A fan including a flow guide device and a flow guide device

Abstract

The present invention relates to a flow guide device (21) and a fan (15) comprising the flow guide device (21). The flow guide device (21) has an annular wall (23) that completely surrounds a central axis (A) in the circumferential direction (U) and defines an inflow channel (27) on its inner surface facing the central axis (A). The downstream end of the annular wall (23) has a trailing edge (31) that does not extend into a single plane oriented perpendicularly to the central axis (A). Rather, the trailing edge (31) forms a plurality of grooves (33) and / or a plurality of ridges (32) with respect to a virtual reference plane (E) oriented perpendicularly to the central axis (A). The trailing edge (31) may have a corrugated and / or sawtooth profile.

Description

Technology Field

[0001] The present invention relates to a flow guide device for a fan and a fan including a flow guide device. The flow guide device is configured to guide air flow to a fan rotor that is rotatably driven. To this end, the flow guide device defines an inlet channel through which air from the environment can flow to the fan rotor. Background Technology

[0002] Such a flow guide is described, for example, in DE 10 2021 123 242 A1. The flow guide has an end having low hardness that can make sliding contact with the fan rotor, and during initial startup, said end is worn down so that a minimum gap is created between said end and the fan rotor. In this way, leakage flow through the gap between the fan rotor and the flow guide is minimized.

[0003] Wear at the ends for improved efficiency offers advantages. In some cases, grinding noise may be heard. Additionally, in some known flow guide devices, noise caused by the air flowing through the fan rotor, such as a whistling noise, may occur. The problem to be solved

[0004] Therefore, the objective of the present invention is to provide a flow guide device for a fan that enables a lower noise level without significantly impairing the efficiency of the fan. means of solving the problem

[0005] This objective is achieved by a flow guide device having the features of patent claim 1 and a fan having the features of patent claim 15.

[0006] The flow guide device according to the present invention is configured to guide air flow to a fan rotor that is rotatably driven. The flow guide device has an annular wall that completely surrounds an inlet channel in a circumferential direction centered on a central axis. In particular, the annular wall is circular and is positioned coaxially with respect to the central axis. The annular wall may extend parallel to the central axis or at an angle to the central axis in the direction of air flow. Consequently, the shape of the inlet channel may be cylindrical or conical. An inlet channel having a conical shape tapers in the direction of air flow. In this case, the annular wall oriented at an angle to the central axis can be described, so to speak, as an inlet nozzle.

[0007] The annular wall has a trailing edge in the direction of airflow. At the installed location of the flow guide, the trailing edge is positioned adjacent to the fan rotor. Along its circumferential extension, the trailing edge has varying distances from a virtual reference plane oriented perpendicular to the central axis. Accordingly, the trailing edge has a plurality of grooves and / or a plurality of ridges with respect to the virtual reference plane.

[0008] The shape of the grooves and / or ridges may vary, for example, to adapt the geometry and / or dimensions of the grooves and / or ridges of the trailing edge to the operating range of the fan, particularly the range of air flow velocity and / or the range of air intake pressure in the trailing edge region. The trailing edge may have a corrugated profile, such as a sinusoidal profile, or a sawtooth profile. It may also be advantageous to combine corrugated and sawtooth shapes in an appropriate manner. In all exemplary embodiments, the trailing edge may be formed of arc-shaped sections and / or linear sections in its extension around a central axis. Each arc-shaped section may be, for example, a circular arc, an elliptical arc, or a sinusoidal arc, wherein one or more arc shapes may be combined with each other.

[0009] At least some or all of the grooves and / or ridges of the trailing edge may be oriented at an angle with respect to the central axis. A central plane passing through one of the grooves and / or ridges may be oriented at an angle with respect to the central axis and / or may be oriented at an angle with respect to the circumferential direction centered on the central axis.

[0010] The extension or profile of the trailing edge around the central axis may be without edges or steps. Mathematically speaking, the profile of the trailing edge may be continuous and / or differentiable. Optionally, at least one groove and / or at least one ridge of the trailing edge may also have one or more edges or one or more steps.

