Centrifugal pump comprising a guide device

Abstract

The invention relates to a centrifugal pump comprising: at least one first chamber (6) which has at least one guide device (3); and at least one further chamber (7). The guide device (3) comprises at least one channel (8) which connects the further chamber (7) to the first chamber (6). Fluid flows through at least one opening (9) in the guide device (3).

Description

[0001] 10525F

[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 comprising at least one guide device and at least one further chamber.

[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. 2 10525F

[0009] DE 10 2014 223 942 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 3224 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 of a centrifugal pump is typically designed and optimized for a specific operating point or a relatively narrow operating range with a fixed geometry. When the centrifugal pump is operated outside this range, flow separation can occur. This leads to efficiency losses, a decrease in delivery 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. 3 10525F

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

[0015] According to the invention, the guide device has at least one channel that connects the further space with the first space, wherein a fluid flow passes through at least one opening in the guide device.

[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] 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.

[0018] 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.

[0019] For example, the guide vane assembly includes a guide wheel and a recirculation wheel. In the guide wheel, a large proportion 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. 4 10525F

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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 vane channel, for example, to the guide vane leading edge inside the guide vane.

[0024] 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.

[0025] Thus, the first chamber is located within a guide wheel, between the support plate and the cover plate of the guide wheel, specifically from the impeller exit to the guide vane leading edge of the guide wheel channel. 5 10525F

[0026] 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.

[0027] 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.

[0028] In a multi-stage centrifugal pump, the additional space is located, for example, in the last guide device when viewed in the direction of flow, since this space has the highest static pressure.

[0029] In an alternative version of the invention, the first space is connected via the channel to another space in the configuration as a fluid reservoir, whereby a fluid flow can flow through an opening in the respective blade from the fluid reservoir or into the fluid reservoir.

[0030] For example, the additional space could also include a pressure vessel.

[0031] For example, at least one channel extends from the support disc of the guide device to the guide vanes of the guide wheel.

[0032] In one variant of the invention, the guide device comprises a system of channels, wherein at least one channel extends into at least one guide vane and opens into at least one opening on the guide vane.

[0033] For example, the guide vane has a ring-shaped channel from which branches supply at least one channel for each guide vane with a fluid flow. In this respect, a channel ring in the guide vane feeds a channel arrangement in the guide vanes with a fluid flow, which flows through an opening in each guide vane to modify the velocity profile in the boundary layer region in order to reduce flow separation. 6 10525F

[0034] In one variant, the guide device has a central system of channels, while a secondary or distribution system of channels is arranged in the guide vanes by means of branches.

[0035] The system of channels terminates in at least one opening per guide vane.

[0036] For example, at least one opening per guide vane in the form of a slot can cover as wide an area of ​​the guide vane channel as possible.

[0037] In another variant, several openings can be arranged per guide vane, so that as large an area as possible of the guide vane channel height can be influenced by a fluid flow.

[0038] 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 efficiently injected and flows along the blade surface.

[0039] In another variant, at least one opening has an angle opposite to the flow direction, so that the opening protrudes against the flow. This orientation of the opening is advantageous for suction. For example, the angle between the blade and the opening is between 90° and 180°.

[0040] For example, the opening of at least one channel is arranged at an angle to the guide vane, where the angle is greater than 0° and less than 90°. This angle creates a fluid flow that flows directly along the guide vane, thus altering the velocity profile in the boundary layer region, thereby at least reducing and ideally completely preventing flow separation.

[0041] In one embodiment of the invention, the angle of the channel to the guide vane is greater than 10° and less than 30°. 7 10525F

[0042] 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 surrounding 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 value of the surrounding flow. 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.

[0043] The boundary layer may detach from the wall. 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 main flow direction. 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. 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.

[0044] The inventive design of a centrifugal pump with at least one guide vane, in which each guide vane has at least one channel through which a fluid flow passes through at least one opening in the respective guide vane 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.

[0045] Flow separations present obstacles that can be blown away or suctioned off, for example, by injecting a fluid stream.

