hydroelectric turbine

Abstract

The invention relates to a water turbine for converting the kinetic energy of flowing water into mechanical rotational energy. The water turbine has a rotor rotatably mounted in a flow-through housing (2), which has a helically wound, ribbon-shaped rotor blade (1). The water turbine is particularly suitable for power generation or for the direct drive of machinery when operating in shallow river sections or in the outflow area of ​​tailings basins.

Description

[0001] The invention relates to a water turbine with a rotor rotatably mounted in a flow-through housing for converting the kinetic energy of flowing water into mechanical rotational energy. The water turbine is particularly suitable for power generation or for the direct drive of machinery when operating in shallow river sections or in the outflow area of ​​tailings basins.

[0002] Among the well-known types of water turbines are water screws. These have a rotor as their central component, with a cylindrical rotor shaft to which one or more helical screw flights are attached. This rotor is located inside a tubular housing, with the rotor shaft rotatably mounted at both ends in corresponding bearing positions within the housing.

[0003] Archimedes' screw turbines are typically installed at an angle of 20° to 30° between an upstream and a downstream water level. The rotational energy is generated—in reverse to the energy difference between the upstream and downstream water levels—from the difference in energy between the upstream and downstream water levels: The water moves downwards in the chambers of the screw, and the force of gravity exerted on the screw's helix sets the rotor in motion. Thus, archimedes' screw turbines convert the potential energy of the water into kinetic rotational energy.

[0004] Such a water turbine screw is disclosed, among other things, in DE 41 39 134 A1. An alternative design of a water turbine screw, in which the screw helix is ​​not arranged on a central solid shaft, but inside a hollow shaft, is described in EP 2 369 168 A2.

[0005] Unlike water screws, water turbines – depending on their design – utilize not only the potential energy from the difference in height between the upstream and downstream water, but also the flow energy of the water. This allows water turbines to be used in flowing waters with little gradient, such as lowland rivers or tidal waters.

[0006] Water turbines of the type known as cross-flow, Francis, Kaplan, or propeller turbines have a rotor with multiple blades that, when water flows past them, set the rotor in motion. These blades are typically designed as rotor vanes with an upstream leading edge and a downstream trailing edge. During operation, the leading edge of the blade cuts into the flowing water; the water then flows along the contours of the blade profile and finally exits the blade at the trailing edge.

[0007] Besides the classic designs, i.e., the cross-flow, Francis, Kaplan, or propeller turbine, turbine-based hydroelectric machines are also known that utilize the flow energy of water vortices to generate power. Such vortex power plants are described, for example, in US 3,372,905 A or WO 2011 / 051421 A2.

[0008] The selection of a hydropower turbine design depends on the specific application, with flow rate, head, and part-load performance being among the most decisive selection factors. Location and operating conditions therefore largely determine whether a screw turbine, a specific water turbine design, or another type of hydropower turbine is suitable for a given application.

[0009] The object of the present invention is to provide an alternative water power machine in the form of a water turbine, by means of which the flow energy of water is converted into kinetic rotational energy. In particular, the water turbine is intended to make use of the natural flow of shallow river courses or the residual flow from outlet basins.

[0010] This problem is solved by a water power turbine with the characterizing features according to claim 1; advantageous further developments of the invention are listed in claims 2 to 9.

[0011] The hydroelectric turbine comprises a casing and at least one rotor rotatably mounted in the casing about an axis of rotation. Water can flow through the casing in a direction of flow along the axis of rotation, from an inlet opening of the casing to an outlet opening of the casing.

[0012] According to the invention, the rotor has at least one ribbon-shaped rotor blade that extends in the form of a helix wound around the axis of rotation. The ribbon-shaped rotor blade is connected at one helix end to a rotor shaft of the rotor, which is rotatably mounted in the housing, and is freely movable at its other helix end. The area between the two helix end regions is referred to as the working area. The rotor shaft is connected to the rotor blade only at one of the helix end regions, namely at the shaft-side helix end region (also called the shaft end). In the working area and at the freely movable helix end region (also called the free end), there is no connection between the rotor shaft and the rotor blade. The rotor shaft is preferably designed as a stub shaft supported at one end.