[0011] The distance from the bottom of each groove and / or the top of each ridge to a reference plane in a direction parallel to the central axis may be the same or may vary at any point in the circumferential direction. Additionally or alternatively, the width of the grooves in the circumferential direction (e.g., the distance between two immediately adjacent tops in the circumferential direction) and / or the width of the ridges in the circumferential direction (e.g., the distance between two immediately adjacent bottoms in the circumferential direction) may be constant or vary. As described, the dimensions and shape or geometric structure of the grooves and / or ridges may be selected to be suitable for the application field and the conditions present therein, particularly to be suitable for the pressure and / or flow velocity of the air flow.

[0012] A non-uniform trailing edge relative to the virtual reference plane allows for the elimination or at least reduction of unwanted noise that may occur when air flows through or exits the inlet channel. For example, regarding volumetric flow or outlet pressure, it has been shown that the non-uniform trailing edge does not impair the efficiency of the fan, or impairs it only to a negligible degree, compared to a trailing edge extending parallel to the reference plane.

[0013] Although corrugated or serrated edges are known in applications in other technical fields, particularly the so-called "chevrons" of aircraft engines, in which case the serrated or corrugated trailing edges are placed at the flow outlet of the aircraft engine and are intended to better mix the inner layer of fast-moving air with the outer layer of slower-moving air. Various "chevrons" are described, for example, in EP 2 245 289 A1, EP 4 015 812 A1, WO 2015 / 036 684 A1, or WO 2023 / 057 704 A1.

[0014] It is advantageous for the above flow guide device to also include a front wall connected to the annular wall. The front wall and the annular wall may form an integral single part. The front wall is connected to the annular wall upstream of the trailing edge at the opposite end of the inlet channel in the flow direction. The front wall may be oriented perpendicular to the central axis. In one exemplary embodiment, the front wall may be an integral part of the fan housing.

[0015] In particular, the flow guide device is configured to guide airflow to the fan rotor only through the inlet channel. Accordingly, the annular wall is preferably configured to guide airflow only on its side facing the inlet channel. On the outer side of the annular wall, far from the inlet channel, air movement may occur as a result of airflow through the inlet channel. However, air does not flow from the environment to the fan rotor along this outer side of the annular wall.

[0016] It is preferable that the front wall does not have a flow opening that allows air to be supplied to the fan rotor. Preferably, the front wall does not have a flow opening that is fluidly connected to an inlet channel. Except for openings for mechanical connection of the flow guide device to other integral parts of the fan, the front wall may have only a single inlet opening leading to an inlet channel. It is understood that this inlet opening may optionally be covered with a grid and / or filter to prevent objects or particles from entering the inlet channel.

[0017] The front wall and the annular wall may be directly connected to each other. Alternatively, the front wall and the annular wall may be indirectly connected to each other, for example, by means of a transition wall. The transition wall is positioned coaxially with the central axis and may transition to the annular wall without forming an edge or step. Additionally, or alternatively, the transition wall may transition to the front wall without forming an edge or step.

[0018] The flow cross-section defined by the above transition wall, for example, the inner diameter, may decrease continuously from the front wall to the annular wall. In a cross-section perpendicular to the circumferential direction, the transition wall may have the shape of a circular arc.

[0019] The front wall, the annular wall, and the optional transition wall can together form an integral front portion of the flow guide device. The front portion can be manufactured, for example, by an injection molding process or other suitable primary molding process.

[0020] In one exemplary embodiment, the flow guide device may additionally include an outer wall. The outer wall is connected to a front wall. The outer wall extends from the front wall in the same direction as the annular wall. The outer wall may surround the annular wall in a circumferential direction. Optionally, the outer wall may be an integral integrated part of the front portion.