[0046] The special design of the guide device with an integrated system of channels with a specially designed outlet angle of the channel opening with simultaneously optimized opening shape creates a fluid flow that advantageously changes the velocity profile in the boundary layer area of ​​the guide vane or recirculation vane, so that flow separations can be reduced or even completely prevented.

[0047] For example, the opening is circular, elliptical, square, rectangular, or polygonal, so that the fluid flow flows as directly as possible along the guide vane and can also influence as large a vane area as possible.

[0048] The guide device includes, for example, a guide wheel with guide vanes and a return wheel with return vanes. The guide vanes of the guide wheel project into the first space, each guide vane having a guide vane entry edge, a guide vane exit edge, and two guide vane longitudinal sides.

[0049] In an advantageous embodiment of the invention, at least one opening is arranged on each longitudinal side of the guide vane.

[0050] The guide vane is equipped with a series of guide blades that direct the fluid flow and change its speed and direction to convert some of the kinetic energy into static pressure energy. These guide blades are arranged at a specific angle to efficiently direct the flow. The guide blades are attached to a central support disc that rotates around the axis of rotation of the 9 10525F.

[0051] The pump rotates and extends. The support disc serves as the structural base for the guide vanes. The guide vane's inlet channel receives the fluid from the impeller outlet of the centrifugal pump. At the end of the guide vane is the return impeller, which directs the fluid flow towards the next impeller of the centrifugal pump. The design of the return impeller ensures minimal turbulence and energy loss. The guide vanes, together with the support disc and the cover plate, form the flow channel through which the fluid is guided. The channel openings are located, for example, near the impeller of the guide vanes.

[0052] The longitudinal sides of the guide vanes of a guide wheel define the guide channel of the guide device between the support disc and the cover disc.

[0053] The guide vane leading edge is the edge that extends towards the outlet of the preceding impeller of the centrifugal pump. The fluid first encounters the guide vane leading edge on its flow path through the guide wheel.

[0054] The guide vane trailing edge is the end piece of the guide vane of a guide wheel and is located upstream of the impeller, which lies behind it in the direction of flow. Starting from the guide vane leading edge, the guide vane extends along its longitudinal sides to the guide vane trailing edge.

[0055] In one embodiment of the invention, at least one opening is arranged in a region, wherein the region is located less than 30% of the distance from the guide vane leading edge to the guide vane exit edge from the guide vane leading edge. This allows the fluid flow to influence the boundary layer along the guide vane from the beginning of the guide vane, thereby effectively reducing flow separation over a large area of ​​the guide vane.

[0056] In one embodiment of the invention, the guide vane's support disk has at least one opening in an inlet area upstream of the guide vane leading edge, through which a fluid flow passes to reduce flow separation. 10 10525F

[0057] The inlet area is the region within the guide vane or guide device of a centrifugal pump that extends in the immediate vicinity of the guide vane leading edge and thus in front of the guide vane channel. The inlet area is bounded by the support disc and the cover disc.

[0058] Unlike an opening in a guide vane, the housing opening, or support disc opening, is located within the support disc. The support disc opening points towards the guide vane channel, allowing the fluid flow within it to influence the flow on the guide vanes and reduce flow separation. For example, the support disc opening can create a fluid flow that extends over guide vane areas, which would be more difficult to achieve with an opening in the guide vane itself. For instance, the support disc opening can create a fluid flow that favorably influences the flow towards the guide vane leading edge.

[0059] In one embodiment of the invention, the guide wheel has a cover plate that limits the guide vane channel on the opposite side of the support plate.

[0060] The shroud of a guide vane is a component located at the edge of the guide vane that connects the guide blades. It forms the outer boundary of the guide vane and can be used to direct and control the flow within the guide vane.

[0061] In one variant of the invention, the channel connecting the second room to the first room can also be integrated into the cover plate.

