U.S. patent application number 13/513976 was filed with the patent office on 2012-11-29 for turbine blade for a water turbine with bi-directional flow.
This patent application is currently assigned to VOITH PATENT GMBH. Invention is credited to Raphael Arlitt, Frank Biskup.
Application Number | 20120301294 13/513976 |
Document ID | / |
Family ID | 43799081 |
Filed Date | 2012-11-29 |
United States Patent
Application |
20120301294 |
Kind Code |
A1 |
Arlitt; Raphael ; et
al. |
November 29, 2012 |
TURBINE BLADE FOR A WATER TURBINE WITH BI-DIRECTIONAL FLOW
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.
Inventors: |
Arlitt; Raphael; (Ulm,
DE) ; Biskup; Frank; (Schwabisch Gmund, DE) |
Assignee: |
VOITH PATENT GMBH
Heidenheim
DE
|
Family ID: |
43799081 |
Appl. No.: |
13/513976 |
Filed: |
December 2, 2010 |
PCT Filed: |
December 2, 2010 |
PCT NO: |
PCT/EP2010/007307 |
371 Date: |
August 13, 2012 |
Current U.S.
Class: |
416/1 ;
416/223R |
Current CPC
Class: |
F03B 3/121 20130101;
F05B 2240/301 20130101; Y02E 10/30 20130101; Y02E 10/20 20130101;
F05B 2210/404 20130101; Y02E 10/223 20130101; Y02E 10/28 20130101;
Y02E 10/38 20130101; F05B 2250/713 20130101; F03B 3/126 20130101;
F05B 2250/72 20130101 |
Class at
Publication: |
416/1 ;
416/223.R |
International
Class: |
F01D 5/14 20060101
F01D005/14 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 9, 2009 |
DE |
10 2009 057 449.2 |
Claims
1. A turbine blade for a water turbine, having a cambered profile
with a median line (32) in at least a portion of its length, that
is designed to be symmetrical about a point in relation to a point
of symmetry (27) lying at the midpoint of the profile length on the
profile chord (20), and forming an S-curve, wherein the median line
(32) divides the profile into a first profile surface (21) and a
second profile surface (22), and wherein the profile comprises a
midline (23) that depicts aright angle to the profile chord (20)
having the symmetry point (27) as its starting point, and which
divides the profile into a first profile half (24) and a second
profile half (25), characterized in that the turbine blade
comprises an overflow device (1), which establishes a fluid
connection between the first profile surface (21) and the second
profile surface (22), wherein the overflow device (1) comprises a
first off-center overflow channel (5, 5.1, . . . , 5.n), which
establishes a fluid connection between the first profile surface
(21) and the second profile surface (22) in the first profile half
(24), and a second off-center overflow channel (6, 6.1, . . . ,
6.n), which establishes a fluid connection between the first
profile surface (21) and the second profile surface (22) in the
second profile half (25), and the first off-center overflow channel
(5, 5.1, . . . , 5.n) has a dedicated first channel closing
component (7.1, 7.2) and the second off-center overflow channel (6,
6.1, . . . , 6.n) has a dedicated second channel closing component
(10.1, 10.2), which are configured for the selective closing of the
respective off-center overflow channels, depending on the direction
of flow.
2. The turbine blade according to claim 1, characterized in that
the selective closing of the first off-center overflow channel (5,
5.1, . . . , 5.n) and the second overflow channel (6, 6.1, . . . ,
6.n) are caused by passive means.
3. The turbine blade according to claim 2, characterized in that a
first elastic profile component (8, 8.1, . . . , 8.n) on the second
profile surface (22) is used for the passive control of the first
channel closing component (7, 7.1, 7.2), and a second elastic
profile component (11) on the first profile surface (21) is used
for the passive control of the second channel closing component
(10.1, 10.2).
4. The turbine blade according to claim 1, characterized in that
the overflow device (1) comprises a first adaptive wall component
(3) and a second adaptive wall component (4), which are disposed
symmetrically about a point of symmetry (27).
5. The turbine blade according to claim 4, characterized in that
the first adaptive wall component (3) and the second adaptive wall
component (4) function as passive components, the contours of which
are affected by the flow forces.
