Centrifugal pump comprising a guide device

Abstract

The invention relates to a centrifugal pump comprising at least one first chamber (6) from which fluid flows to a guide device (3). The guide device (3) comprises at least one guide element (8) and a support element (9). At least one opening (12) through which fluid flows in a channel (13) is arranged upstream of a guide channel (11) of the guide device (3).

Description

[0001] 10527F

[0002] KSB SE & Co. KGaA 67227 Frankenthal

[0003] Description

[0004] centrifugal pump with a guide device

[0005] The invention relates to a centrifugal pump with at least one first chamber from which a fluid flows to a guide device, wherein the guide device has at least one guide element and a support element.

[0006] This guide device can, for example, be equipped with guide vanes, between which guide channels for the conveyed medium are created. Alternatively, such guide devices can also be designed as guide wheels. The conveyed medium exiting the impeller enters the guide device, where kinetic energy is converted into pressure energy, and the direction of the medium changes. Often, the swirl is reduced to ensure a low-loss flow to the next stage.

[0007] Guide devices are those hydraulically active components of centrifugal pumps that modify the swirl flow in front of or behind the impeller. In front of the impellers, these guide devices are usually only used in the form of upstream swirl governors to control the swirl intensity. Guide devices behind the impellers act like diffusers and convert the kinetic energy of the swirl into pressure.

[0008] DE 39 12 279 C2 describes a centrifugal pump of single- or multi-stage design with at least one impeller. A guide vane is arranged downstream of the impeller in the flow direction. The guide vane has several guide blades. 10527F

[0009] DE 102014223942 A1 describes a single- or multi-stage centrifugal pump with a guide device. The pumped medium flows towards a first impeller and thereby experiences a pressure increase. Downstream of the impeller is a guide device, on whose guide channels guiding elements are arranged. The guide device can be designed as a diffuser.

[0010] DE 33 15 350 C2 relates to a guide vane for centrifugal pumps with diffuser-shaped widened guide channels. The outer radial guide channel boundary is formed by a housing that accommodates the guide vane.

[0011] EP 3 224 483 B1 discloses a centrifugal pump with at least one impeller designed as a radial wheel and discharging axially, to which a guide device is arranged which has guide vanes between which guide channels are formed, wherein at the outlet of at least a part of the guide channels guide elements are arranged which are designed as vanes, project at least partially into the guide channels and have a curvature to deflect the flow.

[0012] A conventional guide vane or guide device in a centrifugal pump is typically designed and optimized for a specific operating point or a relatively narrow operating range with a fixed geometry. If the centrifugal pump is operated outside this range, flow separation can occur. This leads to efficiency losses, a decrease in head, and an increased susceptibility to cavitation.

[0013] The object of the invention is to provide a centrifugal pump that exhibits a low tendency to flow separation. The centrifugal pump should have a high efficiency. Furthermore, the centrifugal pump should not be highly susceptible to cavitation. The centrifugal pump should be simple and cost-effective to implement.

[0014] This problem is solved according to the invention by a centrifugal pump according to the features of claim 1. Preferred embodiments can be found in the dependent claims, the subclaims, the description, and the drawings. 10527F

[0015] According to the invention, at least one opening is arranged in front of at least one guide channel of the guide device, through which a fluid flow passes in a channel.

[0016] For example, to reduce flow separation based on boundary layer control, the fluid flow passes through the opening. The fluid flow can be injected or extracted.

[0017] In a preferred embodiment of the invention, at least one opening is arranged in front of each guide channel of the guide device, through which a fluid flow passes in a channel.

[0018] In another embodiment, an opening is arranged in at least one guide channel of the guide device, through which a fluid flow passes in one channel.

[0019] In a preferred embodiment of the invention, an opening is arranged in each guide channel of the guide device, through which a fluid flow passes in one channel.

[0020] For example, the guide vane assembly comprises a guide wheel and a recirculation wheel. In the guide wheel, a large portion of the flow is slowed down and a high degree of swirl is reduced, resulting in maximum static pressure after exiting the guide wheel. The recirculation wheel, for example, accelerates the fluid flow in the inflow to the next impeller.

