Rotor for a fluid energy machine, rotor assembly for a fluid energy machine, and corresponding fluid energy machine and method for operating a fluid energy machine of this type

Abstract

The invention relates to a rotor (1) for a fluid energy machine (13), comprising: a rotor hub (3) which can be rotated about a rotor rotational axis (4); and a plurality of rotor blades (2) which run from the rotor hub (3) and extend outward in the radial direction with respect to the rotor rotational axis (4). According to the invention, each of the rotor blades (2) has an aerodynamic rotor blade profile (5), and a chord angle between a chord (8) of the rotor blade profile (5) and an imaginary plane which contains the rotor rotational axis (4) or is perpendicular to the rotor rotational axis changes in the radial direction from the inside out such that the rotor blade (2), seen in the radial direction with respect to the rotor rotational axis (4), has rotor blade regions (11, 12) which are provided and designed for opposite axial flow directions. The invention also relates to a rotor assembly (14) for a fluid energy machine (13), to a fluid energy machine (13), and to a method for operating a fluid energy machine (13).

Description

[0001] DESCRIPTION

[0002] Rotor for a fluid energy machine, rotor arrangement for a fluid energy machine and corresponding fluid energy machine and method for operating such a

[0003] The invention relates to a rotor for a fluid energy machine, comprising a rotor hub rotatable about a rotor rotation axis and a plurality of rotor blades extending from the rotor hub and outward in a radial direction relative to the motor rotation axis. The invention further relates to a rotor assembly for a fluid energy machine, a fluid energy machine with a rotor and / or a rotor assembly, and a method for operating a fluid energy machine.

[0004] For example, the prior art document WO 2018 / 219856 A1 is known. This document describes a method and device for increasing the efficiency of jet propulsion by recuperating useful power from the propulsion flow. A ducted propeller in the propeller housing, driven by a prime mover via a drive shaft, pumps the fluid for jet propulsion from the interior of a radial turbine. The fluid is accelerated axially and expelled rearward against the direction of travel. This creates thrust. Because the pressure in the interior of the turbine drops, new fluid from the environment flows directly over the blades of the rotating radial turbine from the outside to the inside, thereby driving them. A guide vane is missing. The power of the radial turbine is transferred to the propeller drive shaft via a gearbox, which relieves the load on the prime mover and increases the efficiency of the jet propulsion.

[0005] Furthermore, the document DE 10 2021 005 965 B3 discloses a rotor blade in which a front and a rear wing segment are hinged to a central wing segment by two hinges with axes of rotation and form a variable, three-part wing profile for at least one rotor module of a wind or water turbine with a motor generator, composed of a plurality of rotor blades, or for a rotary-wing vehicle with an engine that can be configured as a helicopter. The rotor blade is straight, bow-shaped, or polygon-shaped and has a longitudinal member formed by the central wing segment, which accommodates an adjustment device in at least one longitudinal section of the rotor blade and forms a housing and an abutment for actuators with an adjustment and holding function.The actuators are actuated on a diameter of the orbit with the radius at opposing and freely adjustable full-angle positions such that the suction side changes twice from the outer to the inner side of the orbit in one revolution of the rotor blade. According to the invention, the adjusting devices for the rotatable front and rear blade segments comprise electric motors, each with a rotor and stator. The middle blade segment is rigidly connected to the stator and forms the abutment for the actuators assigned to the rotors, which actuate the rotatable front and rear blade segments. In the case of the water turbine, a step-locking gear with a holding element is arranged between the rotor and the actuator.

[0006] The object of the invention is to propose a rotor for a fluid energy machine which has advantages over known rotors, in particular enabling the realization of a fluid energy machine with a particularly high degree of efficiency.

[0007] This is achieved according to the invention with a rotor for a fluid energy machine having the features of claim 1. It is provided that each of the rotor blades has an aerodynamic rotor blade profile and a profile chord angle between a profile chord of the rotor blade profile and an imaginary plane receiving the rotor axis of rotation or perpendicular to it changes in the radial direction from the inside to the outside in such a way that the rotor blades, viewed in the radial direction with respect to the rotor axis of rotation, have rotor blade regions that are provided and designed for opposite axial flow directions.

[0008] Advantageous embodiments with useful further developments of the invention are specified in the dependent claims. It should be noted that the exemplary embodiments explained in the description are not limiting; rather, any variations of the features disclosed in the description, the claims, and the figures are feasible.

[0009] The rotor is preferably a component of the fluid energy machine, but can of course also be separate from it. The fluid energy machine serves to convert non-mechanical energy into mechanical energy or vice versa. The non-mechanical energy is, for example, chemical energy and / or thermal energy. In this respect, the fluid energy machine can be referred to as a prime mover, heat engine, or work machine. In the context of this description, only the design of the fluid energy machine as a prime mover will be discussed. However, the statements regarding its design are also transferable to an embodiment of the fluid energy machine that is used as a work machine or is operated as such.

[0010] The fluid on which the fluid energy machine operates can be referred to as the working fluid. Air is preferably used as the working fluid, but in principle any fluid can be used, including a fluid other than air. For example, the fluid can also be a mixture, in particular a fuel-fresh gas mixture, wherein the fresh gas contains fresh air at least temporarily, in particular fresh air taken from an external environment of the fluid energy machine.

[0011] The rotor described here is particularly applicable to a fluid energy machine designed as a turbomachine. In a turbomachine, which can also be referred to as a turbomachine, energy is transferred between the working fluid and the fluid energy machine, in particular its rotor, in an open space due to a working fluid flow according to the laws of fluid dynamics.

[0012] The rotor essentially consists of a rotor hub, which is rotatable or mounted on a rotatable support about the rotor's axis of rotation. To transfer energy between the working fluid and the rotor, the rotor has several rotor blades that extend from the rotor hub and outward in a radial direction relative to the rotor's axis of rotation. The rotor blades can extend directly from the rotor hub or be attached to it at a radial distance from the rotor hub. For example, the rotor blades are permanently connected to the rotor hub.However, it can also be provided that the rotor blades are adjustable blades, and thus the angle of attack of the rotor blades relative to the rotor hub is adjustable, namely by rotating the rotor blades relative to the rotor hub about a longitudinal axis of the respective rotor blade, which is angled relative to the profile chord, i.e., forms an angle with it that is greater than 0° and less than 180°. Preferably, the longitudinal axis is perpendicular to the profile chord.

[0013] Each of the rotor blades has an aerodynamic rotor blade profile. The rotor blade profiles of the rotor blades are preferably identical. The aerodynamic rotor blade profile is a cross-sectional profile of the rotor blade. This has a profile leading edge, in the direction of flow, from which a profile upper surface and a profile underside extend to a profile trailing edge. For example, the profile upper surface and the profile underside merge seamlessly at the profile leading edge, whereas at the profile trailing edge they are angled towards each other, in particular arranged at a trailing edge angle to each other.

[0014] The rotor blade profile has a chord and a profile chord, each of which originates at the profile leading edge and extends to the profile trailing edge. The chord represents the centerline of the profile, meaning that, viewed in cross-section, it always runs centrally between the top and bottom of the profile. It is preferably curved, at least in some areas. The profile chord, on the other hand, is consistently straight. The maximum distance between the chord and the profile chord is referred to as the maximum profile camber. The distance between the profile leading edge and the profile trailing edge, corresponding to the length of the profile chord, is referred to as the profile depth.

[0015] It can be provided that the upper and lower surfaces of the profile run symmetrically with respect to the profile chord; in this case, the skeleton line lies continuously on the profile chord. However, the rotor blade profile is preferably designed asymmetrically, so that the skeleton line deviates from the profile chord accordingly. For example, the skeleton line runs continuously on one side of the profile chord and only coincides with the profile chord at the profile leading edge and the profile trailing edge. Of course, the skeleton line can also intersect the profile chords between the profile leading edge and the profile trailing edge, or at least be tangent to them, resulting in an S-shaped profile.