6. The turbine blade according to claim 4, characterized in that
the first adaptive wall component (3) comprises a first active,
adaptive wall component (16), and the second wall component (4)
comprises a second active, adaptive wall component (17).
7. A method for operating a turbine blade for a water turbine with
bi-directional flow, having a cambered profile with a median line
(32) in at least a portion of its length, that is designed to be
symmetrical about a point in relation to a point of symmetry (27)
lying at the midpoint of the profile length on the profile chord
(20), and forming an S-curve, wherein the median line (32) divides
the profile into a first profile surface (21) and a second profile
surface (22), and the turbine blade comprises a first off-center
overflow channel (5, 5.1, . . . , 5.n), which establishes a fluid
connection between the first profile surface (21) and the second
profile surface (22) in the first profile half (24), and a second
off-center overflow channel (6, 6.1, . . . , 6.n), which
establishes a fluid connection between the first profile surface
(21) and the second profile surface (22) in the second profile half
(25), and wherein the first off-center overflow channel (5, 5.1, .
. . , 5.n) comprises first channel closing component (7.1, 7.2) and
the second off-center overflow channel (6, 6.1, . . . , 6.n)
comprises second channel closing component (10.1, 10.2), and
wherein, by means of the respectively dedicated channel closing
component, depending on the direction of flow, the upstream
off-center overflow channel is closed, and the downstream
off-center overflow channel is opened.
8. The turbine blade according to claim 2, characterized in that
the overflow device comprises a first adaptive wall component and a
second adaptive wall component, which are disposed symmetrically
about a point of symmetry.
9. The turbine blade according to claim 3, characterized in that
the overflow device comprises a first adaptive wall component and a
second adaptive wall component, which are disposed symmetrically
about a point of symmetry.
Description
[0001] The invention concerns a bi-directional flow turbine blade
for a water turbine, which preferably is used in an immersing power
generation facility for the production of energy from a
bi-directional flow of water.
[0002] For energy production from a flow having a variable
direction, such as a tidal current, for example, by means of a free
standing, propeller shaped designed turbine, normally a tracking
mechanism is used, which turns a gondola having the turbines
attached thereto towards the current. If two substantially opposing
main flow directions are present, such as is the case with the ebb
and flow of a tidal current, then a directional tracking of this
type can be obtained with a shuttered or rotating device, which
rotates the gondola from a first position to a second position. The
disadvantage, however, is that for a tracking mechanism of this
type, massive rotational or shutter blinder systems must be used.
Furthermore, if it is the case that the water turbine drives an
electric generator, a device must be provided that prevents a
twisting of the power cable emerging from the electric
generator.
[0003] In order to circumvent this problem, an overall tracking of
the water turbine by means of a pitch adjustment device, which
causes a rotation of the turbine blades through 180.degree. at the
hub, can be used instead to create a device for bi-directional
flow. However, a design of this type also has disadvantages,
because, with a propeller shaped turbine having turbine blades
extending radially outwards, typically lying on the upstream side
of the retaining structure of the gondola for at least one flow
direction, there is a flow impediment reducing the degree of
efficiency. Furthermore, a pitch adjustment mechanism is
structurally elaborate and is disadvantageous, with respect to the
necessity of maintenance, for immersing power production facilities
for obtaining energy from an ocean current.
[0004] As another alternative for creating a water turbine for a
bi-directional flow, it is proposed in WO 2006/125959 A1, that a
double symmetrical profile be selected as the profile contour for
the turbine blades of a rotary water turbine. For this, the chord
line represents a first axis of symmetry. In addition, the profile
is symmetrical along a midpoint line, which is defined as being
perpendicular to the profile chord at 50% of the length of the
chord. The result is a lens-shaped profile, which ensures identical
profile contours for a bi-directional flow. It is disadvantageous,
however, that due to the doubled symmetry selected for the profile
contour in comparison with a cambered profile that is subject to
flow from one side, there is a lower degree of efficiency.
Furthermore, there are disadvantages due to downstream flow
separations and an increased flow resistance of the turbine
blades.