[0062] In one embodiment of the invention, the cover plate of the guide device has at least one cover plate opening in an inlet area upstream of the guide vane leading edge, through which a fluid flow passes to reduce flow separation. 11 10525F

[0063] Unlike an opening in a guide vane, a shroud opening is located within the shroud itself. The shroud opening faces the guide vane channel, allowing the fluid flow within it to influence the flow on the guide vanes and reduce flow separation. For example, the shroud opening can create a fluid flow that extends over guide vane areas in a way that is more difficult to achieve with an opening in the guide vane. For instance, the shroud opening can create a fluid flow that favorably influences the flow towards the guide vane leading edge.

[0064] For example, the canal has at least one bend.

[0065] 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.

[0066] 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.

[0067] In one variant of the invention, the channel has at least one branch.

[0068] The branching indicates a section of the channel where the channel splits or branches to direct the fluid flow to different or multiple openings.

[0069] In one embodiment of the invention, the opening of the channel has a diameter greater than 20% and less than 50% of the guide vane thickness. The shape and size of the opening allow a large area of ​​the guide vane to be influenced by the fluid flow, in addition to altering the velocity profile in the boundary layer region. 12 10525F

[0070] For example, the opening of the channel has a diameter where the diameter is more than 20% and less than 50% of the guide vane height or the local guide vane thickness.

[0071] 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 vane width.

[0072] For example, the channel is generatively integrated into the blade and the support disc.

[0073] In one embodiment of the invention, the channel, in particular the system of channels in the support disc and / or in the cover disc of the guide device and in the guide vanes, is produced by a method in which the channel or channels in at least one guide device of the centrifugal pump are generated by selectively applying energetic radiation to layered powder layers.

[0074] 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.

[0075] 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.

[0076] 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 into 13 10525F. 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.

[0077] After additive manufacturing, the guide device with at least one integrated channel may require post-processing.

[0078] In an alternative version of the invention, the channel comprises at least one switch.

[0079] For example, the channel has a fluidic switch upstream of the opening.

[0080] 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.

[0081] 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 an electronic transistor) or create a single possible flow direction (analogous to an electronic diode).

[0082] A fluidic switch can, for example, control the flow of fluid in a pipe 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 requirements. A key feature is that a fluidic switch can function without any moving mechanical parts, operating solely through the clever combination of geometry and the inertial effects of the flow.

[0083] 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 the 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.

[0084] 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.

[0085] For example, the fluidic switch can be arranged in the channel, with the channel conveying a control pressure from a wheel side chamber, the first chamber, or another chamber to the fluidic switch. This channel section is then designed as a control pressure channel. At the appropriate control pressure, the fluidic switch can now enable flow from another channel section, whereby the channel section then opens a connection to an external reservoir with at least one opening, for example, in the guide vane or in the support or cover plate, thus generating a fluid flow to reduce flow separation.

[0086] For example, the fluidic switch can also implement a channel flow for extraction at the opening of the guide vane when the appropriate control pressure is applied.

[0087] In general, the invention encompasses the use of all known switching technologies, in particular electronic and electromechanical ones. The switching technology can be active or passive and may optionally interact with an external control system. 15 10525F

[0088] In a further embodiment of the invention, a channel system for connecting the first and the further space extends both over the cover plate and over the support plate of the guide wheel into the guide vanes to the opening of the channel in order to realize a fluid flow in the boundary layer region which can effectively prevent flow separation.

[0089] The invention encompasses both single-stage and multi-stage centrifugal pumps.

[0090] According to the invention, a centrifugal pump with a guide device, in whose guide vanes or return vanes integrated channels are arranged starting from the support disc and / or cover disc, is used to broaden the operating point range of the centrifugal pump.

[0091] The boundary layer control achieved through a channel integrated into the guide vane assembly, with at least one opening in the longitudinal sides of the guide vanes, 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 vane leading edges. This shifts, for example, the starting points of boundary layer separation on the longitudinal sides of the guide vanes 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.

[0092] 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.