[0021] Each ridge and each groove has a circumferential width centered on a central axis and a length perpendicular to the circumferential direction and / or parallel to the central axis in the flow direction. The length may be characterized, for example, by the distance from the high point of each ridge to the low point of the immediately adjacent groove. The width and / or length of all ridges may be of the same size. Additionally or alternatively, the width and / or length of all grooves may be of the same size. Alternatively, at least a plurality of the existing ridges and / or a plurality of the existing grooves may have different widths and / or different lengths.

[0022] In all exemplary embodiments, at least a plurality of ridges and / or a plurality of grooves may be curved without edges. In all exemplary embodiments, at least a plurality of ridges and / or some of the grooves may have edges and / or steps. For example, at least a plurality of ridges may have a smooth, edge-free profile in the circumferential direction at each high point, and / or a plurality of grooves may have edges at each low point.

[0023] A center plane containing a central axis may be defined parallel to each high point of the ridge and each low point of the groove. The center plane may divide each ridge and / or groove into symmetric halves. Alternatively, each ridge and / or groove may be asymmetric with respect to its center plane. For example, a ridge and / or groove may have two sides that are inclined differently with respect to the center plane, and these sides merge at the high point of the ridge and / or low point of the groove.

[0024] Any exemplary embodiment of the flow guide device described above may be an integrated part of a fan. In addition to the flow guide device, the fan has a fan rotor that can be driven around a central axis. The fan rotor may also be called a fan wheel. The fan rotor is positioned downstream of the inlet channel of the flow guide device. Preferably, an electric motor driving the fan rotor is positioned downstream of the fan rotor. The fan may be an axial fan, a centrifugal fan, or a mixed-flow fan.

[0025] In a preferred exemplary embodiment of the fan, the fan rotor has an outer ring positioned coaxially with the central axis. The outer ring surrounds an annular wall adjacent to the trailing edge. Preferably, the relative position between the annular wall of the flow guide and the outer ring is such that all grooves and / or ridges of the trailing edge are positioned at least substantially, and preferably completely, within the space enclosed by the outer ring. At least 70%, 80%, or 90% of the total length of the trailing edge along the ridges and / or grooves around the central axis is located within the space enclosed by the outer ring. Brief explanation of the drawing

[0026] Advantageous exemplary embodiments according to the present invention are disclosed in the appended claims, description of the invention, and drawings. Preferred exemplary embodiments according to the present invention are described in detail below with reference to the accompanying drawings. The drawings illustrate the following: FIG. 1 illustrates a perspective view of an exemplary embodiment of a fan having an exemplary embodiment of a flow guide device according to the present invention, FIG. 2 illustrates a cross-sectional view along the central axis passing through the fan of FIG. 1, and FIG. 3 illustrates a modified exemplary embodiment of an annular wall of a flow guide device that can be used in a fan according to FIG. 1 and 2, and FIGS. 4 through 10 each illustrate highly simplified schematic diagrams of the ridge and / or groove of the trailing edge of an exemplary embodiment of the annular wall of a flow guide device, and FIGS. 11 and FIGS. 12 illustrate examples of characteristic curves describing the distance from a reference plane to the high point of a trailing edge ridge and the distance to the low point of a groove, respectively. Specific details for implementing the invention

[0027] FIGS. 1 and FIGS. 2 illustrate exemplary embodiments of a fan (15). The fan (15) may be an axial fan, a centrifugal fan, or a mixed-flow fan.

[0028] The fan (15) has a fan housing (16) having a front portion (17) and a rear portion (18). The front portion (17) and / or the rear portion (18) are each integral and may be manufactured by primary molding, for example, by injection molding. In an exemplary embodiment, the front portion (17) and / or the rear portion (18) may be made of plastic.

[0029] The front portion (17) and the rear portion (18) are mechanically connected to each other to form a fan housing (16), and are particularly separated from each other by shape-joining and / or force-joining connections such as screw connections, plug-in connections, or snap-fit ​​connections.