[0021] In one embodiment of the invention, the guide device can be formed integrally from the guide wheel and the return wheel. The guide wheel is directly connected to the return wheel.

[0022] In a further embodiment of the invention, a space can be arranged between the guide wheel and the return wheel, which, for example, has a higher pressure than the first space. In this embodiment, the guide device can be formed in one piece or composed of a guide wheel and a return wheel with the space arranged between them. 10527F

[0023] In an alternative embodiment of the invention, the guide device can be composed of multiple parts, consisting of a separate guide wheel and a separate return wheel. An additional space can be arranged between the guide wheel and the return wheel.

[0024] The first space, for example, is the space between the impeller and the guide vane, which has a lower pressure. This first space extends from the impeller outlet to just before the inlet of a guide channel, for example, to the guide vane leading edge inside the guide wheel.

[0025] The guide device includes, for example, a guide wheel with guide elements in the form of guide vanes and a return wheel with return vanes. The guide elements of the guide wheel project into the first space, each guide element having an entry edge, an exit edge, and two longitudinal guide element faces.

[0026] The guide channel is formed by two longitudinal guide element sides, a support element on which the guide elements are arranged, and a housing part to which the guide elements connect indirectly and / or directly.

[0027] The guide vane is equipped with a series of guide elements in the form of guide vanes that direct the fluid flow and change its velocity and direction to convert some of the kinetic energy into static pressure energy. These guide elements are arranged at a specific angle to efficiently direct the flow. The guide elements are attached to a central support element that rotates around the pump's axis of rotation. This support element serves as the structural base for the guide elements. The guide channel of the guide vane receives the fluid from the outlet of the centrifugal pump's impeller. At the end of the guide vane is the return impeller, which directs the fluid flow toward the next impeller of the centrifugal pump. The design of the return impeller ensures minimal turbulence and energy losses.The guide elements, together with the support element and the housing part in the form of a cover plate, form a flow channel or guide channel through which the fluid is directed. 10527F.

[0028] The leading edge of the guide element is the edge that extends towards the outlet of the preceding impeller of the centrifugal pump. The fluid first encounters the leading edge on its flow path through the guide wheel.

[0029] The exit edge is the end piece of the guide element of a guide vane and is located upstream of the impeller, which lies downstream in the flow direction. Starting from the entry edge, the guide element extends along its longitudinal sides to the exit edge.

[0030] The embodiment with a return wheel, similar to the guide wheel, features return blades with an entry edge, exit edge, longitudinal sides of the return blades, and a return channel. Accordingly, all embodiments described using the guide wheel as an example also refer to the return wheel. This means that the invention can be implemented either on the guide wheel, on the return wheel, or on both the guide wheel and the return wheel.

[0031] The additional space includes, for example, the space between the guide wheel and the return wheel, and thus the space of the pump, which has a higher fluid pressure than the first space.

[0032] In the design variant of a multi-stage centrifugal pump, the first chamber is always the chamber before the next chamber, which has a lower pressure, depending on the respective stage.

[0033] In a multi-stage centrifugal pump, the additional space, viewed in the direction of flow, is formed, for example, in the last guide device arranged, since this space has the highest static pressure.

[0034] In an alternative embodiment of the invention, the first chamber is connected via the channel to a further chamber configured as a fluid reservoir, whereby a fluid flow can flow through an opening in front of the guiding element from or into the fluid reservoir. 10527F

[0035] For example, the additional space could also include a pressure vessel.

[0036] The channel is preferably designed as a duct-like conduit. The channel can have a round, rectangular, square, trapezoidal, polygonal, cloverleaf-shaped, or complex cross-section. Such cross-sectional shapes can ideally be manufactured additively, e.g., using metallic 3D printing processes, since conventional tools, such as drills, can only produce round cross-sections. In one embodiment of the invention, the cross-sectional shapes can vary along the length of the channel.