[0013] According to the invention, the rotor blade has an arcuately curved airfoil in the working area, wherein the rotor blade has an upstream leading edge and a downstream trailing edge at every position in the working area. That is, in any axial cross-sectional plane extending through the axis of rotation, the chord of the rotor blade airfoil (which connects the leading edge and the trailing edge in a straight line) and the flow direction form an angle of less than 90°, with the leading edge always pointing against the flow. Preferably, the rotor blade is oriented such that the concave side of the arcuately curved airfoil is exposed to the flow.

[0014] In the preferred design of the rotor, the concave side of the rotor blade profile faces the axis of rotation in the working area.

[0015] To operate the hydroelectric turbine, water (for example, diverted from a river) is introduced into the casing through the inlet opening; it then flows through the interior of the casing and finally exits through the outlet opening. As it flows through, the water sets the helically wound rotor blade in rotation, causing it to move in a vortex-like motion within the flowing water.

[0016] To generate electricity, the rotor can be connected to a generator via its rotor shaft.

[0017] A particular advantage of the hydropower turbine according to the invention is that fish, due to the vortex-like movement of the rotor blade, avoid the vicinity of the turbine – just as they would naturally avoid other water turbulence. This reduces the risk of fish entering the turbine and being injured. A protective grid can be fitted at the inlet opening as an additional safeguard. This grid also serves to protect the turbine itself, in particular to prevent objects carried in the water from entering the housing and jamming or damaging the rotor.

[0018] Advantageously, the helix of the ribbon-shaped rotor blade exhibits a radial widening in the working area, from the shaft-side helix end to the freely movable helix end; that is, the diameter of the helix increases from the shaft end to the free end. The widening helices capture a larger flow cross-section than straight helices.

[0019] In particular, according to this embodiment, the rotor blade can be designed such that the helix of the ribbon-shaped rotor blade rests radially outwards against a hull surface in the form of the lateral surface of a straight circular cone lying coaxially to the axis of rotation. The opening angle of this circular cone is preferably in the range of 40° to 70°.

[0020] The helix of the rotor blade has a pitch angle in the preferred range of 10° to 50°.

[0021] Advantageously, the helix of the rotor blade also has at least one fully circulating turn and / or a maximum of three fully circulating turns.

[0022] According to one design of the ribbon-shaped rotor blade, its stiffness decreases continuously or stepwise from the shaft-side helical end to the freely movable helical end. This change in stiffness can be achieved, for example, by altering the inner or outer rotor blade geometry and / or by modifying the rotor blade material. As the rotor blade rotates in flowing water, the pitch of the helix changes due to stretching or compression in the flow. The decrease in rotor blade stiffness from the shaft end to the free end ensures that the helix remains geometrically stable on the shaft side and can adapt to flow changes through deformation towards the free end.

[0023] The rotor blade can be designed in lightweight construction as a hollow profile with a load-bearing core support structure, among other things to adjust the stiffness as required.

[0024] The inner contour of the housing is preferably rotationally symmetrical about the axis of rotation. In the region of the axial position of the freely movable helical end of the rotor blade, a circumferentially extending, semi-open diverting channel towards the axis of rotation is incorporated into the housing wall according to one embodiment of this housing design. This diverting channel reduces vortex formation at the free end of the rotor blade.

[0025] Furthermore, the freely movable helical end of the rotor blade can be designed in a tail-fin shape. This free end, shaped like a fish's tail fin, also reduces vortices at the free end of the rotor blade. Advantageously, this design is combined with the diversion channel in the housing; the tail-fin shape of the free end directs water vortices into the diversion channel.

[0026] According to a further embodiment of the hydropower turbine, it comprises two rotors rotatably mounted in the casing about the same axis of rotation. The rotor blade of the first rotor is referred to as the first rotor blade, and the rotor blade of the second rotor as the second rotor blade. The second rotor is arranged axially in series behind the first rotor in the direction of flow, with the shaft-side helical end of the first rotor blade facing the inlet opening of the casing and the shaft-side helical end of the second rotor blade facing the outlet opening of the casing. Preferably, the helix of both rotor blades widens radially from the shaft-side helical end to the freely movable helical end. The advantage of the second rotor, arranged in series behind the first rotor, is that turbulence is reduced; in addition, rotational energy is generated from the residual flow.