[0016] In order to implement the aforementioned fluid energy machine with particularly high efficiency, each of the rotor blades of the rotor is designed such that the profile chord angle changes in the radial direction from the inside to the outside with respect to the rotor rotation axis, at least in some regions, preferably continuously and / or steadily. The profile chord angle is understood to be an intersection angle between the profile chord and the imaginary plane that accommodates the rotor rotation axis or is perpendicular to the rotor rotation axis, wherein the plane intersects the profile chord. For different radial positions, the respective rotor blade profile has different values ​​of the profile chord angle. For example, a first value of the profile chord angle is present at a first radial position, and a second value of the profile chord angle that is different from the first radial position is present at a second radial position.

[0017] In other words, the respective rotor blade profile is twisted in the radial direction from the inside to the outside. The change in the profile chord angle occurs in such a way that the rotor blades, viewed in the radial direction with respect to the rotor rotation axis, have rotor blade regions that are intended and designed for opposite axial flows. For example, the profile chord angle changes sign over the extension of the respective rotor blade in the radial direction from the inside to the outside, i.e. the sign of the profile chord angle changes once, in particular exactly once, over the extension of the respective rotor blade in the radial direction from the inside to the outside. This results in a design of the rotor blades that is intended and designed for the different and opposite axial flow directions of the working fluid.Preferably, the profile chord angle changes over the extent of the respective rotor blade in the radial direction from the inside to the outside by at least 90°, at least 120°, at least 150° or at least 180°.

[0018] Overall, each of the rotor blades, viewed in the radial direction, has a first rotor blade region in which it is configured for a first axial flow direction, and a second rotor blade region in which it is configured for a second axial flow direction opposite to the first axial flow direction. During a rotational movement of the rotor, a working fluid flow of the working fluid occurs in the first rotor blade region in the first axial flow direction and in the second rotor blade region in the second axial flow direction.Conversely, when the flow onto the rotor in the first rotor blade region in the first axial flow direction and in the second rotor blade region in the second axial flow direction, a torque in the same direction is caused on the rotor, whereas when the flow onto the rotor in the rotor blade regions with the same axial flow direction, i.e. either the first axial flow direction or the second axial flow direction, opposite torques are present on the rotor.

[0019] Using the described rotor, a fluid energy machine can be implemented that operates as a reversible thermal flow machine, in which a Beltrami flow is preferably generated, i.e. a three-dimensional vortex in which the flow direction of the working fluid locally has the same direction as its rotation vector at every point. This means that the Camot process, which has so far only been used for theoretical considerations, can be implemented at least to a better approximation than was previously the case. Accordingly, the fluid energy machine has a particularly high level of efficiency. The rotor can also be referred to as a propeller. Since it is primarily used to generate and / or utilize a Beltrami flow, the term "Beltrami rotor" or "Beltrami propeller" also seems appropriate.

[0020] For example, the invention relates to a rotor for a fluid energy machine, comprising a rotor hub rotatable about a rotor rotation axis and a plurality of rotor blades extending from the rotor hub and outward in a radial direction relative to the rotor rotation axis. This rotor blade is characterized in that each of the rotor blades has an aerodynamic rotor blade profile, and a profile chord angle between a profile chord of the rotor blade profile and an imaginary plane that, on the one hand, receives the rotor rotation axis or is perpendicular to the rotor rotation axis and, on the other hand, intersects the profile chord changes in the radial direction from the inside to the outside, in particular continuously and steadily, such that the rotor blades, viewed in the radial direction relative to the rotor rotation axis, have rotor blade regions that are provided and designed for opposite axial flow directions.

[0021] A further development of the invention provides that an angular gradient of the profile chord angle increases over the distance from the rotor axis of rotation with increasing distance from the rotor axis of rotation, and / or that each of the rotor blades is continuously divided in the radial direction into several radial sections whose extent in the radial direction continuously decreases from the inside to the outside, wherein a profile chord angle difference between adjacent radial sections is consistently identical. The angular gradient is to be understood as a gradient of the profile chord angle over the distance from the rotor axis of rotation, i.e. a derivative of the profile chord angle over a radius with respect to the rotor axis of rotation. The angular gradient increases with increasing distance from the rotor axis of rotation, so that the greater the distance from the rotor axis of rotation, the faster each of the rotor blades is twisted.

[0022] This ultimately results in a design of the rotor blades in which each of the rotor blades is divided in the radial direction from the inside outwards into several radial sections, with each of the radial sections directly adjacent to at least one other radial section. The division of the rotor blades into the radial sections is therefore uninterrupted, so that each of the rotor blades is continuously composed of directly adjacent radial sections. The radial sections extend from an inner side of the rotor blades, which lies on the inside in the radial direction, to an outer side of the rotor blades, which lies on the outside in the radial direction. The radial sections have different extensions in the radial direction, with the extensions in the radial direction becoming continuously smaller from the inside outwards.A radial section located further inside in the radial direction therefore has a greater extension in the radial direction than a radial section located further outside in the radial direction.

[0023] However, the chord angle difference, i.e., the difference between the chord angle values ​​of immediately adjacent radial sections, remains constant across the entire extent of the rotor blade in the radial direction. In the radial direction, from inside to outside, from one radial section to the next, the chord angle always changes by the same chord angle difference. The described design achieves equilibrium between the working fluid flows in the opposite axial flow directions. Ideally, for a given rotor speed, the mass flow of the working fluid in the first axial flow direction is equal to the mass flow of the working fluid in the second axial flow direction, in particular density-adjusted, i.e., based on the same density. This results in a structurally simple design of the fluid energy machine.

[0024] A further development of the invention provides that the angular gradient is selected such that the rotor blade regions of the respective rotor blade in which the profile chord angle has, for example, different signs, have identical rotor blade surface areas, and / or that a first circular ring which delimits the respective rotor blade inwards in the radial direction and runs outwards in the radial direction through a reversal point lying on the profile chord of the rotor blade, in which the rotor blade regions adjoin one another and / or the profile chord angle changes its sign, and a second circular ring which runs inwards in the radial direction through the reversal point and delimits the respective rotor blade outwards in the radial direction, have identical surface areas.The rotor blade surface area refers to the surface areas of the upper and lower surfaces of the profile in the two rotor blade regions where the profile chord angle has different signs and / or is designed and configured for opposite axial flow directions. The surface areas of the rotor blade surface, i.e., the upper and lower surfaces of the profile, should be identical in both regions, so that the aforementioned equilibrium between the working fluid flows is achieved.

[0025] Additionally or alternatively, the first annulus and the second annulus have identical surface areas. The two annuli each lie entirely in an imaginary plane, in particular in the same plane, which is perpendicular to the axis of rotation of the rotor. The first annulus has an inner radius which corresponds to an inner radius of the respective rotor blade. Its outer radius corresponds to a distance from the axis of rotation at the point at which the chord angle changes sign and / or at which the two rotor blade areas adjoin one another. An inner radius of the second annulus, on the other hand, corresponds to the outer radius of the first annulus, whereas an outer radius of the second annulus corresponds to an outer radius of the respective rotor blade. This again achieves flow equilibrium.

[0026] A further development of the invention provides that between radial distances of the rotor blades according to the relationship with n=1, . . . , N identical profile chord angle differences are present, where r n is the radial distance of one of the radial sections, ro is an inner radius of the rotor blades, n is an outer radius of the rotor blades, and N is a number of radial sections. In other words, it is provided that the rotor blades are divided into several radial sections, each of which has a respective radial distance from a rotor blade axis according to the relationship mentioned, where r n is the radial distance of one of the radial sections, ro is an inner radius of the rotor blades, n is an outer radius of the rotor blades and N is a number of radial sections, whereby identical profile chord angle differences exist between immediately adjacent radial sections of the rotor blades.