[0037] In one variant of the invention, the channel is designed as a curved channel. The channel is shaped in such a way as to enable a low-loss and efficient flow of the fluid stream.

[0038] For example, the canal has at least one bend.

[0039] The arc of a channel includes at least one curved section, which differs from the design of a bore in the form of a straight channel due to the curvature.

[0040] For example, the channel has a curve from the inlet opening in the wider chamber to the outlet opening in the first chamber. The design of the curve ensures a low-loss flow of the fluid.

[0041] In one variant of the invention, the channel has at least one branch.

[0042] The branching indicates a section of the channel where it divides or branches to direct the fluid flow to different or multiple openings. 10527F

[0043] In one embodiment of the invention, the opening of the channel has a diameter greater than 20% and less than 50% of the thickness of the guide element. The shape and size of the opening allow a large area of ​​the guide element to be influenced by the fluid flow, in addition to altering the velocity profile in the boundary layer region.

[0044] For example, the opening of the channel has a diameter or equivalent diameter, where the diameter is more than 20% and less than 50% of the guide vane height or local guide vane thickness.

[0045] In one variant of the invention, the opening is designed as a slot, wherein the width of the slot is more than 50% and less than 90% of the local guide element width.

[0046] For example, at least one channel extends from the wider space across the support element of the guide device to in front of each guide element of the guide wheel.

[0047] In one variant of the invention, the guiding device comprises a system of channels, wherein at least one channel extends to in front of each guiding element, opening into an opening in front of the guiding element.

[0048] For example, the guide device has a ring-shaped channel from which branches supply at least one channel, which opens upstream of the guide element, with a fluid flow. In this respect, a channel ring in the guide device feeds a channel arrangement up to the guide elements with a fluid flow, which flows through an opening upstream of each guide element to modify the velocity profile in the boundary layer region or the flow towards the guide elements in order to reduce flow separation.

[0049] In one variant, the guide device has a central system of channels, while a secondary or distribution system of channels is additionally arranged in the guide elements by means of branches. 10527F

[0050] In an alternative version of the invention, the channel comprises at least one switch.

[0051] In an alternative version of the invention, the channel comprises a fluidic switch.

[0052] A fluidic switch is an element integrated into a duct that controls or regulates the flow of a fluid based on specific conditions or signals. Unlike mechanical or electrical switches, which respond to mechanical or electrical signals, a fluidic switch uses the flow properties of a fluid, such as its momentum (inertial effect) or pressure, to control the flow.

[0053] Fluidic switches, analogous to electronic components, can perform Boolean logic operations between multiple fluid flows, as well as control fluid flows by other fluid flows (analogous to the electronic transistor) or create a single possible flow direction (analogous to the electronic diode).

[0054] A fluidic switch can, for example, control the flow of fluid in a duct system depending on pressure, temperature, fluid level, or other parameters. It can be designed to either open or close the flow, or to switch between different flow rates, depending on the system's requirements. A key feature is that a fluidic switch can function without moving mechanical parts, operating solely through the clever combination of geometry and the inertial effects of the flow.

[0055] This specially designed fluidic switch can create a fluid flow through the channel when, for example, flow conditions prevail that promote flow separation at the guide vanes and return vanes, such as in a partial-load or overload operating range of the centrifugal pump. This fluid flow, which flows through the channel to the opening and then modifies the velocity profile in the boundary layer region of the guide vane, can thus reduce flow separation in unfavorable operating ranges of the centrifugal pump.

[0056] In one embodiment of the invention, the fluidic switch provides an inflow from a reservoir or an inflow into this reservoir, so that the fluid flow flows from or into this reservoir to reduce flow separation and is subject to an externally defined pressure.

[0057] For example, the fluidic switch can be arranged in the channel, with the channel conveying a control pressure from a chamber of the centrifugal pump, such as the impeller side chamber, the first chamber, or another chamber, to the fluidic switch. This section of the channel is then designed as a control pressure channel. At the appropriate control pressure, the fluidic switch can now enable flow from another channel section, which then opens a connection to an external reservoir with at least one opening, for example, upstream of the guide elements, thus generating a fluid flow to reduce flow separation.