[0027] To generate electrical energy, the rotor shaft can be connected to an electric generator, as previously explained. An alternative is to make at least part of the rotor blade from a permanent magnetic material, while simultaneously attaching one or more induction coils to the circumference of the housing. The electric current generated by induction during rotor movement can be tapped directly from the induction coils as electrical energy; with this design of the hydropower turbine, the connection of a separate electric generator for energy production is unnecessary.

[0028] The helix of the ribbon-shaped rotor blade can be configured as either left-handed or right-handed. When several rotors are arranged in series, the helices of the rotor blades are preferably either all left-handed or all right-handed.

[0029] The water turbine can, in principle, also be operated with other liquids. In the context of the present invention, water is therefore to be understood as a synonym for other liquid media.

[0030] The invention is explained in more detail below with reference to exemplary embodiments and the schematic drawings, wherein identical or similar features are designated with the same reference numerals. To illustrate this, the following are shown: Fig. 1: one of the hydroelectric turbines with two rotors in longitudinal section, Fig. 2: the rotor of one of the hydroelectric turbines in perspective view, and Fig. 3: The lightweight rotor blade in cross-section.

[0031] The hydroelectric turbine according to the Fig. 1 comprises two rotors arranged in series, rotating around the common axis of rotation 7. The casing 2 of this embodiment of the water turbine has a rotationally symmetrical, barrel-shaped form with the inlet opening 20 covered by the protective grille 23 and the open outlet opening 21.

[0032] The first rotor has the first ribbon-shaped rotor blade 1, 1.1, and the second rotor has the second ribbon-shaped rotor blade 1, 1.2. Both ribbon-shaped rotor blades 1, 1.1, 1.2 are wound helically with several turns around the axis of rotation 7. The first rotor is rotatably mounted at the shaft-side helical end 6 of the first rotor blade 1, 1.1 in the area of ​​the inlet opening 20 in the housing 2; the second rotor is rotatably mounted at the shaft-side helical end 6 of the second rotor blade 1, 1.2 in the area of ​​the outlet opening 21 in the housing 2.

[0033] During operation, water flows through the housing 2 in the flow direction 9, i.e., from the inlet opening 20 to the outlet opening 21. This sets the two rotors in motion, causing them to rotate around the axis of rotation 7 in the direction of rotation 8.

[0034] The free ends 5 of both rotor blades 1, 1.1, 1.2 are each shaped like the tail fin of a fish. During the rotation of the rotor blade 1, the free ends 5 guide the flow into the diverting channel 22 and thereby reduce vortex formation in the central area of ​​the housing 2.

[0035] The detailed representation of the rotor according to the Fig. Figure 2 shows the ribbon-shaped rotor blade 1, which is wound around the axis of rotation 7 in the form of a left-handed helix. The pitch angle of the helix is ​​30° ± 5°. At the shaft end 6, the rotor blade 1 is connected to the rotor shaft 3, which in turn is rotatably mounted in the bearing 4.

[0036] The arc-shaped curvature of the rotor blade profile is described in the Fig. 2 is illustrated by the thin, arc-shaped lines on the surface of the rotor blade 1; the leading edge 10 of the rotor blade 1 is always directed against the flow and the trailing edge 11 of the rotor blade 1 is always directed into the flow. The flow direction 9 is indicated by the arrow.

[0037] The helix of the ribbon-shaped rotor blade 1 widens radially from the shaft end 6 to the free end 8; it rests against a surface in the form of the lateral surface of a right circular cone, coaxial to the axis of rotation 7, with an opening angle α of 60° ± 5°. This cone is illustrated by the dotted lines.

[0038] The direction of rotation 8 of the in Fig. The rotor blade 1 shown in 2 runs clockwise when viewed in the direction of flow 9.