[0093] Additionally, the tendency to cavitation can be reduced by avoiding and / or minimizing separation zones, which generally have lower pressure than their immediate vicinity. 16 10525F

[0094] The design of the integrated channels can be conceived using hydraulic and structural mechanics principles and implemented additively. 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, boundary layer control can be managed without moving components.

[0095] 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 vane leading edges. Due to the driving pressure difference, the fluid flows through a custom-shaped, curved, and branching channel inside the guide vane assembly to the openings at the guide vane leading edges.

[0096] 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.

[0097] This shows:

[0098] Fig. 1 shows a sectional view of a section of a centrifugal pump,

[0099] Fig. 2 shows another sectional view of a centrifugal pump with a fluidic switch,

[0100] Fig. 3 shows a sectional view of a section of a multi-stage centrifugal pump,

[0101] Fig. 4 shows another sectional view from a section of a multi-stage centrifugal pump,

[0102] Fig. 5 shows a sectional view of a section of a multi-stage centrifugal pump with a fluidic switch, 17 10525F

[0103] Fig. 6 shows a sectional view of a guide wheel section,

[0104] Fig. 7 shows a detailed view of a guide vane with an opening for fluid injection.

[0105] Fig. 8 shows a further detailed view of a guide vane with an opening for fluid extraction.

[0106] 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.

[0107] 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.

[0108] 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).

[0109] The guide wheel 4 of the guide device 3 has a channel 8 that connects the further chamber 7 with the guide channel 16, wherein a fluid flow from the further chamber 7 into the guide channel 16 through an opening 9 over the guide vanes 10 to change the velocity profile in the boundary layer region in order to reduce flow separation.

[0110] Channel 8 is generatively integrated into the guide vane 10 and has a curve 11. 18 10525F

[0111] Fig. 2, in addition to Fig. 1, shows a sectional view of a centrifugal pump with a fluidic switch 12. In the illustrated embodiment, the fluidic switch 12 is arranged such that the control pressure behind the return impeller 5 is applied to the fluidic switch 12 via a control channel 13. At the corresponding control pressure, the fluidic switch 12 allows flow through the channel 8 from the further chamber 7 to the opening 9.

[0112] 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 8 leads from the additional chamber 7 to the opening 9 of the first stage. The opening 9 is slot-shaped, allowing a fluid flow to pass over the guide vane 10 to modify the velocity profile in the boundary layer region and thus reduce flow separation.

[0113] In the case of boundary layer extraction through the slot-shaped opening 9, it may be advantageous to design the downstream edge of the slot-shaped opening 9 to be raised compared to the upstream edge in order to achieve efficient extraction of the boundary layer.

[0114] Fig. 4 shows a variant embodiment in which the opening 9 is arranged on a return vane 14 on the return wheel 5. The further embodiment corresponds to the example in Fig. 3. The channel 8 is additively integrated into both the stage housing 15 and the guide device 3.

[0115] Figure 5 shows an embodiment in which the channel 8 is connected to a fluid reservoir 20 (not shown). The fluidic switch 12 receives the control pressure via the control channel 13 from the further chamber 7. At the appropriate control pressure, the fluidic switch 12 initiates a flow through the channel 8 from the fluid reservoir 20 to the opening 9, so that a fluid flow passes over the guide vane 10 to modify the velocity profile in the boundary layer region in order to reduce flow separation.

[0116] Fig. 6 shows a sectional view of a guide wheel section. The conveyed medium flows from the impeller 2 into the guide wheel 4 of the guide device 3. The guide wheel 4 has guide vanes 10, with a guide channel 16 being formed between each pair of adjacent guide vanes 10.

[0117] Each guide vane 10 has a guide vane entry edge 17, a guide vane exit edge 18 and two guide vane longitudinal sides 19.

[0118] The openings 9 of the channel 8 are arranged in an area, the area being less than 30% of the distance from the guide vane entry edge 17 to the guide vane exit edge 18 from the guide vane entry edge 17.