[0058] For example, the fluidic switch can also implement a channel flow for extraction at the opening in front of the guide elements when a corresponding control pressure is applied.

[0059] In general, the invention encompasses the use of all known switching technologies, in particular electronic and electromechanical ones. The switching technology can be designed to be active or passive and may optionally interact with an external control system.

[0060] The channel or system of channels opens into at least one opening in front of each guide element.

[0061] For example, at least one opening per guide element, in the form of a slot, can cover the widest possible area of ​​the guide channel. 10527F

[0062] In another variant, several openings can be arranged in front of each guide element, so that as large an area as possible of the guide channel or the guide elements can be overflowed and influenced by a fluid flow.

[0063] For example, the opening is circular, elliptical, square, rectangular, or polygonal, so that the fluid flow flows as directly as possible along the guide element and can also influence as large an area of ​​the guide channel as possible with an additional fluid flow.

[0064] In one embodiment of the invention, the opening is arranged in the support element.

[0065] In another embodiment of the invention, the opening is arranged in a housing part.

[0066] Furthermore, in a third design variant, both the support element and the housing part can have at least one opening.

[0067] For example, the opening is aligned with a leading edge of the guide element. Furthermore, at least one opening can be aligned with each leading edge of a guide element.

[0068] In one embodiment of the invention, the at least one opening has an angle in the direction of flow, wherein the angle is greater than 0° and less than 90°. The opening thus projects in the direction of the flow, so that the fluid flow can be ideally injected and flows along the blade surface.

[0069] In another variant, at least one opening is angled against the flow direction, so that the opening protrudes against the flow. This orientation of the opening is ideally suited for suction. For example, the angle between the blade and the opening is between 90° and 180°. Alternatively, the opening of at least one channel is arranged at an angle to the guide element, where the angle is greater than 0° and less than 90°. This angle creates a fluid flow that flows directly along the guide element, thus altering the velocity profile in the boundary layer region, thereby at least reducing and ideally completely preventing flow separation.

[0070] In one variant of the invention, the angle of the channel to the guiding element is more than 10° and less than 30°.

[0071] In a further embodiment of the invention, in addition to the at least one opening in front of the guiding element, at least one further opening can also be provided in the guiding element.

[0072] For example, at least one opening per guide element can be in the form of a slot.

[0073] In another variant, several openings can be arranged on each guide element, so that as large an area of ​​the guide channel as possible can be influenced by a fluid flow.

[0074] In an advantageous embodiment of the invention, at least one opening is arranged on each longitudinal side of the guide element.

[0075] In a flowing fluid, the boundary layer is the region where, along solid walls and in close proximity to the wall, the flow velocity increases from the value of the wall velocity to the value of the external flow, unaffected by wall friction. The boundary layer thickness is defined, for example, as the distance from the wall at which the flow velocity reaches approximately 99% of the external flow velocity. Both laminar and turbulent flow can occur within the boundary layer. Even a turbulent boundary layer always has a laminar region, also called a viscous sublayer, in close proximity to the wall. 10527F

[0076] The boundary layer may detach from the wall of the guide channel. Behind the separation point, a separation zone forms, which is heavily permeated by vortices. The flow velocities in this zone are usually disordered in magnitude and direction, and a backflow sometimes develops. The reason for flow separation is generally an excessively slow flow velocity in the boundary layer, i.e., a boundary layer with insufficient kinetic energy. When the external flow decelerates, this is usually accompanied by an increase in pressure in the direction of the main flow. Flow separation occurs when the slow-moving fluid of the boundary layer no longer has enough kinetic energy to flow against the increasing pressure. The deceleration of the external flow occurs primarily at sharp deflections of the main flow on guide vanes.Flow separation is associated with turbulence and resulting additional flow losses. Furthermore, the separation zone of the main flow reduces the effective flow cross-section through the blade channel.