[0039] The rotor blade 1 according to the Fig. 3 is designed as a hollow profile. The concave and convex sides of the rotor blade walls 12 enclose the internal, load-bearing core support structure 13. The leading edge 10 and the trailing edge 11 are coated with a copper alloy to reduce corrosion and cavitation wear.

[0040] The cross-section through rotor blade 1 according to Fig. 3 corresponds to an axial longitudinal section of the rotor blade 1 in the Fig. 2. The flow direction at the leading edge 10 of the rotor blade 1 is illustrated by the arrow 9. Reference symbol list 1 rotor blade 1.1 first rotor blade 1.2 second rotor blade 2 cases 3 Rotor shaft 4 bearings 5. Freely movable helical end region of the rotor blade; free end 6. Helix end region of the rotor blade connected to the rotor shaft; shaft end 7. Rotation axis 8. Direction of rotation 9 Flow direction 10 Entrance edge 11 Exit edge 12 Rotor blade wall 13 Core support structure 20 Inlet opening 21. Outflow opening 22 Diversion channel 23 protective grilles α Opening angle

Claims

[1] Water turbine comprising a casing (2) and at least one rotor rotatably mounted in the casing (2) about an axis of rotation (7), wherein the casing (2) is capable of being permeated by water in a flow direction (9) along the axis of rotation (7) from an inlet opening (20) of the casing (2) to an outlet opening (21) of the casing (2), wherein the rotor has at least one ribbon-shaped rotor blade (1) which extends in the form of a helix wound about the axis of rotation (7), characterized by, that the ribbon-shaped rotor blade (1) is connected only at one helical end region (6) to a rotor shaft (3) of the rotor rotatably mounted in the housing (2) and is freely movable at its other helical end region (5), and wherein the ribbon-shaped rotor blade (1) has an arc-shaped rotor blade profile with an upstream leading edge (10) and a downstream trailing edge (11) in a working region located between the two helical end regions (5, 6), wherein the rotor blade (1) is not connected to the rotor shaft (3) in the working region and at the freely movable helical end region (5), wherein in the working region of the rotor blade (1) in any axially extending cross-sectional plane through the axis of rotation (7) the chord of the rotor blade profile connecting the leading edge (10) with the trailing edge (11) and the flow direction (9) enclose an angle of less than 90°,and wherein the stiffness of the ribbon-shaped rotor blade (1) decreases continuously or stepwise from the shaft-side helical end region (6) to the freely movable helical end region (5). [2] Hydroelectric turbine according to claim 1, characterized by , that the concave side of the rotor blade profile is facing the axis of rotation (7) in the working area. [3] Hydroelectric turbine according to claim 1 or 2, characterized by , that the helix of the ribbon-shaped rotor blade (1) widens radially in the working area from the shaft-side helix end region (6) towards the freely movable helix end region (5). [4] Hydroelectric turbine according to claim 3, characterized by , that the helix of the ribbon-shaped rotor blade (1) lies radially outwards against a cladding surface in the form of the lateral surface of a straight circular cone lying coaxial to the axis of rotation (7). [5] Hydroelectric turbine according to claim 4, characterized by, that the opening angle (α) of the circular cone defining the enclosing surface lies in the range of 40° to 70°. [6] Hydroelectric turbine according to any one of claims 1 to 5, characterized by , that the helix of the rotor blade (1) has a pitch angle in the range of 10° to 50°. [7] Hydroelectric turbine according to any one of claims 1 to 6, characterized by , that the helix of the rotor blade (1) has at least one complete turning and at most three complete turnings. [8] Hydroelectric turbine according to any one of claims 1 to 7, characterized by , that the freely movable helical end region (5) of the rotor blade (1) is shaped like a tail fin. [9] Hydroelectric turbine according to any one of claims 1 to 8, characterized by, that the inner contour of the housing (2) is rotationally symmetric to the axis of rotation (7), wherein a fully circumferential diverting channel (22) extending towards the axis of rotation (7) is provided in the housing wall in the area of ​​the axial position of the freely movable helical end region (5) of the rotor blade (1).

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