[0030] The fan (15) includes a flow guide (21). In the illustrated exemplary embodiment, the flow guide (21) is an integrated part of the front section (17). The flow guide (21) is configured to guide air flow toward the fan rotor (22) of the fan (15) in a flow direction F. To this end, the flow guide (21) has an annular wall (23) positioned coaxially with the central axis A of the flow guide (21) or the fan (15). The annular wall (23) extends completely around the central axis A in a circumferential direction U. In the exemplary embodiment, the annular wall (23) has a circular profile in a circumferential direction U around the central axis A.

[0031] In an exemplary embodiment, the annular wall (23) is an integrated part of the front section (17). The front section (17) also has a front wall (24) connected to the annular wall (23). The front wall (24) and the annular wall (23) may be directly connected to each other or may be in direct contact with each other. In an exemplary embodiment, the front wall (24) is indirectly connected to the annular wall (23) through a transition wall (25).

[0032] In an exemplary embodiment, the front wall (24) extends along a plane oriented perpendicular to the central axis A. An inlet (26) is provided in the front wall (24), which has a circular rim around the central axis A. The inlet (26) is fluidly connected to an inlet channel (27) defined by an annular wall (23). The inlet channel (27) is positioned downstream of the inlet (26) in the direction of air flow F.

[0033] In the exemplary embodiment illustrated in FIGS. 1 and 2, the annular wall (23) is aligned parallel to the central axis A. Thus, this defines a cylindrical inlet channel (27) around the central axis A. Alternatively, the annular wall (23) may be aligned at an angle to the central axis A, for example, as illustrated in FIG. 3. Thus, the defined inlet channel (27) tapers in the flow direction F (e.g., conically), or alternatively tapers against the flow direction F, as illustrated in a very simplified manner by the annular wall (23) shown as a dashed line in FIG. 3. The annular wall (23) may form an inlet nozzle when tapered, for example, having a conical design.

[0034] In the illustrated exemplary embodiment, the inlet (26) is connected to the inlet channel (27) along the transition wall (25). In the exemplary embodiment illustrated herein, the transition wall (25) is curved convexly with respect to the central axis A. In the cross-sectional plane along the central axis A, the curvature of the transition wall (25) may be in the form of a circular arc. Preferably, the transition between the inlet and the annular wall (23) is smooth and / or edgeless.

[0035] In an exemplary embodiment, the inlet opening (26) is the only flow opening of the front wall (24). Radially outward from the inlet opening (26), the front wall (24) has no flow openings at all through which air flow can flow from the environment to the fan rotor (22). In addition to the inlet opening (26), the front wall (24) may optionally include an opening for mechanically securing the front portion (17) to the rear portion (18).

[0036] In an exemplary embodiment, the flow guide device (21) is an integral part of the front section (17), and in particular, a monolithic integral part of the front section (17). The flow guide device (21) comprises, for example, at least an annular wall (23) and a front wall (24) having an inlet opening (26) therein. As described, a transition wall (25) between the front wall (24) and the annular wall (23) is optional.

[0037] In the flow direction F, the annular wall (23) has a trailing edge (31) at its downstream end. The trailing edge (31) of the annular wall (23) has a variable distance from the reference plane E (Figs. 2 to 10). The reference plane E is a virtual plane oriented perpendicular to the central axis A. The position of the reference plane E along the central axis A can be defined in various ways. In the exemplary embodiment illustrated herein, the reference plane E is located, for example, at the forward end of the annular wall (23) upstream of the trailing edge (31), i.e., at the transition point to the transition wall (25) in this exemplary embodiment. The reference plane E may also be located at other positions upstream or downstream of the trailing edge (31), or positioned to bisect the trailing edge. This is merely a virtual auxiliary plane used to describe the profile of the trailing edge (31).