[0027] Each of the rotor blades is divided into a number of radial sections, wherein the number is, for example, at least 8, at least 10, at least 12, at least 14, or at least 16. Between each two of the radial distances, the profile chord angle changes by the profile chord angle difference, for example by at least 10°, at least 15°, or at least 20°. The profile chord angle difference corresponds to at least one of the stated values. Additionally or alternatively, the profile chord angle difference is at most 30°, at most 25°, or at most 20°. For example, a value of 10°, 15°, or 20° is used for the profile chord angle difference. If a diameter or radius of the rotor hub is negligibly small with respect to the dimensions of the rotor blades in the radial direction, the stated relationship can be The described rotor design implements the aforementioned advantages in a simple manner.

[0028] Across the rotor blade, the chord angle changes by a total chord difference. This corresponds to the difference between the radial chord angle at the very outside of the rotor blade and the radial chord angle at the very inside of the rotor blade, or vice versa. The total chord difference therefore corresponds to a twisting or rotation of the rotor blade across its entire extent in the radial direction, or at least describes this. At a point on the rotor blade where the rotor blade areas adjoin one another, the chord angle corresponds to the radial chord angle at the inside of the rotor blade plus half the total chord difference, or conversely, to the radial chord angle at the outside of the rotor blade minus half the total chord difference. The radial distance of this point is therefore, in particular, r = r n=N / 2 and therefore corresponds to the radial distance according to the given relationship for n=N / 2. In other words, for n=N / 2, the rotor blade is twisted or rotated by half the total chord difference.

[0029] A further development of the invention provides that a hollow cylindrical flow guide element is arranged on the rotor blades, which surrounds one of the rotor blade regions in the radial direction. The flow guide element is designed as a right hollow circular cylinder whose longitudinal center axis coincides with the rotor's axis of rotation. The flow guide element separates the different rotor blade regions from one another, thus overlapping one of the rotor blade regions - viewed in longitudinal section. In other words, an imaginary extension of the flow guide element encompasses one rotor blade region, whereas the other rotor blade region lies outside the imaginary extension. The flow guide element preferably rests against the rotor blades and / or is attached to them. In this respect, the flow guide element is, for example, connected to the rotor in a rotationally fixed manner, and is accordingly mounted so as to be rotatable with respect to the rotor's axis of rotation.With the help of the flow guide element, the working fluid flows of the working fluid can be guided separately from each other in the different axial flow directions, thus reducing flow losses.

[0030] A further development of the invention provides that the flow guide element projects beyond the rotor blades in the axial direction at least on one side, preferably on both sides. In this respect, the flow guide element originates from the rotor blades in the axial direction and extends beyond them. For example, the flow guide element has dimensions in the axial direction which correspond at least to a difference between the outer radius and the inner radius of the rotor blades. However, the flow guide element is preferably larger; for example, its dimensions in the axial direction are at least 1.5, at least 2.0, or at least 2.5 times larger than the aforementioned difference. Particularly preferably, the flow guide element also projects beyond the rotor blades in the axial direction on both sides, so that it separates the working fluid flows from one another over a large distance. This further reduces flow losses.

[0031] The invention further relates to a rotor arrangement for a fluid energy machine, comprising a rotor, in particular a rotor according to the embodiments in this description, wherein the rotor has a rotor hub rotatable about a rotor axis of rotation and a plurality of rotor blades extending from the rotor hub and outward in the radial direction with respect to the rotor axis of rotation. It is provided that each of the rotor blades has an aerodynamic rotor blade profile and a profile chord angle between a profile chord of the rotor blade profile and an imaginary plane accommodating or perpendicular to the rotor axis of rotation changes in the radial direction from the inside to the outside in such a way that the rotor blades, viewed in the radial direction with respect to the rotor axis of rotation, have rotor blade regions that are provided and designed for opposite axial flow directions.

[0032] The advantages of such a design of the rotor assembly or rotor have already been pointed out. Both the rotor assembly and the rotor can be further developed according to the explanations in this description, so reference is made to these in this regard.

[0033] A further development of the invention provides that in addition to the rotor there is a stator, in particular designed according to the statements in the context of this description with regard to the rotor, wherein the stator has a stator hub and a plurality of stator blades emanating from the stator hub and extending outwards in the radial direction with respect to the rotor axis of rotation, wherein each of the stator blades has an aerodynamic stator blade profile and a chord angle between a chord of the stator blade profile and an imaginary plane receiving the rotor axis of rotation or perpendicular to it changes in the radial direction from the inside to the outside. In addition to the rotor there is therefore the stator, relative to which the rotor is rotatable. This means in particular that the stator is arranged in a stationary manner, at least in the circumferential direction with respect to the rotor axis of rotation. The rotor is rotatable relative to the stator.Preferably, the stator and the rotor are arranged directly adjacent to each other in the axial direction. The stator, with its stator blades, acts as a guide vane for the rotor, whereby the stator blades can also be referred to as guide vanes. The rotor blades can also be referred to as rotor blades. The distance between the rotor blades and the stator blades in the axial direction is preferably at most 50%, at most 25%, or at most 10% of the extension of the rotor blades and / or the extension of the stator blades in the same direction.

[0034] The stator blades are designed analogously to the rotor blades. This means, in particular, that their respective chord angle changes in the radial direction from the inside to the outside, preferably by the same total chord difference as for the rotor. The total chord difference is the difference between the chord angles of the rotor or stator over their entire extension in the radial direction. Specifically, this means that the total chord difference describes a difference between a chord angle of the rotor blade on its inside, i.e. on its side furthest inside in the radial direction, and a chord angle of the rotor blade on its outside, i.e. on its side furthest outside in the radial direction. The total chord difference is, for example, as already mentioned, at least 90°, at least 120°, at least 150°, or at least 180°.The total profile chord difference is now - at least in a preferred embodiment - identical for the stator to the total profile chord difference for the rotor.

[0035] The stator blades are preferably designed such that, viewed in the radial direction relative to the rotor rotation axis, they have stator blade regions that are provided and designed for opposite axial flow directions. Opposing working fluid flows in the stator blade regions thus cause torques on the stator that are directed in the same direction. The stator blade regions are preferably selected such that, with identical mass flows or volume flows of the working fluid flows, the torques exerted on the stator by the working fluid flows are identical. In summary, the stator is similar to the rotor in terms of its structural design. However, it is preferably arranged with an angle of attack that is different from an angle of attack of the rotor or the rotor blades. Particularly preferably, the rotor is mounted on the machine housing via the stator.In particular, it is provided that the stator is rigidly connected to the machine housing, and the rotor or its rotor hub is mounted on the stator so as to be rotatable about the rotor's axis of rotation. For example, the stator supports an electrical machine, in particular a generator, to which the rotor is connected for drive purposes. Such a design enables a low-blocking mounting of the rotor in the machine housing without the need for additional suspension. Rather, the suspension is formed by the stator.

[0036] A further development of the invention provides that in addition to the rotor there is a further rotor, in particular designed according to the statements in the context of this description with regard to the rotor, wherein the further rotor has a further rotor hub which is rotatable about the rotor axis of rotation and coupled in a rotationally fixed manner to the rotor hub and a plurality of further rotor blades which originate from the further rotor hub and extend outwards in a radial direction with respect to the rotor axis of rotation, wherein each of the further rotor blades has an aerodynamic rotor blade profile and a chord angle between a chord of the rotor blade profile and an imaginary plane which receives the rotor axis of rotation or is perpendicular to it changes in the radial direction from the inside to the outside. In addition to the rotor there is therefore the further rotor which is connected in a rotationally fixed manner to the rotor.For example, the rotor hub of the rotor and the further rotor hub of the further rotor are designed as a common rotor hub.

