. The blade includes at least a blade airfoil 02 and a blade root 03, and the blade can be fixed in the turbine through the blade root 03.

[0054] In the case of guide vanes, a fixing device is typically arranged opposite the blade root 03 at the other end of the blade wing 02. Although the blade according to the invention is preferably used as a guide vane, the illustration of the common device opposite the blade root 03 is omitted here.

[0055] from Figure 1As can be seen from the perspective view, the leaf root 03 has a shape that is easier to manufacture than that of the conventional embodiment.

[0056] For comparison, Figure 2 and Figure 4 The conventional design of the blade root 23 according to the prior art is shown.

[0057] The blade root 23 includes a retaining section 24 defined by opposing, planar retaining surfaces that are inclined relative to each other. The blade root is secured to the turbine 10 by these retaining surfaces.

[0058] Adjacent to the retaining section 24 is the connecting section 25, through which the connection with the blade airfoil 22 is achieved.

[0059] Opposite to the connecting section 25 is the base section 26, which has wide, rounded portions on both sides. The receiving groove in the turbine 10 has approximately the same rounded portion, thus leaving only a very small gap. This minimizes unnecessary flow along the blade root.

[0060] On the side opposite to the blade airfoil 22, a small shoulder is provided after the arcuate portion, through which fixation in the turbine housing is achieved. This shoulder typically extends along the entire length of the blade root.

[0061] In contrast, compared to existing technologies, in Figure 3 and Figure 5 It shows Figure 1 The leaf root 03 of the embodiment shown.

[0062] The blade root 03 similarly includes a retaining section 04 and a connecting section 05 on one side, which connects to the blade airfoil 02. The areas of the retaining section 04 and the connecting section 05 are substantially consistent with the design of the retaining section 24 and the connecting section 25 in the prior art.

[0063] To simplify manufacturing, the normally required curved portion is omitted, and instead, the base portion 06, which is adjacent to the retaining portion 04 and opposite to the blade portion 02, is provided with a flat slope.

[0064] In response, Figure 6 The leaf root 03 of example leaf 01 is shown again.

[0065] The upper portion of the figure shows a part of the blade airfoil 02. Adjacent to it is the connecting section 05. The retaining section 04 is defined on opposite sides by retaining surfaces 14. Here, the retaining surfaces 14 are planes, and a retaining angle 15 is defined between the two retaining surfaces 14 because they are inclined relative to the radial direction 07. In this embodiment, the retaining angle 15 is selected as 45°.

[0066] A base section 06 is provided on the side opposite to the blade airfoil. According to the invention, this base section 06 is similarly defined by base surfaces 16 on opposite sides. The base surfaces 16 are designed to be planar, i.e., flat. Since the base surfaces 16 are inclined relative to the radial direction 07, they define a base angle 17. In this embodiment, the base angle 17 is selected as 85°.

[0067] Furthermore, the shape of the retaining section 04 defines the blade width 13, which is measured transversely to the radial direction 07 and transversely to the blade axis 11.

[0068] A mating surface 08 is provided on the lower side of the blade root 03 away from the blade airfoil 02. This mating surface 08 allows the blade 01 to be installed in the turbine without gaps.

[0069] exist Figure 7 The image again shows a perspective view of the leaf root (03) viewed from below. Figure 1 The example shown illustrates that the leaf root 03 extends straight along the leaf axis 11.

[0070] It can also be seen that the retaining section 04 has a retaining surface. The blade airfoil 02 is connected by the connecting section 05.

[0071] The base section 06 has three independent surfaces on its lower side. Here, the mating surface 08 is located at the center of the blade root 03. This mating surface 08 is parallel to the blade axis and extends transversely to the radial direction 07. Adjacent to both sides of the mating surface 08 are mounting surfaces 09, which are inclined relative to the mating surface 08.

[0072] Therefore, the mating surface 08 is defined in the transverse direction by longitudinal edges, which form part of the boundary of the corresponding base surface 16. The transverse edge of the mating surface 08 adjacent to the mounting surface 09 does not extend transversely to the blade axis 11, but rather from one base surface 16 to the opposite base surface 16, at a 45° angle to the blade axis.

[0073] It can also be seen that the mating surface 08 extends only a small portion of the profile length of the blade root 03 along the direction of the blade axis 11. In this embodiment, the distance between the two lateral edges of the mating surface 08 is approximately 0.15 times the profile length of the blade root.

[0074] Observing again along the transverse edge of mating surface 08, in Figure 8 The arrangement of the mating surface 08 and its corresponding mounting surface 09 is shown. An mounting angle 18 exists between the mating surface 08 and the mounting surface 09, which is approximately 1° in this embodiment (not drawn to scale).

Claims

1. A blade (01) used in a turbine, the blade defining a rotor axis and a radial direction (07), the blade comprising: Blade airfoil (02), the blade airfoil extends in the radial direction (07); as well as The blade root (03) defines the blade axis (11) and has a root width (13) transverse to the blade axis (11). The blade root includes a retaining section (04) extending along the blade axis (11) in profile length, a connecting section (05) on the side facing the blade wing (02), and a base section (06) on the side away from the blade wing (02). In the direction transverse to the blade axis (11), the retaining section (04) is defined by planar, opposite, inclined retaining surfaces (14), and the base section (06) is defined by planar, opposite, inclined base surfaces (16). Its features are, The base section (06) has a planar mating surface (08) on the side opposite to the blade wing (02) that is spaced apart from the end opposite to the blade root (03).

2. The blade (01) according to claim 1. in, The retaining angle (15) between the retaining surfaces (14) is at least 25°, especially at least 35°, and at most 60°, especially at most 50°; and / or The radial height of the retaining section (04) is at least 0.3 times, especially at least 0.35 times, and at most 0.6 times, especially at most 0.5 times, the root width (13).

3. The blade (01) according to claim 1 or 2. in, The base angle (17) between the base planes (16) is at least 60°, especially at least 70°, and at most 120°, especially at most 100°; and / or The radial height of the base section (06) is at least 0.15 times, especially at least 0.2 times, and at most 0.35 times, especially at most 0.3 times, of the root width (13).

4. The blade (01) according to any one of claims 1 to 3. in, The minimum width of the base section (06) is at least 0.6 times, especially at least 0.8 times, and at most 1.2 times, especially at most 1.0 times, the minimum width of the retaining section (04).

5. The blade (01) according to any one of claims 1 to 4. in, The mating surface (08) is centered along the direction of the blade axis (11); and / or The opposing longitudinal edges of the mating surface (08) are adjacent to the corresponding base surface (16).

6. The blade (01) according to any one of claims 1 to 5. in, The opposing, particularly parallel, lateral edges of the mating surfaces (08) form an angle of 30° to 60° with the blade axis (11); and / or The axial distance between the opposing transverse edges of the mating surfaces (08) is at least 0.05 times the profile length, especially at least 0.1 times, and at most 0.3 times, especially at most 0.2 times.

7. The blade (01) according to any one of claims 1 to 6. in, Along the direction of the blade axis (11), on both sides adjacent to the mating surface (08) are planar mounting surfaces (09) that are inclined relative to the mating surface (08).

8. The blade (01) according to claim 7. in, The mounting angle between the mating surface (08) and the mounting surface (09) is at least 0.3°, especially at least 0.5°, and at most 2°, especially at most 1.5°.

9. The blade (01) according to any one of claims 1 to 8. in, The blades are guide blades of a compressor, especially guide blades of a gas turbine compressor.

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