Blade array with microblades

Abstract

The present invention relates to a centrifugal pump with a blade arrangement. The blade arrangement comprises a carrier unit (1) on which the blades are arranged, the blades being subdivided into segments (3). The carrier unit (1) is divided into radially adjacent annular parts (2). The segments (3) in the annular parts (2) are arranged offset from one another.

Description

[Technical field]

[0001] The present invention relates to a centrifugal pump having a blade arrangement, the blade arrangement comprising a carrier unit on which the blades are arranged. [Background technology]

[0002] The main component of a centrifugal pump is the impeller, which transfers mechanical energy as momentum to the pumped fluid. The shape of the impeller determines how the flow leaves the pump. Regarding impeller design, a distinction is made between closed, semi-open, open, or with or without a cover shroud and rear shroud. In the case of closed impellers, the impeller blades are connected to the respective shrouds on both sides. Depending on the progression of the flow lines inside the impeller, impellers can be classified into various impeller shapes: radial impellers, semi-axial impellers, axial impellers, peripheral impellers, etc.

[0003] Centrifugal pumps often have a guide device. The guide device usually has several guide blades, which form several guide channels for the pump medium between two guide blades. Such a guide device can also be designed as a diffuser. The pump medium leaving the impeller flows into the guide device. In the guide device, the kinetic energy is converted into pressure energy. In addition, a deflection of the medium occurs. The vortex can be reduced due to the flow into the following impeller.

[0004] The multiple blades of a centrifugal pump are fixedly or adjustably connected to an impeller and are the most important structural element for converting mechanical power into pump power or converting velocity energy into pressure energy.

[0005] In the flow direction, the blades are bounded by a leading edge, called the suction end, and a trailing edge, commonly called the pressure end, and transversely (cross) to the flow direction, the blades are bounded on the inside by a hub or inner cover shroud and on the outside by a pump casing or outer cover shroud.

[0006] Since there is no normal component of the relative velocity perpendicular to the blades in the impeller, the blade surface presents a flow surface with streamlines that are infinitesimally close to each other.

[0007] The velocity triangles on the streamlines at the blade inlet and blade exit, taking into account the blade thickness, essentially define the blade shape. The progression of the blade centerline between the blade inlet and the blade exit is called the median line. The median line is often represented as a circular arc, but can also be a parabola, S-shape, or other analytical curve.

[0008] As a rule, the blade inlet is designed to provide a vortex-free and shock-free inflow. The blade angle at the outlet can be more or less steep, depending in particular on the pump head to be achieved. The blade angle of radial impellers is generally less than 90 degrees. In this case, the blades are called back-curved. Radially terminating blades are characterized by a blade angle of 90 degrees, while forward-curved blades are characterized by a blade angle greater than 90 degrees.

[0009] The minimum blade thickness is approximately 3 mm for cast iron and 4 mm for cast steel, and in special cases such as inserting or welding steel blades, even thinner blade thicknesses can be achieved.

[0010] The design of the blades and blade shapes is the subject of continuous research and development. In this respect, DE 10 2015 212 203 A1 describes an impeller for centrifugal pumps in which the blades are arranged in a bundled configuration. This allows for an increased pump capacity while ensuring a wide and unobstructed flow path.

[0011] DE 10 2015213451 A1 describes a profile which is produced by superimposing a characteristic median line with a negative blade inlet angle and a thickness distribution or teardrop-shaped flank, which distributes the load evenly on the blade flank.

[0012] DE 102011007907 A1 also describes a blade profile which ensures that the blade is subjected to a uniform load. This is achieved by a highly curved blade profile which starts at an angle less than 0 degrees.

[0013] The above examples generally address the problems of existing impellers for centrifugal pumps. Such developments are expensive to begin with and achieve the desired profitability only in the case of mass production. It is difficult to work out on a large scale the solution for each application, especially the optimization of each pump pressure. Summary of the Invention [Problem to be solved by the invention]

[0014] The object of the present invention is to specify a centrifugal pump with optimized flow control, where it is necessary to allow an individual configuration of the impeller to the needs of the customer, and to allow a simple and cost-effective production of the impeller, and in addition to this, the impeller should be installed in the simplest possible way and be easily recyclable after use. [Means for solving the problem]

[0015] This object is achieved according to the invention by a centrifugal pump having a blade arrangement according to claim 1. Preferred variants are set out in the dependent claims, the description and the drawings.

[0016] According to the invention, the blades are subdivided into segments and the carrier unit is divided into radially adjacent annular parts, the segments being arranged offset from one another in said annular parts. Thus, according to the invention, the segments can be formed as microblades. By replacing a small number of macroblades with a large number of microblades and by forming the microblades preferably in a generative process of a carrier unit of a conventionally manufactured impeller or guide device, a blade arrangement with individually suitable pump pressures can be realized in an efficient and economical way.