[0037] Of course, the rotor arrangement can have any number of rotors, so in addition to the rotor, one or more further rotors can be present. These are particularly preferably arranged equidistant from one another in the axial direction and are each connected to one another in a rotationally fixed manner, in particular via the common rotor hub. The further rotor is preferably designed equivalently to the rotor, in particular it is constructed identically to the rotor. The rotor blades and the further rotor blades preferably overlap one another in the circumferential direction, but they can also be arranged offset from one another. For example, in this case - viewed in the circumferential direction - one of the further rotor blades is located centrally between two of the rotor blades of the rotor. With the help of the rotor arrangement, a multi-stage design of the fluid energy machine can be realized.

[0038] If a stator is present, it is preferably arranged between the rotor and the additional rotor. In particular, each rotor, i.e., the rotor and the additional rotor or several additional rotors, is assigned a stator. Accordingly, a stator with the described design is preferably arranged between each two of the rotors. This achieves a particularly high level of efficiency.

[0039] A further development of the invention provides that the rotor blades and the additional rotor blades are connected to one another via a hollow-cylindrical flow guide element away from the rotor hub and the additional rotor hub. The flow guide element has already been discussed above. In addition to the corresponding embodiments, the flow guide element should extend in the axial direction between the rotor blades and the additional rotor blades, thus connecting them to one another, namely away from the rotor hub and the additional rotor hub, in particular spaced radially from the latter.Preferably, the flow guide element also extends at least on one side or preferably on both sides beyond the rotor blades and the additional rotor blades, so that the flow guide element extends axially beyond the rotor blades in the direction away from the additional rotor blades and / or beyond the additional rotor blades in the direction away from the rotor blades. With the aid of the flow guide element, on the one hand, stiffening of the rotor blades and the additional rotor blades is achieved, and on the other hand, the aforementioned separation of the working fluid flows is achieved, which leads to lower flow losses.

[0040] In addition, the invention relates to a fluid energy machine with a rotor, in particular a rotor according to the embodiments in the context of this description, and / or with a rotor arrangement having a rotor, in particular a rotor arrangement according to the embodiments in the context of this description, wherein the rotor has a rotor hub rotatable about a rotor axis of rotation and a plurality of rotor blades extending from the rotor hub and extending outwards in the radial direction with respect to the rotor axis of rotation.It is provided that each of the rotor blades has an aerodynamic rotor blade profile and a profile chord angle between a profile chord of the rotor blade profile and an imaginary plane that receives the rotor axis of rotation or is perpendicular to it changes in the radial direction from the inside to the outside in such a way that the rotor blades, viewed in the radial direction with respect to the rotor axis of rotation, have rotor blade regions that are provided and designed for opposite axial flow directions.

[0041] Again, with regard to the advantages and possible further developments, reference is made to the further details of this description. A further development of the invention provides that the rotor is arranged in a rotationally symmetrical flow volume which is delimited by a machine housing of the fluid energy machine, wherein the rotor axis of rotation lies on a rotation axis of the flow volume. The flow volume therefore has the shape of a rotary body whose surface is formed by the rotation of a curve around the rotation axis. The flow volume is symmetrical to the rotor axis of rotation so that it coincides with the rotation axis. The flow volume is delimited by the machine housing at least in some regions; preferably, it is delimited continuously by the machine housing in the radial direction outwards in the circumferential direction.For this purpose, the machine housing also has a rotationally symmetrical interior, which limits the flow volume to the outside. The machine housing itself can, but does not have to, also be designed rotationally symmetrically. The rotationally symmetrical design of the flow volume promotes the creation of the aforementioned Beltrami flow. This achieves the particularly high efficiency of the fluid energy machine.

[0042] A further development of the invention provides that a hollow cylindrical flow guide element is connected to the rotor, in particular on its side facing away from the flow volume, which flow guide element encloses a first flow region that radially surrounds a first of the rotor blade regions and, together with the machine housing, delimits a second flow region that radially surrounds a second of the rotor blade regions. Regarding the flow guide element, reference is made to the explanations in this description. In addition to these, the flow guide element delimits the two flow regions, namely the first flow region in the radially outward direction and the second sealing region in the radially inward direction.

[0043] For example, the flow guide element encompasses the rotor hub of the rotor, in particular continuously in the circumferential direction. The first flow region is thus bounded, for example, by the rotor hub in the radially inward direction and by the flow guide element in the radially outward direction. The second flow region is located, viewed in the radial direction, between the flow guide element and the machine housing, so that it is jointly enclosed by them in longitudinal section. Preferably, the flow guide element is designed and / or arranged such that the first flow region and the second flow region, viewed in cross section, have identical flow cross-sectional areas or at least similar

[0044] have flow cross-sectional areas.

[0045] For example, the flow cross-sectional area of ​​the second flow region is at most 10%, at most 20%, or at most 30% larger than the flow cross-sectional area of ​​the first flow region, or vice versa. Preferably, the first end face plane has a smaller flow cross-sectional area than the second end face plane; in particular, the flow cross-sectional area of ​​the first end face plane is at most 50%, at most 30%, or at most 20% of the flow cross-sectional area of ​​the second end face plane. The flow guide element ensures the aforementioned good flow guidance, by means of which a low pressure loss is achieved.

[0046] A further development of the invention provides that the flow volume, viewed in the axial direction with respect to the axis of rotation, is located between an imaginary first end face plane and an imaginary second end face plane, wherein the first end face plane and the second end face plane are arranged parallel to one another and are each perpendicular to the axis of rotation. The flow volume is therefore delimited in the axial direction on one side by the first end face plane and on the other side by the second end face plane. The two end face planes are arranged at a distance from one another and parallel to one another and are each perpendicular to the axis of rotation. Preferably, the rotor or the rotor arrangement lies in one of the end face planes or is penetrated by one of the end face planes. The described embodiment enables a structurally simple provision of a flow volume suitable for generating the Beltrami flow.

[0047] A further development of the invention provides that the flow volume is open via the first end face plane towards the outside environment of the fluid energy machine, and / or that the flow volume is delimited by an end wall of the machine housing which lies continuously in the second end face plane. Preferably, the flow volume is therefore open on the side of the first end face plane and closed on the side of the second end face plane. The rotor or the rotor arrangement is preferably located in the first end face plane, whereas on the opposite side of the flow volume, the end wall of the machine housing delimits the flow volume. The end wall lies continuously in the second end face plane; preferably, the end wall is delimited continuously in the direction of the flow volume by the second end face plane.The second end face plane thus lies continuously within a wall surface of the end wall facing the flow volume, which is completely flat. This design also serves to generate the Beltrami flow in the flow volume.

[0048] A further development of the invention provides that the machine housing has a jacket wall which delimits the flow volume in the radial direction and which, on the one hand, encloses the first end face plane and, on the other hand, the second end face plane or projects up to them. The jacket wall is a component of the machine housing and is located on the side thereof facing the flow volume. The jacket wall completely encompasses the flow volume in the circumferential direction, in particular over its entire extension in the axial direction, i.e. preferably from the first end face plane to the second end face plane. The jacket wall encloses both end face planes, i.e. preferably completely encompasses them in the circumferential direction, or at least projects up to them, i.e. directly borders them.The shroud wall, or an inner surface of the shroud wall facing the flow volume, is designed to be rotationally symmetrical with respect to the rotor's axis of rotation and / or rotational axis. This results in an overall aerodynamically optimized design of the flow volume.

[0049] A further development of the invention provides that the flow volume tapers in the axial direction, in particular starting from the second end face plane up to the first end face plane. This means that a cross-sectional area of ​​the flow volume becomes smaller in the axial direction, so that overall the flow volume has a smaller flow cross-sectional area at the first end face plane than at the second end face plane. The taper of the flow volume preferably proceeds continuously. Particularly preferably, a continuous taper is implemented, so that the flow cross-sectional area of ​​the flow volume becomes continuously and uninterruptedly smaller in the direction of the first end face plane, in particular over at least 70%, at least 18% or at least 90% of an extension of the flow volume in the axial direction. This again promotes the formation of the Beltrami flow.