[0119] The openings 9 are arranged near the leading edge 17 of the guide vane so that as large an area as possible of the guide vane's longitudinal sides 19 is exposed to the fluid flow from the wider chamber 7 or the fluid reservoir 20 to modify the velocity profile in the boundary layer region and thus reduce flow separation. Each opening 9 has a diameter which, in the illustrated embodiment, is approximately 25% of the local blade thickness of the guide vane 10.

[0120] Figures 7 and 8 each show an exemplary detailed view of the guide vane 10 with an opening 9. In Figure 7, the opening 9 is arranged at an angle α to the guide vane 10, where the angle α in the illustrated embodiment is approximately 30° and is suitable for injecting a fluid flow to reduce flow separation in the guide channel 16.

[0121] The opening 9 on the longitudinal side 19 of the blade in Fig. 8 is arranged at an angle α of approximately 110° to the guide vane 10 and is suitable for drawing off a fluid flow to reduce flow separation in the guide channel 16. 10525F

[0122] List of reference signs

[0123] 18 Guide vane exit edge

[0124] 1 wave 19 guide vane longitudinal side

[0125] 2 impeller 20 fluid reservoir

[0126] 3 Guide device a angle

[0127] 4 Guide wheel

[0128] 5 Return wheel

[0129] 6 First Room

[0130] 7 Another room

[0131] 8-channel

[0132] 9 Opening

[0133] 10 guide vanes

[0134] 11 sheets

[0135] 12 Fluidic switch

[0136] 13 Control channel

[0137] 14 Return paddle

[0138] 15-step housing

[0139] 16 guide channel

[0140] 17 Guide vane leading edge

Claims

21 10525F Patent claims centrifugal pump with a guide device 1. Centrifugal pump with at least one first chamber (6) comprising at least one guide device (3) and at least one further chamber (7), characterized in that the guide device (3) has at least one channel (8) connecting the further chamber (7) to the first chamber (6) and through which a fluid flow passes through at least one opening (9).

2. Centrifugal pump according to claim 1, characterized in that the fluid flow flows through the opening (9) to reduce flow separation.

3. Centrifugal pump according to claim 1 or 2, characterized in that the guide device (3) has a guide wheel (4) with guide vanes (10) projecting into the first space (6), each guide vane (10) having a guide vane entry edge (17), a guide vane exit edge (18) and two guide vane longitudinal sides (19).

4. Centrifugal pump according to one of claims 1 to 3, characterized in that the opening (9) is circular or elliptical or square or rectangular or polygonal.

5. Centrifugal pump according to one of claims 3 or 4, characterized in that at least one opening (9) is arranged on the longitudinal side (19) of the guide vane. 22 10525F 6. Centrifugal pump according to one of claims 3 to 5, characterized in that at least one opening (9) is arranged in a region, wherein the region is less than 30% of the distance from the guide vane inlet edge 17 to the guide vane outlet edge 18 from the guide vane inlet edge (17).

7. Centrifugal pump according to one of claims 1 to 6, characterized in that the channel (8) is additively integrated into the guide device (3).

8. Centrifugal pump according to one of claims 1 to 7, characterized in that the channel (8) has at least one bend (11).

9. Centrifugal pump according to one of claims 1 to 8, characterized in that the channel (8) has at least one branch.

10. Centrifugal pump according to one of claims 1 to 9, characterized in that the opening (9) has a diameter wherein the diameter is more than 20% and less than 50% of the thickness of the guide vane (10).

11. Centrifugal pump according to one of claims 1 to 10, characterized in that at least one switch (12), preferably a fluidic switch, is arranged in front of the opening (9).

12. Centrifugal pump according to one of claims 1 to 11, characterized in that the channel (8) is connected to a fluid reservoir (20).

13. Centrifugal pump according to one of claims 1 to 12, characterized in that at least one opening (9) projects at an angle (a) in the direction of flow.

14. Centrifugal pump according to one of claims 1 to 12, characterized in that at least one opening (9) projects at an angle (a) against the direction of flow. 23 10525F 15. Use of a centrifugal pump with at least one guide device (3) in which integrated channels (8) are arranged to broaden the operating point range.

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