[0017] Broadly speaking, a blade arrangement is understood to be an arrangement for energy transmission or energy conversion in fluid machines, such as centrifugal pumps. In this respect, the blade arrangement can be designed as a guide device and / or an impeller. Such a guide device and / or an impeller is divided into radially adjacent annular parts in which the segments are arranged. These segments are ideally designed as microblades.

[0018] According to the invention, the segments are arranged offset from one another. In an advantageous variant of the invention, the segments are arranged offset from one another in the circumferential direction, so that the pumped fluid flows radially from segment to segment and receives a transfer of momentum.

[0019] In another variation of the invention, the segmented blades are simply separated by gaps. Depending on the results of the computer-aided flow optimization, the segments can be arranged in a completely different way, in particular symmetrically or asymmetrically, designed to have the same length and curvature, or designed to be the same or completely different in terms of length and curvature.

[0020] For better structure, the carrier unit is divided into more than 2, preferably more than 3, in particular more than 4 ring portions and / or less than 10, preferably less than 8, in particular less than 6 ring portions.

[0021] By dividing the carrier unit into annular parts, it is preferably possible to easily realize in a computer-aided manner an optimal arrangement of the segments formed by the generative process in the carrier unit, for which purpose the annular width is designed to be the same or different for all annular parts depending on the respective optimization of the pump pressure.

[0022] According to the invention, the annular width is more than 5%, preferably more than 10%, in particular more than 15% and / or less than 45%, preferably less than 40%, in particular less than 30% of the carrier unit radius, which allows an ideal arrangement and configuration of the segments with the annular portions depending on the size of the impeller or guide device and the individual design of the pump pressure device.

[0023] The segments are preferably disposed within the annular portion, where the segments may extend across the entire annular width of the annular portion, and may be disposed within the annular portion in a spaced relationship to adjacent annular portions.

[0024] Alternatively, the segments may extend over at least two annular portions, depending on the size and length of the segments, in each case extending up to 50% over two annular portions.

[0025] According to the invention, depending on the arrangement of the annular parts, the segments are designed as intermediate segments and / or suction edge segments and / or pressure edge segments. In particular, the shape, curvature angle, length, height, thickness of the segments can be individually adapted depending on the load situation determined in each case. Ideally, the segments can be individually designed depending on the allocation of the annular parts. Furthermore, it is also conceivable to individually adapt and optimize the individual segments depending on the flow situation.

[0026] Preferably, the segments are arranged in a meridional direction in the carrier unit, where they may be arranged in line and / or offset from one another, and ideally the segments have a straight and / or radially outwardly curved shape, where all the segments may have a similar curvature, may have a similar curvature within one annular part, or may be designed in a completely different way depending on the individual configuration of the pump pressure.

[0027] In a particularly advantageous variant of the invention, the segments are designed as microblades, so that a particularly efficient transfer of momentum and mechanical forces to the fluid is realized.

[0028] According to the invention, the segments have a length greater than 5%, preferably greater than 10%, in particular greater than 15% of the radius of the carrier unit, and / or a length less than 50%, preferably less than 45%, in particular less than 35%. By being designed short, the segments achieve the shape of the microblades in a particularly ideal manner.

[0029] The carrier unit has more than 10, preferably more than 15, in particular more than 20 segments. By replacing the small number of macroblades with a large number of small microblades that are individually adapted depending on the pressure of the respective pump, it is possible to produce a centrifugal pump that is specifically optimized for the respective application.

[0030] According to the invention, the universally manufactured segments are applied to carrier units of conventionally manufactured blade arrangements. Reference is made in this respect to open impellers. According to the invention, closed impellers are also used. In this case, the carrier unit on which the segments are arranged has a cover shroud. Furthermore, the blade arrangement with the segments can also be designed as a guide device, preferably a diffuser.

[0031] Preferably, the carrier unit is integrally formed with the segments or, in the case of a closed blade arrangement, with the cover shroud, or both. The carrier unit and / or the cover shroud may be conventionally manufactured, for example, as cast parts. Using a generative process, the segments can be applied to the carrier unit, thereby producing an integral part of the centrifugal pump. In an alternative variant of the invention, the blade arrangement may all be manufactured as a cast part.

[0032] According to the invention, the blade arrangement can be manufactured in an innovative process by an integrated manufacturing device, where the carrier unit and / or the cover shroud are manufactured using a primary forming and / or cutting process. Depending on the specific application and pressure requirements, the optimal design and arrangement of the blades in small segment form, especially in the form of microblades, is determined using computer-aided simulation. The result of the simulation is a 3D-CAD data set of the blade arrangement, and the integrated manufacturing device precisely positions the segments in the carrier unit using generative design.