[0050] A further development of the invention provides that the jacket wall runs parallel to the axis of rotation in the first end plane and / or is angled relative to the axis of rotation in the second end plane. This results in a diffuser-like or cup-shaped configuration of the flow volume. The angled arrangement of the jacket wall with respect to the axis of rotation in the second end plane means that there is an intersection angle between the jacket wall and an imaginary straight line running parallel to the axis of rotation which is greater than 0° and less than 180°. In other words, the jacket wall runs at an angle other than 90° in the second end plane with respect to an imaginary plane perpendicular to the axis of rotation and / or the axis of rotation.For example, the shell wall forms an angle with the second end face plane and / or the end wall that is less than 90°, in particular no more than 75°, no more than 60°, or no more than 45°. This achieves low-loss flow guidance.

[0051] A further development of the invention provides that an angle of inclination of the casing wall with respect to the axis of rotation increases continuously in the axial direction. The angle of inclination is in turn understood to be an angle between the casing wall and an imaginary straight line which, on the one hand, runs parallel to the axis of rotation and, on the other hand, intersects the casing wall. The angle of inclination changes in the axial direction; specifically, it increases in the axial direction away from the first end face plane. Preferably, the angle of inclination increases continuously and continuously from the first end face plane to the second end face plane, or at least over at least 70%, at least 18%, or at least 90% of an extension of the flow volume in the axial direction.In the first end plane, the angle of inclination corresponds, for example, to 0° and increases continuously from the first end plane until it reaches an angle different from 0° in the second end plane, for example, an angle of at least 15°, at least 30°, or at least 45°. This promotes the formation of the three-dimensional vortex in the flow volume.

[0052] A further development of the invention provides that the rotor is arranged in the first end face plane, in particular centrally in the axial direction. Reference has already been made to such a configuration. The central arrangement means that the first end face plane intersects the rotor and / or the rotor arrangement in its / their central plane, viewed in the axial direction. However, it can also be provided that the first end face plane intersects the rotor blades of the rotor centrally, viewed in the axial direction, or is arranged centrally between the rotor blades and the other rotor blades of the multiple rotors. In either case, the desired flow guidance is achieved.

[0053] A further development of the invention provides that the end wall and / or the casing wall can be subjected to thermal energy at least in part by means of a heating device. The heating device is, for example, an electrical and / or chemical heating device, so that heating is carried out using electrical and / or chemical energy. The heating device is, for example, arranged on the end wall and serves to heat it at least in part. However, it is particularly preferred for the end wall to be completely heated by means of the heating device, i.e. across its entire surface. The heating device is, for example, arranged in the end wall or on the side of the end wall facing away from the flow volume.

[0054] Additionally or alternatively, the heating device serves to heat the casing wall. For example, the heating device encompasses the casing wall at least partially, but preferably completely, in the circumferential direction. The heating device extends over at least a portion of the casing wall, preferably only a portion of the casing wall, as viewed in the axial direction. For example, the heating device extends over at most 50%, at most 40%, or at most 30% of the casing wall, as viewed in the axial direction.

[0055] It can also be provided that the flow volume serves as a combustion chamber. In this case, the heating device comprises a fuel introduction device, by means of which fuel is at least temporarily introduced into the flow volume and burned there together with the fresh gas. The fresh gas consists, for example, of fresh air or at least contains fresh air. With the help of the heating device, thermal energy is supplied to the working fluid present in the flow volume, which is converted into mechanical energy by means of the rotor. This achieves the aforementioned high efficiency.

[0056] Finally, the invention relates to a method for operating a fluid energy machine, in particular a fluid energy machine according to the embodiments in the context of this description, wherein a rotor of the fluid energy machine has a rotor hub rotatable about a rotor axis of rotation and a plurality of rotor blades extending from the rotor hub and extending outwards in the radial direction with respect to the rotor axis of rotation.It is provided that each of the rotor blades has an aerodynamic rotor blade profile, and a profile chord angle between a profile chord of the rotor blade profile and an imaginary plane accommodating the rotor rotation axis or perpendicular to it changes in the radial direction from the inside to the outside in such a way that, upon rotation of the rotor in a flow volume of the fluid energy machine, a first working fluid flow in a first axial flow direction and a second working fluid flow in a second axial flow direction are established over the rotor. With regard to the advantages and possible advantageous embodiments, reference is again made to the further explanations of this description. Both the fluid energy machine and the method for its operation can be further developed accordingly.

[0057] The first working fluid flow flows in the first axial flow direction and the second working fluid flow flows in the second axial flow direction. The first axial flow direction and the second axial flow direction are oriented oppositely, namely in the axial direction with respect to the rotor rotation axis. The first working fluid flow is located in a first flow region and the second working fluid flow is located in a second flow region, wherein the first flow region and the second flow region each lie entirely in a common imaginary plane. The second flow region encompasses the first flow region, in particular completely in the circumferential direction and is therefore annular. The rotor or its rotor blades are located in the flow regions; in particular, the imaginary plane intersects the rotor blades, for example centrally as seen in the axial direction.

[0058] A further development of the invention provides for the generation of a Beltrami flow in the flow volume. The Beltrami flow represents a three-dimensional vortex in the flow volume, which is toroidal in shape. In the vortex, the working fluid rotates about a first vortex rotation axis, which is circular and encompasses the rotation axis and / or the rotor rotation axis, in particular is arranged symmetrically to it. Furthermore, the working fluid rotates about a second vortex rotation axis, which corresponds to the rotation axis and / or the rotor rotation axis. The three-dimensional vortex therefore initially has the structure of a ring vortex, which, however, additionally rotates about the second vortex rotation axis.

[0059] The Beltrami flow encompasses an outlet flow which flows in the axial direction towards the first end face plane, in particular from the direction of or originating from the second end face plane. As the Beltrami flow flows through the outlet flow, heat is exchanged between the two flows, in particular transferred from the outlet flow to the Beltrami flow. The outlet flow then exits the flow volume, namely via the first end face plane and in particular via the rotor or the rotor arrangement. The outlet flow is present in one of the rotor blade regions, namely in a radially inner one of the rotor blade regions. Conversely, an inlet flow enters the flow volume via the first end face plane, in particular via the rotor or the rotor arrangement.The inlet flow flows through the rotor in a different rotor blade area, namely in an axial flow direction opposite to the axial flow direction of the outlet flow. The inlet flow is set in rotation by the rotor and, accordingly, forced radially outward by centrifugal force. Due to its lower temperature and thus higher density, it surrounds the Beltrami flow and flows between it and the shroud wall toward the second end face plane. Heat is exchanged between the inlet flow and the Beltrami flow, usually from the Beltrami flow to the inlet flow.

[0060] The inlet flow is thus preheated, i.e. brought to a higher temperature level before it reaches the end wall of the machine housing. Through preheating and an additional supply of thermal energy, in particular with the help of the heating device, the temperature of the inlet flow is further increased, so that the density of the working fluid is (further) reduced. Accordingly, the working fluid is forced radially inwards between the Beltrami flow and the end wall, where it merges into the outlet flow. Furthermore, there is naturally a fluid exchange between the inlet flow and the Beltrami flow on the one hand, and between the Beltrami flow and the outlet flow on the other. There is also an exchange of momentum between the aforementioned flows. In the manner described, the fluid energy machine implements the Carnot cycle in a better approximation than was previously possible.

[0061] A further development of the invention provides that an end wall defining the flow volume in the axial direction and / or a jacket wall defining the flow volume in the radial direction are / is heated at least in certain areas. This is achieved using the heating device already mentioned. Reference is made to the corresponding explanations.