[0038] As described, the trailing edge (31) has a profile that does not lie entirely on a single plane aligned parallel to the reference plane E. Rather, the trailing edge (31) has ridges (32) and / or grooves (33) that alternately adjacent to each other in the circumferential direction U. This results in the formation of a corrugated and / or sawtooth profile of the trailing edge (31). Each existing ridge (32) has a high point HP, and each existing groove (33) has a low point TP. The distance of the low point from the reference plane E is the minimum distance of each groove (33), and the distance of the high point HP of each ridge (32) from the reference plane E is the maximum distance of each ridge (32).

[0039] Two immediately adjacent high points HP in the circumferential direction U define the width b of the groove (33) located between these two high points HP (Fig. 4). The distance between two immediately adjacent low points TP in the circumferential direction U defines the width c of the ridge (32) located between them (Fig. 4). The distance x of the low points from the reference plane E defines the minimum length of the annular wall (23) in the groove (33) having the low points TP, for example. The distance y of the high points HP from the reference plane E parallel to the central axis A defines the maximum length of the annular wall (23) in the ridge (32) having the high points HP.

[0040] The width b of all existing grooves (33) may be the same. The width c of all existing ridges (32) may be the same size. Identical widths b and c are illustrated, for example, in FIGS. 4 through 9. As a variation thereof, widths b and c may also have two or more different values, for example, as schematically illustrated in FIG. 10. Therein, the groove may have a first width b1 of the groove (33) or a second width b2 of the groove (33), and the ridge may have a first width c1 of the ridge (32) or a second width c2 of the ridge (32). It is understood that the number of different widths b and c is not limited to two different values, but rather any number of different values ​​may exist for both the width b of the groove (33) and the width c of the ridge (32).

[0041] Similar to widths c and b, the distances x and y of the groove (33) and / or ridge (32) from reference plane E may also vary as illustrated in FIGS. 5 through 8. The distance x of the groove (33) from reference plane E may have at least two different values ​​corresponding, for example, a first distance x1 and a second distance x2 of the groove (33) from reference plane E ( FIGS. 5, 7, and 8). Additionally, or alternatively, the distance y of the ridge (32) from reference plane E may have at least two different values ​​corresponding to a first distance y1 and a second distance y2 of the ridge (32) from reference plane E ( FIGS. 6 through 8).

[0042] When viewed in the circumferential direction U, the dimensions (width and distance from the reference plane) of individual ridges (32) and / or grooves (33) may vary in a repeating pattern or irregularly. FIGS. 11 and 12 merely illustrate, in an exemplary and schematic manner, characteristic curves for the variation of the distance x of the groove (33) from the reference plane E and the distance y of the ridge (32) from the reference plane E as a function of the position in the circumferential direction U. The characteristic curves may be continuous and / or differentiable (Fig. 11) or discontinuous (Fig. 12). The profiles of distances x and y as a function of the circumferential position in the circumferential direction U may be specified according to any characteristic curve suitable for a particular application. For example, a rectangular curve having two or more steps may also be used for distances x and / or y.

[0043] The trailing edge (31) or the ridge (32) and / or groove (33) may be edgeless and / or continuous. For example, the entire trailing edge (18) may have a smooth and / or stepless profile along the extension surrounding the central axis A, as schematically illustrated in FIGS. 1 through 6, FIGS. 9, and FIGS. 10. Alternatively, the ridge (32) and / or groove (33) may have edges or corners ( FIGS. 7 and FIGS. 8). The geometric shape or form of the ridge (32) and groove (33) may be selected to suit the application and the flow or pressure conditions within the fan (15). By doing so, the configurations of the trailing edge (31), ridge (32), and groove (33) illustrated and described exemplarily can be combined with one another as desired.

[0044] FIG. 9 illustrates an exemplary embodiment of a trailing edge (31) in which the ridge (32) and / or groove (33) are asymmetric with respect to a center plane M, wherein the center plane M passes through the high point HP of the ridge (32) or the low point TP of the groove (33) and is oriented perpendicular to the circumferential direction U. The center plane M divides the ridge (32) or groove (33) into two unequal parts as schematically illustrated in FIG. 9. The ridge (32) and / or groove (33) may therefore be asymmetric with respect to each center plane M. In this context, as shown in FIG. 9, all ridges (32) and / or all grooves (33) may be asymmetric, or only some of the existing ridges (32) and / or some of the existing grooves (33) may be asymmetric with respect to each center plane M. Therefore, the exemplary embodiment according to FIG. 9 can be combined with any other exemplary embodiment for the design of the trailing edge (31) as described above and illustrated in the drawings.

