WO2011069615A1

WO2011069615A1 - Turbine blade for a water turbine with bi-directional flow

Info

Publication number: WO2011069615A1
Application number: PCT/EP2010/007307
Authority: WO
Inventors: Raphael Arlitt; Frank Biskup
Original assignee: Voith Patent Gmbh
Priority date: 2009-12-09
Filing date: 2010-12-02
Publication date: 2011-06-16
Also published as: DE102009057449B3; KR20120103624A; EP2510224B1; WO2011069615A4; EP2510224A1; CA2783997A1; US20120301294A1

Abstract

The invention relates to a turbine blade for a water turbine, comprising, at least over part of its length, a curved profiled element having a median line created point-symmetrically in relation to a point of symmetry on the chord of the profiled element, half-way down, in such a way as to form an S-shaped curve. The median line splits the profiled element into a first side and a second side. The invention is characterised in that the turbine blade comprises an overflow device between the first side and the second side of the profiled element.

Description

Turbine blade for a bidirectionally inflatable water turbine

The invention relates to a bidirectionally flowable turbine blade, for a

Hydro turbine, which is preferably used in a submerged power generation plant for the production of energy from a bidirectional flow of water.

For energy from a directional flow, such as a tidal current, by means of a freestanding, propeller-shaped turbine usually a tracking mechanism is used, which rotates a nacelle with the attached turbine into the flow. Lie in

Essentially, two oppositely directed main flow directions, such as at low tide and high tide in a tidal current, such may

Direction tracking can be realized by a folding or rotating device, which pivots the nacelle from a first to a second position. The disadvantage, however, is that for such a tracking mechanism massive rotary or hinged hinge systems must be used. In addition, in the event that the water turbine drives an electric generator, one

Provide device that prevents twisting of the output from the electric generator power cable.

To circumvent this problem, instead of a total tracking of the water turbine by means of a pitch adjustment, the rotation of the

Turbine blades realized by 180 ° on the hub, a device for

bidirectional flow are created. However, such a design is also associated with disadvantages, since for a propeller-shaped turbine with turbine blades directed radially outward, the holding structures of the nacelle typically lie at least for one inflow direction, so that there is a flow-restricting flow-restricting factor. In addition, a pitch adjustment mechanism is structurally expensive and disadvantageous for submerged power plants for extracting energy from a sea current in view of the need for maintenance.

BESTÄTtGUNGSKOPC As a further alternative to the creation of a bi-directionally approachable

Water turbine was proposed in WO 2006/125959 A1, as a profile contour for the turbine blades of a rotor-shaped water turbine a double

symmetrical profile to choose. In addition, a first symmetry axis represents the chord line. In addition, the profile is symmetrical to a center line defined as perpendicular to the chord at 50% of the chord length. The result is a lenticular profile, which ensures identical profile contours for a bidirectional flow. The disadvantage, however, is that due to the double-selected symmetry for the profile contour compared to a one-sided flowed, curved profile results in a lower efficiency. Furthermore, there are disadvantages due to downstream flow separations and increased flow resistance of the turbine blades.

Furthermore, point-symmetrical profiles with a curvature are known from document US 2007/0231148 A1. These are characterized by a symmetry point, which lies at half the profile depth on the chord, so that the point-symmetrical skeleton line makes an S-beat. The thickness distribution of the profile is chosen symmetrically to the center line. The S-shaped profile improves the performance coefficients and reduces the thrust coefficients.

The invention has for its object to make a turbine blade so that a bidirectional flow is possible. This turbine blade should be suitable for a propeller turbine of a diving

Be used to power plant, the turbine blade by a high efficiency and low longitudinal distortion for a

Should distinguish flow from both directions.

The invention is based on the known point-symmetrical profiles with an S-shaped skeleton line and a thickness distribution symmetrical to the center line of the profile. This profile is now further developed in such a way that an overflow device is provided from a first profile side to a second profile side. Due to the point-symmetrical profile shape there is the risk of flow separation on the downstream profile parts for S-impact profiles. Furthermore, strong torsional forces act on a turbine blade with such a profile. By overflowing from the first to the second profile side in the middle part and / or the downstream side of the profile, it is possible to reduce the tendency to flow separation and to simplify the Turbinenblattaussteifung against twisting due to the reduced torsional forces constructive. Furthermore, the turbine blade profile substantially to the

Fluidic conditions are adapted without having to follow competing structural mechanical requirements in the design of the turbine blade. In particular, elongate, slim profiles can be used, which lead to a high glide ratio. Furthermore, the fastenings of the turbine blade to the hub of the rotating unit must absorb reduced torques and can be simplified according to design and manufacturing technology.