[0077] The inventive design of a centrifugal pump with at least one guide device, in which at least one channel with at least one opening is arranged upstream of each guide element, through which a fluid flow flows into the respective guide channel to reduce flow separation, leads to an advantageous energization of the boundary layer (increase in the kinetic energy of the fluid in the boundary layer). The boundary layer can be energized, for example, either by injecting an additional fast fluid flow or by drawing off existing slow flow regions. This energization prevents flow separation, efficiency losses, and head drops, and reduces the probability of cavitation.

[0078] Flow separations present obstacles that can be blown away or suctioned off, for example, by injecting a fluid stream.

[0079] The special design of the guide device with an integrated system of channels with a specially designed outlet angle of the opening with simultaneously optimized opening shape creates a fluid flow that advantageously changes the velocity profile in the boundary layer region of the guide channel or return channel, so that flow separations can be reduced or even completely prevented.

[0080] For example, the channel is generatively integrated into the guide device.

[0081] In one embodiment of the invention, the channel, in particular the system of channels in the guide device, is produced by a method in which the channel or channels in at least one of the guide device of the centrifugal pump are generated by selectively applying energetic radiation to layer-wise applied powder layers.

[0082] Selective laser melting (SLM) is an additive manufacturing process used to produce the channel in the guide device from metal powder. It is a form of 3D printing in which a high-power laser is used to selectively melt the powder and build the guide device with integrated channels layer by layer.

[0083] The guide device with at least one integrated channel is built up layer by layer by applying a thin layer of powder to a build platform. The laser beam is then directed at the selected areas, where it melts the metal powder and fuses it into a solid layer. A new layer is then applied, and the process is repeated until the guide device, consisting of a guide wheel and a return wheel, is complete.

[0084] Preferably, a high-power laser, typically a fiber laser or a CO2 laser, is used. The laser beam is precisely controlled to fuse the metal powder. The laser parameters, such as power, intensity, and feed rate, are set according to the requirements of the process and the selected material, particularly a metallic material. For example, the laser parameters can also be partially adjusted to achieve defined and desired microstructures. 10527F

[0085] After additive manufacturing, the guide device with at least one integrated channel may require post-processing.

[0086] In a further embodiment of the invention, a channel system for connecting the first and the further space extends both over the support element and over the housing part of the guide device up to the opening of the channel in front of the guide elements, in order to realize a fluid flow in the boundary layer area which can effectively prevent flow separation.

[0087] The invention encompasses both single-stage and multi-stage centrifugal pumps.

[0088] According to the invention, a centrifugal pump is used with a guide device in whose guide elements or return elements integrated channels are arranged to broaden the operating point range of the centrifugal pump.

[0089] The boundary layer control achieved through a channel integrated into the guide vane system, with at least one opening upstream of the guide elements, incorporates the concept of boundary layer injection. This involves the targeted introduction of additional kinetic energy and momentum into the boundary layers at the guide element entry edges. This shifts, for example, the starting points of boundary layer separation on the longitudinal sides of the guide elements towards lower or higher flow rates. As a result, the pump hydraulics can advantageously be operated over a wider operating range with higher efficiency, higher delivery head, and reduced cavitation tendency.

[0090] This results in the boundary layer becoming thinner in areas prone to flow separation, and a higher kinetic energy and momentum in the flow direction is present in these areas, which reduces the tendency of the flow to separate there.

[0091] Additionally, the tendency to cavitation can be reduced by avoiding and / or minimizing separation zones, which generally have lower pressure than their immediate vicinity. 10527F

[0092] The design of the integrated channels can be conceived using hydraulic and structural mechanics principles and then additively manufactured. 3D printing offers maximum flexibility in shaping the channels. This allows for the application of fluidic logic principles to achieve adaptive or highly variable hydraulic properties. Consequently, the boundary layer control can be managed without moving components.

[0093] The fluid for injection is tapped, for example, in the wider space, or in the last space in the flow direction, between the guide vane and the return vane. Here, the static pressure is higher than at the guide element leading edges. Due to the driving pressure difference, the fluid flows through a custom-shaped, curved, and branching channel inside the guide device to the openings in front of the guide elements.