[0045] The described flow guide device (21) is positioned within the fan (15) upstream of the fan rotor (22) in the flow direction F. In this context, the fan rotor (22) may include an outer ring (22a) surrounding an annular wall (23) in the region of the trailing edge (31). When viewed parallel to the central axis A, the outer ring (22a) of the fan rotor (22) and the annular wall (23) overlap each other. Preferably, the trailing edge (31) is entirely located within this overlapping region. In other words, all ridges (32) and grooves (33) formed by the profile of the trailing edge (31) are preferably positioned within the space surrounded by the outer ring (22a) (Fig. 2). The ring front edge (22b) of the outer ring (22a) located upstream in the flow direction F defines an axial position parallel to the central axis A, which can be located upstream of the trailing edge (31) of the annular wall (23).

[0046] The fan (15) has an electric motor (37) that can drive the fan rotor (22) to rotate about a central axis A by means thereof. To this end, the fan rotor (22) is rotatably fixed to a drive shaft extending from the fan rotor (22) along the central axis A on the downstream side of the fan rotor (22). The drive shaft is rotatably mounted and can be rotatably driven by the electric motor (37). The electric motor (37) is, for example, at least substantially located within the rear portion (18) of the fan housing (16).

[0047] In an exemplary embodiment, the front portion (17) of the fan housing (16) includes an outer wall (39) extending from the front wall (24) toward the rear portion (18), for example, in a direction parallel to the central axis A. In an exemplary embodiment, the outer wall (39) surrounds the internal space where the annular wall (23) is located. In the exemplary embodiment of the fan (15) described herein, the internal space defined by the outer wall (39) of the front portion (17) also includes the outer ring (22a) and optionally portions of the fan rotor (22) adjacent to the outer ring (22a).

[0048] When the fan (15) is in operation, air from the surrounding environment is drawn in through the inlet opening (26) and enters the inlet channel (27). On the outer surface of the annular wall (23) far from the inlet channel (27), no air flows, or only a small amount of air flows along the annular wall (23). The volumetric or mass flow of the airflow flowing toward the fan rotor (22) is entirely, or at least 80%, or at least 90%, or at least 95%, directed to the fan rotor (22) through the inlet opening (26) and the inlet channel (27).

[0049] Due to the corrugated and / or sawtooth trailing edge (31) of the annular wall (23), noise caused by the incoming air can be minimized. Although air vortices are formed in the region of this trailing edge (31), it has been shown that this does not result in significant efficiency loss or leakage flow. The fan rotor (22) can surround the annular wall (23) in the region of the trailing edge (31), as in the case of the outer ring (22a) of the fan rotor (22) in the exemplary embodiment, and can contribute to reducing efficiency loss.

[0050] The present invention relates to a flow guide device (21) and a fan (15) comprising the flow guide device (21). The flow guide device (21) has an annular wall (23) that completely surrounds a central axis A in the circumferential direction U and defines an inflow channel (27) on an inner surface facing the central axis A. The downstream end of the annular wall (23) has a trailing edge (31) that does not extend within a single plane aligned perpendicularly to the central axis A. Rather, the trailing edge (31) forms a plurality of grooves (33) and / or a plurality of ridges (32) with respect to a virtual reference plane E aligned perpendicularly to the central axis A. The trailing edge (31) may have a corrugated and / or sawtooth profile. Explanation of the symbols