According to a first embodiment, the overflow device comprises a plurality of overflow channels whose orientation to the bidirectional

Direction of flow is adjusted. For a further embodiment, which is applicable as an alternative or in addition to the overflow channels, the overflow device is formed by a split blade profile. In this case, there is at least one partial section in the middle region of the overall profile, for which the thickness distribution along the S-shaped skeleton line assumes the value zero.

For further development, the overflow device can be adaptive

Include wall elements that change depending on the direction of flow from a first to a second position and thus deviations from

Point symmetry of the profile effect. As a result, a targeted overflow to the rear, downstream region of the profile can be effected without a serious loss of efficiency occurs. The adaptive ones can do this

Wall elements are either actively adjusted by an associated actuator or they are designed as passive, elastic components whose contour changes with the flow.

For a further embodiment alternative of the invention, the

Overflow device overflow channels, which depend on the

Flow direction can be closed. Thus overflow channels can also be arranged outside the central region of the profile. The closing of the overflow channels can be effected passively or actively. For a passive embodiment, there is preferably a coupling of channel closure elements in the overflow channels with elastic profile elements, which are arranged along the flow-swept outside of the profile and are deformed by the flow forces. If a hydraulic or pneumatic working medium is received in the elastic profile elements, pressure forces for the actuation of the channel closure elements can be generated and at the same time an adaptive profile can be created.

The invention will be explained in more detail below on the basis of exemplary embodiments in connection with the figure representations, in which the following details are shown:

Figure 1a shows a profile section along the line A-A of Figure 1b for a

Inventive, point-symmetrical profile with an overflow from the first to the second profile side.

Figure 1 b shows a partial section of a turbine blade in plan view for the

Profile of Figure 1a with an applied in the central region of the profile overflow device with limited extent in the longitudinal direction of the turbine blade.

Figure 2a shows a profile section an alternative embodiment of

Invention with a plurality of overflow channels. FIG. 2b shows a plan view of a partial section of a turbine blade with a profile according to FIG. 2a.

FIG. 3 a shows a further profile section according to the invention with off-center, passively controllable overflow channels.

FIG. 3b shows a plan view of a partial section of a turbine blade with a profile according to FIG. 3a.

characters

4a and 4b show a further embodiment of the invention with a paired and point-symmetrical arrangement of elastic elements for influencing the profile in the overflow device from the first profile side to the second profile side.

characters

5a and 5b show active, adaptive wall elements in FIG

Overflow device in different positions for the first and the second direction of flow.

Figure 6 shows a prior art

point-symmetrical, curved profile to form a bidirectionally inflatable turbine blade.

To explain the terminology used below, a profile section corresponding to the state of the art and shown in FIG. 6 is considered first. Shown is a profile that is point-symmetrical to the symmetry point 27 is formed. Here, the symmetry point 27 is arranged at half the profile depth on the chord 20 and is therefore congruent to the intersection of the chord 20 with the center line 23, the latter being perpendicular to

Chord 20 is defined extending. For the illustrated S-shaped profile, the symmetrical point 27 point-symmetrical applied skeleton line 32 has a curvature w on. Furthermore, the above-mentioned symmetry condition leads to a symmetrical profile distribution with respect to the center line 23. Other

Embodiments for bidirectionally flowable, point-symmetrical profiles are conceivable (not shown), for example a skeleton line with at least one

Sectionally linear course in the middle profile section and

point symmetrical to each other shaped profile lugs 30, 31st

For the following explanation, it is conceptually assumed that the profile is divided by the skeleton line 32, which leads to a first profile side 21 and a second profile side 22. Furthermore, through the center line 23 a

Dividing the profile into a first profile half 24 and a second profile half 25 be given. In this case, the first profile half 24 extends from the first profile nose 30 to the center line 23 and the second profile half 25 in accordance with the

Center line 23 to the second profile nose 31st

Furthermore, for the sketched first inflow direction 28, starting from an effective flow, at least in the first profile half 24 on the first profile side 21, a suction effect and on the second profile side 22, a pressure effect. However, due to the S-stroke in the region of the downstream edge of the second profile half 25 on the first profile side 21, i. in the vicinity of the second profile nose 31, for the contemplated first inflow direction 28, a pressure belly is created which reduces the efficiency of the profile and further increases the torsional forces acting on the S-impact profile. For the second

Direction of flow 29 is the pressure and suction-side assignment corresponding mirrored at the point of symmetry 27. For the profile according to the invention shown as profile section in FIG. 1a, there is an overflow device 1 which is arranged in a point-symmetrical manner with respect to the symmetry point 27. For the exemplary embodiment illustrated, the overflow device 1 breaks through the profile in a central region 26, which is defined as that profile part, which ranges from 3/8 to 5/8 of the tread depth.