[0094] Further features and advantages of the invention will become apparent from the description of exemplary embodiments with reference to the drawings and from the drawings themselves.

[0095] This shows:

[0096] Fig. 1 shows a sectional view of a section of a centrifugal pump,

[0097] Fig. 2 shows another sectional view of a centrifugal pump with a fluidic switch,

[0098] Fig. 3 shows a sectional view of a section of a multi-stage centrifugal pump,

[0099] Fig. 4 shows a sectional view of a section of a multi-stage centrifugal pump with a fluidic switch, 10527F

[0100] Fig. 5 shows a detailed view of the support element in front of a guide vane with an opening for fluid injection.

[0101] Fig. 6 shows a further detailed view of the support element in front of a guide vane with an opening for fluid extraction.

[0102] Figure 1 shows a section of a centrifugal pump in a sectional view. At least one impeller 2 is mounted on a shaft 1 to transmit torque. A guide vane 3 is arranged downstream of the impeller 2, which in the illustrated embodiment consists of a guide vane 4 and a return vane 5.

[0103] The centrifugal pump has a first chamber 6 in which the guide vane 4 of the guide device 3 is arranged. The further chamber 7 is located downstream of the guide vane 4 and upstream of the return impeller 5, with the further chamber 7 having a higher pressure than the first chamber 6.

[0104] The conveyed medium exiting impeller 2 enters the guide wheel 4 of the guide device 3, where kinetic energy is converted into pressure energy, and the conveyed medium's direction changes. Furthermore, the swirl of the conveyed medium is reduced by the return wheel 5 to ensure a low-loss flow to another impeller (not shown here).

[0105] The guide wheel 4 of the guide device 3 has at least one guide element 8, a support element 9 and a housing part 10. Several guide elements are arranged between the support element 9 and the housing part 10, thereby forming a guide channel 11 between each pair of guide elements 8 and the support element 9 and the housing part 10.

[0106] Upstream of each guide channel 11 of the guide device 3, at least one opening 12 is arranged, through which a fluid flow from a channel 13 flows to reduce flow separation by influencing the flow towards the guide elements 8. 10527F

[0107] The guide wheel 4 of the guide device 3 has a channel 13 that connects the further chamber 7 with the first chamber 6, wherein a fluid flow from the further chamber 7 into the first chamber 6 through an opening 12 in front of the guide element 8 to reduce flow separation by influencing the flow towards the guide elements 8.

[0108] Channel 13 is additively integrated into the guide device 3 and has a bend 14.

[0109] Fig. 2, in addition to Fig. 1, shows a sectional view of a centrifugal pump with a fluidic switch 15. In the illustrated embodiment, the fluidic switch 15 is arranged such that the control pressure behind the return impeller 5 is applied to the fluidic switch 15 via a control channel 16. At the corresponding control pressure, the fluidic switch 15 enables flow through the channel 13 from the further chamber 7 to the opening 12 in front of the leading edge 17 of the guide element 8.

[0110] Figure 3 shows a sectional view of a section of a two-stage centrifugal pump. The additional chamber 7 is located in the second stage of the centrifugal pump between the return impeller 5 and the guide vane 4. The highest static pressure within the centrifugal pump is found here. A channel 13 leads from the additional chamber 7 to the opening 12 of the first stage. The opening 12 is slot-shaped, allowing a fluid flow to pass in front of the leading edge 17 of the guide element 8 to reduce flow separation by influencing the flow direction.

[0111] Channel 13 has a branch 18 that divides channel 13 into a further opening 19 in the guide element 8. Through opening 12 and the further opening 19, almost the entire guide channel 11 can be influenced by a fluid flow to change the velocity profile in the boundary layer region.