[0062] The features and feature combinations described in the description, in particular the features and feature combinations described in the following description of the figures and / or shown in the figures, can be used not only in the respective combination specified, but also in other combinations or on their own, without departing from the scope of the invention. Thus, embodiments are also to be considered encompassed by the invention that are not explicitly shown or explained in the description and / or the figures, but which emerge from the explained embodiments or can be derived from them. The invention is explained in more detail below with reference to the exemplary embodiments illustrated in the drawings, without limiting the invention. In the drawings:

[0063] Figure 1 is a schematic representation of a rotor for a fluid energy machine with a rotor blade in a first embodiment,

[0064] Figure 2 is a schematic representation of the rotor with the rotor blade in a second embodiment,

[0065] Figure 3 is a schematic sectional view of a fluid energy machine with a rotor arrangement having a rotor in a first embodiment,

[0066] Figure 4 is a schematic representation of the fluid energy machine in a second embodiment, and

[0067] Figure 5 is a schematic representation of a Ts diagram in which a cycle implemented by means of the fluid energy machine is indicated.

[0068] Figure 1 shows a schematic representation of a portion of a rotor 1, namely a rotor blade 2 of the rotor 1. In addition to the rotor blade 2, the rotor 1 has a rotor hub 3 (not shown here), which is rotatably mounted about a rotor rotation axis 4 (also not shown). Several rotor blades 2 are arranged on the rotor hub 3, each of the rotor blades 2 being designed as described below.

[0069] The rotor blade 2 has a rotor blade profile 5, which is designed, for example, as a symmetrical or asymmetrical profile. The rotor blade profile 5 has a profile nose 6 and a profile trailing edge 7. A profile chord 8 of the rotor blade profile 5 runs through the profile nose 6 and the profile trailing edge 7. The profile chord 8 here corresponds to a rotor blade axis 9, from which the rotor blade 2 extends radially outward. The rotor blade axis 9 preferably corresponds to the profile chord 8 on an inner side of the rotor blade 2. The rotor blade axis 9 lies in particular in the rotor rotation axis 4 or intersects it.

[0070] A chord angle exists between the profile chord 8 and an imaginary plane (not shown) that contains the rotor rotation axis 4 or is perpendicular to the rotor rotation axis 4. This angle changes in the radial direction from the inside to the outside, so that the rotor blade 2 is twisted. Overall, the chord angle changes by at least 90°, at least 120°, at least 150°, or - as shown here - at least 180°, so that the profile chord angle has a first value on the inside of the rotor blade 1 and a second value on an outside of the rotor blade 1 that differs by at least one of the stated values.

[0071] For this purpose, the rotor blade 2 is divided into several radial sections 10, of which only a few are identified here as examples. Between immediately adjacent radial sections 10, the profile chord angle changes by a profile chord angle difference, which is identical between all radial sections 10. For example, the profile chord angle changes across each of the radial sections 10 by this profile chord angle difference. It can be seen that the radial sections 10 become smaller in the radial direction from the inside to the outside. Their respective distance from the rotor blade axis 9 can be determined by the relationship where r n is the radial distance of one of the radial sections, n is an outer radius of the rotor blade 2 and N is a number of radial sections 10.

[0072] By changing the chord angle across the extent of the rotor blade 2, the rotor blade 2 is divided into a plurality of rotor blade regions 11 and 12, namely a rotor blade region 11 located on the inside in the radial direction and a rotor blade region 12 located on the outside in the radial direction, wherein each of the rotor blade regions comprises one or more of the radial sections 10. The chord angle has a first value on the inside of the rotor blade 2 and a second value on the outside of the rotor blade 2, located radially outwards. The first rotor blade region 11 extends from the inside of the rotor blade 2 to a point on the rotor blade 2 at which the chord angle has a value that corresponds to the mean of the first value and the second value. The chord angle preferably changes its sign at this point.

[0073] The second rotor blade region 12 extends from this point radially outward to the outer side of the rotor blade 2. In each of the rotor blade regions 11 and 12, the profile chord angle changes by the same profile chord angle difference. In other words, the profile chord angle changes just as much across the first rotor blade region 11 as across the second rotor blade region 12. However, since the radial sections 10 become smaller toward the outside in the radial direction, the first rotor blade region 11 has a greater extension in the radial direction than the second rotor blade region 12.

[0074] Figure 2 shows a schematic representation of a region of the rotor 1, wherein the rotor blade 2 is shown in a second embodiment. The second embodiment essentially corresponds to the first embodiment, so reference is made to the corresponding embodiments, and only the differences are discussed below. These are that the inner side of the rotor blade 2 runs at a distance from the rotor blade axis 9 intersecting the rotor rotation axis 4. In this case, the distances between the radial sections 10 for the rotor blade 2 can be determined using the relationship where n=1, . . . , N The value ro is the inner radius of rotor blade 2.

[0075] Figure 3 shows a schematic representation of a fluid energy machine 13, which has a rotor arrangement 14, which in turn has the rotor 1. The rotor arrangement 14 is designed here with a single rotor 1, which has at least two rotor blades 2, which are arranged diametrically opposite one another. In addition to the rotor 1, the rotor arrangement 14 has a flow guide element 15, which is designed as a hollow cylinder and extends as far as the rotor blades 2. It is arranged such that it overlaps the first rotor blade region 11 of the rotor blades 2, whereas the second rotor blade region 12 of further rotor blades 2 lies outside the flow guide element 15 in the radial direction with respect to the rotor rotation axis 4.

[0076] The flow guide element 15 accommodates a first flow region 16 and delimits a second flow region 17 together with a machine housing 18 of the fluid energy machine 13. The first flow region 16 is arranged in radial overlap with the first rotor blade region 11, and the second flow region 17 is arranged in radial overlap with the second rotor blade region 12. The rotor 1 or the rotor arrangement 14 is arranged in a rotationally symmetrical flow volume 19, which is at least partially delimited by the machine housing 18. In particular, the machine housing 18 has an end wall 20 and a casing wall 21, wherein the end wall 20 delimits the flow volume 19 in the axial direction in the direction facing away from the rotor 1, and the casing wall 21 delimits the flow volume 19 in the radial direction.

[0077] Overall, the flow volume 19 is delimited in the axial direction by an imaginary first end face plane 22 and an imaginary second end face plane 23, wherein the flow volume 19 is open in the first end face plane 22, namely towards an external environment 24 of the fluid energy machine 13. In the second end face plane 23, the flow volume 19 is continuously closed by the end wall 20. The two end face planes 22 and 23 run parallel to one another and are perpendicular to a rotation axis of the flow volume 19 (not shown here). The flow volume 19, or the machine housing 18 delimiting it, has roughly the shape of an Erlenmeyer flask.For this purpose, the casing wall 21 runs parallel to the rotation axis and the rotor rotation axis 4 in the first end face plane 22, whereas in the second end face plane 23, or at least away from the first end face plane 22, it is angled relative to the latter, i.e., it forms an angle with the first end face plane or a straight line parallel to it that is greater than 0° and less than 180°. As a result, the flow volume 19 tapers toward the first end face plane 22.

[0078] During operation of the fluid energy machine 13, the end wall 20 is heated at least temporarily and at least in part by a heating device 25, shown here as a component of the end wall 20. Thermal energy is supplied to a working fluid present in the flow volume 19 via the end wall 20. Upon rotation of the rotor 1, the indicated working fluid flows 26, 27, and 28 are created, with the working fluid flow 26 being the inlet flow, the working fluid flow 27 being the Beltrami flow, and the working fluid flow 28 being the outlet flow. The inlet flow 26 flows through the second flow region 17 from the external environment 24 into the flow volume 19 and flows through it in the direction of the second end face plane 23 or the end wall 20.

[0079] The working fluid flow 28, on the other hand, is present as an outlet flow, which flows from the direction of the second end face plane 23 or the end wall 20 in the direction of the first end face plane 22. The outlet flow 28 exits the flow volume 19 through the first flow region 16 via the rotor 1. In doing so, it flows through the flow guide element 15. Between the inlet flow 26 and the outlet flow 28, the working fluid flow 27, present as a Beltrami flow, occurs. Roughly speaking, this is to be understood as an annular vortex in which the working fluid rotates, on the one hand, about a circular vortex axis of rotation, but, on the other hand—as in the flows 26 and 28—additionally about a vortex axis of rotation which corresponds to the axis of rotation and / or the rotor axis of rotation 4. The working fluid flow is indicated here only in longitudinal section; the rotation in the circumferential direction is not shown.