[0005] Furthermore, from document US 2007/0231148 A1, profiles that
are symmetrical about a point, having a camber, are known. These
are characterized by a point of symmetry, which at the midpoint of
the profile length, lie on the profile chord, such that the
point-symmetry designed median line follows an S-curve. The
thickness distribution of the profile is selected such that it is
symmetric to the midline. In this manner, the S-curve shaped
profile improves the performance coefficients and limits the thrust
coefficients.
[0006] The invention assumes the objective of designing a turbine
blade such that a bi-directional flow can be accommodated. This
turbine blade should also be suitable for use in a propeller shaped
turbine of an immersing power production facility, wherein the
turbine blade per se should be characterized by a high degree of
efficiency and limited longitudinal torsion for a flow arriving
from both sides.
[0007] The invention builds on the known point-symmetrical profiles
having an S-curve shaped median line and a thickness distribution
that is symmetrical over the midline of the profile. This profile
is then further developed such that an overflow device from one
profile surface to the second profile surface is provided.
[0008] Due to the point-symmetrical profile shape, there is the
risk for S-curve profiles of a flow separation at the downstream
profile components. In addition, strong torsion forces act on a
turbine blade having a profile of this type. Through an overflow
from the first to the second profile surface in the middle portion
and/or the downstream surface region of the profile, there is the
possibility of reducing the tendency towards flow separation, and
due to the reduced torsion forces, of structurally simplifying the
reinforcing of the turbine blade against twisting.
[0009] In addition, the turbine blade profile can be substantially
adjusted to the technical properties of the flow, without the need
for following competing structural mechanical requirements in the
construction of the turbine blade. For this, elongated, slender
profiles may be used, which result in a high glide ratio. In
addition, the attachments of the turbine blade at the hub of the
rotating unit have to accommodate reduced torques and can be
correspondingly simplified structurally and in terms of the
production technology.
[0010] According to a first embodiment, the overflow device
comprises numerous overflow channels, whose orientation is adjusted
to the bi-directional flow direction. For another embodiment
variation, which can be used as an alternative or in addition to
the overflow channels, the overflow device is formed by a divided
blade profile. For this, there is at least one partial section in
the central region of the overall profile, at which point the
thickness distribution along the S-curve shaped median line assumes
the value of zero.
[0011] For a further development, the overflow device may comprise
adaptive wall components, which, depending on the direction of
flow, change from a first setting to a second setting, thus
creating deviations in the point-symmetry of the profile. By this
means, a targeted overflow to the back, downstream side region of
the profile can be effected, without resulting in a serious loss in
efficiency. In this case, the adaptive wall components can be
displaced by means of a dedicated actuator, either actively, or
said components can be designed as passive, elastic components,
whose contour changes with the flow.
[0012] In another design alternative of the invention, the overflow
device comprises overflow channels, which can be closed, depending
on the flow direction. By this means, overflow channels can also be
disposed outside of the central region of the profile. The closing
of the overflow channels can be effected either passively or
actively. For a passive execution, there is preferably a coupling
of channel closing components in the overflow channels having
elastic profile components, which are disposed along the exterior
of the profile that the current is flowing over, and become
deformed by means of the flow forces. If a hydraulic or pneumatic
working substance is accommodated in the elastic profile
components, then pressure for actuating the channel closing
components can be generated and at the same time, an adaptive
profile is created thereby.
[0013] In the following, the invention shall be explained more
precisely based on embodiment examples in connection with the
drawings, in which the following is depicted:
[0014] FIG. 1a shows a profile section, cut along the line A-A in
FIG. 1b, for a profile according to the invention, having a
symmetry about a point, with an overflow device from the first to
the second profile surface.
[0015] FIG. 1b shows a partial section of a turbine blade from
above, for the profile from FIG. 1a, having an overflow device
applied in the central region of the profile, with a limited
extension along the longitudinal axis of the turbine blade.
[0016] FIG. 2a shows as a profile section, an alternative
embodiment example of the invention having numerous overflow
channels.
[0017] FIG. 2b shows a top view of a partial section of a turbine
blade having a profile in accordance with FIG. 2a.
[0018] FIG. 3a shows another profile section according to the
invention, having off-center, passively controllable overflow
channels.
[0019] FIG. 3b shows a top view of a partial section of a turbine
blade having a profile in accordance with FIG. 3a.