[0033] The term generative design includes all manufacturing processes in which material is applied layer by layer, thereby producing a three-dimensional component. The layer structure is realized under computer control with one or more liquid or solid materials according to given dimensions and shapes. During production, physical or chemical hardening or welding processes take place. Typical materials for 3D printing are plastic materials, synthetic resins, ceramics, metals, carbon and graphite materials.

[0034] A productive manufacturing process or additive manufacturing process is understood to mean a process in which material is applied layer by layer to produce a three-dimensional element. According to the invention, the segments are formed in a productive manufacturing process. Selective laser welding, also known as build-up welding, and cladding are used to form the segments. Cooling gas spraying and extrusion in combination with the application of a meltable plastic material are also applicable processes in alternative variants of the invention.

[0035] Generatively manufactured segments are particularly advantageous in terms of their high-performance, thin-walled design. The micro-segments, whose flow is optimized by computational fluid dynamics (CFD), transfer momentum to the fluid in a particularly efficient way, practically without losses. The complex structure of the segments prevents vortex formation and flow separation, and they are also characterized by a low component mass.

[0036] In selective laser welding, the segments are manufactured according to a process in which a layer of build-up material is first applied to the base. The build-up material for manufacturing the segments preferably consists of metal powder particles. In a variant of the invention, iron-containing and / or cobalt-containing powder particles are used for the segment manufacturing. Additives such as chromium, molybdenum or nickel may be present. The metal build-up material is applied to the plate as a thin layer in powder form. Then, using radiation, the powder material is completely melted locally in each case where required, and after solidification a solid material layer is formed. The base is then lowered by one layer thickness and powder particles are applied again. This cycle is repeated until all layers are melted and the finished segment is manufactured. According to the invention, this results in a blade profile that is designed to be particularly high-performance and flow-optimized.

[0037] A laser beam can be used as radiation, for example, to generate segments from the individual power layers. The data for irradiating the laser beam is generated in software based on a 3D-CAD body. As an alternative to selective laser melting, an electron beam (EB) can be used.

[0038] In build-up welding or cladding, segments are manufactured according to a process of covering a base structure by welding, where build-up welding uses filler metal in wire or powder form to increase the volume and in particular to achieve a high-performance, flow-optimized shape of the segment.

[0039] The rear shroud and / or the cover shroud can be manufactured by primary forming or subtractive manufacturing processes. Primary forming processes are the main group of manufacturing processes that manufacture solid bodies with a geometrically defined shape from amorphous materials. Primary forming processes manufacture the initial shape of the solid body and create material bonds. In primary forming processes, blanks made of plastically deformable materials undergo concrete machining into different shapes without removing material from the blank. In subtractive manufacturing processes, material is removed from the workpiece. Tips are generally mainly manufactured in addition to the produced component. The cover shroud is preferably manufactured from cast materials.

[0040] In a particularly preferred variant, the segments are manufactured in a flow-optimized manner and a number of segments are arranged on a carrier unit according to an optimal pump pressure.

[0041] Despite the above, the invention is not limited to single-stage centrifugal pumps, but in particular also applies to multi-stage centrifugal pumps.The impeller according to the invention or the guide device according to the invention is characterized by its particular applicability, since the segments, arranged in an individually optimized manner for each pump stage, can be formed on any conventionally manufactured carrier unit.

[0042] Further features and advantages of the invention are set forth in the description of exemplary embodiments with reference to the drawings, and in the drawings themselves. [Brief description of the drawings]

[0043] [Figure 1] FIG. 1 shows a cross-sectional view of a centrifugal pump having a spherical casing. [Diagram 2] FIG. 2 shows a plan view of a blade arrangement with carrier units and segments. [Diagram 3] 1 shows a plan view of a blade arrangement having different annular portions and segments. [Figure 4]1 shows a plan view of a blade arrangement with segments across multiple annuli. [Diagram 5] FIG. 2 shows a plan view of a blade arrangement having radially curved segments. [Figure 6] FIG. 1 shows a plan view of a blade having radially curved segments with different lengths. [Figure 7] FIG. 2 shows a plan view of an impeller with segments and a guide device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0044] Figure 1 shows, by way of example, a cross-sectional view of a centrifugal pump with a spherical casing 14. The medium enters the centrifugal pump via the suction port 11, is subjected to kinetic energy via an impeller 15 rotatably fixed on a shaft 12, and leaves the pump casing via a pressure nozzle 13. A bearing carrier cover 10 closes the pump chamber in the drive direction.