[0051] 15 Pan 16 Fan housing 17 Front 18 rear 21 Flow guidance device 22 fan rotor 22a outer ring 22b The front edge of the ring 23 Circular wall 24 front wall 25 Transition wall 26 entrance opening 27 Inflow channels 31 rear edge 32 ridge 33 home 37 electric motor 39 exterior wall A central axis b The width of the home b1 The first width of the home b2 The second width of the home c width of the ridge c1 The first waterfall of the ridge c2 The second waterfall of the ridge E Reference plane F Flow direction HP peak M Middle surface TP low point U Wonju direction x Distance of the groove from the reference plane x1 The first distance of the groove from the reference plane x2 Second distance of the groove from the reference plane y Distance of the ridge from the reference plane y1 The first distance of the ridge from the reference plane y2 The second distance of the ridge from the reference plane

Claims

Claim 1 A flow guide device (21) for a fan (15) configured to guide air flow to a rotatably driven fan rotor (22), wherein the flow guide device (21) comprises an annular wall (23) having a trailing edge (31) positioned downstream in the flow direction (F) of the air flow, and the trailing edge having grooves (33) and / or ridges (32) with respect to a reference plane (E) oriented perpendicularly to the central axis (A). Claim 2 In claim 1, the annular wall (23) is a flow guide device aligned parallel to or at an angle to the central axis (A). Claim 3 A flow guide device according to claim 1 or 2, further comprising a front wall (24) connected to the annular wall (23) on one side of the inflow channel (27) opposite the trailing edge (31). Claim 4 In paragraph 3, the front wall (24) is a flow guide device oriented perpendicularly to the central axis (A). Claim 5 A flow guide device according to claim 3 or 4, wherein the front wall (24) has no flow openings to supply air to the fan rotor (22). Claim 6 A flow guide device, wherein in any one of claims 3 to 5, a transition wall (25) connecting the front wall (24) and the annular wall (23) to each other is further included. Claim 7 In claim 6, the annular wall (23), the front wall (24), and the transition wall (25) are integral parts of the monolithic front section (17) of the flow guide device. Claim 8 A flow guide device according to any one of claims 3 to 7, further comprising an outer wall (39) connected to the front wall (24) and surrounding the annular wall (23) in the circumferential direction (U). Claim 9 A flow guiding device configured to guide the air flow only through the inlet channel (27) to the fan rotor (22) in any one of claims 1 to 8. Claim 10 A flow guide device according to any one of claims 1 to 9, wherein the ridges (32) all have the same distance (y) with respect to the reference plane (E) and / or the grooves (33) all have the same distance (x) with respect to the reference plane (E). Claim 11 A flow guide device according to any one of claims 1 to 10, wherein the ridges (32) all have the same width (c) in the circumferential direction (U) and / or the grooves (33) all have the same width (b) in the circumferential direction (U). Claim 12 A flow guide device according to any one of claims 1 to 10, wherein at least a plurality of the ridges (32) have different distances (y1, y2) with respect to the reference plane (E) and / or at least a plurality of the grooves (33) have different distances (x1, x2) with respect to the reference plane (E). Claim 13 A flow guide device according to any one of claims 1 to 10 or 12, wherein at least a plurality of the ridges (32) have different widths (c1, c2) in the circumferential direction (U) and / or at least a plurality of the grooves (33) have different widths (b1, b2) in the circumferential direction (U). Claim 14 A flow guide device according to any one of claims 1 to 13, wherein each ridge (32) has a center plane (M) extending perpendicularly to the circumferential direction (U) through its high point (HP), and each groove (33) has a center plane (M) extending perpendicularly to the circumferential direction (U) through its low point (TP), and at least a plurality of the ridges (32) and / or at least a plurality of the grooves (33) are asymmetric with respect to their respective center planes (M). Claim 15 A fan (15) comprising a flow guide device (21) according to any one of claims 1 to 14 and a fan rotor (22) that can be driven to rotate around a central axis (A) and is positioned downstream of an inlet channel (27). Claim 16 In claim 15, the fan rotor (22) comprises an outer ring (22a) surrounding the annular wall (23) in the trailing edge (31) region.

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