The overflow device 1 can, according to a first embodiment, extend longitudinally over the entire turbine blade 13, so that one over the entire

Longitudinal split profile is present. According to an alternative embodiment shown here, the overflow device 1 extends over a limited section of the longitudinal extension of the turbine blade 13

Embodiment is outlined in Figure 1 b, which is a plan view of the turbine blade 13 with the profile according to the invention shown in Figure 1a. In this case, a plurality of overflow devices 1 can be provided along the turbine blade 13, which are separated from each other by the structure stability improving transverse webs. This is not shown in detail in the figures. The effect of an inventive overflow device 1 for a point-symmetrical, bidirectionally flown S-impact profile is the following: The main buoyancy effect is for the first direction of current flow 28 through the front profile part, i. the first profile half 24 causes. Accordingly, for an opposite energization direction, i. in the direction of the second Anstromungsrichtung 29, the essential effect of the profile through the second profile half 25, which is then upstream. By the invention

Overflow device 1 is an overflow from the pressure side to

downstream region of the opposite profile side causes. Accordingly, for the first energization direction 28, a part of the profile flow around the first profile half 24 on the second profile side 22 over the

Overflow device 1 led to the second profile half 25 of the first profile side 21 and there reduces the risk of flow separation on the one hand and the torsional moment on the turbine blade 13 to the other.

From the profile section shown in Figure 2a along the section line B-B of Figure 2b shows a further embodiment of the invention can be seen.

Shown is a variety of overflow 2, 2.1, 2.2, 2.n to Forming the overflow opening 1. According to Figure 2b, the individual overflow 2, 2.1, 2.2, 2.n over the longitudinal extent of the turbine blade 13 are arranged parallel and offset from each other. Embodiments are also conceivable for which adjacent channels are oriented in an angular position or provided with branches. In addition, the cross sections of the

Overflow 2, 2.1, 2.2, 2.n be changed. Preferred is an alternative embodiment with slit-shaped overflow channels 2, 2.1, 2.2, 2.n. Such embodiments are not shown in detail in the figures. In Figures 3a and 3b, a further embodiment of the invention is shown. The profile section C-C in FIG. 3 a shows a first off-center flow channel 5 and a second off-center flow channel 6, which are arranged outside of the middle region 26 at least over parts of their extent. To the

Closure of the first off-center transfer port 5 are the first

Channel closure elements 7.1 and 7.2 provided. For the first sketched

These flow direction 28 are closed so that no overflow from the first profile side 21 to the second profile side 22 occurs through the first off-center overflow channel 5 and thus in the region of the first profile half 24. The situation is different for the second off-center overflow channel 6. Here, for the first inflow direction 28 shown, the associated second

Channel closure elements 10.1, 10.2 open, so that in the second profile half the desired overflow from the first profile side 21 to the second

Profile page 22 results. For the illustrated embodiment, a passive control of the first and second channel closure elements 7.1, 7.2, 10.1, 10.2 is effected. In this case, a first elastic profiled element 8, which comprises a pressure-absorbing working medium, is compressed for the first inflow direction 28 shown, wherein a connection between the first channel closure elements 7.1, 7.2 and the first elastic profiled element 8 is provided via the first coupling channel 9. Accordingly, a compression of the first elastic profile element 8 due to its pressure side position for the first direction of flow 28 to Another is the case for the second elastic profile element 11, which is point symmetrical relative to the symmetrical point 27 to the first elastic profile element 8 and thus for the first Flow direction 28 is suction side. Accordingly, the second channel closure elements 10.1, 10.2 are retracted via the second coupling channel 12 due to the fluidic coupling and released against the second off-center flow channel 6. For the second flow direction 29, not shown, is the first elastic

Profile element 8 on the suction side and the second elastic profile element 11 on the pressure side, whereby the first channel closure elements 7.1, 7.2 release the first eccentric overflow channel 5 and the second channel closure elements 10.1, 10.2 close the second off-center overflow channel 6. FIG. 3b shows a plan view of a turbine blade 13 with a profile according to FIG. 3a. It can be seen that the first elastic profile elements 8, 8.1, 8.n, which are each assigned to a first off-center overflow channel 5, 5.1, 5.n, have a limited extent in turbine blade longitudinal direction, in order to transport the working medium under centrifugal force avoid.