[0045] The impeller 15 comprises a carrier unit 1 which is populated with blades. The carrier unit 1 is formed in one piece with the blades and a cover shroud 17 and is designed as a closed impeller 15. Around the periphery of the impeller 15 a guide device 18 is arranged which collects the discharge flow from the impeller 15 and converts the kinetic energy into pressure energy.

[0046] 2 shows a carrier unit 1 with a blade arrangement in the form of an impeller for a centrifugal pump having a carrier unit radius 5. The carrier unit 1 is subdivided into three annular sections 2, each annular section 2 immediately adjacent to each other. All annular sections 2 have the same annular width 4. The linear segments 3 are arranged within the annular sections 2 and are offset from each other from annular section 2 to annular section 2.

[0047] In a variant of the invention, the outer shape of the segments 3 is adapted depending on their position in the annular part 2. In this respect, the segments 3 in the innermost annular part 2 are designed as suction edge segments 6, the segments 3 in the intermediate annular parts 2 are designed as intermediate edge segments 7 and the segments 3 in the outer annular parts 2 are designed as pressure edge segments 8.

[0048] 3 shows a carrier unit 1 with a blade arrangement in the form of an impeller for a centrifugal pump having annular portions 2 with different annular widths 4. The segments 3 are arranged centrally in the annular portion 2, the length of the segments 3 being adjusted depending on the respective annular width 4. The segments 3 are arranged offset from one another depending on their position in the annular portion 2.

[0049] 4 shows a carrier unit 1 having annular portions 2 with the same annular width 4. Segments 3 are disposed within the annular portions 2 and across the annular portions 2. The segments 3 are offset from one another and are non-contiguous in the carrier unit 1.

[0050] 5 shows a carrier unit 1 with radially curved segments 3. The segments 3 are arranged in an annular section 2 and are designed such that the distance from the annular end of the annular section 2 is the same for all segments 3. The segments 3 are arranged in the carrier unit 1 in a meridian direction.

[0051] 6 shows a carrier unit 1 having radially curved segments 3 overlapping a number of annular portions 2, where the curvature of the segments 3 is adapted individually to the respective annular portion 2.

[0052] 7 shows a plan view of the impeller 15 and the guide device 18. Both the impeller 15 and the guide device 18 have a carrier unit 1, which is each subdivided into annular parts 2 and in which radially curved segments 3 are arranged. The segments 3 are arranged within the annular part 2 and are designed such that the spacing from the annular end of the annular part 2 is the same for all segments 3.

Claims

1. A centrifugal pump having a blade array, wherein the blade array has a carrier unit (1) on which the blades are arranged, the blades are subdivided into segments (3), the carrier unit (1) is divided into annular parts (2) adjacent to each other in the radial direction, the segments (3) are arranged offset from each other in the annular part (2), and the centrifugal pump is characterized in that.

2. The centrifugal pump according to claim 1, wherein the carrier unit (1) has more than two annular parts (2) and / or less than ten annular parts (2).

3. The centrifugal pump according to claim 1 or claim 2, wherein all the annular parts (2) are designed such that the annular width (4) is the same.

4. The centrifugal pump according to claim 1 or claim 2, wherein the annular parts (2) are designed such that the annular width (4) is different.

5. The centrifugal pump according to claim 1 or claim 2, wherein the annular width (4) is greater than 5% and / or less than 45% of the carrier unit radius (5).

6. The centrifugal pump according to claim 1 or claim 2, wherein the segment (3) is arranged within the annular part (2).

7. The centrifugal pump according to claim 1 or claim 2, wherein the segment (3) is arranged over at least two of the annular parts (2).

8. According to the arrangement of the segment (3) in the annular part (2), the segment (3) is designed as an intermediate segment (7) and / or a suction edge segment (6) and / or a pressure edge segment (8), and the centrifugal pump according to claim 1 or claim 2 is characterized in that.

9. The centrifugal pump according to claim 1 or claim 2, wherein the segment (3) is arranged in the meridian direction of the carrier unit (1).

10. The centrifugal pump according to claim 1 or claim 2, wherein the segment (3) has a linear shape and / or a shape curved radially outward.

11. The centrifugal pump according to claim 1 or claim 2, wherein the segment (3) is designed as a micro blade.

12. The centrifugal pump according to claim 1 or claim 2, wherein the segment (3) has a length greater than 5% of the carrier unit radius (5) and / or less than 50%.

13. The centrifugal pump according to claim 1 or claim 2, wherein the carrier unit (1) has more than 10 segments.

14. The centrifugal pump according to claim 1 or claim 2, wherein the blade arrangement has a cover shroud (17).

15. The centrifugal pump according to claim 1 or claim 2, wherein the segment (3) is integrally formed with the carrier unit (1) and / or the cover shroud (17).

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