[0112] In the case of boundary layer suction through the slot-shaped opening 12, it can be advantageous to design the downstream edge of the slot-shaped opening 12 to be raised compared to the upstream edge in order to achieve efficient suction of the boundary layer. 10527F

[0113] Figure 4 shows an embodiment in which the channel 13 is connected to a fluid reservoir 20 (not shown). The fluidic switch 15 receives the control pressure via the control channel 16 from the further chamber 7. At the appropriate control pressure, the fluidic switch 15 initiates a flow through the channel 13 from the fluid reservoir 20 to the opening 12, so that a fluid flow passes in front of the leading edge 17 of the guide element 8 to reduce flow separation by influencing the flow direction.

[0114] Figures 5 and 6 each show an exemplary detailed view of the housing part 10 with an opening 12. The opening 12 is aligned with the leading edge 17 of the guide element.

[0115] 8 aligned and arranged in Fig. 5 at an angle a to the housing part 10, wherein the angle a in the illustrated embodiment is approximately 30° and is suitable for injecting a fluid flow to reduce flow separation in the guide channel 11.

[0116] The opening 12 is arranged in Fig. 6 at an angle a of approximately 110° to the housing part 10 and is suitable for the extraction of a fluid flow to reduce flow separation in the guide channel 11.

[0117] 10527F

[0118] List of reference signs

[0119] 18 branching

[0120] 1 wave 19 Further opening

[0121] 2 impeller 20 fluid reservoir

[0122] 3 Guide device a angle

[0123] 4 Guide wheel

[0124] 5 Return wheel

[0125] 6 First Room

[0126] 7 Another room

[0127] 8 guide element

[0128] 9 Support element

[0129] 10 Housing part

[0130] 11 Guide channel

[0131] 12 Opening

[0132] Channel 13

[0133] 14 sheets

[0134] 15 Fluidic switch

[0135] 16 control channels

[0136] 17 Entrance edge

Claims

10527F Patent claims centrifugal pump with a guide device 1. Centrifugal pump with at least one first chamber (6) from which a fluid flows to a guide device (3), wherein the guide device (3) has at least one guide element (8) and a support element (9), characterized in that at least one opening (12) is arranged in front of at least one guide channel (11) of the guide device (3), through which a fluid flow flows in a channel (13).

2. Centrifugal pump according to claim 1, characterized in that the fluid flow flows through the opening (12) to reduce flow separation.

3. Centrifugal pump according to claim 1 or 2, characterized in that at least one opening (12) is arranged in at least one guide channel (11) of the guide device (3), through which a fluid flow flows in a channel (13).

4. Centrifugal pump according to one of claims 1 to 3, characterized in that the opening (12) is arranged in the support element (9). 10527F 5. Centrifugal pump according to one of claims 1 to 4, characterized in that the opening (12) is arranged in a housing part (10).

6. Centrifugal pump according to one of claims 1 to 5, characterized in that the opening (12) is aligned with an inlet edge (17) of the guide element (8).

7. Centrifugal pump according to one of claims 1 to 6, characterized in that at least one switch (15), preferably a fluidic switch, is arranged in front of the opening (12).

8. Centrifugal pump according to one of claims 1 to 7, characterized in that the fluid flows into a further chamber (7) after exiting the guide channel (11 ), wherein the first chamber (6) is connected to the further chamber (7) via the channel (13).

9. Centrifugal pump according to one of claims 1 to 8, characterized in that the first chamber (6) is connected to a fluid reservoir (20) via the channel (13).

10. Centrifugal pump according to one of claims 1 to 9, characterized in that the opening (12) is circular or elliptical or square or rectangular or polygonal.

11. Centrifugal pump according to one of claims 1 to 10, characterized in that at least one opening (12) projects at an angle (a) in the direction of flow. 10527F 12. Centrifugal pump according to one of claims 1 to 10, characterized in that at least one opening (12) projects at an angle (a) against the direction of flow.

13. Centrifugal pump according to any one of claims 1 to 12, characterized in that the opening (12) has a diameter wherein the diameter is more than 20% and less than 50% of the thickness of the guide element (8).

14. Centrifugal pump according to any one of claims 1 to 13, characterized in that the channel (13) has at least one bend (14).

15. Centrifugal pump according to one of claims 1 to 14, characterized in that the channel (13) has at least one branch (18).

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