Due to the deformation caused by the flow forces of the elastic

Profile elements 8, 8.1, 8.n, 11 was an adaptive adaptation of the profile as a function of the direction of flow. This is understood to mean a refraction of the point symmetry caused by deformation of the profile, wherein the direction of deformation reverses when the direction of flow changes.

FIGS. 4a and 4b show a further embodiment alternative of the invention, for which a first adaptive wall element 3 and a second adaptive wall element 4 are provided for a further embodiment of a overflow device 1 corresponding to FIG. 1a. The first is adaptive

Wandungselement 3 arranged in that part of the overflow device 1, the the first profile half 24 is assigned to the first profile page 21. For this point-symmetrical to the symmetry point 27 is the second adaptive

Wall element 4, which is assigned to the second profile half 25 on the second profile side 22.

FIGS. 4a and 4b show the passive adjustment of the contour of the first and second adaptive wall elements 3, 4, which are elastic

Components are formed or have a flowable or compressible filling. Due to the deformation of the adaptive wall elements 3, 4 results in a flow to the profile of a symmetry breaking the

Contour of the overflow device 1, which causes an improvement of the flow guidance in the overflow device 1. The basic contour of the profile, i. the state without flow, however, is unchanged point symmetrical to the

Symmetry point 27.

FIGS. 5a and 5b show a design alternative with a first active, adaptive wall element 16 and a second active, adaptive wall element 17. The first is active, adaptive

Wall element 16 of the first profile half 24 of the first profile side 21 assigned and the second active, adaptive wall element 17 is part of the second profile half 25 on the second profile page 22. For execution

Rotary movement about a first pivot point 14, which is located near the outer edge of the overflow device 1, the first adaptive wall elements 16 is associated with a first actuator 18, which may for example comprise a hydraulic cylinder. For small actuating movements can be used as actuators 18 and piezo elements. Accordingly, the second adaptive

Wall elements 17, a second actuator 19 and a second pivot point 15 assigned. For the first inflow direction 28 shown in FIG. 5a, the second active, adaptive wall element 17 is extended and corrects

Overall contour of the second profile half 25. The first active, adaptive Wall element 16 remains in the retracted state. When changing the flow to the second direction of flow 29, the first active, adaptive wall element 16 is extended accordingly and corrects the

associated profile area. On the suction side, the second active, adaptive wall element 17 will remain in its original state. This situation is shown in FIG. 5b.

The embodiment according to FIGS. 5 a and 5 b uses actively tracked adaptive elements in the region of the overflow device 1 according to the invention, whereby an increased outlay on equipment for the control is necessary in comparison to a purely passive system. Compared to the previously used, active devices for adaptation to a flow direction change by means of a full rotation of the turbine blade 13 by a mounted at the interface to the hub pitch adjustment, there is the advantage that a plurality of separately switchable, adaptive elements

Anströmungsrichtungs adjustment of the profile contour can be effected for the flow forces can be distributed to several individual components. In addition, the failure of individual adaptive elements does not lead to a complete

Functional loss of the turbine blade 13.

Further embodiments of the invention are conceivable. Thus, for example, within the profile, a channel structure with an inlet opening in the region of a profile nose can be created, which displaces flow components along the skeleton line within the profile up to an outlet opening in the region of a profile section lying downstream and on the suction side. Further design variants result from the subsequent protection claims. Bezugszeicheniiste

1 overflow device

2, 2.1, 2.2, 2.m Overflow channel

3 first adaptive wall element

4 second adaptive wall element

5, 5.1, .... 5.n first eccentric transfer port

6, 6.1, 6.n second eccentric overflow 7.1, 7.2 first channel closure element

8, 8.1, 8.n first elastic profiled element

9 first coupling channel

10.1, 10.2 second channel closure element

11 second elastic profile element

12 second coupling channel

13 turbine blade

14 first fulcrum

15 second pivot point

16 first active, adaptive wall element 17 second active, adaptive wall element 18 first actuator