[0020] FIGS. 4a and 4b show a further development of the invention
have a paired and point-symmetrical configuration of elastic
components for influencing the profile in the overflow device from
the first profile surface to the second profile surface.
[0021] FIGS. 5a and 5b show active, adaptive wall components in the
overflow device in different settings for the first and the second
flow directions.
[0022] FIG. 6 shows a point-symmetrical, cambered profile
corresponding to the prior art, for the creation of a
bi-directional flow turbine blade.
[0023] For the purpose of explaining the terminology used in the
following, first a profile section corresponding to the prior art,
depicted in FIG. 6, shall be examined. A profile is shown, designed
such that it is point-symmetrical in relation to the symmetry point
27. For this, the symmetry point 27 is disposed on the profile
chord 20 at the midpoint of the profile, and is, accordingly,
covering the intersection of the profile chord 20 at the midline
23, whereby the latter is defined as running perpendicular to the
profile chord 20.
[0024] For the S-curve shaped profile, the median line 32, applied
symmetrically in relation to the symmetry point 27, exhibits a
camber w. Furthermore, the aforementioned condition of symmetry
results in a symmetrically applied profile thickness distribution
with respect to the midline 23. Other embodiments for
bi-directional flow, point-symmetrical profiles are conceivable
(not shown), such as a median line having at least one linear
course in sections, in the central profile section and profile tips
30, 31 designed such that they are point-symmetrical to one
another.
[0025] For the following explanation, a conceptual division of the
profile through the median line 32 is assumed, resulting in a first
profile surface 21, and a second profile surface 22. In addition, a
division of the profile through the midline 23 into a first profile
half 24 and a second profile half 25, is to be assumed. For this,
the first profile half 24 extends from the first profile tip 30 to
the midline 23, and the second profile half 25, accordingly,
extends from the midline 23 to the second profile tip 31.
[0026] Furthermore, for the indicated first flow direction 28,
wherein an effective flow is assumed, there is a suction effect in
at least the first profile half 24 on the first profile surface 21,
and there is a pressure effect to the second profile surface 22.
However, due to the S-curve in the region of the downstream edge of
the second profile half 25 on the first profile surface 21, i.e. in
the vicinity of the second profile tip 31, a pressure node may
occur for the observed first flow direction 28, which reduces the
efficiency of the profile, and further increases the torsion acting
on the S-curve profile. For the second flow direction 29, the
pressure and suction surface configuration is reflected over the
symmetry point 27.
[0027] For the profile according to the invention, depicted as a
profile section in FIG. 1a, there is a point-symmetrically applied
overflow device 1, which is symmetrical in relation to the symmetry
point 27. In the embodiment example depicted, the overflow device 1
interrupts the profile at a central region 26, which is defined as
that part of the profile that extends from 3/8 to 5/8 of the
profile length.
[0028] The overflow device 1 can extend, according to a first
design, longitudinally over the entire turbine blade 13, such that
there is a divided profile over the entire length. According to an
alternative, presently depicted design, the overflow device 1
extends over a limited section of the length of the turbine blade
13. This design is illustrated in FIG. 1b, which depicts a top view
of the turbine blade 13 having the profile according to the
invention depicted in FIG. 1a. For this, numerous overflow devices
1 can be provided along the length of the turbine blade 13, which
are separated from one another by cross-bars, which improve the
structural stability. These are not shown in detail in the
figures.
[0029] The effect of an overflow device 1 provided according to the
invention for a point-symmetrical, bi-directional S-curve profile
subjected to flow is as follows: the substantial lift effect is
caused, for the first flow direction 28, by the front profile
section, i.e. the first profile half 24. Correspondingly, for a
flow direction in the opposite direction, i.e. in the direction of
the second flow direction 29, the substantial effect of the profile
is provided by the second profile half 25, which is then upstream.
By means of the overflow device 1 according to the invention, an
overflow from the pressure side to the downstream region of the
opposite profile surface is caused. Accordingly, a portion of the
profile current is guided along the first profile half 24 on the
second profile surface 22, via the overflow device 1, to the second
profile half 25 on the first profile surface 21 for the first flow
direction, thereby reducing the danger there of flow separations on
the one hand, and torque being applied to the turbine blade 13, on
the other hand.