[0080] Figure 4 shows a schematic representation of the fluid energy machine 13 in a second embodiment. This basically corresponds to the first embodiment, so reference is made to the corresponding embodiments, and only the differences will be discussed below. These consist in the fact that the rotor arrangement 14 has a stator 29 in addition to the rotor 1. The stator 29 is identical to the rotor 1 with regard to its stator blades (not shown in detail here) and is merely offset from the rotor 1 in the axial direction with respect to the rotor rotation axis 4. However, the stator blades preferably have a different angle of attack than the rotor blades 2.The flow guide element 15 is designed in several parts, wherein a first part of the flow guide element 15 is rigidly connected to the rotor 1 and a second part of the flow guide element 15 is rigidly connected to the stator 29, so that the flow guide element 15 in turn delimits the first flow region 16 and the second flow region 17.

[0081] The two parts of the flow guide element 15 preferably adjoin one another directly in the axial direction. Any gap that may exist between them preferably serves only to compensate for temperature-induced dimensional changes. Particularly preferably, the second part is rigidly connected to the machine housing 18, so that the stator 29 is also rigidly connected to it. The rotor 1 is, for example, connected to the machine housing 18 exclusively via the stator 29, in particular, is rotatably mounted on the machine housing 18 via the stator 29. Furthermore, the rotor hub 3 projects comparatively far into the flow volume 19. For example, it penetrates the flow volume 19 in the axial direction by at least 10%, at least 15%, or at least 20%. This has the advantage of efficient flow guidance.

[0082] During operation of the fluid energy machine 13, the working fluid is initially set into rotation about the rotor rotation axis 4 by means of the rotor 1 upon or after its flow into the fluid energy machine 13 (inlet flow 26). This rotation is maintained throughout the entire cycle implemented by the fluid energy machine 13, i.e., until the working fluid flows out of the fluid energy machine 13. Due to centrifugal force, the working fluid is forced radially outward and flows there axially toward the end wall 20. During this time and / or only in the region of the end wall 20, thermal energy is supplied to the working fluid. Supported by its resulting decrease in density, the working fluid escapes radially inward, from where it flows counter to the inflowing working fluid toward the rotor 1, where it releases the energy gained and exits the fluid energy machine 13 (outlet flow 28).An exchange of thermal energy takes place between the inlet flow 26 and the outlet flow 28, which flow in opposite directions to each other, with no or only minimal fluid exchange. This enables recuperation, which contributes to high efficiency in the conversion of thermal energy into mechanical energy. According to previous observations, an efficiency of at least 70%, at least 80%, or at least 90% of an equivalent Camot cycle can be achieved using the fluid energy machine 13.

[0083] Figure 5 shows a Ts diagram depicting several cycles 30, 31, and 32. The Camot cycle 30 shown on the left in the diagram runs between four states, indicated by points 33, 34, 35, and 36. Points 33 and 34 are connected by an isentropy 37, points 34 and 35 by an isotherm 38, points 35 and 36 by an isentropy 39, and points 36 and 33 by an isotherm 40. A hatched area 41 indicates heat generated during the process. Points 33 and 36 are at a temperature Ti, and points 34 and 35 are at a temperature T4. Points 33 and 34 occur at an entropy s'i and points 35 and 36 at an entropy s'2.

[0084] The cyclic process 31 shown in the center describes the process implemented by the fluid energy machine 13, at least according to current knowledge. Its states are indicated by points 42, 43, 44, and 45. Points 42 and 43 are connected by an isochore 46, points 43 and 44 by an isotherm 47, points 44 and 45 by an isochore 48, and points 45 and 42 by an isotherm 49. A hatched area 50 indicates the heat generated. Points 42 and 45 are at temperature Ti, and points 43 and 44 are at temperature T4. Entropies s"i, s"2, s"s, and s"4 are available for points 42, 43, 44, and 45. Alternatively, the cyclic process 31 can also be operated up to a higher temperature T5. For these, the points 43 ' and 44 ' are indicated, which take the place of the points 43 and 44 and are connected via the isotherm 47' replacing the isotherm 47.It is obvious that isochores 46 and 48 slope extremely steeply above temperature T4 up to temperature T5. For example, temperature T4 is at most 100 °C, at most 50 °C, or at most 20 °C. Preferably, a temperature of at least 1,000 °C, at least 1,500 °C, at least 1,750 °C, or at least 2,000 °C is used as temperature T4 or temperature T5.

[0085] Given the current state of knowledge, it is not yet definitively known whether the fluid energy machine 13 actually implements the cycle 31 as described, or whether, instead of the isotherms, there may be an isobar 49' running between point 42 and a point 45' replacing point 45. Point 45' lies at a temperature that is (slightly) higher than temperature Ti. In the latter case, the heat generated is slightly greater than indicated by region 50, as can be directly seen from the illustration. In any case, the cycle 31 is a good approximation of the Camot cycle, which is practically impossible to implement and is used only for theoretical considerations. In any case, the cycle 31 is reversible, or at least approximately reversible, analogous to the Carnot cycle 30.In addition, it can be implemented using the fluid energy machine 13, which is preferably in the form of a turbomachine, so that only minor losses occur.

[0086] The fluid energy machine 13 converts thermal energy into mechanical energy or vice versa. In the former case, mechanical energy is first supplied to the working fluid and then thermal energy. The supplied energy is subsequently extracted from the working fluid, namely in the form of mechanical energy. This is then converted, for example, into electrical energy. Unlike piston engines, the fluid energy machine 13 is intended and designed to supply the mechanical energy to the working fluid not through compression, but through acceleration of the working fluid (acceleration). This is achieved using the rotor 1 according to Bernoulli's law. Similarly, when the kinetic energy is extracted, there is little or no relaxation of the working fluid. Instead, it is slowed down by the rotor (deceleration).

[0087] Finally, the Joule cycle 32 shown on the right runs between four states, indicated by points 51, 52, 53 and 54. Points 51 and 52 are connected by an isentropy 55, points 52 and 53 by an isobar 56, points 53 and 54 by an isentropy 57 and points 54 and 51 by an isobar 58. A hatched area 59 again indicates the heat generated. Point 51 is at temperature T1, point 52 is at temperature T2, point 53 is at temperature T4 and point 54 is at temperature T3. For points 51 and 52 the entropy is s" ' 1, and for points 54 and 54 the entropy is s'"2. The Joule cycle 32 cannot be implemented reversibly. Finally, it should be noted that the Carnot cycle 30 and the Joule cycle 32 are merely for comparison purposes. Only cycle 31 is implemented using the fluid energy machine 13.With the described procedure and, in particular, with the described design of the fluid energy machine 13, the properties of the Beltrami flow 27 are utilized to convert the heat supplied to the working fluid into mechanical energy particularly efficiently, i.e., with high efficiency. The rotor 1 is coupled, for example, to a generator, so that the mechanical energy is converted into electrical energy. This also achieves a very high overall efficiency.