19 second actor

20 chord

21 first profile page

22 second profile page

23 center line

24 first profile half

25 second profile half

26 middle area

27 point of symmetry

28 first direction of flow

29 second direction of flow

30 first profile nose second profile nose skeleton line

bulge

Claims

Patent claims

1. Turbine blade for a water turbine, which has a curved profile with a skeleton line (32) at least in a partial area of its longitudinal extent, which is point-symmetrical to a point of symmetry (27) lying on the profile chord (20) at half the profile depth and has an S- Impact executes, with the skeleton line (32) transforming the profile into a first

Profile page (21) and a second profile page (22);

characterized in that

the turbine blade comprises an overflow device (1) which establishes a fluidic connection between the first profile side (21) and the second profile side (22).

2. Turbine blade according to claim 1, characterized in that the

Overflow device (1) comprises at least one overflow channel (2, 2.1, 2.n).

3. Turbine blade according to claim 1, characterized in that the profile is designed as a split profile, for which the

Overflow device (1) the profile thickness distribution assumes the value zero at least in a partial area.

4. Turbine blade according to one of the preceding claims, characterized

characterized in that the overflow device (1) is formed in a central region (26) of the profile, which ranges from three-eighths to five-eighths of the profile depth.

5. Turbine blade according to one of claims 1 - 3, characterized in that the turbine blade (13) has a first eccentric overflow channel (5, 5.1, .., 5.n), which has a fluidic connection between the first profile side (21) and the second profile side (22) in the first profile half (24), and a second eccentric overflow channel (6, 6.1, 6.n), which establishes a fluidic connection between the first profile side (21) and the second profile side ( 22) in the second profile half (24).

6. Turbine blade according to claim 5, characterized in that the first eccentric overflow channel (5, 5.1, ..., 5.n) has a first

Channel closure element (7.1, 7.2) and the second off-center

A second channel closure element (10.1, 10.2) is assigned to the overflow channel (6, 6.1, 6.n), which selectively closes the assigned eccentric overflow channels depending on the direction of flow.

7. Turbine blade according to claim 6, characterized in that the

selective closure of the first off-center overflow channel (5, 5.1,

5.n) and the second eccentric overflow channel (6, 6.1, 6.n) is passively effected.

8. Turbine blade according to claim 7, characterized in that for passive control of the first channel closure element (7, 7.1, 7.2) a first elastic profile element (8, 8.1, 8.n) on the second profile side (22) and for passive control of the second Channel closure element (10.1, 10.2) a second elastic profile element (11) is used on the first profile side (21).

9. Turbine blade according to one of the preceding claims, thereby

characterized in that the overflow device (1) comprises a first adaptive wall element (3) and a second adaptive wall element (4), which are arranged symmetrically to the point of symmetry (27).

10. Turbine blade according to claim 9, characterized in that the first adaptive wall element (3) and the second adaptive wall element (4) act as passive elements whose contour is influenced by the flow forces.

11. Turbine blade according to claim 8, characterized in that the first adaptive wall element (3) is a first active, adaptive

Wall element (16) includes and the second adaptive

Wall element (4) comprises a second active, adaptive wall element (17).

12. Method of operating a turbine blade for a bidirectional

flowable water turbine, which at least in a partial area of its longitudinal extent has a curved profile with a skeleton line (32), which is point-symmetrical to a point of symmetry (27) located at half the profile depth on the profile chord (20) and executes an S-shape, whereby the skeleton line (32) divides the profile into a first profile side (21) and a second profile side (22); and

the turbine blade has a first eccentric overflow channel (5, 5.1, .., 5.n), which establishes a fluidic connection between the first profile side (21) and the second profile side (22) in the first profile half (24), and a second eccentric one Overflow channel (6, 6.1, 6.n), which provides a fluidic connection between the first profile side (21) and the second

Profile side (22) in the second profile half (24), comprises; and wherein the first eccentric overflow channel (5, 5.1, 5.n) has a first channel closure element (7.1, 7.2) and the second eccentric

Overflow channel (6, 6.1, 6.n) comprise a second channel closure element (10.1, 10.2); and

whereby the respective associated channel closure element in

Depending on the direction of flow, the upstream eccentric transfer channel is closed and the downstream eccentric transfer channel is opened.