[0030] Another design example of the invention is evident from the
profile section depicted in FIG. 2a, cut along the line B-B in FIG.
2b. A number of overflow channels 2, 2.1, 2.2, . . . , 2.n are
depicted for defining the overflow opening 1. According to FIG. 2b,
the individual overflow channels 2, 2.1, 2.2, . . . , 2.n are
disposed over the length of the turbine blade 13, parallel and
offset to one another. For this, designs are also conceivable for
the adjacent channels, oriented at angles to one another, or
provided with branches. In addition, the cross-sections of the
overflow channels 2, 2.1, 2.2, . . . , 2.n can be modified. An
embodiment alternative having slit shaped overflow channels 2, 2.1,
2.2, . . . , 2.n is preferred. Embodiments of this type are not
depicted in detail in the figures.
[0031] Another design of the invention is depicted in FIGS. 3a and
3b. The profile section C-C in FIG. 3a shows a first, off-center
flow channel 5 and a second off-center flow channel 6, which at
least for portions of their lengths are disposed outside of the
central region 26. The first channel closing components 7.1, 7.2
are provided for closing the first off-center overflow channel 5.
For the illustrated first flow direction 28, these are closed, such
that no overflow occurs through the first off-center overflow
channel 5, and thereby in the region of the first profile half 24,
from the first profile surface 21 to the second profile surface 22.
This is different in the case of the second, off-center overflow
channel 6. In this case, the second channel closing components
10.1, 10.2, designated for the illustrated first flow direction 28,
are open, such that in the second profile half, the desired
overflow from the first profile surface 21 to the second profile
surface 22 results.
[0032] For the depicted design, a passive control of the first and
second channel closing components, 7.1, 7.2, 10.1, 10.2 occurs. For
this, a first elastic profile component 8, comprising a pressure
accommodating working substance, is compressed for the illustrated
first flow direction 28, by means of which, a connection is
provided between the first channel closing components 7.1, 7.2 and
the first elastic profile component 8 via the first coupling
channel 9. Accordingly, a compression of the first elastic profile
component 8, due to its location on the pressure side for the flow
direction 28, results in an expanding of the bellows shaped channel
closing components 7.1, 7.2 applied thereto, and thereby to the
aforementioned flow interruption in the first off-center overflow
channel 5. This is different in the case of the second elastic
profile component 11, which lies point-symmetrically opposite the
first elastic profile component 8, in relation to the symmetry
point 27, and therefore is on the suction side for the first flow
direction 28. Accordingly, the second channel closing components
10.1, 10.2 are contracted due to the liquid coupling via the second
coupling channel 12, and not impeding the second off-center flow
channel 6. For the, not depicted, second flow direction 29, the
first elastic profile component 8 is on the suction side, and the
second elastic profile component 11 is on the pressure side, as a
result of which, the first channel closing components 7.1, 7.2 open
the first off-center overflow channel 5, and the second channel
closing components 10.1, 10.2 close the second off-center overflow
channel 6.
[0033] In FIG. 3b, a top view of a turbine blade 13 having a
profile according to FIG. 3a is shown. It is evident that the first
elastic profile components 8, 8.1, . . . 8.n, which, in each case,
are dedicated to a first off-center overflow channel 5, 5.1, . . .
, 5.n, have a limited extension in the longitudinal direction of
the turbine blade, in order to prevent a transporting of the
working substance through centrifugal force.
[0034] As a result of the deformation of the elastic profile
components 8, 8.1, . . . , 8.n, 11 caused by current forces, an
adaptive adjustment of the profile results, dependent on the
direction of flow. This is understood to be a breakdown of the
point-symmetry as a result of the deformation of the profile,
wherein the deformation direction is reversed with a change in the
direction of flow.
[0035] FIGS. 4a and 4b show another design alternative of the
invention, for which a first adaptive wall component 3 and a second
adaptive wall component 4 are provided for a further development of
an overflow device 1 corresponding to that in FIG. 1a. For this,
the first adaptive wall component 3 is disposed in that part of the
overflow device 1, that is dedicated to the first profile half 24
on the first profile surface 21. Respectively, the second adaptive
wall component 4, dedicated to the second profile half 25 on the
second profile surface 22, is located in a point-symmetrical manner
to this, reflected over the symmetry point 27.