[0088] LIST OF REFERENCE SYMBOLS

[0089] 1 rotor

[0090] 2 rotor blades

[0091] 3 Rotor hub

[0092] 4 Rotor rotation axis

[0093] 5 Rotor blade profile

[0094] 6 profile nose

[0095] 7 Profile trailing edge

[0096] 8 profile tendon

[0097] 9 Rotor blade axis

[0098] 10 Radial section

[0099] 11 1. Rotor blade area

[0100] 12 2. Rotor blade area

[0101] 13 Fluid energy machine

[0102] 14 Rotor arrangement

[0103] 15 Flow guide element

[0104] 16 1. Flow area

[0105] 17 2. Flow area

[0106] 18 machine housing

[0107] 19 Flow volume

[0108] 20 front wall

[0109] 21 Coat wall

[0110] 22 1. Front side level

[0111] 23 2nd front side level

[0112] 24 Outdoor environment

[0113] 25 Heating device

[0114] 26 Current

[0115] 27 Current

[0116] 28 Current

[0117] 29 Stator

[0118] 30 Cyclic process

[0119] 31 Cyclic process

[0120] 32 Circular process 33 Point

[0121] 34 points

[0122] 35 Points

[0123] 36 Point 37 Isentrope

[0124] 38 Isotherm

[0125] 39 Isentrope

[0126] 40 Isotherm

[0127] 41 Gebiet 42 Punkt

[0128] 43 Points

[0129] 44 Points

[0130] 45 Points

[0131] 46 Isochore 47 Isotherm

[0132] 48 Isochore

[0133] 49 Isotherm

[0134] 50 Gebiet

[0135] 51 point 52 point

[0136] 53 points

[0137] 54 points

[0138] 55 Isentrope

[0139] 56 Isobar 57 Isentrope

[0140] 58 Isobar

[0141] 59 Gebiet

Claims

CLAIMS 1. Rotor (1) for a fluid energy machine (13), with a rotor hub (3) rotatable about a rotor axis of rotation (4) and a plurality of rotor blades (2) extending from the rotor hub (3) and outwards in the radial direction with respect to the rotor axis of rotation (4), characterized in that each of the rotor blades (2) has an aerodynamic rotor blade profile (5) and a profile chord angle between a profile chord (8) of the rotor blade profile (5) and an imaginary plane receiving the rotor axis of rotation (4) or perpendicular to it changes in the radial direction from the inside to the outside in such a way that the rotor blades (2), viewed in the radial direction with respect to the rotor axis of rotation (4), have rotor blade regions (11, 12) which are provided and designed for opposite axial flow directions.

2. Rotor according to claim 1, characterized in that an angular gradient of the profile chord angle increases over the distance to the rotor rotation axis (4) with increasing distance to the rotor rotation axis (4), and / or that each of the rotor blades (2) is continuously divided in the radial direction into a plurality of radial sections (10), the extent of which in the radial direction continuously decreases from the inside to the outside, wherein a profile chord angle difference between adjacent radial sections (10) is consistently identical.

3. Rotor according to one of the preceding claims, characterized in that the angular gradient is selected such that the rotor blade regions (11, 12) of the respective rotor blade (2) have identical rotor blade surface areas, and / or that an imaginary first circular ring, which in the radial direction inside limits the respective rotor blade inwards and in the radial direction outwards runs through a reversal point lying on the profile chord (8) of the rotor blade (2), at which point the rotor blade regions adjoin one another, and an imaginary second circular ring, which in the radial direction inside runs through the reversal point and in the radial direction outside limits the respective rotor blade (2) outwards, have identical surface areas.

4. Rotor according to one of the preceding claims, characterized in that between radial distances of the rotor blades (2) according to the relationship identical profile chord angle differences are present, where rn the radial distance of one of the radial sections (10), ro is an inner radius of the rotor blades (2), n is an outer radius of the rotor blades (2) and N is a number of radial sections (10).

5. Rotor according to one of the preceding claims, characterized in that a hollow cylindrical flow guide element (15) is arranged on the rotor blades (2), which surrounds one of the rotor blade regions (11, 12) as seen in the radial direction.

6. Rotor arrangement (14) for a fluid energy machine (13), with a rotor (1), in particular a rotor (1) according to one or more of the preceding claims, wherein the rotor (1) has a rotor hub (3) rotatable about a rotor rotation axis (4) and a plurality of rotor blades (2) extending from the rotor hub (3) and outward in the radial direction with respect to the rotor rotation axis (4), characterized in that each of the rotor blades (2) has an aerodynamic rotor blade profile (5) and a profile chord angle between a profile chord (8) of the rotor blade profile (5) and an imaginary plane receiving the rotor rotation axis (4) or perpendicular to it changes in the radial direction from the inside to the outside in such a way that the rotor blades (2), viewed in the radial direction with respect to the rotor rotation axis (4), have rotor blade regions (11, 12) which are provided and designed for opposite axial flow directions.

7. Rotor arrangement according to claim 6, characterized in that in addition to the rotor (1) there is a stator (29) which has a stator hub and a plurality of stator blades extending from the stator hub and extending outwards in the radial direction with respect to the rotor axis of rotation (4), wherein each of the stator blades has an aerodynamic stator blade profile and a profile chord angle between a profile chord of the stator blade profile and an imaginary plane receiving the rotor axis of rotation or perpendicular to it changes in the radial direction from the inside to the outside.

8. Fluid energy machine (13) with a rotor (1), in particular a rotor (1) according to one or more of claims 1 to 5, and / or with a rotor arrangement (14) having a rotor (1), in particular a rotor arrangement (14) according to claim 6 or 7, wherein the rotor (1) has a rotor hub (3) rotatable about a rotor rotation axis (4) and a plurality of rotor blades (2) extending from the rotor hub (3) and extending outwards in the radial direction with respect to the rotor rotation axis (4), characterized in that each of the rotor blades (2) has an aerodynamic rotor blade profile (5) and a profile chord angle between a Profile chord (8) of the rotor blade profile (5) and an imaginary plane receiving the rotor rotation axis (4) or perpendicular to it changes in the radial direction from the inside to the outside in such a way that the rotor blades (2) have rotor blade regions (11, 12) viewed in the radial direction with respect to the rotor rotation axis (4) which are provided and designed for opposite axial flow directions.

9. Fluid energy machine according to claim 8, characterized in that the rotor (1) is arranged in a rotationally symmetrical flow volume (19) which is delimited by a machine housing (18) of the fluid energy machine (13), wherein the rotor rotation axis (4) lies on a rotation axis of the flow volume (19).

10. Fluid energy machine according to one of the preceding claims, characterized in that the flow volume (19) is present in the axial direction with respect to the axis of rotation between an imaginary first end face plane (22) and an imaginary second end face plane (23), wherein the first end face plane (22) and the second end face plane (23) are arranged parallel to one another and are each perpendicular to the axis of rotation.

11. Fluid energy machine according to one of the preceding claims, characterized in that the flow volume (19) is open via the first end face plane (22) in the direction of an external environment (24) of the fluid energy machine (13), and / or that the flow volume (19) is delimited by an end wall (20) of the machine housing (18) lying continuously in the second end face plane (23).

12. Fluid energy machine according to one of the preceding claims, characterized in that the machine housing (18) has a jacket wall (21) which delimits the flow volume (19) in the radial direction and which, on the one hand, encloses the first end face plane (22) and, on the other hand, the second end face plane (23) or projects up to them.

13. Fluid energy machine according to one of the preceding claims, characterized in that the flow volume (19) tapers in the axial direction.

14. Fluid energy machine according to one of the preceding claims, characterized in that the end wall (20) and / or the casing wall (21) can be subjected to thermal energy at least in regions by means of a heating device (25).

15. A method for operating a fluid energy machine (13), in particular a fluid energy machine (13) according to one or more of claims 8 to 14, wherein a rotor (1) of the fluid energy machine (13) has a rotor hub (3) rotatable about a rotor rotation axis (4) and a plurality of rotor blades (2) extending from the rotor hub (3) and outwardly in the radial direction with respect to the rotor rotation axis (4), characterized in that each of the rotor blades (2) has an aerodynamic rotor blade profile (5) and a profile chord angle between a profile chord (8) of the rotor blade profile (5) and an imaginary plane receiving the rotor rotation axis (4) or perpendicular to it changes in the radial direction from the inside to the outside in such a way thatthat during a rotational movement of the rotor (1) in a flow volume (19) of the fluid energy machine (13) across the rotor (1), a first working fluid flow in a first axial flow direction and a second working fluid flow in a second axial flow direction are established.

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