[0036] The passive adjustment of the contour of the first and the
second adaptive wall components 3, 4 is shown in FIGS. 4a, 4b,
which are constructed as elastic components, or contain a filling
that can adapt to the current, or can be compressed. Due to the
deformation of the adaptive wall components 3, 4, a symmetry
breakdown of the contour of the overflow device 1 occurs when the
profile is subjected to a flow, which results in an improvement of
the flow guidance in the overflow device 1. The basic contour of
the profile, i.e. its state when not subjected to flow, is not
changed, however, in the point-symmetry in relation to the symmetry
point 27.
[0037] A design alternative having a first active, adaptive wall
component 16 and a second active, adaptive wall component 17 is
shown in FIGS. 5a and 5b. For this, the first active adaptive wall
component 16 is dedicated to the first profile half 24 of the first
profile surface 21, and the second active, adaptive wall component
17 is a part of the second profile half 25 on the second profile
surface 22. For the execution of a rotational movement about a
first center of rotation 14, which lies in the vicinity of the
outer edge of the overflow device 1, the first adaptive wall
component 16 has a dedicated first actuator 18, which may comprise
a hydraulic cylinder, for example. For small adjustments, piezo
components can also be used as actuators 18. Accordingly, the
second adaptive wall components 17 have a dedicated second actuator
and a second center of rotation 15.
[0038] For the first flow direction 28, depicted in FIG. 5a, the
second active, adaptive wall component 17 is extended, and corrects
the overall contour of the second profile half 25. The first
active, adaptive wall component 16 remains in the retracted state.
When the flow is changed to the second flow direction 29, then,
accordingly, the first active, adaptive wall component 16 is
extended and corrects the associated profile region. On the suction
side, the second active, adaptive wall component 17 remains in its
original state. This situation is depicted in FIG. 5b.
[0039] The embodiment according to FIGS. 5a and 5b uses active,
added, adaptive wall components in the region of the overflow
device 1 according to the invention, wherein an increased technical
expenditure is necessary for the control in contrast to a purely
passive system. Compared to the active devices for the adaptation
to a change in the direction of flow by means of a complete
rotation of the turbine blade 13 using a pitch adjustment device
applied at the intersection with the hub, that have been used until
now, there is the advantage that by means of numerous adaptive
components that can be activated separately, an adaptation of the
profile contour to the direction of flow can be caused, that can be
distributed to numerous individual components for the flow forces.
In addition, if individual adaptive components cease to function,
this does not result in a complete loss of function to the turbine
blade 13.
[0040] Other designs of the invention are conceivable. As such, a
channel structure having an intake opening in the region of a
profile tip can be applied within the profile, for example, which
displaces the flow parts along the median line within the profile
to an output opening in the region of a downstream and suction side
section of the profile. Other design variations can be derived from
the following Claims.
LIST OF REFERENCE SYMBOLS
[0041] 1 Overflow device [0042] 2, 2.1, 2.2, 2.m Overflow channel
[0043] 3 First adaptive wall component [0044] 4 Second adaptive
wall component [0045] 5, 5.1, . . . , 5.n First off-center overflow
channel [0046] 6, 6.1, . . . , 6.n Second off-center overflow
channel [0047] 7.1, 7.2 First channel closing component [0048] 8,
8.1, . . . , 8.n First elastic profile component [0049] 9 First
coupling channel [0050] 10.1, 10.2 Second channel closing component
[0051] 11 Second elastic profile component [0052] 12 Second
coupling channel [0053] 13 Turbine blade [0054] 14 First center of
rotation [0055] 15 Second center of rotation [0056] 16 First
active, adaptive wall component [0057] 17 Second active, adaptive
wall component [0058] 18 First actuator [0059] 19 Second actuator
[0060] 20 Profile chord [0061] 21 First profile surface [0062] 22
Second profile surface [0063] 23 Midline [0064] 24 First profile
half [0065] 25 Second profile half [0066] 26 Central region [0067]
27 Point of symmetry [0068] 28 First direction of flow [0069] 29
Second direction of flow [0070] 30 First profile tip [0071] 31
Second profile tip [0072] 32 Median line [0073] w camber
* * * * *